where do loop diuretics act
TAL
where do thiazide diuretics act
distal tubule
where does spironolactone and amiloride act
collecting tubule
what happens in the thick ascending loop
impermeable to water
active reabsorption of Na Cl
what is the function of ADH
increases permeability to water of the collecting duct. this means more can be reabsorbed into the blood producing more concentrated urine
what is the function of aldosterone
increases permeability of ions and water in the collecting duct
how is sodium reabsorbed in the distal nephron
swapped for K and H ions
how do diuretics work
cause naturesis which causes diuresis
what is furosemide (loop diuretic)
loop diuretic.
inhibits absorption of ions in the TAL
they inhibit the counter current multiplier which sets up the concentration gradient
causes loss of K and H and increase in bicarbonate
increase renal prostaglandins which change renal blood flow
moderated in DCT which exchanges for sodium for K/H
very effective diuretic
how do potassium sparing diuretics work. eg spironolactone
•Inhibits aldosterone-sensitive sodium pump by renal prostaglandin production
how do carbonic anhydrase inhibitors work
inhibit transport of bicarbonate from the PCT into the interstitium leading to less sodium reasorbtion - very weak
how are diuretics used in heart failure
decrease pre load which decreases blood pressure
decreases venous return
decreases oedema
what are the symptoms of inappropriate ADH secretion
- Nausea and/or vomiting
- Cramps/tremors
- Depressed mood, irritability, personality change, memory issues, hallucinations
- Seizures
- coma
what are the causes of inappropriate ADH secretion
•CNS – infections, brain tumour or bleed, hydrocephalus, Guillain-Barre, MS •Cancers – Carcinomas of lung, GIT, GUT; lymphomas; sarcomas •Medication – antibiotics - some anti -epletics - some major sedatives - oxytocin - MDMA ( Ecstasy) •Lung disease •Hypothyroidism or parathyroidism •HIV •Sarcoid
how is inappropriate ADH secretion treated
fluid restriction
saline
tolvaptan
what might polycythaemia be caused by
kidney tumour causing increase EPO production
what is AZT for
anti retroviral therapy
what hormones are produced in the adrenal cortex
- Glucocorticoids e.g. cortisol
- Mineralocorticoids e.g. aldosterone
- Androgens
what hormones are produced in the adrenal medulla (catecholamines)
- adrenaline
* noradrenaline
what is beclometasone
used to treat asthma, psoriasis, hayfever etc
steroid- glucocorticoid
what is prednisolone used to treat
autoimmune and inflammatory disorders e.g. RA, asthma UC- glucocorticoid
what is dexamethasone
glucocorticoid- anti inflammatory used in allergy and asthma
what is fludrocortisone
mineralcorticoid-low blood pressure or to replace aldosterone
addison’s disease
where is aldosterone produced
adrenal cortex
why do loop diuretics cause metabolic alkalosis
lower plasma volume but same volume of bicarb. excretion of hydrogen ions
what are the side effects of loop diuretics
risk of hypokalaemia and metabolic alkalosis
where do thaizides act
DCT
inhibit sodium chloride transporter
used in hypertension
where is carbonic anhydrase found
PCT
results in bicarb accumulation in the urine by inhibiting carbonic anhydrase which inhibits transport of bicarb
what type of diuretic is aldosterone antagonist
potassium sparing e.g. spironolactone and eplerenone
they prevent sodium reabsorption by inhibiting the aldosterone sensitive sodium pump
what is normal haematocrit
45%
what is synthetic EPO used for
kidney failure pts
antiretroviral therapy pts
chemo and cancer pts
describe the HPA axis (hypothalamus, anterior pituritary, adrenal cortex)
hypothalamus releases corticotropin releasing hormone to the anterior pituitary gland which signals to the adrenal gland using adrenocorticotropic hormone which releases cortisol from the adrenal cortex
what are corticosteroids
reduce inflammation and suppress the immune system
Where does aldosterone act
collecting duct
therefore spironolactone and eplenerone act here too (potassium sparing)