Kelly Ann Wright   Physiology   Access to Health Sciences

1) Describe the main components of the blood.

Blood is composed of two components: Plasma, a watery liquid which contains dissolved substances and formed elements, which are cells and cells fragments. The blood consists of about 45% formed elements and 55% plasma.
Plasma itself is around 90% water and the remaining 10% is made up of dissolved solutes such as, minerals, urea, glucose and hormones, also containing plasma proteins such as albumin and immunoglobulins (antibodies that fight infection), these proteins never leave the blood.
Without plasma, blood cells would have no medium to travel on as they travel throughout the body.
The formed elements of the blood include three principle components which are Red blood cells (Erythrocytes), White blood cells (Leukocytes) and platelets.
Red blood cells are the most common cell in the blood and carry oxygen around the body from the heart. Erythrocytes contain an oxygen carrying protein called haemoglobin, a pigment that gives blood its red colour. They are biconcave discs with a diameter of 7-8 um, and their plasma membrane is strong and flexible which allows the red blood cell to change shape without rupturing as they squeeze through the narrow capillaries. Red blood cells lack a nucleus and organelles   giving it a larger surface area to carry more oxygen. The typical lifespan of a red cell is 90-120 days. (class notes)

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Neutrophills are the most common type of white blood cell comprising of about 50-70% of all white blood cells. They contain non staining granules and are phagocytic meaning that they can ingest other cells, though they do not survive the process. Neutrophills are fairly uniform in size with a diameter between 12 and 15 micrometres. The nucleus consists of 2-5 lobes which are joined together by hair like filaments
Neutrophills are the first immune cells to arrive at a site of infection, through a...