The Circulatory System

Front 1

Transportation function of blood

Back 1

1. Transport :-

.Transport of digested food from the alimentary canal to the tissues. These substances are simple sugars like glucose , amino acids , vitamins, mineral salts , etc.

.Transport of oxygen from the lungs to the tissues. It occurs by means of red blood cells in combination with haempglobin in the form of an unstable compound oxyhaemoglobin , which on reaching the tissues breaks up to deliver oxygen.

.Transport of carbon dioxide from the tissues to the lungs. It occurs partly in combination with haemoglobin and partly as solution in blood plasma.

.Transport of excretory material from thr tissues to the liver, kidney or the skin for elimination or to render them harmless.

.Distribution of hormones secreted by endocrine glands directly into the blood.

.Distribution of heat to keep the temperature of the body uniform.

Front 2

Protection by blood

Back 2

Blood forms a clot wherever there is a cut in a blood vessel. The clot serves to prevent

.further loss of blood

.the entry of disease causing germs.

Its white blood corpuscles protect the body from diseases by engulfing bacteria which may have entered the body.

It produces antitoxins and antibodies which neutralize the poisonous substances or kill the germs which enter the body.

Front 3

Fluids in our body

Back 3

Three :-

1.blood contained in the heart and in the blood vessels (arteries, veins and capillaries) of the circulatory system.

2.tissue fluid occupying spaces between cells in the organs.

3.lymph contained in lymph vessels and lymphatic organs such as spleen and tonsils.

Front 4

Plasma

Back 4

Plasma is the light yellow alkaline liquid which forms 55-60% of the total blood volume. It mainly consists of :

Water : 90-92%

Proteins : 7-8%

Inorganic salts : 1%

Other substances : traces.

The inorganic salts include mainly sodium chloride and sodium bicarbonate. Among other substances contained in the plasma are glucose, amino acids, fibrinogen, hormones, urea, etc.

Front 5

Serum

Back 5

Serum is the blood plasma from which fibrinogen, the blood clotting protein has been removed. It is a yellow coloured fluid.

Front 6

Cellular elements of blood

Back 6

The formed or cellular elements of blood (i.e. shaped structures visible under magnification) are of three categories:-

1.Red blood cells (erythrocytes)

2. White blood cells (leukocytes)

3. Blood platelets (thrombocytes)

Front 7

Increase in efficiency of mammalian RBCs

Back 7

1.loss of nucleus , makes the red blood cells biconcave thus kncreasing their surface area volume ratio for absorbing more oxygen.

2.loss of mitochondria means that the RBCs cannot use oxygen for themselves . Thus all the oxygen absorbed from the lungs is transported and delivered to the tissues unconsumed. Secondly , loss of mitochondria means full transport of glucose in blood plasma unused by the RBCs.

3.no endoplasmic reticulum means increased flexibility of RBCs for their movement through narrow capillaries.

Front 8

Carbon monoxide poisoning

Back 8

Haemoglobin has very strong affinity for carbon monoxide forming a atable compound carboxyhaemoglobin . This cuts down the capacity of the blood of transporting oxygen , sometimes resulting in death.

Front 9

Phagocytosis

Back 9

Phagocytosis is a process in which most WBCs and particularly the neutrophils engulf particle-like solid substances , especially bacteria.

This is a defensive mechanism against disease germs .

An abnormal increase in WBC count up to about 50000 or more per cubic mm indicates some infection in the body.

Front 10

Inflammation

Back 10

Inflammation occurs due to the reaction of tissues to iinjury and to localized invasion of germs.

The inflamed spot has several characteristics - increased local heat, redness, swelling , pain, etc.

Here the leucocytes (especially the monocytes and neutrophils) migrate through the walls of the blood vessels by diapedesis, and fight against disease causing germs.

They also destroy the damaged cells by phagocytosis .

Pus is mainly composed of the dead white blood cells together with the tissue cells destroyed by the bacteria.

Front 11

Antibodies

Back 11

When disease causing germs gain entry into the blood stream , they produce poisonous substances called toxins. In response , the lymphocytes of the blood produce chemical substances called antibodies which circulate free in the blood plasma. The antibodies act as antitoxins which neutralize the poisonous effect of the toxins. Antibodies may persist long after the disease has been overcome, and the person who has recovered becomes immune to the disease . This is the underlying principle of vaccination, a deliberate introduction of weakened disease germ to stimulate production of the specific antibodies.

Front 12

Leukemia

Back 12

A cancer of the tissue forming WBCs whose number increases manifold at the cost of RBCs . It is usually a fatal disease.

Currently the only treatment is blood transfusion.

Front 13

Clotting of blood steps

Back 13

1. Thrombokinase or thromboplastin is released at the site of the wound by the disintegrated platelets.

2. Prothrombin is converted into thrombin by the thombokinase with the help of calcium ions present in the plasma.

3. Soluble fibrinogen of the plasma reacts with the thrombin in the presence of calcium ions and gets converted to insoluble fibrin. Fibrin forms threads which are sticky and form a mesh at the wound.

. Blood cells are trapped in the network of the fibrin .

4. The network then shrinks and squeezes out the rest of the plasma which is in the form of a clear liquid serum . The solid mass which is left behind is called clot/thrombus.