Which are the special proteins in muscles that contract and relax to cause movement?

 

Plants grow in size both in height and in grith. Enlargement  of cells already present cannot contribute much to the growth. Only addition of more and more cells could increase the size of the plant considerably.

Hearts are of several types. In some invertebrates the heart is simulated by the nervous system to do its work. Such hearts are called Neurogenic hearts. The Human heart is myogenic. i.e, it recieves the stimuli for contraction from the muscular node called sinu-auricular node or pace maker.

The clotting of blood is a chain reaction initiated by the enzyme Thrombokinase produced by the platelets. This causes Prothrombin and calcium salts in plasma to join and produce thrombin. Thrombin combines with Fibrinogen to produce Fibrin threads which entangles the corpuscles  to create a clot.

Goitre is characterized by the swelling of the neck region. This is due to the enlargement of the thyroid gland which secretes hormone thyroxine. Thyroxine has iodine as an integral part of it. If there is not sufficient iodine in one's  diet, the thyroid gland swells up.

Heparin is a hormone secreted by the liver. This is anticoagulant in its property. It prevents cloting of blood inside the heart and blood vessels. Heart attack is the result of a block in the blood vessels supplying blood to the walls of the heart.

The hormone adrenaline also called epinephrine is known as a stress harmone. In emotional upset (like fear, anger etc.) this harmone is poured into the blood and it accelerates heart beat. The hormone acetylcholine decelerates heartbeat rate.

The red blood corpuscles  or erythrocytes usually carry antigens and there are two types of antigens. The A group persons have antigen A in their red corpuscles and the B group have antigen B in their red corpuscles. The AB group person have both antigen A and antigen B in their erythrocytes. The 'O' group persons have no antigens in their red corpuscles.

The clotting of blood is a chain reaction initiated by the enzyme thrombokinase produced by the platelets. This causes prothrombin to be converted into thrombin in the presence of Ca++ion.

Thrombin combines with fibrinogen  to produce fibrin threads which entangles the corpuscles to form the clot.