Following on from the series on The Circulatory System it is now time to look at the incredibly complex fluid that uses the network to take the essential supplies such as oxygen and nutrients around the body to keep us alive.
Blood is one of the constituents of our bodies that we tend to take for granted. Unless we suffer a catastrophic accident and resulting in major injuries most of us just need a plaster from time to time to patch ourselves up. However, blood is alive with an amazing group of components completing several vital roles every second of every day to ensure that we survive.
If our blood is not healthy we can suffer from anaemia, inefficient immune systems, slow healing and frequent infections. Long term blood disorders lead to much more serious illnesses such as cancer and organ failure.
Without a microscope we are unable to see the enormity of the life that is contained in just one small drop of blood. Once you understand some of the properties and duties of your blood and appreciate how vital it is to maintain its integrity, it will be easy to make sure that you include foods in your diet that promote its health and therefore your own.
The Cardiovascular System
Our cardiovascular system’s function is to pump blood around the body. If this process stops for more than a few seconds we will lose consciousness. Every part of our body requires oxygen and nutrients on demand, including additional supplies when we are under pressure. Our cardiovascular system deals with this process without any thought or involvement from us and in addition it will remove any waste products from our systems at the same time. A healthy cardiovascular system is essential and the quality of our blood is vital to our survival.
In the last few posts I looked at our circulatory system which is made up of arteries, veins and capillaries. The arteries carry the oxygenated blood from the lungs into smaller arterioles, which connect to the veins via capillaries. Unlike the muscle-walled arteries, veins have thin, flexible walls that can expand to hold large volumes of blood. De-oxygenated blood returning to the heart in the veins is at a lower pressure than in the arteries and movement is assisted by a succession of one-way valves that prevent blood from flowing backwards. The links between the arteries and the veins are the capillaries, which are tiny blood vessels with permeable walls, which allow the exchange of nutrients, oxygen and waste between blood and tissue cells.
Blood is a liquid tissue and your body contains around 8 to 12 pints depending on your age and if you are male or female. Without blood you would die. It performs a number of crucial functions within the body, including the transportation of oxygen and carbon dioxide, food molecules (glucose, fats and amino acids), ions, waste (such as urea), hormones and heat around the body. One of its major functions is the defence of the body against infections and other ingested toxins.
The components of Blood
Within blood is plasma, which is the pale yellow liquid that can easily be replaced by your body when it needs to. It is mainly water and proteins which assist your body in controlling bleeding and fighting infection. It is essential for the circulation of our red and white blood cells and platelets and also ensures that our natural, chemical communication system is operational. This communication system reaches every part of the body via the capillaries and is fuelled by minerals, vitamins, hormones and antibodies.
What are the different blood cell types?
- White blood cells are called leukocytes and there are five types carrying out specific roles within the blood. Neutrophils, Eosinophils, Lymphocytes, Monocytes and Basophils.
- Neutrophils are the most abundant of the white blood cells and are the first line of defence. They squeeze through the capillaries to infected areas in the body and consume and destroy invading bacteria and viruses. Even when we are healthy this process is essential as we are constantly ingesting, absorbing or inhaling harmful substances in our everyday environment. If our blood is healthy and well-populated with Neutrophils we can prevent these invasions leading to illness and disease.
- Eosinophils are not very abundant in the blood but they are on stand-by and can increase their numbers dramatically if the body comes under attack from certain types of parasites. The cell will rush to the infected area such as the intestines and release a toxic substance over the parasite to destroy it.
- Lymphocytes are the name given to a group of different cells with a specific role within the immune system.
- Red blood cells, or erythrocytes, are the most numerous type of blood cell. They are shaped specifically to ensure that they absorb as much oxygen from the lungs as possible. In just one minute 120 million of your red blood cells will die but in the same time frame exactly the same amount will be replaced from the bone marrow. The process actually starts in the kidneys, which release a hormone called erythropoietin, which travels to the bone marrow where it stimulates the production of erythrocytes. This is another reason why it is so vital to maintain the function of your kidneys with a healthy eating plan.
- B-Lymphocytes (B Cells)are responsible for making our antibodies in response to an infection.
- T-Lymphocytes (T-Cells)are a family of cells including Inflammatory T-cells that rally Neutrophils and macrophages to the site of an infection quickly where they will consume bacteria.
- Cytotoxic T-Lymphocytesthat kill virus infected and possibly cancerous tumour cells.
- Helper T-Cellsthat enhance the production of antibodies.
- Monocytesleave the blood and become macrophages, which are large cells that ingest and destroy any invading antigens that enter the body and also any dead and dying cells from the body.
- Basophilsalso increase production during an infection and will leave the blood stream via the capillaries and collect at the site of an infection where they will discharge granules that will stimulate the release of histamine, serotonin, prostaglandins and leukotrines. This increases the flow of blood to the infected site and results in an inflammatory reaction. An example of this might be a wasp sting or an allergic reaction to ingesting pollen resulting in a hay-fever attack.
What else is in the blood that is so vital for our health?
We have already established that without blood we die and we need a system in place that ensures that any break in the circulatory system is plugged and repaired as quickly as possible.
- Platelets are fragments of cells and must be kept at sufficient density in the blood to ensure that when blood vessels are cut or damaged the loss of blood can be stopped before shock and possible death occurs. This is accomplished by a process called coagulation or clotting.
A clot is formed when platelets form a plug, which is enmeshed in a network of insoluble fibrin molecules. This forms over any break in the circulatory system preventing any further loss of blood.
Now that we have some of the components of our blood, next time I will be looking at how it transports oxygen, removes waste from our bodies and some of the conditions that are the result of poor blood health.
Here are the three posts on the circulatory system.