44&45: Renal Physiology Flashcards
What are the 3 extracellular fluid compartments?
- Interstitial
- Transcellular
- Intravascular
Hypotonic solution causes cells to ____
Hypertonic solution causes cells to ____
Hypotonic - swell
Hypertonic - lose water
Where does the majority of salt and water absorption occur?
Proximal tubule (65-75%)
Where does aldosterone act?
DCT and CD
What are some causes of hypernatremia?
- Impaired thirst or consciousness
- No water access
- Burns/diarrhoea/blood loss
- Solute diuresis
- Diabetes insipidus
What is the consequence of rapid correction of cerebral oedema?
Central pontine myelinosis
What is the distribution of Mg in the body?
- 99% in bone, muscle and soft tissue
- intracellular conc. range from 5-20 mmol/L
- Extracellular Mg 1%
What are the roles of Mg?
- Bone formation
- Cofactor in enzymatic reactions
- Regulation of vascular tone
- Cardiac rhythm
- Platelet activated thrombosis
What are the dietary sources of Mg?
High - plants (green, leafy vegetables)
Intermediate - cereals, nuts, meat, fish
Low - diary, processed food
The majority of Mg absorption occurs in the ____ and regulation related to filtration and reabsorption in the ____
Absorption - small intestine
Filtration and reabsorption - kidney
Where does the bulk of Mg reabsorption occur?
Loop of Henle (paracellularly)
Which tests are used to assess Mg?
- Serum Mg
- Red cell Mg
- 24 hour excretion
- Mg retention test
- Isotope analysis
How do you treat hypomagnesaemia?
IV magnesium
How is K distributed in the body?
- 300 mmol in skeleton
- 80 mmol in ECF
- 90% in cells
How is K homeostasis maintained:
- In the long term
- In the short term
- Long term: kidney
- Short term: movement into or out of skeletal muscle via insulin and catecholamines
