Homeostasis

Question 0

Where does homeostasis occur?

Answer 0

Cellular and whole body level

Question 1

Define homeostasis?

Answer 1

Maintenance of a stable internal environment despite external changes

Question 2

What is homeostasis essential for?

Answer 2

Normal cell function

Question 3

What do your cells maintain?

Answer 3

Volume, pH, rate of division, ionic gradients, electrolyte concentration, rate of protein synthesis, level of nutrients & waste

Question 4

What is a negative feedback loop?

Answer 4

Control system within the body that acts to restore the level of some variable to within a given range following any disturbance

Question 5

What 3 things are required to form a feedback loop?

Answer 5

Receptors, integrator, effectors

Question 6

Under what condition can a negative feedback loop be reset or overridden?

Answer 6

Bp during exercise

Question 7

What makes positive feedback loop different to a negative one?

Answer 7

Magnifies a change, rather than negates it

Question 8

When would a positive feedback loop be present?

Answer 8

Childbirth, lactation, ovulation, blood clotting

Question 9

What happens to proteins when temperature reaches 42-43•c?

Answer 9

Become denatured (irreversible change)

Question 10

What are the 4 different types of heat transference?

Answer 10

Radiation, conduction, convection, evaporation

Question 11

What type of feedback loop is thermoregulation?

Answer 11

Negative

Question 12

What are the receptor, integrator & effectors in thermoregulation?

Answer 12

Thermoreceptors, hypothalmus, physical responses

Question 13

Where are thermoreceptors located?

Answer 13

Central nervous tissue & deep tissue

Question 14

Where are peripheral thermoreceptors located?

Answer 14

Skin

Question 15

Thermoregulators can only respond to one thing, what is this?

Answer 15

Either a fall or rise in temperature. Not both

Question 16

How does the hypothalmus work as part of a negative feedback loop?

Answer 16

Receives information from thermoreceptors and organises appropriate effectors

Question 17

Define effectors?

Answer 17

Strategies used by the body to restore normal levels

Question 18

Effectors can be put in 2 categories. What are they?

Answer 18

Physical & behavioural

Question 19

What responses does the body make to a fall in temperature?

Answer 19

Vasoconstriction of cutaneous blood vessels - blood flows to core away from surface, Shivering - muscles contract and relax very quickly to generate heat, Piloerection - hairs stand on end, Increased metabolic rate - heat is generated by the release of certain hormones

Question 20

What hormones are secreted to help raise temp by increasing the bodies metabolic rate?

Answer 20

Adrenaline & thyroxine

Question 21

What responses does the body make to a rise on temperature?

Answer 21

Vasodilation of cutaneous blood vessels - skin vessels widen so blood flows towards the skin (flushed), radiation, convection, conduction, hairs lie flat, sweating (evaporation)

Question 22

What gland in the secretes sweat?

Answer 22

Eccrine glands of the skin

Question 23

How much sweat is lost when cold?

Answer 23

Less than 500ml a day

Question 24

How much sweat is lost when hot?

Answer 24

1.5 & 6 litres per hour in very hot weather and exercise

Question 25

What do we loose from the body when we sweat?

Answer 25

Water & sodium chloride (salts)

Question 26

What is it vital to replace to prevent heat exhaustion?

Answer 26

Fluids & salts

Question 27

Why is thermoregulation harder for the elderly?

Answer 27

Thin skin, less hair, immobility, poor nervous system function, loss of subcutaneous fat, poor shivering, poor sweating

Question 28

Define pyrexia?

Answer 28

Raised core temperature that is not caused by exercise or the enviroment

Question 29

What can cause pyrexia?

Answer 29

Following infection by a virus or bacterium, hypothalmic set point is raised

Question 30

In hyperthermia the body temperature rises. What temperature is it safe for the body to raise to for short periods of time?

Answer 30

43•c

Question 31

What temperature for prolonged periods can lead to brain damage?

Answer 31

Excess of 40•c

Question 32

What are the features of heat stroke?

Answer 32

Hot dry skin, weak respiration, low bp, cerebral oedema, convulsions, coma, death

Question 33

Hypothermia is a drop in body temperature. At what temperature do your bodies thermoregulatory mechanisms fail?

Answer 33

33-34•c

Question 34

What are the signs of hypothermia?

Answer 34

Comatose, shivering stops, sluggish reflexes, mental confusion, hallucinations, feeling of wellbeing may precede loss of consciousness, cardiac arrhythmias may occur leading to death from heart failure!