Homeostasis

Question 1

Define homeostasis

Answer 1

The maintenance of a constant internal environment within tolerable limits

Question 2

Why is homeostasis important

Answer 2

To achieve a certain degree of independence from the external environment, so internal environment is maintained in an optimal condition and state of maximum efficiency for optimal functioning of physiological processes.

Question 3

What is the sequence of events to restore the body back to optimal state(norm) called

Answer 3

Corrective actions

Question 4

Sequence of events in negative feedback mechanism

Answer 4

Stimulus > Receptor > Control Centre > Effector(s) > Negative Feedback > Receptor

Question 5

How does body detect temperature change internally

Answer 5

Thermoreceptors located in the hypothalamus detect internal temperature changes by monitoring the temperature of blood flowing through it

Question 6

How does body detect temperature change externally

Answer 6

Thermoreceptors located in the skin detect external temperature changes

Question 7

How are nerve impulses sent from thermoreceptors

Answer 7

Thermoreceptors send nerve impulses to hypothalamus. Hypothalamus sends nerve impulses to various effectors for them to carry out corrective actions

Question 8

Corrective action: Arterioles in skin when temperature increases

Answer 8

Vasodilation > More bloody to flow into capillaries near skin surface > more heat lost to surroundings by (all three)

Question 9

Corrective action: Sweat glands when temperature increases

Answer 9

Sweat glands become more active > sweat production ^, water in sweat evaporates, remove latent heat of vapourisation from body

Question 10

Corrective action: Erector muscle when temperature increases

Answer 10

Relax; Hair shafts flatten and allow free circulation of air over hairs > Moving air conducts heat away from body

Question 11

Corrective action: Liver when temperature increases

Answer 11

Metabolic rate decreases so less heat is released

Question 12

Corrective action: Arterioles when temperature decreases

Answer 12

Vasoconstriction of arterioles allows less blood flow to capillaries near the skin surface. Less heat lost by all three and heat is conserved in the body

Question 13

Corrective action: Sweat glands when temperature decreases

Answer 13

Sweat glands become less active and sweat production decreases, skin comparatively dry, no evaporation, no cooling effect

Question 14

Corrective action: Erector muscles when temperature decreases

Answer 14

Contracts, hair shafts become perpendicular to skin surface, trapping air. Trapped air is poor conductor of heat so heat is retained to keep the skin warm

Question 15

Corrective action: Liver when temperature decreases

Answer 15

Increase metabolic rate, more heat is released

Question 16

Corrective action: Skeletal muscles when temperature decreases

Answer 16

Skeletal muscles undergo spasmodic contraction. Releases heat due to muscle respiration to release energy for contractions. Not effective for long periods of time

Question 17

What happens after body temperature returns to normal

Answer 17

Body temperature increases/decreases back to norm, negative feedback is sent to control centre via the receptors to stop further corrective actions