There are several factors which affect normal vision and eyesight. These factors include diet, heredity, environmental factors including exposure to artificial light, age, etc. Hormones can also affect our vision considerably.
The flow of blood in the capillaries is controlled by structures called precapillary sphincters. These structures are located between arterioles and capillaries and contain muscle fibers that allow them to contract. When the sphincters are open, blood flows freely to the capillary beds of body tissue.When the sphincters are closed, blood is not allowed to flow through the capillary beds. Fluid exchange between the capillaries and the body tissues takes place at the capillary bed.hen the sphincters are open, blood flows freely to the capillary beds of body tissue. When the sphincters are closed, blood is not allowed to flow through the capillary beds. Fluid exchange between the capillaries and the body tissues takes place at the capillary bed.
A) tunica intima. Permitting the exchange of nutrients and gases between the blood and tissue cells is the primary function of ______. A) arterioles B) arteries C) veins D) capillaries. D) capillaries. The arteries that are also called distributing arteries are the ________.n the dynamics of blood flow through capillaries, hydrostatic pressure ________. A) and osmotic pressure are the same B) is the same as capillary blood pressure C) generally forces fluid from the interstitial space into the capillaries D) is complete.