homeostasis

Question 1

what happens when glucose concentration rises

Answer 1

stimulus: BGC rises above normal levels
receptor: islets of langerhans in pancreas stimulated
corrective mechanism: IoL secretes more insulin which is transported by blood to liver and muscle
-permeability of cell surface membrane to glucose increase
-liver and muscles convert excess glucose into glycogen stored in liver and muscles
-BGC falls and insulin production decreases, BGC returns to normal

Question 2

what happens when blood water potential falls

Answer 2

-BWP falls during sweating
-osmoreceptors in the hypothalamus is stimulated
-posterior pituitary glands secrete more ADH that increases permeability of collecting duct to water and more water is reabsorbed by kidney tubules
-urine is more concentrated and less is produced, so less water is excreted
-BWP rises and returns to normal

Question 3

osmoregulation is fish

Answer 3

-ocean is hypotonic to fish and loses water through gills and and skin, hence little urine production, large water intake and active transport to remove excess salts at gills
-freshwater is hypertonic to fish and takes in too much water and too little salt, hence production of dilute urine active transport at gills to take in salts

Question 4

features of epidermis

Answer 4

water resistant outer cornified to prevent uncontrolled water loss, entry of microorganisms and prevent mechanical injury
-malpighian layer that contains pigment giving skin colour, protect skin from harmful ultra violet rays from sun

Question 5

regulating body temperature on a hot day

Answer 5

-blood and skin temperature rises
-temperature receptors detect changes and sends signals to the brain
-hypothalamus stimulated and sends signals to revenant body parts
-arterioles in skin dilate and more warm blood flows to capillaries in skin, heat radiates from skin surface
-sweat gland more active, sweat production increase, more latent heat loss as sweat evaporates