9.4 Body Fluid; Blood Pressure Regulation, Electrolyte Balance & Renin-Angiotensin-Aldosterone System (RAAS) Flashcards
Are men or women made up of more water? Why does this make sense?
- Men
- Women have more fat; insoluble in water
What percentage of body fluids are intracellular/extracellular?
- 2/3 Intra
- 1/3 Extra
What percentage of extracellular fluids are interstitial/plasma?
- 80% Interstitial
- 20% Plasma
Name three processes by which the body takes up water (from most to least)
- Ingested liquids
- Ingested foods
- Metabolic water (not regulated; generated in rxns)
Where is water gain regulated? What is this input interpreted as?
- Hypothalamus
- Interpreted as drop in BP and blood volume
Name four pathways of water loss from most to least
- Kidneys
- Skin
- Lung
- GI Tract
How is fluid lost from the kidneys?
- Follows salt out
Explain how water could be lost following a salty meal
- More Na+ and Cl- in the plasma
- Water from ICF -> ECF -> Plasma along osmotic gradient
- Hence, more water is excreted
What are electrolytes?
Charged ions in solution
What are the three functions of ions?
- Control osmosis
- Maintain acid-base balance
- Carry electrical currents
What is the normal range of blood pH?
7.35-7.45
Why is maintaining pH homeostasis important?
Without it, active site becomes denatured and protein loses function
Symptoms of acidosis
Depresses CNS -> coma
Symptoms of alkalosis
Excites CNS -> Spasms, convulsions, death
How do buffer systems increase/decrease pH?
Absorb/release H+ ions through chemical reactions
How do the lungs influence pH?
- Inc resp rate: increased carbonic acid breakdown, increased removal of H+
- Dec resp rate: decreased carbonic acid breakdown, increased H+ in blood
How do the kidneys influence pH?
- Increase secretion/excretion of H+
- Conserve H+ and release bicarbonate instead
Aldosterone vs ADH
ADH: Aquaporins -> water reabsorption
Aldosterone: sodium -> osmotic gradient -> water
What does the macula densa “taste” for?
Sodium or chloride
Which cells in the Juxtaglomerular apparatus secrete renin?
JG Cells (from storage granules)
What is renin?
Enzyme and hormone
What is the effect of Ang II produced following renin release on the vasculature of the nephron?
- Constricts afferent arteriole
- Constricts efferent arteriole more, creating back-pressure
What does the macula densa release if salt is too high/low?
High: Adenosine (inhibits renin)
Low: signals JG cells to secrete renin
What is the effect of adenosine on blood vessels in the kidney?
Constricts Afferent arteriole
