homeostasis Flashcards
what secrete the alpha and beta cells?
and which hormones do each cell secrete?
🌄🌕🌙💞
islets of langerhan
alpha- glucagon
beta- insulin
what if blood glucose levels are too high?
🤍
insulin is secreted from beta cells
triggers liver and muscle cells to take up glucose (& store as glycogen)
inverts glucose to glycogen (glycogenesis)
cells respire more glucose
define homeostasis🌃
the regulation of a cell or organism to maintain stable optimum conditions in response to internal and external changes
define hormone🌞
chemical messages secreted by the glands of the endocrine system- they’re released directly into the blood stream by endocrine glands and travel to cells in the blood- they have a specific comp receptor- these are the target cells
endocrine systems def🌺
this uses hormones which are released form specialised tissues called glands and travel through the blood stream to various effector organs
why is glucose constantly needed in cells?🧚🏼♀️
to produce ATP and provide energy. also contributes to the water potential of blood outside the cells
what’s ultrafiltration?🧜🏼♀️
the wider lumen of the afferent than efferent arteriole causes high hydrostatic pressure which forces small molecules out of blood plasma into the bowman’s capsule. capillary walls + filtration slits stop large molecules entering filtrate
what’s selective re absorption?🧞♀️
as the glomerular filtrate moves through the PCT, 85% of it is reabsorbed into the blood, including: all the glucose and AA, most the water, some ions.
cells lining the PCT are adapted to maximise absorption
describe part 1 of the reabsorption of water👑
loop of henle creates a low water pot in the medulla. na+ are AT out the ascending limb to the descending limb which incs the conc of na+ in medulla- lowering the water pot in the tissue around the loop. water follows this down the osmotic gradient and is reabsorbed into the blood. filtrate passes into the DCT where even more water is reabsorbed to blood by osmosis.
describe part 2 of the reabsorption of water in the blood🌙
concentration of urine enters the collecting duct. the permeability of the memb of this part of the nephron is regulated by ADH in blood. osmoreceptors in the hypothalamus control the release of ADH from the pituitary gland in the brain and its controls how much enters the urine.
where does ultrafiltration occur?🌑
which arteritole enters and leaves the glomerulus?🌑
what is the glomerulus?🌑
glomerulues
afferent enters
efferent leaves
bundle of capillaries
which arteriole has a wider lumen?🏰
afferent
role of the renal artery?🤍
role of the renal vein?🤍
artery-supplies the kidney with blood from the heart via the aorta
vein-returns blood to the heart via the vena cava
why does the urine not contain:
protein and blood cells?
glucose?
💍
p+bc: proteins are too large to be filtered out the blood
g: all glucose is absorbed at the selective reabsorption stage in the PCT
selective reabsorption adaptations?🦜
microvilli provide a large SA for reabsorption
lots of mitochondria provide energy for AT
