Peripheral resistance is affected primarily by:
A) the length of myocardial fibers.
B) blood viscosity and the diameter of arterioles.
C) the capacity of the blood reservoirs.
D) elasticity of the heart.

Question

Quizplus · Accepted Answer

Peripheral resistance refers to the amount of force that the heart must exert to push blood through the blood vessels. The two primary factors that affect peripheral resistance are blood viscosity and the diameter of arterioles. Blood viscosity refers to the thickness or stickiness of the blood, while the diameter of arterioles refers to the width of the small blood vessels that feed into the capillaries. When arterioles narrow, peripheral resistance increases, while dilation of arterioles decreases peripheral resistance. Factors that affect blood viscosity include the concentration of red blood cells and plasma proteins. Other factors, such as wall thickness of veins and the elasticity of the heart, may play a role in peripheral resistance, but they are not the primary factors.

Peripheral Resistance Is Affected Primarily By