Inglese - inglese medico

living cells. Frequen-tly they contain non-living mineral matters such as calcium salts.The structures made of such non-living material can neverthlessgrow and change as a result of the activities of living cells whichdissolve away and replace the hard material.

b. the function of the skeleton can be grouped conveniently under theheadings: support, protection, locomotion and muscle attachment.

3. Support. A rigid skeletal ssupport raises the body from the groundand allows rapid movement, it suspends some of the vital organsand prevents them from crushing each other and maintains the sha-pe of the body despite vigorous muscular activity.

4. Protection. Certain delicate and important organs of the body areprotected by a casing of bone. The brain is enclosed in the skull,the spinal cord in the vertebral column, while the heart and lungsare surrounded by a cage of ribs between the sternum and thevertebral column.

Locomotion. Where two bones meet, a joint is formed.

5.Sometimes, as in the

If stimulated by a nervous impulse, muscles will contract to about two-thirds or one half their resting length. This makes the muscle as a whole shorter and thicker and, according to its attachment at each end, it can pull on a bone and so produce movement. Muscles can contract and relax, they cannot lengthen of their own accord. Consequently, most muscles are in pairs, one for producing movement in one direction, and one for the opposite movement. Where such antagonist pairs act across a hinge joint they are called extensor and flexor muscles. When the body is at rest, the antagonist muscles remain in a state of tension or tone and so hold the body in position.

QUESTIONS

1. Define the discipline of Anatomy
2. In which way does Anatomy differ from Pathology?
3. What is systematic Anatomy?
4. Outline systematic and microscopic Anatomy
5. Describe the skeleton
6. Outline the functions of the skeleton
7. Explain the function of the bone cases
8. What are muscles?
9. What is the Periosteum?
10. What are the

Blood as Haemoglobin

Haemathology

Blood cells

BLOOD: composition and function

Human blood is composed of a liquid (plasma) in which are suspended red and white cells, platelets and fat globules.

The amount of blood is around 85 millilitres per kilogram of body weight, or 8.5 per cent of the weight of the body.

The functions of the blood are:

1. nutrition and respiration of tissues located far from the food and air supplies;
2. transportation of waste products from the tissues to the excretory organs;
3. chemical and thermal coordination of the body;
4. defence against infections through the action of antibodies and phagocytes.

1. The chief function of the blood, the conveying of oxygen to the cells of the body, is indicated by its colour, which is due to a pigment, haemoglobin, that can pick up oxygen and release it readily. Not only does the blood carry oxygen to the tissues but it takes up the waste materials of cells.

Chemical compound which readily combines with oxygen and readily releases it, depending on certain factors in the environment such as oxygen concentration and acidity. The process of combination, which occurs in the lungs when blood passes through the alveolar capillaries, turns the purplish reduced haemoglobin into bright-red oxy-haemoglobin. The reverse process occurs in active tissues of the body and accounts for the difference in colour between arterial and venous blood.

White cells are of two main types: those with and those without granules in their cytoplasm. The granular cells (granulocytes), which are formed in the marrow, are phagocytic and can engulf foreign matter (such as bacteria), and in the presence of tissue damage, they are stimulated to activity. Most of the non-granular cells are lymphocytes. When exposed to foreign materials, like transplanted tissues or microorganisms, lymphocytes multiply and play a part in the elaboration of antibodies in an effort to neutralize.

The alien substances. They are thus involved in the fight against infection and in the rejection process.

The immediate arrest of haemorrhage after injury to small blood vessels is due to vaso-constriction and plugging of the leaks by aggregation of the platelets which control the bleeding until a firm blood-clot forms. Coagulation is a complex process and involves the interaction of many coagulation factors.

Fibrinogen is a vital substance for the clotting of the blood, which consists essentially of the conversion of fibrinogen to fibrin. This forms a fibrous net and together with enmeshed platelets and red and white cells makes up the clot.

Platelets are very fragile. If vessels walls and tissues are damaged, as occurs whenever there is bleeding, they break up and release substances which react with a number of other substances in the blood and tissues to form thromboplastin.

Prothrombin, which like fibrinogen is another plasma protein, in the presence of calcium salts, is converted by

The newly-produced thrombo-plastin is converted into thrombin. Thrombin is the agent that induces clot formation, as it is a protein-destroying enzyme that digests part of the fibrinogen. The remaining fibrinogen then combines with itself to form fibrin.

The fluid part of the blood, known as plasma, is a colorless solution containing proteins and smaller amounts of salts, glucose, amino acids, and other substances. The plasma proteins are quantitatively significant.