Venous Hemodynamics Flashcards
What is the primary function of the venous system?
The primary function of the venous system is to return blood from the capillaries back to the heart and act as a reservoir to maintain homeostasis.
What percentage of blood volume is typically found in the veins?
Approximately 65% of blood volume is found in the veins.
What factors affect venous compliance and capacitance? 4
Venous compliance and capacitance are affected by
1. Limb position
2. Muscle pump activity
3. Venous valve function
4. Blood volume.
How does compliance of the venous system affect venous flow?
The compliance of the venous system allows for a large increase in venous flow without significant increases in venous pressure.
What mechanisms aid in the return of blood through the veins against gravity? 4
The mechanisms include
1. Cardiac function
2. Respiratory function
3. Skeletal muscle contraction
4. Venous valves.
How does cardiac function affect venous return?
Changes to the heart during systole and diastole affect venous return, particularly in central vessels.
What is the A-wave in venous flow?
The A-wave demonstrates retrograde flow during atrial systole.
What happens during ventricular systole in terms of venous flow?
Ventricular systole creates a pressure gradient that draws blood into the right atrium, resulting in the S-wave.
What is respirophasicity?
Respirophasicity refers to the changes in venous flow in response to respiration.
How does muscle contraction affect venous blood flow?
Muscle contraction increases pressure outside the vein, forcing blood to move towards the heart.
What role do venous valves play?
Venous valves direct blood flow back to the heart and prevent retrograde flow.
What is hydrostatic pressure?
Hydrostatic pressure is the pressure exerted by a column of blood at any given point, influenced by gravity and patient position.
What is transmural pressure?
Transmural pressure is the difference between intraluminal and interstitial pressures, determining the shape of a vein.
What is the Valsalva maneuver?
The Valsalva maneuver increases thoracic and abdominal pressure, affecting venous flow.
What is an abnormal response to the Valsalva maneuver?
An abnormal response is a reversal of flow, indicating possible valve insufficiency.
