ROLES OF KIDNEY IN SALT AND WATER RETENTION Flashcards
REGULATION OF WATER HOMEOSTASIS IS CONTROLLED BY:
- OSMOLALITY WHICH IS DETECTED BY THE OSMORECEPTOR
- BLOOD VOLUME WHICH IS DETECTED BY THE VOLUME RECEPTOR
DEFINE OSMOLALITY.
TOTAL NO. OF PARTICLES IN A SOLUTE PER KG OF WATER
OSMOLALITY DEPENDS ON
PLASMA SODIUM
OSMOLALITY IS NOT DEPENDS ON
WEIGHT, SIZE OR TEMPERATURE
NORMAL PLASMA OSMOLALITY IS
275 - 295 MOSM/KG
DEFINE OSMOLARITY.
NO OF PARTICLES IN A SOLUTE PER LITER OF SOLUTION
OSMOLARITY DEPENDS ON
TEMPERATURE
THE NO OF PARTICLES IN A SOLUTION
WITH INCREASING PLASMA OSMOLARITY, ADH CONCENTRATION IS
RISE STEEPLY AND LINEARLY
WHEN PLASMA OSMOLARITY IS LOW, THE ADH SECRETION IS
SUPPRESSED
BRIEFLY DESC THE MECHANISM REGULATING BODY FLUID OSMOLALITY.
WHEN THE PLASMA OSMOLALITY IS HIGH, THIS WILL BE DETECTED BY THE OSMORECEPTOR -> AS A RESULT, IT WILL STIMULATE THE THIRST RECEPTOR IN WHICH IT WILL INCREASE THE WATER INTAKE -> AT THE SAME TIME, IT WILL ALSO STIMULATE THE ADH SECRETION SO THAT WATER RETENTION CAN OCCUR -> HENCE THE PLASMA OSMOLALITY CAN BE REDUCED AND THIS CAN CAUSE DILUTION OF ECF.
ADH IS SYNTHESISED IN THE
CELL BODIES OF THE MAGNOCELLULAR NEURONS IN THE SUPRAOPTIC NUCLEI (SON) AND PARAVENTRICULAR NUCLEI (PVN)
STATE THE EFFECT OF ADH IN BLOOD VESSELS.
ADH WILL BIND TO THE V1 RECEPTOR AND CAUSE THE INTRACELLULAR CA2+ TO BE INCREASED IN THE BLOOD VESSELS. AS A RESULT, VASOCONSTRICTION WILL OCCUR.
STATE THE EFFECT OF ADH IN THE KIDNEY.
ADH WILL BIND TO THE V2 RECEPTOR AND CAUSE THE CAMP TO BE INCREASE IN LEVEL. AS A RESULT, THERE WILL BE MOBILISATION OF THE AQUAPORIN CHANNEL IN WHICH IT WILL BE INSERTED INTO THE APICAL MEMBRANE OF THE DISTAL TUBULES AND CELLS OF COLLECTING DUCT. HENCE, WATER REABSORPTION INCREASED.
