renal 2 Flashcards
Osmolarity:Hypertonicity
cell
causes
shrink
insuffient water uptake
excessive water loss
Diabetes insipidus
Osmolarity:Hypertonicity
symptoms
- shrinking of neurons — confusion , irritability
- Circulatory disturbances—- low bp
- dry skin and tongue
Osmolarity:Hypotonicity
cell
causes
-swell
- Inability to excrete a dilute urine (renal failure)
- when water is rapidly ingested
Osmolarity:Hypotonicity
Symptoms and effects
- swelling of neurons - confusion …
- weakness due. to swelling of muscles cells
mainstream of reabsorption
Proximal convoluted tubule
Renin-angiotensin-aldosterone system (RAAS)
involved in
regulating Na+
RAAS
- angiotensiogen produced by liver
- low bp and high sympathetic activity stimulate renin secretion
- decreased Na stimulates renin
- Angiotensin I produced
- Angiotensin II produced
Angiotensin II:
stimulates
stimulates ADH release and thirst
when renin-angiotension-aldosterone mechanism is activated to conserve Na+
how does aldosterone work:
stimulates
stimulates opening of both sodium and potassium channels
stimulates synthesis of potassium/sodium pumps
Roles of Angiotensin II: 4 mechanisms that increase blood pressure
- systemic arterioles
- adernal cortex
- posterior pituatary
- hypothalamic neurons
systemic arterioles
↑ vasocontsriction
↑total peripheral. resistance
adrenal cortex
aldosterone secretion. ↑
na reabsorption in distal tubules and collecting ducts ↑
extracellular fluid osmolarity ↑
which then ↑ ADH secretion from the post pituitary mechanism
posterior pituitary
↑ADH secretion
↑water reaborption in distal tubules and collecting duct
↑plasma volume
hypothalamic neurons
thirst stimulation ↑
plasma volume ↑
ADH function
maintain blood pressure, blood volume and tissue water content
by controlling the amount of water and hence the concentration of urine excreted by the kidney.
How ADH aids water reabsorption
- ADH binds to receptor on membrane of principal cell
- activation of a g protein activates enzyme to catalyse cAMP
- activates protein kinase A
- stimulates insertion of new water channels
