(1) What is the maximum resolution of the eye?
— The human eye’s range of vision is about 576 megapixels but only 7 megapixels are highly focused whilst the rest is blurred out.
(2) What is the smallest thing the eye can see?
— Experts believe the smallest objects an unaided naked eye can see are about as small as 0.1mm.
(3) What’s the farthest the eye can see?
— Depending on how many light particles or photons a distant object emits and gets detected by our eye, the farthest object visible to the naked eye is the Andromeda galaxy, located 2.6 million light years from Earth. This galaxy contains about 1 trillion stars that collectively emit a few 1000 photos per square centimetre of Earth every second on a dark night.
(4) How far can we move our eyes laterally?
— Your voluntary eye movements to track objects of interest like Smooth Pursuit, Vergence shifts and Saccades varies depending on your extraocular muscles. It’s known that the outer boundaries of our peripheral vision for a single are:
i. 60 degrees superior (upwards)
ii. 60 degrees nasal (towards the nose)
iii. 70-75 degrees inferior (downwards)
iv. 100-110 degrees temporal (away from the nose and towards the temple)
— The combined field of vision for both eyes is 130-135 degrees vertical and 200-220 degrees horizontal.
(5) What’s the fastest object the human eye can see?
When the human eyes see an object, it takes about 0.1 second for the brain to process that information. Your brain doesn’t think the object is in a position where the eye tells the brain it is. The object is shifted forward in the direction that it’s moving, so we are predicting where objects would be going. This means your brain perceives objects to be farther along in their trajectory than what a person actually sees. A fundamental problem arises because your brain doesn’t work in real-time. By the time that information from the eye is received and processed by the brain and then sent back to the eye, that information is already out of date by the time it gets to the visual cortex, about 0.2 seconds in the past.
There are 2 types of eye movements that are used to track moving objects:
a) Smooth Pursuit
= Slow eye movements that stabilise the projection of the moving target into the Fovea. The upper limit of velocity for these is about 80 - 100 degrees / second. After the target exceeds this velocity, your eye will switch to using ‘catch up saccades’.
b) Saccadic Movements
= A quick, simultaneous movement of both eyes between 2 or phases of fixation in the same direction. In other words, they are fast jumps from 1 eye position to another whereas in smooth pursuit movements, eyes move smoothly instead of in jumps. The upper limit of velocity of a saccade is about 900 degrees / second. This means the eye could be tracking an object at 78.525 m/s only for saccadic movements.
(6) How much force can our bodies resist?
A cubic inch of bone can bear a load of 8,626kg (19,000 lbs) or more which is roughly the weight of 5 pickup trucks ramming at you, making it about 4 times as strong as concrete. However whether or not human bone can withstand immense loads depends on how quickly that force is exerted. Theoretically your bones will shatter above 200 x 10^6 Pascals of compression, or roughly 50 x 10^3 Newtons of Force.
(7) How much electricity can our bodies resist?
The amount of electricity your body can take depends on the current and the length of time the current passes through your body. Under dry conditions, our bodies have a resistance as high as 100,000 Ohms. However, when skin is wet or scarred, the resistance will decrease to 1000 Ohms. If you increase the voltage of electricity your body has to take, this is decrease the resistance even further to about 500 Ohms. The amount of voltage your body can take depends on your body’s resistance using the formula V = IR. What is for certain if that current above 50mA is enough to cause painful shock, paralysis, severe muscle contractions and respiratory arrest. Current above 1 Amp will cause severe conditions like ventricular fibrillation, cardiac arrest, severe burns increasing the risk of death.
(8) How much pressure can our bodies resist?
The lowest atmospheric pressure the human body can withstand is around 6% sea level pressure, or 6.18 KiloPascals. Below that pressure then water and blood in your body will start to boil.
The record for the deepest dive is around 330m deep underwater which implies that our bodies can survive pressures up to about 33 atm. The limits are set by the ability to breathe the Helium Oxygen mixture to work at high pressures which eventually becomes “too thick” to breathe.
(9) What are the hottest and coldest temperatures our bodies can resist?
Human skin burns to varying degrees of severity depending on fat content in your skin, amount of muscles present in a particular body part and structural integrity of your skin. You will feel a burning pain when skin temperature rises to 43.8889°C (32°F). 1st degree burns develop at 47.7778°C (118°F). 2nd degree skin burns occur at 55°C (131°F). If skin temperature continue to rise, your pain receptors will overload, decompose and become numb at 60°C (140°F). Ultimately human tissue is destroyed on contact when skin temperature hits 72.2222°C (162°F).
Your normal body temperature hovers between 36.5 - 37°C (97.7 - 98.6°F) thanks to homeostatic mechanisms that control thermoregulation. As the temperature drops your circulatory system will direct blood away from skin and outer extremities such as fingers, toes and nose, and toward its core. This process is called vasoconstriction and it helps limit the amount of heat you lose to the environment. The next response will be intense shivering when your core temperature starts to drop below homeostatic settings. If your body is soaked, you will lose body heat about 25 times faster than when your body is dry. At 35°C (95°F), you will begin to experience “hypothermia”. At 32.7778°C (91°F), you will experience amnesia which involves a temporary loss of memory. At 27.7778°C (82°F), you will become unconscious. If your body temperature falls below 21.1111°C (70°F), you will have profound hypothermia and death can occur. The world record for the lowest body temperature at which an adult is known to survive is measured at 13.7222°C (56.7°F) after being submerged in cold, icy water.
Frostbite is a condition when your skin or tissues freezes after exposure to cold temperatures. If your skin experiences wind chills below -15°C, your skin will start to become damaged. The severity of frostbite is classified by 4 different stages (degrees). For more information about Frostbite, check the link below:
https://en.wikipedia.org/wiki/Frostbite
(10) How tall can we get?
The world record for the tallest person or man that have ever known to existed belongs to American Robert Wadlow. On the day he died (27 June 1940), aged 22, his height was measured to be 2.72 m (8ft 11.1 inch) tall. If you compare the height of today’s humans to those who lived 150 years ago, we are on average about 10 cm taller.
(11) How fast can we run on bare feet?
Olympic champion sprinter Usain Bolt ran at a top speed of 45.0616 kph (28 mph) in the 100-metre sprint. However, studies claim humans have potential to run as fast as 64.3738 kph (40 mph). The factors that contribute to our running speed are age, the short time duration to apply force to the ground from every step we take while sprinting, intense rhythmic core training and concentration of fast-twitch fibres in skeletal muscles of the legs. However this is not enough to outrun the cheetah, because its top speed of 112.654 kph (70 mph).
(12) How far can we walk on bare feet without stopping?
That depends on the surface we walk on such as rocky, grassy, wet, muddy, icy, soft, sandy, carpet, etc. and how steep the gradient is. It also depends on the climate, your fitness and health, and how hydrated and energetic you are. The average adult about walks about 3.22 - 4.83 km (2 - 3 miles) every day but they can walk about 4.83 - 6.44km (3 - 4) per hour at a comfortable pace. The world record for the longest distance in 24 hours (1 day) was set by Paul Porthomme in 1984, when he walked 140.693 miles (226.58 km), but it’s not known whether he did this without stopping or with a few breaks.
(13) What’s the maximum number of neurons our brain can contain?
The exact number of neurons the human brain can contain is not known yet. The average human brain contains about 86 billion neurons, despite a myth stating that the human brain has the capacity to store 100 billion neurons or more. Between these neurons there are over 1000 trillion connections which shows that memory and brain function is quite complex.
(14) What’s the maximum amount of data our brain can store?
Each neuron in your brain forms about 1000 connections to other neurons, amounting to more than a 1 trillion connections. If each neuron could only help store a single memory, running out of splice would be a problem. The theoretical memory capacity is about 2.5 Petabytes (2.5 x 10^12), which is enough to hold 3,000,000 hours of your favourite show continuously running on your TV for more than 300 years. However, it is quite difficult to calculate exactly what is the brain’s exact storage capacity for memories, and what process can be used to measure the size of a memory. Certain memories involve more details and thus take up more data space, whilst other memories are forgotten due to degradation of mature neurons, thus freeing up space for novel information.
(15) How many different emotions can we have?
— As early as the 4th century BC, philosopher Aristotle identified 14 irreducible emotions: Fear, Confidence, Anger, Friendship, Calm, Enmity, Shame, Shamelessness, Pity, Kindness, Envy, Indignation, Emulation, and Contempt.
— Robert Plutchik’s Wheel of Emotions identifies 8 basic emotions: Joy, Sadness, Trust, Disgust, Fear, Anger, Surprise, and Anticipation. These basic emotions mix and combine to form a variety of feelings. e.g. Anticipation and Joy combine to form Optimism.
— Eckman’s research reveals that the human face is capable of creating more than 7000 different facial expressions. Emotions, and how we experiences and express them, can be both abundantly apparent and remarkably subtle.
(16) What’s the maximum volume of blood our circulatory system can store?
The average adult (70kg) has about 4.5 - 5.5 L of blood in your circulation right now. It accounts for 8 - 10% of your body weight. Whether a human’s circulatory system can hold more blood depends on the elastic nature, diameter and amount of blood vessels you have. Every cubic metre of human blood contains about 5 million Red Blood Cells, or Erythrocytes; 5,000 to 10,000 White Blood Cells, or Leukocytes, and 200,000 to 300,000 Platelets or Thrombocytes. 45% of your blood is composed of a yellowish fluid called plasma. People living in high altitudes, where the air contains less Oxygen, have about 1.9 L more blood than people who live in low altitude regions.
(17) What’s the maximum magnitude of force can we exert?
Every muscle fibre can generate 0.3 x 10^-6 Newtons of Force. This translates to about 100 Newtons (roughly 10kg) for each square centimetre of cross-sectional area of any muscle. The current record for the hardest punch was landed by boxer Max Baer in 1931 in a fight with Ernie Schaff who unfortunately never recovered and eventually died 6 months later.
(18) How high can we jump?
That depends on the planetary surface you are standing on at the moment. Because each planet has a differential gravitational pull towards its core, the maximum height of our jump will vary. Back on Earth, American Charles Austin set a world record in the 1996 Olympics High Jump event by leaping 7 feet 10 inches, equivalent to 2.38759999… m. The highest jump by a woman is about 6 feet 8 inches, equivalent to 2.032 m. However these jumps occur when a person is running towards a target over a bar, meaning there are jumping with momentum. The highest vertical jump (from a standstill) ever goes to NBA basketball player DJ Stephens at 46 inches or 1.1684 m. How high you jump depends on how you train your muscles in your lower limbs and the amount of motor-neuron nerve endings that stimulate contraction of those muscles, whether it be fast-twitch or slow-twitch.
(19) How high can we climb up vertically?
The higher you climb above sea level, the level of oxygen in the atmosphere decreases. The highest known mountain, Mount Everest, in the Himalayas, Nepal is 8.848 km high. Oxygen levels at the summit are 30% of that at sea level and temperatures would be between -19 degrees (in summer) and -36 degrees Celsius (in winter) which is a certain death wish if you were teleported there immediately. You would suffer from hyperventilation, frostbite, severe vasodilation, hypothermia and hypoxia (lack of oxygen) and you would be dead within minutes. The theoretical “vertical limit” (the highest altitude humans can survived unassisted) is understood to be approximately 5.4864 km (18,000 feet). Any altitude above the vertical limit is “Death Zone” territory and you would require plenty of oxygen tanks, a team of experienced hikers, mountaineering equipment and plenty of food to keep your energy levels up.
(20) What’s the least pressure of oxygen we can survive under?
According the Occupational Safety and Health Administration, the optimal range of oxygen in the air for humans runs between 19.5 - 23.5%. When oxygen concentrations drop below 19.5% to about 16%, your cells will start to fail receiving the oxygen it needs to function correctly. Mental functions like decision-making become impaired and respiration intermittent at Oxygen concentrations that drop from 10 - 14%; at these levels, your body becomes exhausted. No human would survive with Oxygen levels at 6% or lower.
(21) How much can we eat before we feel full?
Known as the “satiety” hormone the chemical that makes you feel full is Leptin. The more you consume food, the less of the “Hunger” hormone Ghrelin is secreted into your stomach. More Leptin is secreted by Adipose (Fat) cells as components of food are absorbed into your bloodstream. and your Pancreas secretes Insulin to enable nutrients to access your cells. The cells that receive nutrients are chosen by chance and opportunity depending on the number of Insulin receptors being activated and deactivated. Leptin is delivered to the brain to signal us to suppress eating in response to the expansion of the stomach, our sensory responses and the brain’s responses to the food and drink consumed. After the first bite, it can take between 15 - 20 mins for the full range of satiety signals to reach the brain. Therefore it’s not the calories and the foods you eat that control when you feel full, it’s how quickly your body breaks down food and absorbs the nutrients into your bloodstream, and your voluntary decision whether to continue eating or not when feeling full or start eating when hungry. It’s inferred that emotional states and the social situation around an eating occasion you’re in may influence when you become sate.
(22) What’s the maximum amount of energy the human body has?
Using Einstein’s formula E = m*c^2, c = speed of light ~ 299,792,458 m/s. If the average adult human being is about 70kg, it is calculated that it would contain about 89.6 GigaJoules (89,602,639,569 J).
(23) What’s the maximum metabolic rate of the human body?
Your maximum metabolic rate is determined by the maximal rate that the cardiovascular system can deliver Oxygen to Mitochondria in muscle tissue. Factors that influence your metabolic rate include
— Body Size
— Amount of Lean Muscle Tissue you have
— Amount of Body Fat
— Crash dieting, Starving or Fasting
— Age
— Growth / Development
— Gender
— Genetic Disposition
— Hormonal and Nervous Controls
— Environmental Temperature
— Infection or Illness
— Amount of Physical Activity
— Drugs
— Dietary Deficiencies
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/metabolism#lp-h-1
(24) How much energy can we expend?
The average human being, at rest (Basal Metabolic Rate, BMR), produces around 100 Watts of power, which is about 2000 Kilocalories of food energy, which is your recommended daily intake. This means our bodies expend about 8.37 x 10^6 Joules every day in the form of infrared radiation.
(25) How much force is required to pull our limbs apart?
Depending on the body structure, the answer can vary. Also it depends on what kind of force is used (gradual or sudden) and in what direction it is applied. Each joint is stabilised by many strong musculoskeletal tendons and collagen ligaments and a lubricated meniscus. It’s estimated somewhere between 7000N and 30,000 N is required to pull out an arm.
(26) What’s the quickest talking rate?
According to the Guinness World Records, Steve Woodmore is the world’s fastest speaker at 637 words per minute. But to answer this question, it depends on the language you speak because some languages are spoken faster than others. For instance, Russian, Spanish, Polish, Vietnamese and Japanese have low information density which are spoken at more than 7.0 syllables per second compared to English and Chinese Mandarin which have high-density information that are spoken at less than 7.0 syllables per second.
(27) How loud can we legibly speak?
So far, the loudest human scream was detected at 129 dB (decibels) performed by Jill Drake. That’s louder than a fired-up jet engine. If your ears detect any sound louder than 140 dB, you could suffer severe hearing damage and possibly become permanently deaf. The volume of sound you make depends on your airflow (lung capacity), vocal cords within your Larynx and articulators such as your Tongue, Palate, Cheeks, Nasal Cavity and Lips.
(28) How many different languages can one person speak fluently?
Unfortunately, there is no Guinness World Record for a person who could speak the most number of languages fluently because there is disagreement on the definition of ‘fluency’. A person who can speak 6 to 7 different languages fluently is a hyperpolyglot or multilingual person. This is no confirmation on who righteously holds the record for the most number of fluently spoken languages. There are claims that German diplomat Emil Krebs (1867-1930) learned the phrase “kiss my ass” in 40 different languages. Another claimed polyglot was Sir John Bowring (1792-1872), the 4th Governor of Hong Kong, who allegedly spoke over 100 different languages. However there seems to be no proof to determine his gifted talent other than peers who knew him personally. It is known that the world’s greatest living polyglot is Alexander Arguelles who has learned and studied over 50 languages. The definition of fluent will always be subjective from competently holding a conversation about various topics to being able to speak confidently with little hesitation or mistakes. You can watch a scene from a Chilean TV chat show featuring Zlad Youssef Fazah who claims to fluently speak 40 different languages. See how it panned out for him.
https://www.youtube.com/watch?v=9-N_Xl9DyGs
(29) What’s the steepest incline or decline we can trek?
Whether we can conquer a steep incline or decline safely depends on many environmental conditions and the fitness and perseverance of the climber. For instance, is the ground slippery or icy, dry, rocky, sandy, grassy or mossy? This questions the amount of friction on the surface of the incline. The steepest incline in the world is the Johnstown Include Plane in Johnstown, Cambria County in Pennsylvania. It is situated in a valley at the confluence of the Stonycreek and the Little Conemaugh Rivers, to the borough of Westmont on Yoder Hill. This steep incline has a grade of 70.9%. We all know it’s physically impossible to walk upright on a 90 degree angle but with efficient training and the correct climbing gear, fitness and mental stamina people can walk up to 66 degrees.
(30) How long can we go without sleeping?
The longest period anyone has voluntarily stayed awake is 264 hours (about 11 days), a record set by 17 year old Randy Gardner for a high school science fair project in 1965. After the experience he was essentially a vegetable with his droopy eyes open. It’s possible that staying awake for 2 weeks or more straight may cause potential death according to experiments done with rats but no one has successfully attempted to go beyond the current world record.
(31) What are the maximum rotations of our joints? i.e. Wrist, fingers, Shoulders, Hips, Necks (Spine), Knees, Ankles
https://design.tutsplus.com/articles/human-anatomy-fundamentals-flexibility-and-joint-limitations--vector-25401
(1) Neck:
— Flexion = 70-90 degrees, Extension = 55 degrees, Lateral bending = 35 degrees (Neck is not bent), Rotation = 70 degrees
(2) Lower Back:
— Flexion = 75 degrees, Extension = 30 degrees, Lateral Bending = 35 degrees
(3) Shoulder:
— Abduction = 180 degrees, Adduction = 45 degrees, Horizontal Flexion = 130 degrees, Horizontal Extension = 45 degrees, Vertical Flexion = 180 degrees, Vertical Extension = 60 degrees
(4) Elbow:
— Extension = 180 degrees, Flexion = 150 degrees, Supination = 180 degrees, Pronation = 90 degrees
(5) Wrist:
— Extension = 70 degrees, Flexion = 80 - 90 degrees, Radial Deviation = 20 degrees, Ulnar Deviation = 30-50 degrees
(6) Fingers:
— Extension/Flexion ~ 90 degrees
(7) Hip:
— Flexion = 110 - 130 degrees, Extension = 30 degrees, Abduction = 20 - 30 degrees, Internal Rotation = 40 degrees, External Rotation = 45 degrees, Abduction (Toes Forward) = 45 - 50 degrees, Abduction (Toes Outward) = 170 degrees
(8) Knee:
— Flexion = 130 degrees, Extension = 15 degrees, Internal Rotation = 10 degrees
(9) Ankle:
— Flexion = 45 degrees, Extension = 20 degrees, Pronation = 30 degrees, Supination = 20 degrees
(32) How much can we talk in one breath?
That depends on how rapidly we speak and how aggressively we express our thoughts, which influences how long we might be able to talk between breaths. It also depends how much air in your lungs needs to be exhaled mostly comprising of Carbon Dioxide and Water Vapour. An average person speaks about 20 - 50 words every breath. In 2012, a Canadian man named Mike Smith recorded himself counting to 125 in 1 breath. This is equivalent to 288 words.
https://recordsetter.com/world-record/highest-number-counted-breath/17691
(33) What’s the frequency range of our hearing?
Humans can hear sounds at frequencies from about 20 Hz to 20,000 Hz, though we hear sounds best from 1000 Hz to 5000 Hz, where human speech is centred. However there are sound within this frequency range that we can’t hear.
(34) What’s the loudest thing we can hear before our eardrums rupture?
The loudest sound human ears perceive before ripping its eardrums is at 160 dB (decibels).
(35) What’s the softest thing we can hear?
The quietest sound humans can hear is just above 20μPa (MicroPascals) of pressure. Of course, this is for healthy young adults.
(36) How much we can write or type without stopping?
When a person writes continuously for a set period of time without regard to spelling, grammar, or topic, this technique is called “free writing”. Writers often utilise this technique to overcome apathy and self-criticism and collect initial thoughts and ideas on a particular topic. On average, people can write about 700 words per hour but the fastest writers can write more than 2000 words per hour.
(37) What are the ranges of accents, tones, pitches and timbre our voices can make?
Vocal range is the measure of the breadth of pitches that a human voice can phonate. It is mostly used in the context of singing that helps classify singing voices into groups called voice types. The following types range from lowest to highest pitch:
— Soprano = Highest Female Voice (C4 - C6)
— Mezzo-Soprano = Female Voice (A3 - A5)
— Contralto (Alto) = Lowest Female Voice (F3 - E5)
— Tenor = Highest Male Voice (B2 - A4)
— Baritone = Male Voice (G2 - F4)
— Bass = Lowest Male Voice (E2 - E4)
C4 = Middle C
Some men, in Falsetto voice or as a result of a due physiological conditions, can sing in the same range as women. These men don’t fall into the female categories, but instead called Countertenors within classical music.
(38) How flexible can we be?
Flexibility of limberness refers to the absolute range of movement in a joint or a series of joints, and length in muscles that cross the joints to induce a bending movement or motion. Refer to the limitations of the rotations of all anatomical joints. The most flexible person in the world is a Russian gymnast named Julia Günthel aka Zlata. Watch videos of her displaying her mesmerising talent:
http://www.smash.com/get-yoga-lesson-zlata-worlds-flexible-woman/
(39) What’s the heaviest thing we can carry?
The heaviest deadlift ever recorded was by British weightlifter Andy Bolton who lifted 457.5 kg from the floor to this thigh. The record for an overhead lead is 263.5 kg. However the heaviest weight ever lifted was a backlift by Paul Anderson is 2.844 tons on June 12, 1957, in Toccoa, Georgia. That’s equivalent to putting 2 Jeep Chericos on your back.
(40) How small can we get?
The shortest man in the world, named Chandra Bahadur Dangi, has a height of about 0.546 m. He is currently living age 77 and lived most of his life in a remote Nepal village. The world’s shortest woman ever recorded by Guinness, named Jyoti Amge, weighs about 5kg at age 18. There is a claim a woman who died in 1890 was the shortest person ever was 3 inches shorter than Jyoti. This shortage in height is called “dwarfism”, a genetic condition commonly caused by Growth Hormone Deficiency and Achondroplasia.
(41) How much radiation can we absorb?
Every day depending on our occupation and our whereabouts, our bodies are exposed between 0.05 to 40 μSv (Microsieverts). A nuclear meltdown with radiation of 1 Sv would cause negative health effects seen in Acute Radiation Syndrome (ARS). Exposure to radiation at 2 Sv would be fatal including several damage to vital organs and tissues. Without prompt and effective treatment, exposure to more than 4 Sv of radiation would cause instant death. Since the Chernobyl meltdown (50 Sv radiation), those who work in high radiation jobs like nuclear power plants and nuclear medicine haves a recommended limit of less than 0.05 Sv per calendar year.
(42) What’s the largest acceleration or deceleration our bodies can cope with?
g = 9.8 m/s^2; A typical person can handle about 5 g (49 m/s^2). This means you can pass out when riding a high-g rollercoaster before losing consciousness. Those who work in the aviation industry and the Air Force especially fighter pilots are exposed to incredible amounts of g-force. The record for peak experimental horizontal g-force tolerance belongs to John Stapp, in his series of rocket sled deceleration experiments culminating in a 1954 test in which he was clocked in just over a second from a land speed of Mach 0.9. He survived a peak force of 46.2 g, almost popping his eyeballs out, and more than 25 g for 1.1 seconds. Major John Bleeding, an Air Force volunteer, endured a staggering 83 g for 0.4 seconds during the sled’s nearly instantaneous halt. Fortunately he too survived and walked away none worse for wear. Experts estimate that in during Princess Diana’s fatal car accident, her chest experienced about 70g while her head experienced about 100g. That acceleration was enough to tear her Pulmonary Artery in her heart. Had she worn a seatbelt, she would have minimised that G-force to about 35 g.
The limit to “negative” or “downward” g, which drives blood up towards the head is within the -2 to -3g range (-20 to -29 m/s^2).
(43) What are the highest or lowest body temperature we can survive under?
For higher temperatures, the limits at which our bodies can withstand depends on the humidity and time of exposure to the elements. Short term exposure lasts for a few seconds to a few minutes. Long term exposure lasts for hours or even days.
— Dry Air: 120 degrees C (Short term), 70 degrees C (Long term)
— Tropical Air: 60 degrees C (Short term), 47 degrees C (Long term)
— Saturated Air: 48 degrees C (Short term), 35 degrees C (Long Term)
— Water: 46 degrees C (Short term), 41 degrees C (Long term)
Your cells start to die around 41 - 45 degrees C, but with proper training and sustained dehydration we can survive higher temperatures. A healthy person could make a day trip to Death Valley on a 55 degree C day, so long as you avoid dehydration, you have a chance of surviving.
For lower temperatures, when your body becomes too cold, your core body temperature drops below 35 degree C, called Hypothermia. This condition is then further subdivided into levels of seriousness if left untreated or unclothed.
— Mild: 32 - 35 degrees C = Shivering, Vasoconstriction, Liver Failure, Hypo-/
Hyperglycemia
— Moderate: 28 - 32 degrees C = Pronounced shivering, sufficient vasoconstriction, induced shock, cyanoiss in extremities and lips (i.e. turning blue), Muscle mis-coordination
— Severe: 20 - 28 degrees C = Your body starts to rapidly give up. Heart rate, Respiratory rate and Blood pressure fall to dangerous levels (HR of 30 bpm). Multiple organs fail and clinical death (where the heart stops beating and breathing ceases).
(44) Any chemicals we cannot let in our bodies?
Chemicals that are toxic or poisonous to the human body when in contact can kill you almost instantly. Chemicals that can kill you the fastest are:
— Cyanide = Either ingested as Sodium Cyanide (NaCN), or inhaled as Hydrogen Cyanide (HCN), is able to kill a healthy adult human within a minute. It works by preventing blood from carrying Oxygen to the cells in our body and blocking the uptake of any oxygen already in the body by those cells.
— Tetrodotoxin = A complex biochemical found in the blue-ringed octopus, the puffer fish and slugs which is used by those creatures in the act of self-defence. If injected into an adult human after a bite by the octopus or ingested a piece of incorrectly prepared puffer fish (fugu), it can within kill within a minute by blocking nerve responses thus paralysing the body, preventing breathing and stopping the heart. As little as 1 mg of this toxin is enough to kill you within minutes.
Other best known toxic chemicals that can kill you in small concentrations include:
— Botulinum toxins, Snake toxins, Arsenic, Polonium-210, Mercury
https://en.wikipedia.org/wiki/List_of_extremely_hazardous_substances
The best know toxic gases include:
— Hydrogen Monoxide, Chlorine Gas, Nitrogen Dioxide and Phosgene
https://en.wikipedia.org/wiki/List_of_highly_toxic_gases
Radioactive substances (or Isotopes) can also cause serious harm to your body in small amounts by emitting harmful ionising radiation as it degrades over time. They can also cause mutations to DNA killing cells via Apoptosis or cause cancer if these mutations are not repaired.
— Uranium, Cobalt-60, Plutonium, Iodine, Caesium.
https://en.wikipedia.org/wiki/List_of_radioactive_isotopes_by_half-life
(45) What’s the brightest thing we can see without going blind?
A phenomenon known as “flash blindness” causes visual impairment during and following exposure to a light flash of extremely high intensity, lasting a few seconds to a few minutes. Examples include a camera flash, searchlights, flash grenades and laser dazzlers / pointers . It’s not how bright the stimulus can cause brightness, it’s the contrast of light compared to which the eye is accustomed to. This is why at night the army uses red light in the bush to avoiding flash blindness because your pupil dilates to adapt to the darkness and flash blindness has a greater effect and lasts longer compared to in the daylight.
(46) How much can we spin before we go dizzy?
When you’re spinning, you are experiencing inertia because your body is accelerating towards the centre as you change your velocity. Inertia is when your body resists any change to its state of motion, unless a force is applied to it according to Newton’s First Law of Motion.
Our vestibular system in inner ear is the reason we perceive dizziness. This system is responsible for maintaining balance of our bodies sensing whether your body is upright, lying down or accelerating forwards or backwards or standing still. In the labyrinth structure of the inner ear, there are 3 Semicircular Canals arranged at right angles to one another, such that each of the canals individuals senses movement along the 3 axes. These canals are filled with a fluid called Endolymph, which sloshes around as our bodies move. This endolymph resists changes in motion, and due to inertia of rest, lags behind, which stimulates nerve cells. These nerve cells come in the form of small hairs (about 20,000 fibres), which transmit messages to the brain.
You may have seen ballerinas, figure skaters and ice skaters spin around and around and around many times without showing signs of dizziness. A trick dancers use is keeping their eyes fixed on 1 point, followed by whipping their heads around rapidly when their necks cannot turn anymore. While the rest of their body keeps spinning, their eyes trick their vestibular system into thinking that they are standing still.
Ice skaters, however, spin much faster than those of choreographers. They will instead stare at a fixed point at the end of each spin move, but they don’t whip their heads around continually, as they risk contracting neck injuries due to high rotational speeds. They instead keep their eyes relatively horizontal, so the view only spins around 1 axis, and gradually training oneself to overcome the dizziness over the course of extensive practice.
(47) How much sperm can a man produce over a lifetime?
Every day of abstinence, an average human male produces about 0.4mL of seminal plasma. According to a study, the average ejaculate is about 3.2 mL +/- 1.4 mL. Maximal semen volumes of 10 - 11mL have been recorded. As abstinence continues, seminal volume will be resorbed by the male reproductive tract. Evolution theory suggests the rate at which men produce sperm is infinite but no one really knows what the average man produces over his lifetime. That number could be in the millions if not in the billions.
(48) How many eggs can a woman produce over a lifetime?
Every woman is born with approximately 2 million eggs in their ovaries, but about 11,000 of them die every month prior to puberty. As a teenager, a woman has only 300,000 to 400,000 remaining eggs, and from that point on, approximately 1000 eggs are destined to die each month. This phenomenon happens independently of any hormone production, birth control, pills, pregnancies, nutritional supplements and health or lifestyle. So far, there is nothing that can stop this inexorable death of approximately 1000 eggs every month regardless of ovulation, ovarian inhibition, or stimulation. Whenever the woman runs out of her supply of eggs, her ovaries ceases to make Oestrogen, and then she goes through Menopause.
Population studies have demonstrated over several decades that the average fertile woman becomes infertile in their 40s, and undergoes Menopause by the age of 50.
http://www.infertile.com/beating-biological/
(49) How many babies can a woman deliver over a lifetime?
There is no exact of babies one woman can deliver throughout her lifetime. An average woman experiences menstruation from early teens to early 50s when she experiences menopause. Technically, an woman can get pregnant every 10-11 months while she is still fertile for about 40 years meaning theoretically an average women can go into labour around 40 times but that doesn’t mean she will deliver about 40 children. The world record for most number of naturally-born babies delivered belongs to a Russian woman (name unknown, 1707 - 1782) who was married to Feodor Vassilyev. She gave birth to 69 children, including 16 pairs of twins, 7 sets of triplets and 4 sets of quadruplets.
(50) How many times can a couple have sex over a lifetime?
According to a study conducted on Britain’s population, it is found the average Brit will have sex about 5,778 times over a lifetime. In addition, we will fall in love on average 6.5 times and have about 8 romantic partners. Using the current life expectancy of 83 years, it also means we’ll be dumped about 5.5 times and 6 unrequited loves. Those numbers sound staggering than what you’re normally used to but if you do the mathematics, it actually is true no matter where you live especially in countries ravaged by HIV and AIDS.
(51) How long can we go without water?
We’ve been taught the old saying “we can only survive 3 days without water”. But is this scientifically true? At least 60% of our body is made of water and every living cell needs to stay hydrated to maintain its complex biological functions. For example, water can:
— Act as a lubricant for our joints
— Regulate our body temperature through sweating, respiration
— Expelling waste products through concentrated urine secreted by our nephrons in the kidneys
— Maintaining interstitial fluid concentration of ions crucial for cellular integrity, molecule transport via vesicles
— Generation of action potentials in nerve fibres.
— Formation of saliva for digestion
— Moisten mucosal membranes
— Cellular growth, reproduction and survival
— Manufacture neurotransmitters and hormones in the brain’s neurons and pituitary gland respectively.
— Act as a shock absorber for the brain and spinal cord in the form of Cerebrospinal Fluid
— Convert food to molecules needs for survival.
— Deliver oxygen throughout the body
Theoretically, the longest anyone can go without water is about a week given the right conditions like standard lab conditions, 25 Degrees Celsius and 1 atm (units of atmospheric pressure). This estimate would be shorter in other extreme conditions like high temperatures. The limit is based on observations of people at the end of their lives, when food and water intake is cut off completely.
(52) How heavy can we get?
In March 1978, American Jon Brower Minnoch recorded himself as the heaviest human ever weighing in at 635kg, caused by water accumulation due to congestive heart failure. After being admitted to University Hospital, Seattle, it took a dozen firemen and an improvised stretcher to move him from his home to a boat. After 2 years on a 1200-calories-per-day diet since, he was discharged at 216 kg i.e. Losing a record-breaking 419 kg. Unfortunately he passed away in September 1983 weighing in at 362 kg because his oedema was deemed incurable and difficult to treat. It’s theorised 640 kg may the limit of human weight but we don’t really know the actual answer.
(53) How much pain can we resist?
So far, pain is not yet quantifiable and it still remains subjective. Scientists used a term called 'Pain Tolerance’, which is the maximum level of pain that a person is able to tolerate. Clinical studies have found that men have higher pain tolerance than women, hence higher pain thresholds and lesser pain ratings. Whether you receive something as painful or not depends on the sensitivity, adaptability of your nociceptors in your skin. Regular exposure to painful stimuli may desensitise these nociceptors increasing the ability to handle pain by becoming more conditioned to it. However other studies suggest long-term potentiation may occur through regular painful experiences. Willpower may be a factor to resist pain which is still not well understood.
(54) How much blood can we make over a lifetime?
The process of making blood is called Haematopoiesis. It’s estimated our body produces around 10 mm of new Red Blood Cells every hour in the steady state. i.e. Around 42mL of blood every day. Each new Red Blood Cells lasts about 120 days and a daily turnover of about 0.8-1%. Many factors influence the rate of which new red blood cells are produced like:
— Your current volume of blood relative to its homeostatic setting
— Presence of Erythropoietin (EPO) produced by the kidneys
— Iron (Fe3+) - A limiting factor.
(55) How long can we keep our eyes open without blinking?
A man from the Northern Territory, Australia was recorded to keep his eyes open for 40 mins. Blinking is a semi-autonimic reflexive rapid closing of your eyelid, which helps spread your tears across and remove irritants from the surface of your Cornea and Conjunctiva. Each blink lasts about 100 - 400 ms depending on focused and tired you are. Every adult blinks every 2 to 10 seconds, or about 10 blinks per minute in a normal situation. When you are focused on an object for an extended period of time like reading a novel, your rate of blinking decreases to about 3 - 4 times a minute. This may explain why your eyes dry out and become exhausted during reading.
(56) What’s the sharpest object we can touch without getting lacerated?
When a sharp object like a sword or knife interacts with skin, all the kinetic energy to pierce the skin including dermis, epidermis, muscle, tissue and fat is concentrated onto a miniature point. The required force to puncture your skin depends on a number of parameters like the angle/direction of the force and momentum of the sharp object, width of the blade, the material the blade is made of, and exact configuration of your skin cells. But reports conclude that the median puncture force is about 1.22N, while the range was 0.5 mN - 19.2 N. So far there is no known unit of measurement for sharpness of a blade. When something is really sharp like an obsidian blade, it means they are only a few molecules thick at the tip. There’s a theory that the tip of the knife doesn’t really touch the skin, rather it forces the molecules that make up the phospholipid bilayer aside due to electrostatic repulsion, making its way through the skin.
(57) How long can we stand before we have to sit and vice versa?
The world record for being motionless the longest whilst standing upright belongs to Indian Arkshinthala Seshu Babu who stood for 35 hours and 22 mins in 2015 before it was interrupted due to an insect bite. The record attempt involves no toilet breaks, no facial movements except involuntary blinking, no sitting and no movement of your legs and feet.
The world record for sitting down the longest known as “world’s greatest couch potato” belongs to a Chicago man named Jeff Miller who sat for 72 hours straight in front of the television without getting a wink of sleep. He resorted himself to meaningless sporting events, heaving snacking and heaving drinking between scheduled bathroom breaks.
But the world record for sitting on the toilet bowl belongs to a woman from Kansas who sat on her boyfriend’s home toilet for 2 years because she was stuck. After being finally rescued by police and medics, her legs were wasted away and she became disoriented. I’m surprised after that foul-odoured bummer of a moment, she is still dating the same boyfriend who fed her and kept her hydrated and didn’t help her instantly even if she said she wasn’t ready to come out.
You will hear health experts say that you should stand up for at 2 hours daily at work. No matter what task you’re doing, if you sit for too long not only a sore, flat bottom would result but:
— Muscles in your legs and flutes will atrophy hence weaken, increasing your risk of lower leg injury
— An important enzyme that helps process fat and sugar called Lipoprotein Lipase would be secreted less, increasing your risk of Metabolic Syndrome, and gaining more fat cells across your middle.
— Your Hip Flexors will shorten and you will compromise your back causing pain and bad posture. This can cause compression on your vertebrate discs in your spine which can lead to premature degeneration, resulting in chronic pain.
— Anxiety & Depression
— Stiff shoulders and necks, hunched back
— Increased risk of certain types of cancers like Lung, Uterine, and Colon cancers
— Increased risk of Cardiovascular disease, Diabetes (due to Insulin resistance),
— Cause Varicose veins when blood begins to pool in your legs, which can cause blood clots.
— Deep Vein Thrombosis
On the other hand experts will tell you to not sit in one 1 position for more than 20 mins or stand in one position for more than 8 mins. Prolonged standing can many health complications like:
— Slouching or Kyphosis = Non-neutral spine —> Improper posture
— Varicose Veins = Gravity forces blood to the bottom of your body accumulating in your legs, ankles and feet. Your valves will weaken and eventually fail meaning less blood is returned to the heart.
— Carotid Atherosclerosis
— Joint Compression —> Reduces lubrication and cushioning of Synovial Joints, causing them to tear
— Muscle Fatigue, especially in the lower back, legs, ankles and feet.
(58) How many different words can our brain cite?
In terms of processing language and speech, the average human brain can articulate 120 - 150 words per minute for speech (Broca’s Area) and process around 350 - 500 words per minute your ears hear (Wernicke’s Area).
(59) What’s the largest object we can fit into our mouths?
In an adult, the maximum jaw range of motion (ROM) or maximum mouth opening (MMO) is related to body size and height. Usually taller people can wider mouths than shorter people, men more than women too. MMO for adults has generally been around 50 mm, with a range from 32 mm to 77 mm. Men can open their jaws to about 50 - 60 mm, and women to 45 - 55 mm.
(60) How far can we stretch without tearing out our limbs?
Your upper and lower limbs are held onto their sockets through collagen ligaments and muscle tendons. Depending if your muscles are contracting or not affects the amount of force required to tear out a limb via pulling. Unlike metals, bodily tissues are quite viscoelastic, meaning they can behave like solids and liquids so tendons will continue to stretch when a constant pulling force is applied to it. Therefore there is no finite or measurable amount of force needed to stretch a tendon up to the point of suture tearing, because that depends on the rate at which the stress was applied. Apply the force over a long enough period of time, it will break the tendon at a lower force than if you try to pull a limb off instantly.
— Nonetheless, there are a range of estimates of about 30 - 200 kN required to tear an arm off.
— Strangling someone requires about 3.5 N / cm^2. But rippling out a human head vertically upwards, this requires around 100 N / cm^2. This all depends on the size of the person’s head and the width and muscle strength of the person’s neck.
— Death by hanging involves a vertical force from the noose of a rope ripping your head off your spine. Depending on the weight of the body, and the distance of the “long drop” (between 1 - 3 m), it is estimated to exert 5600 N, fracturing your neck between the 2nd and 5th cervical vertebrate. This is enough to cause decapitation.
(61) How many mutations in our DNA is required to cause cancer?
In general, the mutation rate in a human genome accumulates around 64 new mutations per generation. The mutation rate is the frequency of new mutations in a single gene or organism over a period of time. Most of these new mutations are detected and repaired by DNA repair systems during DNA Mitosis but it’s not perfect. The mutations that matter the most are on Proto-Oncogenes when mutated become Oncogenes, and inhibition or loss-of-function of Tumour Suppressor Genes. These critical mutations have the potential to cause cancerous tumours and metastasise to form cancers. Because these mutations occur randomly and unpredictably, the development of cancer doesn’t depend on a finite number of mutations.
(62) How much sweat, saliva, urine, faeces and other chemicals do we generate over a lifetime?
— The average human produces 125 - 128 grams of faecal matter per day. The average lifetime is about 70 years so on average you will produce 3193.75 kg of poo in your lifetime.
— Every day a human produces on average 1 - 2 L of urine every day of variable concentrations. Over an average lifetime, for instance 80 years, you would produce 43,800 L of urine.
— The average human produces over 23,658.824 L (25,000 Quarts) of Saliva over a lifetime.
— The average human produces about 0.94 L of sweat every day, secreted by Eccrine Sweat glands in your skin. There’s about 2.5 million of these Sweat Glands. How much you sweat depends on the air temperature, humidity, daily exercise, fitness and weight.
(63) How strong can our teeth and jaws be?
The limit of your bite is not determined by your muscles, but by your teeth themselves. Your jaws are like a pair of oversized tongs. Most of the force is applied near the joint, while the work is performed at the opposite extremity of the jaw levers. The average adult would exert 760.646 N (171 pounds) of force through their molars and much less force for their Bicuspids and Incisors. According to a study, some people can exert 1223.26 N (275 pounds) or more through their molars.
(64) How far can we smell?
Smell, or olfaction, is considered to be our oldest sense. Studies have found that humans have around 400 different olfactory receptors in the Olfactory Bulb. According to genetic analyses, of around 1000 known olfactory genes for receptors, about 40% are non-functional “pseudogenes meaning they don’t actually code for odour receptors. This suggests that natural selection in humans may have favoured other senses like vision and taste. However no one really knows how good an average human’s sense of smell actually is. The latest studies have found that each organism regardless of the size of their olfactory bulb have an approximately similar number of neurons (about 10 million) necessary and sufficient to achieve olfactory function.
(65) What can or can’t we smell?
There’s a myth predicted by scientists that humans can distinguish over 1 trillion smells whilst others believe humans can only smell 10,000 different odours. Anosmia is the inability to perceive an odour or lacking function of olfactory, whilst hyperaemia is the antonym of anosmia. What we can or can’t smell depends on the sense we are either describing or recording what the smell is.
— Listing of the chemicals in the smell, and the concentrations of these chemicals e.g. Geranyl Acetate (Rose, Floral),
— Grouping smells into different classes e.g. Sweet, Pungent, Putrid, Floral, Fruity, Woody, Smokey.
— Describing the processes by which odours reacts with receptors in the nose, generating nerve signals to the brain, and the brain combines these olfactory signals with stored information to identify a smell.
https://en.wikipedia.org/wiki/Aroma_compound#List_of_chemicals_used_as_fragrances
(66) How hairy can we get?
Every hair on your body and head grows 1 cm every 28 days. Without cutting, the hair on your head eventually grows up to 40.6 cm (16 inches) long max. This occurs because each of your follicles goes through 3 phases of growth:
Anagen Phase (Growth Phase)
Catagen Phase (Transitional Phase - Cessation of Melanin production in hair bulb and apoptosis of Follicular Melanocytes)
Telogen Phase (Resting Phase - Follicle remains dormant for 1 - 4 months)
Hairs on your legs, chest, arms and head have different Anagen phase periods which explains why your leg hair doesn’t grow as long as your head hair. Depending on your genetics, different people have different lengths of anagen periods for a given body part to other people. For head hair, the average Anagen phase period is about 2 - 7 years. For arm, leg and eyebrow hair etc., the Anagen phase lasts between 30 - 45 days. At any given time, about 85% of your head hair is in Anagen phase, whilst about 10 - 15% is in Telogen phase.
— The world’s longest hair ever belongs to Xie QiuPing from China, growing up to 5.627m measured on 8 May 2004. She had been growing her hair since 1973 from the age of 13.
(67) What are the limits of our immune system?
The limits in which antigens, pathogen and bacteria our immune system can tackle with depends on the number of types of T-Cells which secrete highly specific antibodies and how much memory T-Cells it has. The way antibodies of different specificities are made is done by somatic recombination. Instead of just having a piece of linear DNA encoding each TCR (T-Cell Receptor), there are a series of pieces of DNA that can be combined to make a different TCR. On each antibody, there’s an α-chain and a β-chain. The α-chain has 50 V-segments and 50 J-segments. The β-chain has 20 V-segments, 13 J-segments and 2 segments. So based on that, you can make (50 x 50) = 2500 α-chains and (20 x 13 x 2) = 520 β-chains, and in theory any α-chain can pair with any β-chain. During VDJ recombination, there are enzymes that add a few nucleotide bases in between these DNA segments, further increasing the diversity of TCRs. However not all T-Cells with their TCRs made in the Thymus are secreted into the bloodstream. Only those that are wanting are either killed or die of neglect. TCRs too high of affinity to antigen are a risk of auto reactivity (autoimmune disease), or too low of affinity and they don’t get growth and survival signals it needs to mature. All these complex processes are done quite efficiently and quickly when you’re young but as you get older it slows down. A good estimate of the number of TCRs at any time is about 2.5x10^7 which is a lot, but because of antigenic drift of bacterial species and random mutations in common viruses, there is never enough TCRs to cope with every mutant and every bacterial specimen there is at this moment.
(68) How old can an individual person get?
This question is a mystery but what’s for certain is that our life expectancy for both men and women have substantially increased since the birth of the homo sapien around 200,000 years ago. The world’s oldest person that’s confirmed to have ever lived was Frenchwoman Jeanne Calment, who passed away in 1997 at 122 years old. In fact the top 10 oldest people that are confirmed to have ever lived were all female and were born between 1875 and 1900 with 2 of them still living today. They are Emma Morano from Italy and Violet Brown from Jamaica. According to VSauce, the first person to ever live up to 150 is already born but we don’t know who that person is. Since the 1800s, our curiosity and motivation to protect ourselves against nature’s deadliest epidemics like Influenza, Bubonic Plague and Smallpox have increased our knowledge and understanding of the impact of bacteria and microbes on us on a molecular (microscopic) level. Although we have invented anti-microbial drugs and antibiotics to inhibit the function of currently incurable diseases like HIV, Malaria, AIDS and Cancer, we are still nowhere near closer to unlocking the door to human immortality. The major source of these deadly microbes are from faeces contaminating our water system and atmosphere when the first ever toilets invented were connected to the water system that runs our kitchen and bathroom taps and shower nozzles. Thanks to our modern water sanitising sewage system and flush toilets we use today, residents living in developed countries like Australia, UK, USA and New Zealand have access to clean fresh water and are on the way to living longer lives whilst their waste is transported away in tightly sealed sewage tunnels far away towards sewerage plants in remote wetlands. However developing countries in Africa, Asia and South America are yet to have a water sanitation sewage system installed which is a major concern with cost and political will being the biggest and understandably frustrating obstacles.
(69) How long can we hold onto an object until we have to drop it?
When your hand has a load added it to it, your muscle spindles in your Biceps in your arm are stretched which sends an impulse to the spinal cord. This impulse results in the activation of motor neurons at your spinal cord sending the impulse back to the same muscle. This impulse tells the muscle to contract with greater force in order to decrease the speed at which the muscle is being stretched. This is known as the “stretch reflex” and it kicks in within milliseconds in order to protect yourself from serious injury or muscle tissue damage. How long you can hold onto an object before you have to drop it depends on your willpower and your psychological training to resist the inhibitory nerve signals telling you to drop the load.
(70) How long can we learn something until we get bored?
The answer depends on who you ask this question. Different people get bored at different times. Some take as long as several seconds whilst some take hours and hours of doing the same task before becoming bored. When you’re bored, your mind urgently seeks novelty, distraction and attention in order to satisfy and reward itself with stimulation from Dopamine. How long you take to get bored depends on Noradrenaline secreted by your Locus Coeruleus, which controls your focus and attention span on a particular task at hand. In addition, your ability to self-stimulate with your own thoughts, stimulating brain exercises and general knowledge can also come in handy when handling boredom. Nevertheless this depends on context such as study, work, holiday, relationships etc. Boredom usually comes about when your task is repetitive and easy to handle and you’re habituated to it, then you lose that excitement of novel experiences and are no longer highly stimulated by that experience.
(71) How much water can we continuously drink?
You can drink up to 10 L of water in an hour without diluting your electrolyte levels which may result in having seizures or experiencing death.
(72) What’s the fastest reading rate?
Reading is not just seeing words on a piece of paper, it depends on how quickly you process the information detected from your eyes then is transmitted into your brain’s Frontal Lobe which then deciphers the information decoding the message written on the paper in front of you. The majority of readers on average read at 200 words per minute. The rare fastest readers known as speed-readers have reading rates up to 1000 words per minute with near 90% comprehension. You can train your brain and eyes to speed-read by practising reading work documents, newspapers, magazines or books for at least one hour a day.
(73) What’s the most amount of carbon dioxide our body can cope with?
Hypercapnia is the condition when you have excess CO2 in your bloodstream that decreases physiological pH due to its slight acidic character. If the Pa(CO2) is greater than 10kPa or 75 mmHg, symptoms include arrhythmias, disorientation, panic, hyperventilation, convulsions, unconsciousness and eventually death may occur.
https://en.wikipedia.org/wiki/Hypercapnia
(74) What can or can’t we see with our night vision?
When you turn off the lights to be in the dark, your eyes temporarily goes blind because your rods and cones lack the light stimulus hence all of your Rhodopsin cannot break down into Retinal and Opsin. Over the course of 30 minutes, however, Retinal and Opsin recombine back into Rhodopsin, and you can see again. Your eyes are now in ‘night vision’ mode. We can only see objects that emit photos detectable for our photoreceptors (cones and rods) to change configuration and stimulate our visual system. Found in owls, dogs and cats which can see well in the dark, we don’t have the Tapetum Lucidum, a reflective membrane that acts as a biological mirror to provide light-sensitive Retinal cells with a 2nd opportunity for photon-photoreceptor stimulation, thereby enhancing visual sensitivity at low light levels.
(75) What diseases or pathogens can’t our immune system eliminate?
Currently there are about 27 incurable diseases, most notably Alzheimer’s Disease, Parkinson’s Disease, HIV and ALS, with the possibility of more incurable diseases to arise.
https://en.wikipedia.org/wiki/List_of_incurable_diseases
There are some viruses that cleverly and sneakily evade the immune system and don’t cause symptoms until much later in life. This is called “Virus Latency”. The most famous latent viruses include HIV, Herpes (Simplex, Chicken Pox) Virus and Epstein-Barr Virus.
https://en.wikipedia.org/wiki/Virus_latency
Because of antibiotics, bacteria affected can rapidly acquire mutations that allow them to develop a resistance to the drugs. There are currently 6 strains of the most common Escherichia Coli (E.Coli) and this allows E. Coli to develop resistance to phagocytosis via Macrophage and promote virulence.
(76) How big can our facial expressions be?
All of us show emotions on a daily basis. This common and obvious facial expressions like smiling and frowning is transmitted either consciously or subconsciously and viewed across cultures as a sign of happiness and friendliness especially when greeting someone. There are 43 different muscles in the face, most of which are controlled by the Facial Nerve (VII). This nerve exits the Cerebral Cortex and emerges from your skull just in front of your ears which then splits into 5 primary branches: Temporal, Zygomatic, Buccal, Mandibular and Cervical. These branches innervate different muscles in different areas of the face that allow that twisting and contorting of variety of expressions. However no one really knows how many of facial muscles is required to smile or frown because not everyone has the same number of facial muscles, some have more or less than 43.
(77) What can or can’t we taste?
So far scientists have discovered 5 different types of taste buds in the Papillae of the Tongue which account for 5 basic tastes: Bitter, Sour, Salty, Sweet and Umami. You have about between 2000 - 5000 taste buds located at the back and front of the tongue and with each taste bud containing 50 - 100 taste receptors, so you can have up to 500,000 taste receptors. In addition there are other tastes not generally included in the basic tastes which are detected by the somatosensory system instead of the 3 Cranial Nerves; Facial Nerve (VII), Glossopharyngeal Nerve (IX), and a branch of the Vagus Nerve (X). These other tastes include:
— Pungency (Spiciness, Hotness) i.e. Ethanol, Capsaicin
— Coolness (“Freshy”, “Minty”) e.g. Peppermint, Menthol, Spearmint, Camphor
— Numbness (Numbing-and-hot, Mati Rasa) = 麻辣 (MaLa) i.e. Sichuan Pepper
— Astringency (Puckering) i.e. Tannins, Calcium Oxalate in Tea, Red Wine, Rhubarb, Unripen Bananas and Persimmons.
— Metallicness i.e. Medicines or Amalgam Dental fillings, Blood
— Calcium
— Fattiness (Oleogustus) i.e. Triglycerides, Fatty acids
— Heartiness (Kokumi) i.e. γ-L-Glutamyl peptides
— Temperature
— Starchiness i.e. Starch (Glucose Oligomer)
(78) What’s the most amount of cells we can be made out of?
It’s estimated your human body is made out of 37.2 trillion cells (give or take). This number includes:
— 700 million cells of Trabecular bone tissues
— 1.1 billion cells of cortical bone tissue
— All 80,000 km of capillaries, of average diameter of 0.75 mm, All blood vessels lined by endothelial cells about 60 microns long and 20 microns wide (Micron = 1x10^-6 m). This gives about 2.5 trillion endothelial cells in capillaries.
(79) What’s the fastest speed our body can travel at before disintegrating?
On foot, humans can run at speeds up to 45 kph.
If you’re referring to interstellar travel, theoretically there is no maximum speed a human can travel assisted. We can travel at the speed of light, but accelerating up to that incredible cannot be instantaneous. The average survivable acceleration is about 16g (157 m/s) sustained for 1 minute. That means it will take about 22 days to reach the speed of light without breaking apart.
(80) How long can we go without food?
We know the old saying “we can’t go 3 weeks without food”. But is this scientifically true? Assuming a human is sufficiently hydrated, it is difficult to predict their survival without food. There were cases both in history and in patients under medical supervision who survived for many months to years in concentration camps and famines. What your body does in a time of near-total starvation is moderate your metabolism in order to conserve energy and that individual survival will vary markedly depending on psychological willpower and mental stability. The body’s main fuel is Glucose made from Glycogenolysis of Glycogen. But if there is a lack of Glucose, your body converts fats then amino acids in proteins to replenish the levels of Glucose. These processes are called Glucogenesis.
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