What are the 3 factors that affect vascular resistance?
The factors that affect TPR are blood viscosity, total vessel length, and overall vessel diameter. When the hematocrit is high, such as for people living in high altitudes, the viscosity is greater and the blood is thicker and stickier.
What increases vascular resistance?
When blood vessels constrict (vasoconstriction) this leads to an increase in SVR. When blood vessels dilate (vasodilation), this leads to a decrease in SVR. If referring to resistance within the pulmonary vasculature, this is called pulmonary vascular resistance (PVR).
How does vasoconstriction affect the body?
Vasoconstriction reduces the volume or space inside affected blood vessels. When blood vessel volume is lowered, blood flow is also reduced. At the same time, the resistance or force of blood flow is raised. This causes higher blood pressure.
What factors affect peripheral resistance?
Peripheral resistance is determined by three factors: Autonomic activity: sympathetic activity constricts peripheral arteries. Pharmacologic agents: vasoconstrictor drugs increase resistance while vasodilator drugs decrease it. Blood viscosity: increased viscosity increases resistance.
What are the 5 factors that affect blood pressure?
Five factors influence blood pressure:
- Cardiac output.
- Peripheral vascular resistance.
- Volume of circulating blood.
- Viscosity of blood.
- Elasticity of vessels walls.
What has the greatest effect on blood pressure?
Blood pressure increases with increased cardiac output, peripheral vascular resistance, volume of blood, viscosity of blood and rigidity of vessel walls. Blood pressure decreases with decreased cardiac output, peripheral vascular resistance, volume of blood, viscosity of blood and elasticity of vessel walls.
What happens to blood pressure when peripheral resistance increases?
In summary, any increases in cardiac output (HR and/or SV), blood viscosity or total peripheral resistance will result in increases in BP.
What is the relationship between blood flow and resistance?
Blood flow is inversely proportional to resistance, and a change in resistance is the major mechanism for changing blood flow, particularly in arterioles. Resistance can either be measured for the entire systemic vascular system, called total peripheral resistance, or measured in a single organ.
What is the most important determinant of vascular resistance?
What is the most important determinant of vascular resistance?
…
- Combination of neural and hormonal mechanisms?
- The diameter of the arterioles.
- Friction between the blood and the vessel walls.
- Differences in the length of the blood vessels.
What are the causes of vasoconstriction?
Vasoconstriction is the narrowing (constriction) of blood vessels by small muscles in their walls. When blood vessels constrict, blood flow is slowed or blocked. Vasoconstriction may be slight or severe. It may result from disease, drugs, or psychological conditions.
What triggers vasoconstriction?
Cutaneous vasoconstriction will occur because of the body’s exposure to the severe cold. Examples of endogenous factors include the autonomic nervous system, circulating hormones, and intrinsic mechanisms inherent to the vasculature itself (also referred to as the myogenic response).
Does caffeine cause vasoconstriction?
Caffeine is a commonly used neurostimulant that also produces cerebral vasoconstriction by antagonizing adenosine receptors. Chronic caffeine use results in an adaptation of the vascular adenosine receptor system presumably to compensate for the vasoconstrictive effects of caffeine.
What are the three factors that influence peripheral resistance?
Three main sources of peripheral resistance: Blood vessel diameter, blood viscosity, and total vessel length. If arteries lose their elasticity and become more rigid, blood pressure increases.
Is resistance higher in veins or arteries?
In the arterial system, as resistance increases, blood pressure increases and flow decreases. In the venous system, constriction increases blood pressure as it does in arteries; the increasing pressure helps to return blood to the heart.