A human red blood cell in an artery of the left arm is on its way to deliver oxygen to a cell in the thumb. To travel from the artery to the thumb and then back to the left ventricle, this red blood cell must pass through . A human red blood cell in an artery of the left arm is on its way to deliver oxygen to a cell in the thumb. To travel from the artery to the thumb and then back to the left ventricle, this red blood cell must pass through . two capillary beds four capillary beds one capillary bed three capillary beds

A human red blood cell in an artery of the left arm is on its way to deliver oxygen to a cell in the thumb. To travel from the artery to the thumb and then back to the left ventricle, this red blood cell must pass through two capillary beds.

Explanation:

Capillary beds are the netwrok of capillaries present in all tissues of body. They are the sites of diffusion and exchange of material within the body (oxygen, CO2 , glucose etc)

As the humad red blood cell travels from the artery of left arm to thumb, it passes through one capillary -bed as it has to supply oxygen to  a cell in thumb and as it moves through the artery back to the left ventricle, it again pass through another capillray-bed.

Hence the Red blood cell will pass through two capillary beds.

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.