Transportation is the movement of materials from one part to another, usually from the region of their availability to the region of their use, storage or elimination. Transportation occurs in all organisms, from microscopic ones to large size trees and animals.
Transportation in Human Beings
It is carried out by circulatory system. In human beings, the circulatory system is made of tubes, a pumping heart and circulating fluids, blood and lymph. Depending upon the fluid, the circulatory system is of two types, blood vascular system and lymphatic system.
Blood
It is a mobile fluid connective tissue of reddish color that circulates in the human body, supplying nutrients and oxygen to all the living cells and taking away waste products as well as carbon dioxide from them. The blood carrying oxygen attached to haemoglobin (as oxyhaemoglobin) is called oxygenated blood. The blood carrying carbon dioxide and little oxygen is called deoxygenated blood. An adult human has a total of 5-6 liters of blood. Blood is made up of two components, plasma and blood corpuscles.
Functions of blood
1. Transport of Nutrients. Sugars, amino acids, minerals and vitamins are picked up by blood from intestine and transported to different parts of the body for storage and assimilation.
2. Transport of Oxygen. It transports oxygen from the respiratory surface to the tissues for utilizsation in respiration.
3. Transport of Carbon Dioxide. Carbon dioxide formed during respiration is taken by blood to the respiratory surface for elimination.
4. Transport of Waste Products. It carries nitrogenous wastes from various parts of the body to the kidneys for separation and elimination.
5. Transport of Hormones. Endocrine glands pour their hormones into blood for transport to target tissues.
6. Maintenance of water Balance. Circulating blood provide water and inorganic salts in the region of deficiency and removes the same in the area of excess.
7. Regulation of Body Temperature. Blood distributes heat to all parts of the body. It also conducts heat to the surface for dissipation.
8. Maintenance of pH. Blood maintains the pH of tissue fluids with the help of various buffers.
9. Body Defence. Blood contains phagocytic leucocytes, and immunocytes for defence against germs.
10. Plugging Areas of Injury. In the region of injury the blood coagulates and seals the region to prevent loss of body fluids and check the entry of germs.
Heart
Heart is a conical muscular double pump structure that brings about circulation of blood in the body. The broader base is upwards while the narrow pointed apex is downwards and tilted towards left. Heart is reddish in color with a size of our fist (12 cm length, 9 cm breadth)and a weight about 300 gm (250 gm in women). Heart lies in the thoracic cavity in between the two lungs. It rests obliquely over the diaphragm. Feeling of the presence of heart on the left side is due to forceful beating of its apical or vernacular region. Heart is covered by a narrow fluid filled membranous sac called pericardium. It helps in frictionless movement as well as provides protection from shock.
Heart is completely partitioned into chambers to prevent mixing of oxygenated and deoxygenated bloods. Their are four chambers. Two upper or superior chambers are smaller and thin walled. They are called auricles or atria (sing. atrium). The other two lower or inferior chambers are larger and thick walled. They are called ventricles. An irregular transverse groove called coronarysucul occurs between the auricles and ventricles.
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