Things that control venous pressure

Question 1

What are two determinants of venous pressure?

Answer 1

hormones and paracrine factors which lead to venodilation/venoconstriction

Question 2

What can cause venoconstriction?

Answer 2

the sympathetic nervous system

Question 3

How does the sympathetic nervous system lead to venoconstriction?

Answer 3

the sympathetic nervous system releases noradrenaline which binds to α1-adrenergic receptors. This leads to venocontriction

Question 4

What is the effect of venoconstriction?

Answer 4

increased flow

Question 5

How does posture affect venous pressure?

Answer 5

horizontal: similar pressure throughout the body
vertical: blood pressure differs (it is higher below the heart than above the heart)

Question 6

How does thermoregulation change blood distribution?

Answer 6

Cutaneous veins dilate in extreme heat

Question 7

How does inhalation facilitate venous return?

Answer 7

The diaphragm contracts, decreasing the intrathoracic pressure and increasing the intra-abdominal pressure to pull blood into the superior vena cava and compresses the inferior vena cava to facilitate venous return

Question 8

How does exhalation affect venous return?

Answer 8

During exhalation, the diaphragm relaxes which increases the intrathoracic pressure and decreases the intra-abdominal pressure. This would push blood the other way but the valves prevent the backflow