2.11B. Splanchnic circulation and circulation of the skin.

Question 1

I. Splanchnic circulation
1. Definition of Splanchnic circulation

Answer 1

• Describes the flow to the abdominal organs (GI, liver, spleen, pancreas)
• Blood originating from celiac A, superior mesenteric and inferior A

Question 2

I. Splanchnic circulation
2. What are the functions of Splanchnic circulation

Answer 2

Splanchnic circulation serves both as:
1. Site of adjustable resistance
2. Major reservoir of blood
-> Extensive interconnections between arterial branches provide collateral pathways through which blood can reach different parts
-> Lessens the risk of ischemia during arterial occlusion

Question 3

I. Splanchnic circulation
3. What is the value of splanchnic blood flow?

Answer 3

QS = 1500mL/min

Question 4

II. Regulation of Splanchnic circulation
1. How do we regulate Splanchnic circulation?

Answer 4

1. Increased blood flow during gastrointestinal activity
2. Nervous control of GI flow
3. Autoregulation

Question 5

II. Regulation of Splanchnic circulation
2A. How do we regulate Splanchnic circulation with Increased blood flow during gastrointestinal activity?

Answer 5

• Blood flow increases by the release of vasodilator substances from mucosa of intestinal tract like choleocystokinin, gastrin, and secretin.
• Decreased oxygen conc. in gut wall can increase intestinal blood flow and lead to an increase of adenosine => VASODILATION

Question 6

II. Regulation of Splanchnic circulation
2B. What is Postprandial circulation?

Answer 6

• Postprandial circulation: is an increase in blood flow through GI-tract after a meal

Question 7

II. Regulation of Splanchnic circulation
3. How do we regulate splanchnic circulation by Nervous control of ganstrointestinal flow?

Answer 7

• Stimulation of parasympathetic nerves going to stomach and lower colon increases local blood flow at stomach.
• Sympathetic stimulation causes intense vasoconstriction of the arterioles (⍺1-R).
  => This allows shutoff of GI and other splanchnic blood flow for short periods during exercise for example, when the skeletal muscle and heart need increased flow.

Question 8

II. Skin circulation
1. What is the value for skin blood flow?

Answer 8

• Qskin = 100-300 mL/min

Question 9

II. Skin circulation
2. What are the characteristics of Skin circulation?

Answer 9

Skin has blood vessels with dense sympathetic innervation, which alter blood flow for regulation of body temperature.

Question 10

II. Skin circulation
3. How is skin circulation regulated?

Answer 10

1/ ↑body temp→ sympathetic centers controlling cutaneous blood flow is inhibited→ vasodilation.
=> Increased circulation serves for heat loss
=> Qskin >7000 ml/mins

2/↓body temp→ activation of sympathetic→ vasoconstriction.
=> Qskin <100 ml/mins