Hydrostatic Pressure in Capillaries Quiz

Hydrostatic Pressure in Capillaries Under Different Conditions

• Arteriolar vasoconstriction (sympathetic stimulation): Hydrostatic pressure in the capillary decreases. Constriction reduces blood flow into the capillary bed, thus reducing pressure within.

• Arteriolar vasodilation (exercise): Hydrostatic pressure in the capillary increases. Dilation increases blood flow into the capillary bed, raising pressure within.

• Venular hypertension (heart failure): Hydrostatic pressure in the capillary increases. Elevated pressure in the venules forces fluid into the surrounding tissues.

• Arteriolar vasoconstriction with venular hypertension: Hydrostatic pressure in the capillary increases. While constriction lowers pressure entering the capillary, if venular pressure exceeds the force of resistance from the constriction, the overall effect is increased pressure.

Blood Flow Through Capillary Beds and Poiseuille's Law

• Poiseuille's Law: Describes pressure-driven flow, stating that blood flow through a vessel is directly proportional to the pressure difference and the fourth power of the vessel radius and inversely proportional to the vessel length and the viscosity.

• Resistance: Increased resistance in the capillaries means decreased blood flow. Resistance is influenced by factors like vessel diameter, vessel length, and viscosity. Resistance opposes blood flow.

• Pressure: Pressure differences drive blood flow. A higher pressure gradient leads to faster flow. Blood flows from higher pressure to lower pressure.

• Viscosity/Hematocrit: Viscosity (resistance to flow) increases with higher hematocrit (proportion of red blood cells in blood). Increased viscosity reduces blood flow through the capillary bed. A higher hematocrit makes the blood thicker, impeding its movement.

Test your understanding of hydrostatic pressure in capillaries under different physiological conditions. This quiz covers concepts related to arteriolar vasoconstriction, vasodilation, and the effects of heart failure on blood flow. Prepare to explore the implications of Poiseuille's Law in relation to capillary function.