In this article we cover all these body organs and parts of the body:
The skin is the largest organ in the body, having a total area of roughly 2m2. Its function is to regulate body temperature, protect us from microbes and external substances, and to help us navigate our external environment through our sense of touch.
It is composed of 3 layers:
Hair is a ubiquitous feature of mammals - the phylogenetic class of organisms that humans, apes, and many others belong to. Its function includes protection, thermal insulation, and also as sense organs so we can perceive the world around us.
Hair is an elongated protein filament called keratin which is covered by an oily sheath known as sebum. Sebum is needed for lubrication and protection of the keratin underneath. Both are produced from hair follicles and sebaceous glands which are found in the dermis of the skin.
Analogous to hair, nails are also derivatives of the skin. They lie on the distal phalanges (fingers and toes) and function for protection, scratching, and aid in picking objects up. Nails are composed of a tough protein called keratin which is also found in horses' hooves and animal horns.
Along with the nutrients that are beneficial for the skin and hair, Vitamin B12 is a key regulator of nail health. Insufficient Vitamin B12 can lead to darkened and rounded nails which are weaker than usual6. Due to the high number of important vitamins and minerals necessary for a healthy body, multivitamins may aid in increasing intake without spending hours taking different supplements.
The brain is the primary organ of the central nervous system controlling the majority of the bodies conscious and unconscious actions. It is surrounded by the skull and also suspended in cerebrospinal fluid for further protection. In a human adult, it weighs around 1.2 - 1.4kg (around 2% of the average body mass) and consumes the most energy out of any organ in the body (20% of the bodies total energy expenditure).
The brain is composed of 3 main parts - brainstem, cerebellum, and cerebrum. Each part is responsible for different processes, however every single part of the brain has to be healthy for normal functioning. Due to the complexity of the human brain there is much research investigating the effects of diet on brain function7.
The eye is the optical apparatus responsible for sight. It has many components that are crucial to focus an image onto the retina, which is then transported by the optic nerve to the brain for processing. Some key components of the eyes include:
The word vasculature comes from the latin word vascularis and refers to the arrangement of blood vessels in the body. The blood plays a fundamental role to the body by supplying oxygen and nutrients to the cells around the body, removing waste such as carbon dioxide, and regulating temperature. Therefore movement of the blood is imperative for these to function normally. There are three main types of vessels:
Every artery is comprised of three layers of tissue:
How to keep it healthy?
Muscles are responsible for many things including movement and posture. The human body has around 650 muscles from the prominent gluteus maximus (bottom) to the much smaller masseter which helps close the jaw. On the face alone there are 43 muscles which are necessary for eating, controlling senses, and making facial expressions4.
There are three groups of muscles:
What you can do to improve muscular health:
The heart is the most important muscle in the human body. It is responsible for pumping blood (which contains nutrients and expels wastes) around the body. There are two main circuits: the systemic circuit that pumps oxygenated blood around the body so each cell has the sufficient nutrients, and the pulmonary circuit which pumps deoxygenated blood to the lungs where toxic carbon dioxide can be expelled whilst oxygen can diffuse back into the blood. Just like all muscles it contracts, and this contraction forces blood away from the heart at high pressure, whereas relaxation allows the heart to fill with blood. It houses four chambers: the right atrium, right ventricle, left atrium, left ventricle. Blood is pumped out through the ventricles and allowed in at the atria. In an average lifespan the heart will pump over 3 billion times4!
As the heart is a muscle it requires blood supply so the muscle fibres have the nutrients enabling them to contract at a high force. This blood supply does not directly come from the blood in the atria and ventricles because this blood is pumped at such a high pressure that the cells would not be able to absorb any oxygen. Instead the heart receives blood through the coronary arteries which become implicated in diseases such as the common and aptly named coronary heart disease (see vasculature).
How to ensure your heart is healthy:
Bones are living growing tissues that are constantly breaking down and remodelling. Collagen is a protein that forms a soft framework and calcium phosphate is a mineral that adds strength and rigidity to this framework. The combination of hard and soft makes bones strong and flexible enough to withstand the many stresses of daily life4. Bones also contain connective tissues, nerves, blood vessels, marrow, and are the location for blood cell formation.
Joints (also known as articulations) allow for the strong and rigid skeletal system to move. They are strong connections joining bones, teeth, and cartilage together. They can be categorised either by function or structure - below are the categories based on function:
Arthritis is a general term for conditions affecting the joints and surrounding tissue. This often involves inflammation and becomes more prevalent as people age. A couple of strategies to maximise joint health:
The lungs are intricately linked with the vasculature (blood vessels) and the heart. The heart is responsible for pumping blood around the body whilst the lungs serve to oxygenate this blood and remove the toxic carbon dioxide. Humans have two lungs (right and left) that are both surrounded by ribs for protection.
Air enters the body through the nose or mouth and then travels down the trachea (also known as windpipe). The trachea then splits into two bronchi, each going to a separate lung. The bronchi then branch off many times and get smaller and smaller, eventually reaching the site of gas exchange that is known as alveoli. It is here that oxygen can diffuse into the capillaries and carbon dioxide can diffuse out. It is estimated that if the lungs were spread out completely, its surface area would cover roughly one side of a tennis court!
How can we improve our lung health?
After food is swallowed, it travels via the oesophagus down towards the stomach. The stomach is a bean shaped organ that is stretchy and can hold up to 2-3L of food. It acts as a food blender, primarily chemically digesting the food before it can continue along into the small intestines. A mixture of acid and digestive enzymes (Gastric juices) are secreted into the stomach, converting eaten food into a semiliquid mixture known as chyme. This chyme can be seen (and smelled!) when someone vomits4,23,24.
The liver is the largest gland in the human body and the largest organ after the skin. It weighs approximately 1.5 kg and is located on the right side of the body protected by the bottom of the rib cage. Its function is to filter the blood coming from the digestive tract before it continues around the rest of the body. This means that it has to filter out potential toxic substances such as alcohol, medicine, and other foreign matter.
To maintain a healthy liver it is mostly about avoiding detrimental actions rather than trying to consume things to improve its health. The most effective action is to cut consumption of alcohol as alcohol is the most frequent cause of liver disease in western countries. It has been reported that heavy alcoholics who consume at least 80 g of alcohol (around 6 standard drinks) per day for more than 10 years will develop liver disease at a rate of nearly 100%25.
The intestines are a long and winding tube that connects the stomach to the anus. It is the main site for absorption of nutrients from our food.
The small intestine is connected to the stomach and is in the more central area compared to the large intestine. It is extremely tortuous (winding) and when an adult humans is stretched completely, it is around 7 m long! The chyme from the stomach passes through here and most of the nutrients from this mixture are absorbed. It is divided into three parts: duodenum, ileum, jejunum.
The large intestine is where food travels after passing through the small intestine. Contrary to the name, it is actually shorter than the small intestine, only having a length of around 1.5m. It surrounds the small intestine and absorbs water from the chyme. Once the water has been absorbed, the remaining chyme hardens forming a semi-solid stool commonly known as faeces4. The large intestine is divided into five main parts: cecum and appendix, the transverse colon, descending colon, sigmoid colon, and the rectum.
So what can we do to maintain the health of our intestines?
The pancreas is an oddly shaped accessory gland located behind the stomach nestled near the liver and spleen. The function of the pancreas is not as well known as the stomach for example, but it has extremely important functions. It secretes pancreatic juices into the small intestine to aid in digestion of some foods, and it also secretes glucagon and insulin into the blood. Insulin and glucagon are hormones that are released in response to changing blood glucose levels. This needs to be maintained at a constant level, as all the cells in the body use glucose as an energy source. If blood glucose levels drop too low then important organs such as the brain cannot get the energy they need which can lead to fainting. This is an issue in diseases such as diabetes4.
The spleen is a fist shaped organ located near the stomach in the left part of the abdomen. It has a wide range of important functions such as filtering the blood, controlling the amount of red blood cells, and helps fight infection. Consuming plentiful water can improve spleen health as this provides the necessary water that helps flush out toxins from the body.
The kidneys remove excess wastes, salts, and water from the blood to form urine. Most humans have two functioning kidneys although it is possible to survive with only one. They lie towards the back of the body, just above the waist and near the spine. All the blood in the human body flows through the kidneys multiple times per day, and the filtration takes place in millions of microscopic units known as nephrons.
How to ensure kidney health:
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