Thermoregulation

Question 1

Define core temperature?

Answer 1

Operating temperatures of the internal environment of a resting body

Question 2

State values for:

Hyperpyrexia:
Hyperthermia:
Primary (initial) hyperthermia:
Normal:
Mild Hypothermia:
Moderate Hypothermia:
Severe Hypothermia:

Answer 2

Hyperpyrexia: >40
Hyperthermia: 38 - 40
Primary (initial) hyperthermia: 37.5 - 38
Normal: 36.5 - 37.5
Mild Hypothermia: 32 - 36.5
Moderate Hypothermia: 28 - 32
Severe Hypothermia: <28

Question 3

Where are the thermoreceptors found for external and core temperature?

Answer 3

External: Skin
Core: Pre-Optic Area in the hypothalamus

Question 4

Where is the controller for thermoregulation found and what does it do?

Answer 4

Found in the Pre-optic Area of the hypothalamus

Uses the signals from thermoreceptors to generate a correcting (actuating) signal for the effectors.

Question 5

What are the effectors and how do they work?

Answer 5

Sweat glands: lower external temperature when secreted sweat evaporates from the surface of the skin

Skeletal muscle: raise the core temperature in the limbs when they contract rapidly (hydrolysing ATP) and releasing energy

Arterioles (primary effectors): can lower/raise core temperature by dilating/contracting allowing more/less conductance through the skin

Question 6

What is pyrexia and why do our body’s do it?

Answer 6

Raised core temperature due to infection/injury

Prevent the multiplication of bacteria

Question 7

How is pyrexia caused?

Answer 7

Pyrogens are released into the blood and cause; vasoconstriction, increased metabolic rate, decreased blood flow to the limbs (+ heat exchange via venae comitantes).
(Shivering in the extremities causes limb temperature to increase)

Question 8

What complications are there of pyrexia in the young?

Answer 8

Febrile seizures (children aged 6 months - 6 years):
Simple: single, short, whole-body
Complex: multiple, long, part of the body

Question 9

What complications are there of pyrexia in the old?

Answer 9

Decreased ability to shiver
Impaired hypothalamus (temperature set-point may be wrong)