b3.3 spec - maintaining water levels

Question 1

if the blood is a higher water potential than animal cells, what is the effect?

Answer 1

water moves into cells through osmosis, causes them to swell and may burst
(no cell wall)

called LYSIS

Question 2

what condition would cause cells to shrink?

and how do they shrink

Answer 2

• too high solute in bloodstream
• lower water potential in bloodstream compared to cells
• so water moves out of blood cells

Question 3

what does urine contain?

Answer 3

urea, excess salts, excess water

Question 4

how does the kidney maintain water balance of the body?

Answer 4

controls the amount and concentration of urine (which affects the amount of water excreted/in the bloodstream)

Question 5

describe really simply how urine ends up in the bladder

Answer 5

kidneys filter urea out of blood
urine trickles through ureter
which leads to bladder which stores urine

Question 6

what is the role of the renal artery?

Answer 6

brings blood containing urea + other substances to kidney

Question 7

what is the role of the renal vein?

Answer 7

carries blood away from kidney (once substances have been removed)

Question 8

what is the role of the urethra?

Answer 8

a tube where urine passes to the outside of the body (from bladder)

Question 9

what causes urea to be produced (and where is it produced)?

Answer 9

• produced in the liver

- waste product of protein synthesis

Question 10

GO TO ANKI FOR KIDNEY + NEPHRON STRUCTURE

Answer 10

GO WHEN DONE

Question 11

what kind of feedback loop is volume of urine controlled by?

Answer 11

a negative feedback loop

Question 12

what detects water levels in the bloodstream?

Answer 12

hypothalamus

Question 13

what releases ADH?

Answer 13

pituitary gland

Question 14

what does ADH do?

Answer 14

• makes collecting ducts more permeable to water

- more water reabsorbed into the blood

Question 15

when would ADH be released?

Answer 15

• when blood water potential is too low

want less water to be wasted

Question 16

describe the process that goes on in the kidneys to produce urine

Answer 16

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
FILTRATION

6) filtrate moves through nephron tubule, loop of henle and collecting duct
7) water, urea, salts are reabsorbed SELECTIVE REABSORBTION

8) filtrate travels down collecting duct
9) urine collected in the bladder

Question 17

what is the glomerulus?

and what does it do

Answer 17

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)

Question 18

symptoms of dehydration?

Answer 18

• dark urine
• headache + dizziness
• lack of energy

Question 19

effects of ‘over hydration’

Answer 19

• water move by osmosis into cells
• cell burst
• concentration of sodium drops
• muscle cramping/confusion/seizures

Question 20

what is the difference between hypertonic, hypotonic and isotonic drinks?

Answer 20

hypertonic - high levels of glucose + salts
hypotonic - low levels of glucose + salts
isotonic - equal ion concentration in blood plasma