Regulation of Body Temperature - Lecture 6

Question 1

What components of our bodies must be kept within narrow homoeostatic ranges? (5)

Answer 1

Pressures and volumes

Body Temperature

Concentration of nutrients e.g. glucose

Concentration of O2 and CO2

concentration of waste products e.g. urea

Question 2

In terms of temperature control, how can the body be divided?

Answer 2

Core

Outer Shell

Question 3

What is the outer shell composed of? (2)

Answer 3

Skin

Subcutaneous Tissue

Question 4

How is the Core Temperature maintained?

Answer 4

By Homoeostasis - Involving a negative feedback system

Question 5

What is a normal Core body temperature?

Answer 5

37.8°C

Question 6

What happens to the Core Body temperature in environmental changes?

Answer 6

The Core Temperature is kept constant (37.8°C)

Question 7

What is Normothermia?

Answer 7

The normal core body temperature (normothermia) is optimum for cellular metabolism and function

Question 8

What does increased body temperature do?

Answer 8

Increase cellular metabolism

Question 9

What does overheating of the body cause?

Answer 9

Protein denaturation
Nerve malfunction
Convulsions
Death

Question 10

How can the Core Body Temperature be defined?

Answer 10

The temperature of structures deep within the body

Question 11

What does decreased body temperature cause to the body?

Answer 11

Slows down the rate of cellular reactions.

Question 12

What are the site for monitoring temperature?

Answer 12

Ear Drum (Tympanic)
Rectal
Oral

Question 13

What is the range for temperature of the Tympanic site?

Answer 13

35.5°C - 37.5°C

Question 14

What is the range for temperature of the Rectal site?

Answer 14

36.7°C - 37.5°C

Question 15

What pattern does body temperature display?

Answer 15

Diurnal Variation

Question 16

What point of the day is temperature at its lowest?

Answer 16

Morning

Question 17

What must be equal for core body temperature to stay constant?

Answer 17

Heat gain and heat loss must be equal

Question 18

How is heat gained from the internal environment?

Answer 18

Metabolic Heat

Question 19

How is heat gained from the the external environment? (3)

Answer 19

Radiation
Convection
Conduction

Question 20

How is heat lost to the external environment? (4)

Answer 20

Convection
Conduction
Radiation
Evaporation

Question 21

How is Metabolic heat produced?

Answer 21

Oxidation of metabolic fuel derived from food in the body

Question 22

What is the Basal Metabolic Rate (BMR)?

Answer 22

Minimum amount of energy required to sustain vital body functions

Question 23

How can the BMR be increased? (3)

Answer 23

Hormones
Muscle Activity
Shivering

Question 24

What leads to the basic level of Heat Production?

Answer 24

Basal Metabolic Rate (BMR)

Question 25

What are the hormones that increase the BMR? (3)

Answer 25

Adrenaline Noradrenaline Thyroxine

Question 26

What is Radiation of heat?

Answer 26

Emission of heat energy in the form of electromagnetic waves from a surface - The body emits and absorbs radiant heat

Question 27

What is conduction of heat?

Answer 27

Transfer of heat between objects in contact Heat moves from warmer to cooler object

Question 28

What does Conduction depend upon?

Answer 28

Heat conduction depends on temperature gradient and thermal conductivity

Question 29

What is Convection of heat?

Answer 29

Transfer of heat energy by air (or water) currents that help to carry the heat away from the body

Question 30

What two forms of heat transfer are combined to dissipate heat from the body?

Answer 30

Convection | Conduction

Question 31

What is Evaporation of heat transfer?

Answer 31

Energy is required to convert water in the skin surface and the lining of the respiratory airways into vapour energy comes from the body resulting in evaporative heat loss - cools the body

Question 32

What is Passive Evaporative Heat Loss?

Answer 32

Water molecules continuously passively diffuse from the surface of the skin and the linings of the respiratory airways

Question 33

What is Active Evaporative Heat Loss?

Answer 33

Sweating is an active evaporative heat loss process controlled by the sympathetic nervous system

Question 34

What affects the amount of evaporation?

Answer 34

Relative Humidity

Question 35

What is required a negative feedback system?

Answer 35

Sensor Control Centre Effectors

Question 36

What are the sensors of the negative feedback system for Temperature Control? (2)

Answer 36

``` Central thermoreceptors (in hypothalmus, abdominal organs, elsewhere) Peripheral thermoreceptors (in skin) ```

Question 37

What the control centre of the negative feedback system for Temperature Control?

Answer 37

Hypothalamus

Question 38

What are the effectors of the negative feedback system for Temperature Control? (2)

Answer 38

Skeletal Muscles Skin Arterioles Sweat Glands

Question 39

Where are the negative feedback receptors for temperature regulation located on the Hypothalamus?

Answer 39

The Neural Inputs of the Hpothalamus

Question 40

What part of the Hypothalamus is activated by cold?

Answer 40

The Posterior Hypothalamic Centre

Question 41

What part of the Hypothalamus is activated by warmth?

Answer 41

The Anterior Hypothalamic Centre

Question 42

What systems does the Hypothalamus have connections with?

Answer 42

Limbic System Cerebral Cortex Motor Neurones - control skeletal muscles Sympathetic Nervous System

Question 43

What is the response of the Skin Arterioles when exposed to cold?

Answer 43

Vasoconstriction - Decreases heat loss

Question 44

What is the response of the Skeletal Muscle when exposed to cold? (3)

Answer 44

Increased muscle tone Shivering Increased voluntary movement

Question 45

What is the response of the Skin Arterioles when exposed to Heat?

Answer 45

Vasodilation - Increased Heat Loss

Question 46

What is the response of the Sweat Glands when exposed to Heat?

Answer 46

Sweating - Evaporation of sweat Increased Heat Loss

Question 47

What is the response of the Skeletal Muscle when exposed to Heat? (3)

Answer 47

Decreased muscle tone Decreased voluntary Movement Decreased heat Production

Question 48

What is an endogenous pyrogen?

Answer 48

Stimulate the release of prostaglandins in the hypothalamus

Question 49

What is the function of a Postaglandin?

Answer 49

prostaglandins act on the hypothalamic thermo-regulatory centre to “reset” the thermostat at a higher temperature

Question 50

What action does the Hypothalamus carry out when prostaglandins act on the it?

Answer 50

Hypothalamus initiate mechanisms to heat the body “cold response" to raise the body temperature to the new higher temperature, resulting in Fever

Question 51

How is the Hypothalamic temperature set point raised? (6)

Answer 51

- Infection causes Macrophages to release chemical to produce endogenous pyrogen Release of Postaglandins Hypothalamic set point increased Initiation of cold response Heat Production increase - heat loss decreased Increased Body Temperature

Question 52

What temperature is the new set point for a fever?

Answer 52

38°C - 40°C

Question 53

What is hyperthermia?

Answer 53

Extreme uncontrolled increase in body temperature | Temperature above 40°C

Question 54

What is hypothermia ?

Answer 54

Drop in body temperature below that required for cellular metabolism Temperature at or below 35°C