Venous Return Mechanisms
- Created by: Elise_parfitt
- Created on: 12-06-19 10:16
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- Venous Return Mechanisms
- Pocket Valves
- One-way valves located in the veins which prevent the backflow of blood.
- Gravity
- Blood from the upper body, above the heart, is helped to return by gravity.
- Smooth Muscle
- The layer of smooth muscle in the vein wall venoconstricts to create venomotor tone which aids the movement of blood.
- Muscle Pump
- During exercise, skeletal muscles contract compressing the veins located between them, squeezing the blood back to the heart.
- Respiratory Pump
- During inspiration and expiration, a pressure difference between the thoracic and abdominal cavity is created, squeezing the blood back to the heart. As exercise increases respiratory rate, the respiratory pump is maximised.
- After we finish exercising and enter recovery, cardiac output is still high.
- However, there may not be sufficient pressure to return the vast quantity of blood back to the heart. This can cause feelings of being lightheaded or dizzy.
- Equally, this blood may sit in the pocket valves and pool. This is known as blood pooling and is often described as the feeling of 'heavy legs' after exercise.
- To combat this effect and maintain venous return, it is essential to complete an active recovery (cool down). This low-intensity exercise maintains the muscle and respiratory pump to aid the return of blood to the heart.
- Equally, this blood may sit in the pocket valves and pool. This is known as blood pooling and is often described as the feeling of 'heavy legs' after exercise.
- However, there may not be sufficient pressure to return the vast quantity of blood back to the heart. This can cause feelings of being lightheaded or dizzy.
- Pocket Valves
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