The Circulatory System About the system Blood Heart Vessels

About the circulatory system Heart Blood vessels – arteries and veins Blood

Functions of the circulatory system Transportation of gases, nutrients, ions and waste Transports oxygen, carbon dioxide Transports glucose, fats, amino acids Transports hormones Regulation of body temperature Defense against disease – clotting and immunity

A few nights working in a trauma center would tend to convince one that the body is just a huge bag of blood. In fact, an "average" 70 litre human body contains only about 5 litres of blood, or 7% by volume. In the normal state, blood has no business anywhere except in the confines of the heart and blood vessels and in the sinusoids of the marrow, liver, and spleen. Of the average 5 L of blood, only 2.25 L, or 45%, consists of cells. The rest is plasma, which itself consists of 90% water (by weight) and 10% solids (mostly proteins, the greatest proportion of which is albumin). Of the 2.25 L of cells, only L (1.6%) are leukocytes. The entire circulating leukocyte population, if purified, would fit in a bartender's jigger. The total circulating platelet volume is even less -- about L -- or a little over one teaspoonful. Use this information to complete the table in your worksheet

Composition of Blood Plasma 55% Blood Cells 45%

Blood plasma – 55% 55% of the blood slightly alkaline fluid typical yellowish color 90 % water, 10% dry matter organic substances – glucose, lipids, proteins dissolved minerals

Blood cells – 45% Red Blood Cells 99% White Blood Cells <1% Platelets

Blood cells – 45%

Red Blood Cells = Erythrocytes Most numerous blood cells No nucleus Biconcave shape Rich in haemoglobin … a protein which can bind oxygen Last 120 days then recycled

White blood cells = Leukocytes Less than 1% of blood cells Vital for defense against disease Many different types Neutrophils Basophils Eosinophils Monocytes Lymphocytes

Cells in the blood Erythrocytes Lymphocytes Monocyte Platelets

How blood cells are made

Platelets The main function of platelets is to stop the loss of blood from wounds. To this purpose, they aggregate and release factors which promote the blood coagulation. reduce the diameter of damaged vessels slow down blood flow in that area trap cells to form the clot. Even if platelets appears roundish in shape, they are not real cells.

The Heart  Size of a clenched fist  Approximately 300 g  5-35 litres per minute  70 beats/minute

Blood vessels Heart Arteries Veins Arterioles Venules

The whole system

Sickle cell anaemia

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