December 1, 2021

I, Science

The science magazine of Imperial College

Joanna Blackburn shines light on important but often forgotten organs of the human body

Body_diagram_with_labels_1024wDo I need my appendix?

The appendix is a thin tube around four inches long found in the lower right of the abdomen between the small and large intestines. The appendix is a vestigial structure, which means it has lost most of its original function. Therefore, it can be removed without long-term consequences and is often removed in cases of appendicitis. It is thought to have had a role in plant digestion, which has since been lost. There is a growing body of thought that the appendix may have an important role in maintaining gut flora. This theory posits that the appendix acts as a storehouse for good bacteria that can replace stores lost due to diarrhoea.

Why is the thymus essential to my health?

The thymus gland is located between your lungs and it produces the hormone thymosin. Thymosin stimulates the development of white blood cells, also called lymphocytes, into T lymphocytes. These T lymphocytes are crucial in fighting disease through the adaptive immune response. Removing the thymus during infancy can have serious immune consequences. However, removal after childhood has little effect. This is because after puberty, the thymus begins shrinking and this continues for the rest of your life. Nevertheless, this shrinkage may be one reason why the immune systems of elderly people are less robust than those of younger individuals.

What are the advantages of having adrenal glands?

Situated on top of the kidneys the adrenal glands secrete four main hormones. First, they produce cortisol and aldosterone that help regulate metabolism and control blood pressure respectively. While these functions are crucial to life it is the adrenal glands’ production of nonessential hormones, such as adrenaline and noradrenaline, which is better known. These help your body respond to stress as part of the fight or flight response, and particularly important in this process is adrenaline, which increases the heart rate and blood sugar levels.

What does my spleen do for me?

Your spleen is primarily a blood filter. Blood first enters the white pulp where immune cells screen the blood for disease-causing microorganisms, called pathogens. A subtype of immune cells called T cells recognise invading pathogens while a second type, called B cells, make antibodies which can then help to fight off an infection. Subsequently, blood enters the red pulp. Here old red blood cells are removed and platelets, which are involved in blood clotting, are stored. In addition, before-birth the spleen can also produce new red blood-cells. In spite of the spleen’s importance it is not actually vital for life, however people without a spleen may be more prone to infection.

What is the importance of my microbiome?

A microbiome consists of all the microorganisms that live within us. These microbes outnumber our own human cells by 10 to 1. We have a particularly important relationship with our gut microbiome. Found in our intestines, the gut microbiome has many important functions including food digestion and forming a barrier that protects against enemy microorganisms as part of the immune system. They also produce the vitamins B and K. About two-thirds of this gut microbiome is common to all humans with the remaining one-third unique to individuals.

Why is my skin special?

The skin is the largest organ of the human body and it accounts for ~16% of our body weight. Skin serves several functions including protection from microbes, regulation of body temperature and enabling the sensations of touch, heat and cold. The outer layer of skin, called the epidermis, is replaced around every 30 days by the deepest layer of epidermis that is made of constantly dividing cells. The inner dermis, made of collagen and elastic fibres, contains touch, pressure and pain receptors along with hair follicles and sweat and oil glands. It is the decreasing number of collagen and elastic fibres as we age that causes wrinkles. Melanin-producing cells called melanocytes determine skin colour by producing a protein called melanin.

Joanna Blackburn is studying for an MS in Science Communication

Image: Kate Whittington