Kidney

Question 1

describe the structure of the kidney.

Answer 1

glomerulus - capillaries at the beginning of a nephron, filtering small molecules and water out of the blood

Proximal Convoluted Tube - PCT

Loop of Henle - U shaped portion of the nephron - has an ascending limb and a descending limb - acts as a countercurrent gradients

Distal Convoluted Tubule - DCT

Collecting Duct and Distal Collecting Duct

Question 2

describe how the structure of the kidney allows for water and sodium transport out of the nephrons and back into the blood

Answer 2

PCT
- Na+ active transport reabsorbed
- Water follows via osmosis

Loop of Henle - Descending
- water is reabsorbed, isn’t permeable to Na+

Loop of Henle - Ascending
- Na+ active transport reabsorbed, isn’t permeable to water

DCT
- sodium reabsorbed

Collecting Duct
- Na+ reabsorbed
- more aquaporins inserted on the membrane - more water reabsorbed

Question 3

give the functions of the kidney.

Answer 3

• fluid balance - controls amount of urine produced
• acid-base balance - regulate NH3 (lowers pH) and H+ (raise the pH) in the blood
• sodium balance
• renin-angiotensin system
• anti-diuretic hormone
• aldosterone levels
• excretion of drugs

Question 4

describe the blood supply for the kidneys.

Answer 4

blood from the aorta via renal arteries

filter 1,500L of blood/day

Question 5

what is the countercurrent multiplier system?

Answer 5

• water leaves the descending limb
• sodium leaves the ascending limb

= concentration gradient in the tissue
- deeper into the kidney = saltier

• makes more water osmotically leaving the urine = more concentrated urine to help the body save water and maintain balance

Question 6

what is secreted and absorbed through the kidney?

Answer 6

secreted:
NH4
penicillin
H+

absorbed
sodium
water
glucose
lactate

Question 7

how is the concentration of the urine controlled in the collecting duct?

Answer 7

by the ADH - antidiuretic hormone
- secreted by the pituitary gland
- stimulates resorption of the water
= decreased urine output

Question 8

how does the renin-angiotensin system work in the kidney?

Answer 8

• the juxta-glomerular apparatus senses «< in blood pressure or»_space; urine conc
• stimulates release of renin
• converts angiotensin into angiotensin I
• ACE (angiotensin converting enzyme) converts angio I into angio II

= > vasoconstriction and BP

= aldosterone secretion
= > water and Na retention

Question 9

give some signs of kidney dysfunction.

Answer 9

• low or high urine output
• dark urine
• proteinuria
• haematuria
• fluid retention - oedema, hypertension

Question 10

describe acute kidney injury.
- aetiology
- risk factors
- management

Answer 10

a decrease in urine output and secretory function from an impaired Na/K balance

aetiology
- pre-renal - dehydration, low BP, heart failure
- intra-renal - inflammation, embolism, scarring/damaged nephron
- post-renal - obstruction, stones

risk factors
- pre-existing kidney disease, heart disease
- elderly
- dehydration
- trauma
- unwell

tx:
- refer px
- assess urine output >0.5ml/kg/hr is normal
- blood tests - urea, creatine, Na, K
- manage fluid and Na/K balance
- assess current medication

Question 11

describe chronic kidney disease
- risk factors
- which medication should be avoided?
- management

Answer 11

hypertension, sodium retention, heart failure

risk factors
- unmanaged AKI
- atherosclerosis
- hypertension
- diabetes
- SLE - widespread inflammation
- scleroderma
- kidney stones

avoid NSAIDS

management:
- monitor BP
- perform a urinalysis and blood tests
- ultrasound/CT/MRI
- manage fluid and Na/K balance
- renal dialysis
- kidney transplant

Question 12

what is a renal dialysis?

Answer 12

extracting the blood
- filter the blood
- adjust fluid and salt level
- put the blood back into the body

• takes a long time as a lot of blood needs to be filtered

Question 13

what’s the risks of kidney transplants?

Answer 13

• tissue type needs to match
• there is a risk of rejection
• have to suppress the immunity to reduce risk of rejection - more prone to infection and cancers

Question 14

describe anaemia, bleeding and calcium and bone metabolic complications of chronic kidney disease?

Answer 14

anaemia
- erythropoietin hormone is not produced by kidney
- pluripotent stem cells are not stimulated in the bone marrow
- RBC are not produced

bleeding
- abnormal platatel formation
- abnormal platelet/vessel wall interaction
- affects Virchow’s Triad

• dialysis px take anticoagulants

calcium and bone metabolism
- CKD = reduced levels of active D3 (1,25 dihydroxyvitamin D3) in kidney
- needed for Ca absorption
- negative feedback = > parathyroid hormone
- parathyroid hormone = > osteoclast
= > bone turnover

Question 15

give 4 diuretic drugs which act on the kidney.

Answer 15

1. Thiazide
2. Loop Diuretic
3. K-sparing Diuretics
4. Osmotic Diuretics - Vasopressin

Question 16

what’s the issue with Diuretics?

Answer 16

can interfere with countertransport of K

leads to hypokalaemia