y4.1 homeostasis ⚖

Question 1

define homeostasis

Answer 1

homeostasis is the maintenance of a constant internal environment within tolerable limits

Question 2

What factors are regulated by homeostasis?

Answer 2

1) temperature
2) blood glucose concentration
3) water potential of blood
4) pH of bodily fluids

Question 3

structures of the skin (refer to diagram)

Answer 3

• capillaries
• hair shaft
• hair erector muscle
• sweat gland
• thermoreceptor
• (underneath:) adipose tissue

Question 4

describe the general process of the negative feedback mechanism

Answer 4

stimulus (internal/external) -> receptor sends signals to -> control centre send signals to -> effectors carry out corrective actions to bring back to -> norm -> negative feedback is sent to the control centre via receptors to stop further corrective action

Question 5

describe the body response to increase in body temperature

Answer 5

1) thermoreceptors in the hypothalamus (internal) or skin (external) detect an increase in body temp
2) thermoreceptors send nerve impulses to the hypothalamus. hypothalamus sends nerve impulses to the various effectors:
- arterioles in skin carry out vasodilation for more blood flow to capillaries near skin surface to increase heat lost by conduction, convection and radiation
- sweat glands become more active, sweat production increases, more heat lost to latent heat of vapourisation
- liver decreases metabolic rate to release less heat in the body
3) body temperature returns to norm
4) negative feedback is sent to the control centre via the receptors to prevent further corrective action

Question 6

describe the body response to decrease in temperature

Answer 6

1) thermoreceptors in hypothalamus (internal) or skin (external) detect a decrease in body temperature
2) thermoreceptors send nerve impulses to the hypothalamus. hypothalamus sends nerve impulses to the effectors:
- arterioles in skin undergo vasoconstriction to reduce blood flow into capillaries near skin, decreasing heat lost by conduction, convection and radiation
- sweat glands become less active, sweat production decreases and less heat is lost to latent heat of vapourisation
- liver increases metabolic rate to release more heat
- [drastic] skeletal muscles undergo spasmodic contractions to release heat due to muscular respiration
- [animals] hair erector muscles contract, hair shafts become perpendicular to skin, trapping air. air is a poor conductor of heat, hence heat is retained to keep skin warm
3) body temperature increases to norm
4) negative feedback is sent to the control centre via the receptor to stop further corrective action

Question 7

what is the importance of maintaining blood glucose concentration?

Answer 7

• if blood glucose is too high, water inside body cells will leave the cells via osmosis
• if blood glucose is too low, brain cannot receive sufficient glucose

Question 8

describe the body response to increase in blood sugar concentration

Answer 8

1) pancreas detects the increase in blood sugar concentration and secretes more insulin. blood transports insulin to body cells, stimulating effectors:
- promotes the uptake of glucose by almost all body cells, especially liver, muscle and adipose tissue
- stimulates liver and muscle cells to convert excess glucose into glycogen to be stored
2) blood sugar concentration decreases back to norm
3) negative feedback is sent back to the pancreas to prevent further corrective action

Question 9

describe the body response to decrease in blood sugar concentration

Answer 9

1) pancreas detects a decrease in blood sugar concentration and secretes more glucagon. blood transports glucagon to liver and muscles, stimulating:
- liver and muscles to convert glycogen into glucose
- liver to increase the release of glucose into blood
2) blood sugar concentration increases back to norm
3) negative feedback is sent back to the pancreas to stop further corrective action

Question 10

what is the cause of type 1 diabetes?

Answer 10

caused by deficiency of insulin, where pancreas is unable to produce insulin

Question 11

what is the treatment for type 1 diabetes?

Answer 11

insulin injections

Question 12

what is the cause of type 2 diabetes?

Answer 12

body resistance to insulin

Question 13

what is the treatment for type 2 diabetes?

Answer 13

lifestyle changes, regulating diet and exercising

Question 14

why is glucose present in the urine of a diabetes patient?

Answer 14

elevated blood glucose levels exceed the reabsorption capacity of the kidneys, causing the glucose to remain in the filtrate

Question 15

what is osmoregulation?

Answer 15

osmoregulation is the maintenance of a correct balance between water and dissolved solute in the blood to maintain constant water potential in the body

Question 16

what is the body response to increase in water potential?

Answer 16

1) osmoreceptors in the hypothalamus detect an increase in water potential and sends nerve impulses to the hypothalamus
2) hypothalamus sends nerve impulses to the pituitary glands to release less anti-diuretic hormone (ADH) into the bloodstream, transported to the kidneys via blood
3) ADH stimulates the walls of the distal convoluted tubule and collecting duct to become less permeable to water
4) less water is reabsorbed back into blood
5) urine is more diluted, higher volume
6) water potential decreases back to norm
7) osmoreceptors send negative feedback to the hypothalamus to prevent further corrective action

Question 17

what is the body response to decrease in water potential?

Answer 17

1) osmoreceptors in the hypothalamus detect a decrease in water potential and send nerve impulses to the hypothalamus to release more anti-diuretic hormone (ADH) into the bloodstream, transported to kidneys via blood
2) ADH stimulates the walls of the distal convoluted tubule and collecting duct to become more permeable to water
3) more water is reabsorbed back into the bloodstream
4) urine is more concentrated, lower volume
5) water potential increases back to norm
6) osmoreceptors send negative feedback to the hypothalamus to prevent further corrective action