Question

Compare the movement thru a capillary (what is it called?) to that thru the aorta (surgy)and thru a small artery/arteriole (continuous) and explain what is responsible for those differences

Answer 1

Arteries carry blood away from the heart ,aorta is the main artery which carry blood away from the heart .Capillaries carry blood from the body and exchange nutrients,waste and oxygen with tissues at cellular level.

Aorta is the largest artery and it has the highest blood flow with high pressure and when it reaches to arterioles,the blood pressure decrease and finally pressure is lowest in the capillaries.

Cross sectional area of aorta and arteries is smaller than the cross sectional area of capillaries due to which velocity of blood flow is highest in aorta, than arterioles and slowest in capillaries.

Pressure of blood in the blood vessels depend upon the cross sectional area of the vessel.

As the cross sectional area increases ,the flow decreases gradually. Blood flow is slowest in the capillaries as they have large cross sectional area,so proper exchange of blood and nutrients occur in capillaries and blood flow is maintained constant in the arteries because they are baroreceptor present over their surface which controls high or low blood pressure. Capillaries are small in diameter so they offer large resistance and due to which there is slow blood flow in them.

Blood pressure is due to resistance offered by the vessels diameter. As the diameter decrease, resistance increases and blood flow decreases.

Arteries are made up of 3 different layers (tunica interna ,tunica externa and tunica media) capillaries are single layer thin wire like.