Sage-Tips

Why is hydrostatic pressure lower at the venous end?

The force of hydrostatic pressure means that as blood moves along the capillary, fluid moves out through its pores and into the interstitial space. This movement means that the pressure exerted by the blood will become lower, as the blood moves along the capillary, from the arterial to the venous end.

Why is the filtration pressure higher on the arterial end versus the venous end of a capillary?

the net filtration pressure of the blood is higher at the arterial end than it is at the venous end. The fluids reenter the capillaries at the venous end because… the net filtration pressure of the blood is higher at the arterial end than it is at the venous end.

Which end of a capillary has the greatest hydrostatic pressure?

arteriolar end
This pressure drives fluid out of the capillary (i.e., filtration), and is highest at the arteriolar end of the capillary and lowest at the venular end. Depending upon the organ, the pressure may drop along the length of the capillary by 15-30 mmHg (axial or longitudinal pressure gradient).

How does capillary pressure compare to arterial and venous pressure?

The value of R a/R v is typically 4 or more in systemic organs, so capillary pressure is more sensitive to venous pressure than to arterial pressure. This is why venous congestion affects filtration rate so markedly (see Figure 9.3).

Why hydrostatic pressure is more in arteries than veins?

Blood pressure in the arteries is much higher than in the veins, in part due to receiving blood from the heart after contraction, but also due to their contractile capacity. The tunica media of arteries is thickened compared to veins, with smoother muscle fibers and elastic tissue.

What is increased capillary hydrostatic pressure?

Increased capillary hydrostatic pressure (as occurs when venous pressures become elevated by gravitational forces, volume expanded states, in heart failure or with venous obstruction) Decreased plasma oncotic pressure (as occurs with hypoproteinemia)

Why does most filtration take place at the arterial end of a capillary?

Why does most filtration take place at the arterial end of a capillary? **CHP is higher at the arterial end. Fenestrations are larger in diameter. There are more solutes to be filtered there.

What happens at the arterial end of a capillary?

At the arterial end of the capillary, hydrostatic pressure exceeds oncotic pressure, so fluid moves out of the capillary into the interstitial compartment. At the venous end of the capillary, the two forces are reversed, so fluid moves back from the tissue into the capillary.

What increases capillary hydrostatic pressure?

An increase in small artery, arteriolar, or venous pressure will increase the capillary hydrostatic pressure favoring filtration. A reduction of these pressures will have the opposite effect.

How does venous pressure affect capillary hydrostatic pressure?

Hydrostatic Forces Under physiologic conditions, the average capillary hydrostatic pressure is estimated to be about 17 mm Hg. An increase in small artery, arteriolar, or venous pressure will increase the capillary hydrostatic pressure favoring filtration. A reduction of these pressures will have the opposite effect.

Do capillaries have more resistance than arteries?

Therefore, a parallel arrangement of vessels greatly reduces resistance to blood flow. That is why capillaries, which have the highest resistance of individual vessels because of their small diameter, constitute only a small portion of the total vascular resistance of an organ or microvascular network.