b3.3 spec - maintaining water levels Flashcards
if the blood is a higher water potential than animal cells, what is the effect?
water moves into cells through osmosis, causes them to swell and may burst
(no cell wall)
called LYSIS
what condition would cause cells to shrink?
and how do they shrink
- too high solute in bloodstream
- lower water potential in bloodstream compared to cells
- so water moves out of blood cells
what does urine contain?
urea, excess salts, excess water
how does the kidney maintain water balance of the body?
controls the amount and concentration of urine (which affects the amount of water excreted/in the bloodstream)
describe how urine ends up in the bladder (3)
kidneys filter urea out of blood
urine trickles through ureter
which leads to bladder which stores urine
what is the role of the renal artery?
brings blood containing urea + other substances to kidney
what is the role of the renal vein?
carries blood away from kidney (once substances have been removed)
what is the role of the urethra?
a tube where urine passes to the outside of the body (from bladder)
what causes urea to be produced (and where is it produced)?
- produced in the liver
- waste product of protein synthesis
GO TO ANKI FOR KIDNEY + NEPHRON STRUCTURE
GO WHEN DONE
what kind of feedback loop is volume of urine controlled by?
a negative feedback loop
what detects water levels in the bloodstream?
hypothalamus
what releases ADH?
pituitary gland
what does ADH do?
- makes collecting ducts more permeable to water
- more water reabsorbed into the blood
when would ADH be released?
- when blood water potential is too low
want less water to be wasted
describe the process that goes on in the kidneys to produce urine (7)
1) blood enters kidney under high pressure (from renal artery)
2) each end of renal artery leads to a glomerulus
3) blood vessels narrow and pressure increases
4) this forces small molecules out of the capillary wall into the bowman’s capsule (like water, glucose, salts, urea)
5) large molecules too large to fit through capillary wall + remain in bloodstream
ULTRAFILTRATION
6) filtrate moves through nephron tubule, loop of henle and collecting duct
7) some water, all glucose, some salts are reabsorbed SELECTIVE REABSORBTION
8) filtrate travels down collecting duct
9) urine collected in the bladder
what is the glomerulus?
and what does it do
a knot of capillaries inside the bowman’s capsule
- it increases blood pressure and forces small molecules out from the capillary wall to the bowman’s capsule (like water, glucose, salts, urea)
symptoms of dehydration? (3)
- dark urine
- headache + dizziness
- lack of energy
symptoms of overhydration (3)
- muscle cramping
- confusion
- seizures
what is the difference between hypertonic, hypotonic and isotonic drinks?
hypertonic - high levels of glucose + salts
hypotonic - low levels of glucose + salts
isotonic - equal ion concentration in blood plasma
