Components of Blood

Identifying and comparing the main components of blood.
By
Jason T Morrison.

Blood, what an amazing substance. It has only been since being set this task by one of my tutors, Dr C Dublon that I have truly realised how amazing blood really is.

Blood is not as some people may think just made up of one component, but many different components working together in an almost symbiotic relationship. The average human being carries approximately five litres of blood, which is equivalent to about 8% of their body weight. Out of the five litres(8%) of blood that we have we can categorise this blood into four main category’s, Plasma, Erythrocytes, more commonly known as Red Blood Cells(RBC), Leukocytes, more commonly known as White Blood Cells(WBC) and Platelets. These simplified four fields can and will be sub-categorised within this assignment.

My research tells me that 55% of blood is comprised of Plasma, 45% of Erythrocytes and 1% of WBC. Plasma is comprised mostly of water; in fact, 92% of plasma is water with the remaining 8% being protein. The main type of protein in plasma is albumin, which has two main jobs, the first being to reduce the fluid from leaking out of blood vessels. The second task that it performs is to attach its self to other substances such as hormones and other certain drugs. As with most of the other parts of the human body, plasma also has secondary functions such as being a reservoir of water, so that if the body requires it can replenish any additional liquids that are required. It is also a major part of making sure that the body’s blood vessels do not collapse by maintaining circulation and blood pressure. Last but by no means is least, within blood; plasma is the main contributor to the regulation of thermal heat energy (core temperature) by carrying warm blood to the extremities of the body, such as fingers and toes.

Erythrocytes, more commonly known as Red blood cells (RBC), are the only cell in the whole body that do not have a nucleus. As previously stated make up 45% of the total volume of blood. Within these Erythrocytes there is a protein called Haemoglobin (Hb). The iron within Hb gives blood its vibrant red colour. In addition, the Hb enables the blood to carry oxygen (which now becomes oxyhaemoglobin) within the circulatory system, around the body, to the cells so that the production of energy can take place. Carbon dioxide is a by-product, which the Erythrocytes (carbamino haemoglobin) then transport to the lung for dispersion. There is a condition when the count of Erythrocytes is too low, known as anaemia. The symptoms of this being fatigue and weakness. However if the Erythrocytes count is too high ( polycythemia ) the blood could become too thick which can increase the likelihood of a blood clot as well as a heart attack or stroke.

Leukocytes, more commonly known as White Blood Cells (WBC), are far fewer in number than Erythrocytes, with their count being as low as 1:700 or even 1:600 the lower number being Leukocytes and the higher being Erythrocytes. The main job of Leukocytes is that of defending the body against any type of infection. Due to the amount of different types of threats that are to be had, Leukocytes are split into five main sub-categories, which are Neutrophils. - Responsible for killing and ingesting bacteria and fungi, but also ingests foreign debris. Monocytes. - Are responsible not only for the disposing by engulfment (by means of phagocytosis, from the Greek phagein, to eat and kytos, vessel, referring here to the cell) of dead or damaged cells, but also defend against many other infectious organisms. Basophils: - described more easily as an allergy response unit. Eosinophils – Which respond to any allergic responses, as well as killing parasites. In addition, if that was not enough they even kill some types of cancer cells! Last, for good reason are the Lymphocytes. I say for good reason because these too can be sub- categorised into three. Which are the T lymphocytes and natural killer cells, which not only protect against viral infections but also detect and destroy cancer cells as does, if you remember, Eosinophils. The third and last of the sub-categorised parts of the Lymphocytes are called the B lymphocyte, which actually develop into cells that produce antibodies. I think it is also worth mentioning that not all WBCs sit and wait for the infection/ problem to come to them, they actually try and actively hunt the infection/ parasite out by even penetrating tissue. What I think is truly awe inspiring about the WBCs however, is that much like the common honey bee, that once it stings you it releases a smell that attract other bees, WBCs do the same by releasing a substance that attract other WBC. Consequently in a matter of no time you have a microscopic army attacking a foe you might not even know you had. Whilst they “attack the enemy”, they also produce antibodies that attach themselves to the organisms.

Thrombocytes (platelets) with regards to their size are smaller than both Leukocytes and Erythrocytes, with a ratio of 1:20. 1 being the platelet and 20 being Erythrocytes. Platelets are a main contributing factor in the clotting process by assembling at a bleeding site and clotting together, forming a natural plaster. Whilst doing this it also releases different substances that encourage further clotting. Like with anything in the body if you have too much or too little then problems can arise. Too little an amount of platelets and the condition is thrombocytopenia, the symptoms of this condition being bruising and abnormal bleeding become more likely. Too much platelets and you would have a condition called thrombocythemia, with the condition causing a potential blood clot, stroke or even a heart attack.

We can surmise that blood has nine main functions: 1. Supply of oxygen to tissues 2. Supply of nutrients such as glucose, amino acids and fatty acids 3. Removal of waste such as carbon dioxide and lactic acid 4. Immunological functions 5. Coagulation- which is one of the body’s self-repair mechanisms. 6. Messenger functions-the transport of hormones. 7. Regulation of bodies Ph (7.35-7.45) 8. Regulation of body core temperature (37 ) 9. Hydraulic functions.