Lecture 3- Skin blood flow

Question 1

How is skin blood flow controlled?

Answer 1

Smooth muscle in the walls of arteries and pre-capillary sphincters are innervated by the sympathetic nervous system. Noradrenaline acts on alpha 1 receptors on the vascular smooth muscle in the skin.

Question 2

What do G-protein coupled receptors do?

Answer 2

They couple to intracellular 2nd messengers, which increases intracellular calcium. This leads to restriction and eventually reduced blood flow

Question 3

What does reducing SNS activity cause?

Answer 3

Relaxation (dilation) of the arteries to the skin, which increases skin blood flow.

Question 4

What happens when body temperature increases?

Answer 4

The hypothalamus contains a pre-optic area which contains both the cold and hot sensitive neurons (central thermoreceptors). If blood temperature goes above the set point, the heat loss centre is activated. SNS activation of a1 on skin blood vessels decreases causing vasodilation, and there is an increase in sweating.

Question 5

What happens when core body temp is below the set point?

Answer 5

It detects the heat gain centre. This includes increasing the generation of body heat. Non-shivering themogenesis and shivering thermogenesis. There is a need for conservation of body heat.

Question 6

What happens when core body temp is below the set point?

Answer 6

It detects the heat gain centre. This includes increasing the generation of body heat. Non-shivering themogenesis and shivering thermogenesis. There is a need for conservation of body heat.

Question 7

Primary mechanisms of heat transfer include
A. Evaporation, radiation, convection and conduction.
B. Radiation, respiration, convection and transduction
C. Thermoregulation, vasodilation, evaporation and thyroxinesecretion
D. Convection, conduction, evaporation and respiration

Answer 7

A

Question 8

Shivering

Answer 8

Increased tone of skeletal muscles, when tone is above critical level, shivering begins due to oscillatory contractions of both antagonist and agonist muscles mediated by muscle spindles.

Question 9

Non-shivering thermogenesis

Answer 9

Increased SNS and increased circulating, increased cellular metabolism (increased glycogenolysis in liver and muscle). Heat produced instead of ATP

Question 10

What are the potential complications of burns?

Answer 10

• Dehydration and hypovolemic shock
• Infection and sepsis
• Hypothermia