B12: Water levels

Question 1

what is DEAMINATION?

Answer 1

process of breaking down excess proteins in LIVER.
- enzymes split amino acids - part containing CARBON —> glycogen
- pat containing NITROGEN —> ammonia
- AMMONIA IS TOXIX so converts to UREA

Question 2

FUNCTION OF KIDNEY?

Answer 2

• control water conent /concentration of substances dissovled in fluids in body

Question 3

how does kidney work?

Answer 3

• when blood passes through kidney , PRESSURE INSIDE IT increases
• forces small moleucles to pass through pores (FILTRATION)
• includes GLCUOSE, UREA, WATER,IONS (FILTRATE)

Question 4

what happens to large substances in the kidney ?

Answer 4

RBCs/proteins are too big to filter/remain in blood plasma- REABSORBED INTO BODY (ACITVE)

Question 5

What happens to substances that arent reabsorbed?

Answer 5

• forms urine /stored in bladder until excreted
  UREA is not reabsorbed / conc of UREA IN URINE is higher than in blood
• water is reabsorbed into blood (dilute), so conc of urea is higher in urine than in blood

Question 6

structures that allow filtrate to pass through on it way to bladder?

Answer 6

TUBULES - water reabsorbation happnes along these tubules

Question 7

when is water reabsorbed?

Answer 7

if water content in blood is too low

Question 8

negative feeback of controlling water levels?

Answer 8

1) water level increases
2) hypothalamus detects change in water content/ acts on pituitary
3) pituitary releases less ADH–> less water reabsorbed
4) MORE DILUTE URINE

1) water levels decreases
2) Hypothalamus detects change/ acts on pituitary
2) pituitary releases more ADH, so more water reabsorbed
3) MORE CONCENTRATED URINE

ADH affects permeability of tubules

Question 9

what is DIALYSIS and how does it work?

Answer 9

• acts as artifical kidney to remove most of UREA/ maintain water level/salt
• in machine , blood/dialyis fluid is sperated by PARTIALLY PERMEABLE MEMBRANE - blood flows in opposite direction to dialysis fluid
• allows exchange to occur

Question 10

what does dialysis fluid contain?

Answer 10

glucose conc similar to blood
salt conc similar to blood
no urea

Question 11

kidney transplant AD/DIS?

Answer 11

AD: better for long term
- more freedom
- less restricted diet
- dialysis is expensive

DIS: - donor wont have same antigens causing IMMUNE RESPONSE to new kidney
- immunodepressant drugs have side effects
- not enough donors

Question 12

dialysis AD/DIS?

Answer 12

AD: no risk of rejection
- readily available

DIS: restricted diet
expensive
limited time

Question 13

Describe how the detection of a stimulus by a receptor

Question 14

Describe how the detection of a stimulus by a receptor of nervous system can result in stimulation of endocrine system?

3 marks

Answer 14

• receptors detect chnages away from normal value
• the signal moves through reflex arc
• motor neurone stimulates release of hormones

Question 15

why does the increase of urea lead to more urine?

Answer 15

• high quantity of urea, increases urea in filtrate
• makes filtrate concentrated , so water must move in by osmosis from dilute –> concentrated
• so less reabsorbtion of water from kidney
• lead to larger vol of urine produced