What Is Disease?
31st August 2017
Types Of Hypertension
31st August 2017

Facts About The Human Body


The human body is amazing:
From around six weeks gestation your heart starts to beat while still in the womb. A healthy baby’s heart beats between 120 to 160 per minute.
In an adult the heart beats an average of 70 beats per minute, your heart beats over 100,000 times every day, more than 36 million beats every year.
On your seventieth birthday your heartbeats will have exceeded 2,575,440,000 (that's over 2.5 billion!).
Even the most powerful computers in the world are no match for the human body.

When the heart pumps blood that puts pressure on the walls of the arteries. The pressure of blood passing through an artery is used as the measurement of blood pressure - ideal pressure is around 120mmhg/80mmHg or less.
If the arteries have narrowed, it requires the heart to increase pressure, which in turn causes blood pressure to rise.
Red blood cells carry oxygen using a protein called haemoglobin, together with nutrients from food. Blood travels through the maze of arteries and capillaries to provide oxygen and nourishment to body cells, where they are converted into energy that keep us alive.
Once oxygenated blood has transferred nutrients and oxygen to the cells in our body, they take oxygen-depleted blood, Carbon Dioxide (CO2) and waste products through a maze of veins back to the heart and eventually to the alveoli in the lungs via the pulmonary arteries.
At this point you breathe out carbon dioxide CO2 and breathe in fresh oxygen O2.
The oxygen passes through the alveoli into the pulmonary vein which takes fresh oxygenated blood to the heart, where the process starts again.
This is a basic explanation of the circulatory system, further information has been detailed below, and more appears in Section (20).

Arteries, veins and capillaries

Arteries, veins and capillaries have some incredible facts. If you joined all your arteries, capillaries and veins end to end, they would total 60,000 miles or 96,000 kilometres. You could wrap them around the world nearly two and half times!

Blood Vessels and Capillaries

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Blood vessels and tissue protect your brain from dangerous substances reaching the brain, this is termed the “Blood Brain Barrier”.

Capillaries are extremely small, anything between 6 and 10 micrometres, compared with a human hair that measures around 100 micrometres. This means ten capillaries can fit into the same space as one human hair.

Capillaries are the lifeline that takes oxygenated blood and nutrients to every tissue and organ in the body, collecting carbon dioxide waste that ultimately is expelled from the lungs.

The human lung contains alveoli which are extremely small air sacs that exchange oxygen and carbon dioxide between the lungs and the bodies bloodstream. There are around 500 to 700 million alveoli inside the lungs, in alveolar sacs. The tar from smoking damages the alveoli, gradually reducing the level of oxygen into the bloodstream and potentially causing many life-threatening conditions.

Some good news: Dark chocolate is good for the health of the heart, arteries, veins and capillaries, as within dark chocolate there are flavonoids which are powerful antioxidants.

Read more in the sections about smoking

One interesting fact...

It’s your arteries that carry fresh oxygenated blood away from your heart, and the veins that carry deoxygenated blood back to the heart. There are two exceptions to this: The pulmonary arteries (left and right) carry deoxygenated blood from the heart to the lung. The pulmonary veins (two from the left lung and two from the right lung) carry oxygenated blood to the heart. In simple terms:
  • The two pulmonary arteries are the only arteries that carry deoxygenated blood.
  • The principle is that ALL arteries carry blood away from the heart. The pulmonary arteries do the same, they carry blood away from the heart, albeit it’s deoxygenated blood.
  • Equally, ALL veins carry blood to the heart. The 2 pulmonary veins do the same, ie they carry blood to the heart, however, they are the only veins that carry oxygenated blood.
  • Pulmonary hypertension is elevated blood pressure in the lungs. The mechanism of pulmonary hypertension can be separated into problems or diseases affecting the lungs and structures within the lung or problems in the heart.
    The term pre-capillary hypertension is used to define diseases involving the lungs and blood vessels, whilst post capillary hypertension is used to define diseases involving the heart. Pulmonary hypertension can be very complex and can be found on other websites that specialises on this topic.
    Some causes of pre-capillary hypertension include Emphysema/COPD (smoking related damage to the lungs), connective tissue diseases (lupus, rheumatoid arthritis, scleroderma), and clots in the lungs (pulmonary emboli).
    The elevated pressure in the lungs can then affect the right side of the heart, which, in turn, can cause the right side of the heart to become enlarged and walls of the heart to thicken.
  • Normally the right side of the heart is less muscular, as it only needs to push blood through the pulmonary artery over the short distance between the heart and lung.
  • By comparison, the left side of the heart is far more muscular, because it’s solely responsible for circulating blood around the whole body at a higher pressure.
  • Measuring blood pressure from the left side of the heart can easily be achieved, but measuring pulmonary blood pressure in the pulmonary arteries using a catheter can be invasive. However, Kings College London have developed a cuff monitor that can measure Central Blood Pressure. For more information, click on the link below.
Click this link to view a page with information on "The world's first arm cuff monitor"

When we breathe...

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It’s a fact that, when we breathe in, we are breathing in gases. Only 21% of air is oxygen, the remaining gases include nitrogen, some 78% of it, the remaining 1% is argon, and a minute amount of carbon dioxide (and other gases too):
  • We breathe out the same amount of nitrogen as we breathe in (78%). Although the body needs nitrogen, the nitrogen we breathe in cannot get into our blood stream, we get the necessary nitrogen in our blood stream from food we eat. We also breathe out less oxygen and more carbon dioxide than we take in, around a 4% difference.
  • It’s a fact, oxygen has a boiling point of -183 degrees Celsius.
  • It’s a fact, nitrogen has a boiling point of -196 degrees Celsius.
  • It’s a fact, argon has a boiling point of -185.8 degrees Celsius.
  • All the elements above are gases in our atmosphere.
When flying, the air we breathe is drawn into the pressured cabin by various means. However, when planes climb to altitudes around 35,000 feet, air pressure is reduced compared to air pressure at sea level. This can cause some passengers to experience breathing problems. It’s not all due to the reduction of oxygen, it’s also connected to the low cabin pressure at high altitudes.
We need the same air pressure we experience at sea level, this air pressure gets oxygen into the lungs, ensuring we breathe without difficulties. However, when the air pressure drops, breathing problems can start, requiring some passengers needing supplementary oxygen.
Some more interesting facts
  • The blood in your body contributes to just over 7% of your body weight.
  • The average adult has 10 pints of blood, around 5.7 litres, 5 quarts or 200 fluid ounces.
  • An adult heart pumps up to 5 quarts of blood around your circulatory system every minute, that’s 7200 quarts or 1800 gallons every day.
  • The right side of your heart pumps blood to your lungs.
  • The left side of your heart pumps blood to all of the body.
  • Blood pressure in veins is lower than blood pressure in arteries.
  • Cells within the muscle of your heart stay with you throughout your life.


Two of the rarest blood types are AB Negative and AB Positive, for this reason, there is a worldwide call for people with these blood groups to become a plasma donor. Although it’s the rarest blood type, AB Plasma can be given to every person, regardless of their own blood type.
Blood type “O” Negative red cells are considered safe as the only blood that can be given to a patient in emergency situations. However, persons with type A, B, & AB cannot give blood to each other, it can be life threatening.
There are around 28 different blood groups/types.
Every week in the UK around 50,000 people give blood, there are four main types, they are A, B, AB and O, each of these can be RhD Positive or RhD Negative. For people who may want to consider giving blood, this is a great website to read. (Click on the link below for information written in 2016)
Global call for blood donors of the future | Blood Donation - Give Blood

Human Blood Cells

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Human Blood cells are suspended in blood plasma. The total volume of blood is made up of four different components in approximate percentages:

(1) 44% of the total are red blood cells
(2) 1% of the total are platelets
(3) 1% of total are white blood cells *
(4) 54% of the remaining total is plasma.
However, plasma is made up of different components. 95% of plasma is water, some of the remaining 5% is made up of ions, nutrients, hormones, minerals, glucose.
* NOTE: See more below on White blood cells

The function of plasma is to move red blood cells, white blood cells, platelets, nutrients, proteins and hormones. All these travel around the bodies circulatory system, providing oxygen and all the components to keep us alive and healthy.
Plasma is extremely important to health. When people donate blood, technicians can isolate plasma, taking ingredients from the plasma which goes through a process to provide a product for medical emergencies, such as shock and burns. Plasma is an interesting subject, I’ve covered just a small amount of information, there is so much more on the internet. Check out this site. Click Here
Blood, excluding plasma, is made up of red blood cells, white blood cells and platelets which are cells that play an important part if a blood vessel is damaged. The platelets form blood clots which stop the flow of blood, so that the damaged area can be repaired.
The red blood cells collect oxygen from the lungs and take rich oxygenated blood around the body to keep the organs working and the brain functioning.
New red blood cells, some 180 million of them, are released from your bone marrow every hour, they carry oxygenated blood cells that keep you alive.
The Red blood cells travel though arteries, veins and capillaries for around sixteen weeks before returning to die in your bone marrow where they were born. During the sixteen weeks they can circulate some 260,000 times.

White Blood Cells

White blood cells make up a small percentage of your blood, no more than 1% to 2% and are part of your immune system. If you develop an infection, the number of white blood cells can substantially increase, in medical terms referred to as a White Blood Cell Count (WBC) or C-Reactive protein (CRP), both are clinical markers. Normal CRP, measured in mg/dl is around 3. When CRP levels increase, it signifies inflammation.
White blood cells circulate around our bodies behaving like an army, having been dispatched by our immune system to defend our bodies from infections, bacteria, viruses and disease.
Following any battle with infection, the bodies left behind are referred to as “Pus”, in simple terms, “Pus” is a buildup of dead white blood cells.
White blood cells are made up of six different types of cells, Basophils, Lymphocytes, Monocytes. Neutrophils, Eosinophils & Monocytes.
C-Reactive protein (CRP), is a clinical marker. Normal CRP, measured in mg/dl is around 3, when CRP levels increase beyond that, it signifies inflammation or infection.

Water and Fat

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More facts about Blood

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The Cornea

The cornea in the eye has no blood supply. It takes oxygen directly from the air, exchanging gases within the atmosphere, and because there are no blood vessels passing blood, the tissue remains transparent.
There is a lot of technology involved in the design and production of contact lenses, as they cover the cornea, reducing the amount of surface area exchanging gases. Hence gas-permeable contact lenses.

The Human Brain

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The human brain is incredible, everything we do or say has an impact on the brain. However, there is what I would call an interface between the brain and the spinal cord and the rest of your body referred to as the “Brain Stem”
The brain stem is like a central computer that, involuntarily keeps us breathing, keeps our heart beating, controls blood pressure, even controls actions such as sneezing and coughing and more, even when we’re sleeping.

Below are some more facts on the brain.

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However, some diseases of the brain cause an unnatural death of neurons, one being Parkinson’s Disease.

Parkinson’s Disease

Neurons in an area of the brain called the Basal Ganglia and the Substantia Nigra produce Dopamine, which is a neurotransmitter controling muscles and movement. When these neurons die, it affects movement and muscles in the body.
Michael J Fox who starred in the film “Back to The Future” is living with this condition and has set up “The Michael J Fox Foundation for Parkinson’s Research” Please click on the link below to see his website, it’s really inspirational.

Every time your heart beats, the arteries and capillaries in your brain take up to 25% of all the blood in your circulatory system. The brain then uses around 20% of the oxygen and nutrients carried by the blood.
There is a separate blood supply to each side of the brain via the carotid and vertebral artery each side of the neck.
The left side of the brain controls the right side of your body, the right side controls the left side of your body.
Neurons can travel at very low speeds or travel at speeds more than 250mph, 402kph.
So when people ask “What is the speed of thought?” this is the answer!

Muscles in the body

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Muscles in the body make it possible for humans to function in so many ways. What is the largest, strongest muscle? There’s no set accurate way to measure muscle strength, however, these are some opinions:
  • Possibly the strongest muscle in the body is he masseter muscle, more commonly known as the jaw muscle - the molars (Back Teeth) generate a force of up to 160 lbs when you chew, the front teeth (incisors) generate a force around 60 lbs. Even a one year-old baby can give a powerful bite!
  • The largest muscle is the gluteus maximus, a very powerful muscle that helps the human body stay erect.
  • The smallest muscle in the body is called the stapedius - less than 2mm long, the stapedius is located in the middle ear.
  • The heart muscle works harder than all muscles in the body, which get tired for many reasons, but the heart muscle, although it works hard all of the time, it never gets tired.
  • There are around 600 to 800 muscles in the human body, depending how you count them.


Your ears can be permanently damaged by a loud explosion or other extreme noise.

Apart from hearing it’s your ears that help you to maintain balance. In the simplest of terms, within the inner ear there are three semi-circular canals which are connected to each other and positioned at right angles acting the same as a gyroscope.
Within each canal there are tiny hairs, and as you move your head the hairs move in the same direction as the fluid, detecting movement in the body.
It’s a combination of these components inside the ear that is sensed by Neurons (Nerves) located within the canals that connect with the brain to maintain balance.

More facts on bones

The largest and strongest bone in the body is the femur, also known as the thigh bone, the length in an adult is around 500mm.

The hands have the most bones in the body, totalling 54 in both hands, this is closely followed by the feet with a total of 52 in both feet.

In total there are 206 bones in the human body.

Interestingly, a baby has more bones than an adult, a baby has around 290 bones, an adult some 206 bones. The reason being, as babies develop, bones fuse together.

The human mouth has some interesting statistics

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A French kiss could exchange some 60 million bacteria/germs.
Providing you practice good oral hygiene you could have up to 50,000 bacteria living on each of your teeth.

Should oral hygiene be less than the recommended cleaning methods, people could have anything between 80 & 600 million bacteria living on each tooth.
That’s more bacteria than the total population of the UK, France, Germany, North America, Japan, Spain and Italy all put together!
Your tongue is a muscle, made up of eight different muscles, they are referred to as intrinsic and extrinsic. The four intrinsic muscles are the muscles that can change the shape of your tongue, they are not connected to any bones.
The four extrinsic muscles can change the position of your tongue, unlike intrinsic muscles, extrinsic muscles are attached to the bone.

Your tongue has between 4000 and 8000 taste buds, that allow you to distinguish between sweet, sour, salty, and bitter.
Although most of the taste buds are on your tongue, there are also taste buds at the back of your throat that go all the way down the oesophagus to the epiglottis that lets food into the stomach.

Younger adults have around 9500 taste buds, sadly as you age the number of taste buds decrease to around 4000. Some good news, on average every five days taste buds are regenerated, although the time taken to regenerate taste buds increases as we age.

A few more facts about the human body

Your Nose

Why does your nose run when the weather turns cold?
When you’re outside and it turns cold, your brain senses that the nose needs more warm blood, this causes the blood vessels in your nose to dilate or widen, which in turn produces more mucus.


Your Skin

Your skin is on average only about the thickness of the lens in the average pair of spectacles, or around 2mm thick. However, 12% of the blood being pumped from your heart is supplying your skin. It’s also the largest external organ, and in fact also the largest organ in general.

One last fact

One last fact.
The food you eat passes down the oesophagus, the stomach then mixes food with hydrochloric acid and pepsin (produced by glands in the stomach wall), killing bacteria in the food we eat and breaking it down into minute nutrients.
These nutrients pass through the sphincter muscle into the small intestine, also called the small bowel. The nutrients are then absorbed through the wall of the small intestine into your bloodstream, to provide the body with nourishment to keep us alive.

The acid in your stomach is so strong it can quickly burn through a piece of wood, and can also dissolve some metals. The pH Level
pH Level - A measure of acidity or alkalinity of water soluble substances (pH stands for 'potential of Hydrogen'). A pH value is a number from 1 to 14, with 7 as the middle (neutral) point. Values below 7 indicate acidity which increases as the number decreases, 1 being the most acidic. Source - www.businessdictionary.com/definition/pH-scale.html
of stomach acid ranges between 1.5 & 3.0, comparing with battery acid (pH level of 1. 0), cranberry juice (pH level around 2.5), or Coca-Cola™ (pH level around 2.5).

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