Physio 3
Physio 3
Physio 3
- Glomerulotubular balance
Intrinsic mechanism
Ability of PCT to increase reabsorption capacity due to increased tubular load
Prevent overloading of the distal tubular segments when GFR ↑
ADH:
Acts also on distal and collecting duct
Increase ↑H2O reabsorption
Production of more concentrated urine
Angiotensin II:
Secreted in response to fall in BP
Responsible for the reabsorption of Na+
Acts on almost all segment of the nephron
Activate the secretion of aldosterone
Constrict the efferent arteriole
Decreases peritubular hydrostatic pressure
Increases the filtration fraction
Increases plasma colloid osmotic pressure
Increases the tubular reabsorption
Receptors (AT1) are found on basolateral &
luminal surfaces
Activates multiple transporters that reabsorbs Na+
Na-K pump on basolateral membrane
Na-HCO3 cotransporter on basolateral membrane
Na-H counter-transporter on luminal membrane
Acidifies urine and plays a role in acid-base balance
Vasopressin
Also known as anti-diuretic hormone (ADH)
Secreted from the posterior pituitary gland
The major stimulus for secretion is ↑ plasma
osmolality
Acts primarily on DCT and collecting tubules
Increases water reabsorption
Its receptors (V2) are GPCR & found on basolateral membrane
Binding to receptors increases c-AMP that stimulates PKA
PKA causes phosphorylation and activation of aquaporins (AQP2)
Causes translocation of AQP2 channels to luminal membrane
Parathyroid hormone
Works on PCT, thick ascending loop of Henle and distal tubule
Decreases phosphate reabsorption
Increase calcium reabsorption
- Hypokalemia
Weakening in the excitable tissue
Reduction in the depolarization
Hyperpolarization of cell membranes
Fatigue, muscle weakness
Hypoventilation
Delayed ventricular repolarization