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Mock paper 2 > 31 Kidney functions and malfunctions > Flashcards

31 Kidney functions and malfunctions Flashcards

1
Q

what are the functions of the kidneys?

A

filtering the blood of waste products

excretion of urea and waste products

maintaining water potential of the blood

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2
Q

how is urea formed?

A

ammonia formed from excess amino acids being deaminated

combined with CO(2) in ornithine cycle

converted to urea

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3
Q

what are the components of a nephron?

A

Bowman’s capsule

glomerulus

PCT

loop of Henle

DCT

collecting duct

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4
Q

what is ultrafiltration?

A

the filtering of the blood at a molecular level

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5
Q

what is selective reabsorption?

A

absorption of useful molecules back into the blood from the fluid in the nephron tubule

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6
Q

what is required for ultrafiltration?

A

high hydrostatic pressure in arterioles

filter (to retain molecules with Mr > 65000

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7
Q

outline the process of ultrafiltration

A

blood brought in via afferent arteriole

hydrostatic pressure in glomerulus ∴ small molecules in plasma forced into Bowman’s capsule

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8
Q

what are the layers of the Bowman’s capsule and their functions?

A

endothelium
- narrow fenestrations to allow transfer of plasma and solutes

basement membrane

  • fine mesh of collagen and glycogen
  • prevents passage of molecules with Mr > 65000

podocytes
- projections allow filtered fluid to enter lumen of Bowman’s capsule

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9
Q

where does selective reabsorption take place in?

A

PCT (90%)

LoH

DCT

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10
Q

outline some of the adaptations in cells of the PCT

A

microvilli - incr. SA for osmosis/facilitated diffusion and co-transporter proteins

basal membrane - incr. SA for transporter proteins

mitochondria - ATP synthesis

tight junctions - prevents substances from moving between cells, ensuring transcellular movement

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11
Q

how is water reabsorbed in the loop of Henle?

A

Na+ and Cl- actively pumped out ascending limb

w.p. decreases in medulla’s tissue fluid (ascending limb impermeable to water)

∴ water moves out of descending limb by osmosis

w.p. decreases in filtrate to tip of hair pin

Na+ and Cl- diffuse out of ascending limb ∴ w.p. increases

w.p.g. created between cortex and medulla

collecting duct permeable to water ∴ water moves out by osmosis into medulla

concentrated urine production

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12
Q

what is osmoregulation?

A

the regulation of the water potential of body fluids

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13
Q

what is ADH?

A

a hormone produced by specialised nerve cells known as neurosecretory cells

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14
Q

what is the function of osmoreceptors?

A

detecting changes in the w.p. of the blood flowing through the hypothalamus

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15
Q

how do osmoreceptors respond to low water potential?

A

ADH is secreted from the posterior pituitary gland into the blood plasma

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16
Q

what is the effect of ADH?

A

acts on the cells in the walls of the collecting duct

attaches to receptors on CSM

causes cyclic AMP concentration to increase

aquaporins stimulated to fuse with membrane

water passes through the channels ∴ w.p. of urine increases ∴ concentration of urine increases

17
Q

when is EPO secreted?

A

when blood O(2) levels falls

18
Q

when is renin secreted?

A

when blood volume falls

19
Q

what is the effect of renin?

A

catalyses conversion of angiotensinogen

increases blood volume by constricting blood vessels

increases blood pressure

∴ ADH secreted to increase water reabsorption in kidneys

20
Q

give two causes of acute kidney failure

A

bacterial infection

kidney stones

21
Q

give two causes of chronic kidney failure

A

uncontrolled diabetes mellitus (type 1 or 2)

hypertension

22
Q

how is kidney failure diagnosed?

A

reduction in urine volume

bloody/cloudy urine

oedema (accumulation of fluid in tissues)

high concentration of creatinine in urine

23
Q

what are the consequences of untreated kidney failure?

A

accumulation of toxins –> death

increased renin production –> hypertension

less EPO produced

cardiovascular diseases

24
Q

how is kidney failure treated by haemodialysis?

A

blood taken from artery and passed through dialysis machine (artificial filtering)

heparin added to prevent clotting

takes several hours, 3x a week

25
Q

how is kidney failure treated by peritoneal dialysis?

A

peritoneum acts as dialysis membrane

takes minutes, several times a day

26
Q

what are the conditions required for a successful kidney transplant?

A

compatibility of donor RBC antigens and haplotype

arteries, veins and ureter must be attached

immunosuppressant drugs must be administered to prevent an immune response

27
Q

what is the future of kidney transplants?

A

growing kidneys from induced pluripotent stem cells

embryonic stem cells used for therapeutic cloning

Mock paper 2 (9 decks)

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