Lec 17 - Fluid, Electrolyte, and pH Homeostasis

How does the cardiovascular system respond to changes in blood pressure and volume?

• When blood volume and pressure decrease, cardiac output and vasoconstriction increases.

• When blood volume and pressure increase, cardiac output and vasodilation increase

How does the urinary system respond to changes in blood pressure and volume?

• When blood volume and pressure decrease, H2O is conserved to minimize volume loss

• When blood volume and pressure increases, kidneys will excrete H2O and salts in urine, decreasing ECF and ICF volume

How does water inputs and outputs contribute to water mass balance

Water input or intake must equal the output to keep balance. Intake consists of cellular metabolism and ingestion of liquids while output consists of feces and urine.

General filtrate concentration values as it passes through nephron

Sensors and stimuli for release pertaining to ADH actions at the nephron

Targets and overall response at target cell (distal nephron) pertaining to ADH actions at the nephron

How does ADH actions influence blood pressure as it pertains to ADH actions at the nephron

ADH causes an increase in reabsorption to the blood vessels, increasing volume which increases blood pressure. Vice versa applies when ADH is low in nephron

Anatomical properties of countercurrent exchange system within the nephron

How does countercurrent exchange system within the nephron aids in water reabsorption at the distal nephron

ALOH is permeable to solute, but impermeable to water. As it arrives to DCT, filtrate is hypo osmotic, causing it to reabsorb water to balance.

What impact do high salt diets have in the heart and kidney

Increases water retention and intake, increasing liquid around cells and in blood stream, increases blood volume and BP which forces heart and kidneys to work harder to filter and pump

Homeostatic responses for salt ingestion by vasopressin and thirst

As more salt is ingested, drawing in water, There is an increased release of vasopressin which increases water reabsorption. Water conservation and fluid intake increased

RAAS pathway in detail

Various stimuli that increases renin secretion

Low blood pressure, GFR, and NaCl transport

Various functions of Angio II (targets and overall responses)

What does aldosterone do at it’s target cells

• Non- Genomic Effects

  • Increases open time for Na+ and K+ channels at apical membrane

  • Allows increase for NA = reabsorption and K+ secretion

• Genomic effects

  • Up-regulates new protein channels and Na-K-ATPase at both membranes

What are ACE inhibitors and how do they work to alleviate hypertension

• Angiostatin Converting Enzyme inhibitors

• Group of Pharmaceuticals that are used primarily in the treatment of hypertension

• Blocks the ACE-mediated conversion of ANGIO I to ANGIO I, which relaxes blood vessels and lowers BP