y4.1 homeostasis ⚖ Flashcards
define homeostasis
homeostasis is the maintenance of a constant internal environment within tolerable limits
What factors are regulated by homeostasis?
1) temperature
2) blood glucose concentration
3) water potential of blood
4) pH of bodily fluids
structures of the skin (refer to diagram)
- capillaries
- hair shaft
- hair erector muscle
- sweat gland
- thermoreceptor
- (underneath:) adipose tissue
describe the general process of the negative feedback mechanism
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
describe the body response to increase in body temperature
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
describe the body response to decrease in temperature
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
what is the importance of maintaining blood glucose concentration?
- 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
describe the body response to increase in blood sugar concentration
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
describe the body response to decrease in blood sugar concentration
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
what is the cause of type 1 diabetes?
caused by deficiency of insulin, where pancreas is unable to produce insulin
what is the treatment for type 1 diabetes?
insulin injections
what is the cause of type 2 diabetes?
body resistance to insulin
what is the treatment for type 2 diabetes?
lifestyle changes, regulating diet and exercising
why is glucose present in the urine of a diabetes patient?
elevated blood glucose levels exceed the reabsorption capacity of the kidneys, causing the glucose to remain in the filtrate
what is osmoregulation?
osmoregulation is the maintenance of a correct balance between water and dissolved solute in the blood to maintain constant water potential in the body
