Transportation in Animals and Plants

The transport of food and other substances in the body is done with the help of circulatory system. It consists of blood vessels, heart and blood.

Bloodconsists of plasma, RBCs, WBCs and platelets. Plasma is the fluid part of the blood.Red blood cells (RBCs) contain a red pigment called haemoglobin which carries oxygen from the lungs to the cells of the body.White Blood cells (WBCs) fight against germs.Platelets help in the formation of clot.

The network of tubes through which the blood circulates in the body is called blood vessels. The blood vessels include arteries, arterioles, capillaries, venules and veins. Arteries carry blood to all parts of the bodyfrom the heart while veins bring blood back to the heartfrom all parts of the body.An English physician, William Harvey discovered blood circulation.

Heartis a pumping organ that pumps blood to other organs. It is located in the left side of the chest cavity. Human heart is divided into four chambers. Two upper chambers are called atria and two lower chambers are called ventricles.

Heartbeat isthe rhythmic contraction and relaxation of heart muscles is called heartbeat. It is measured with the help of Stethoscope.Normal heart rate in human beings is 72-80 beats/minute.

The process of removal of wastes from body is called excretion. The excretory system comprises of two kidneys, two ureters, a urinary bladder and urethra.

Kidneys are the bean-shaped organs present in the abdominal area. They filter wastes from blood. Ureters arethe tubes which carry urine from kidney are called ureter. One ureter arises from each kidney and passes their content into the urinary bladder.Urinary bladder is a pouch like structure, which receives urine from the kidney via ureters. The urine can be stored in urinary bladder for a considerably long time.Urethra is located at the bottom of the bladder and act as the opening to pass out urine.Urine is the fluid excreted by the kidney and contains metabolic waste products. It is composed of 95% water, 2.5% urea and 2.5% other wastes.Urea is the major excretory product in humans.

Ammonia is the excretory product of aquatic animals such as fish. Birds, insects and lizards excrete uric acid in semi-solid form.

The Plants take water and mineral nutrients from the soil through roots and transport it to the leaves. The leaves prepare food for the plant, using water and carbon dioxide during photosynthesis.

In plants, absorption of water and minerals takes place through root hairs.Vascular tissues i.e. xylem and phloem are involved in transportation.Xylem is involved in thetransport of water and minerals while phloem is involved in the transport of food.

Transpiration refers to the process of evaporation of excess water from leaves through stomata. Besides cooling the plants, it also helps in the absorption of water by rootsas it generates a force which pulls up water absorbed by the roots, to reach the aerial parts of a plant.

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