Regulation of Body Temp

Question 1

How is a fever initiated and what follows?

Answer 1

1.) fever caused by macrophage and dendritic cells phagocytosis of foreigner. They release cytokines. They turn up hypothalamic thermostat. Body temp will attempt to reach new setting.
2.) Mechanisms to raise body temp: vasoconstriction, shivering, epinephrine secretion, piloerection.
3.) Crisis: fever comes to end. Thermostat turned back down to normal. Have to get rid of heat. Mechanisms: Vasodilation, sweat

Cytokines reset hypothalamic thermostat via PROSTAGLANDIN E2.

Question 2

How does ambient air humidity affect body temperature regulation?

Answer 2

Evaporative cooling becomes less effective as ambient air humidity increases
- Sweat loss is less effective at cooling the body

Question 3

How do sweat glands contribute to regulation of body temperature?

Answer 3

Coiled glands thats producing sweat.

Coil cells secrete Cl-. Na+ follows this into lumen of duct. Water follows this too.

Secretion of sweat under sympathetic stimulation with release of ACETYLCHOLINE, NOT EPINEPHRINE.

Duct cells reabsorb Na+. Secretion rate = salt content. Sweat comes from this.

Question 4

What is meant by a hypothalamic thermostat?

Answer 4

the hypothalamus integrates the temperature signals from central (mostly) and peripheral temperature senses and regulates heat loss or heat production
o Heat loss through vasodilation of skin vasculature, sweating, and decreased heat production
o Heat production through shivering, non shivering/chemical thermogenesis, and long-term adaptation
- Heat/cold sensory found in anterior and preoptic nuclei
- Usually set around 37C/98.6F