WEEK 9: 9.4 RAAS Flashcards
(22 cards)
What are the 2 categories of body fluid?
Intracellular fluid - inside cells
Extracellular fluid - outside cells
What are the 2 categories of bodily fluid in extracellular fluid
plasma - fluid in blood
interstitial fluid - between cells and within tissues
What are the components of fluid
water, protein, electrolytes
What are the functions of fluid
transport/carriage, colloid osmotic pressure, membrane excitability, buffering
What barriers are bodily fluid compartments seperated by? Describe
Capillary wall - separate plasma and interstitial fluid, passive movement via pores (sodium, potassium, chloride)
Plasma cell membrane - separate interstitial and intracellular fluid- movement regulated by passive/active mechanisms
What is a key difference in electrolyte composition between plasma and intracellular fluid as well as composition in overall bodily fluid
ICF- more potassium and phosphate
plasma has higher concentrations of sodium
ICF- 2/3 of body fluid plasma-1/15
Describe how fluid is gained
ingested liquids, food, metabolic production
Describe how fluid is lost
urinary loss, sweating, resp evaporation, GI losses
How is fluid regulated
Thirst mechanism
RAAS
Describe the thirst mechanism
It response to a change in serum osmolarity (due to loss of water)
It is detected by osmoreceptors in hypothalamus
stimulates thirst centre in hypothalamus
increase desire to drink water
increase water intake
increase body water
What is acid base balance
concentration of free H ions
acids give up H+
bases bind to H+
What is a major source of H+
when it is metabolically produced from CO2
Hence what role does the resp system play in acid base regulation
increased resp - decreased CO2 - reduced H+
decreased resp - increased CO2 - increased H+
What pH range does normal cellular function work in?
Very narrow pH
7.35-7.45
What pH is acidosis
<7.35
What pH is alkalosis
> 7.45
What would happen to a patient with a high acid concentration
they will compensate for the high H+ by increasing their resp rate to create an acid base balance (to reduce the CO2 conversion into H+)
What is the JGA
collection of specialised cells within the nephron (granular cells, macula densa)
What is the purpose of JGA
detects stretch - blood pressure changes
detects sodium levels - changes in blood osmolality (macula dense is sensitive to the sodium levels then triggers body to hold onto water)
release of renin from granular cells
describe RAAS
decreased sodium -> JGA -> released renin –> renin activates angiotensinogen to angiotensin 1 —> angiotensin 1 is converted by angiotensin converting enzyme to angiotensin 2 —> ang 2 stimulates adrenal cortex to release aldosterone —> acts on kidney to increase sodium reabsorption (DCT) –> prompts more water to be reabsorbed
ang 2 also triggers posterior pituitary to release ADH —> increased water reabsorption as increased aquaporin channels inserted in collecting ducts
ang 2 also triggers thirst centers –> increase fluid intake orally
ang 2 also is an arteriolar vasoconstrictor -> increase blood pressure
What causes does overproducing renin cause
increase BP —> hypertension
What does aldosterone do?
It is key in electrolyte balance
works on principal cells of DCT
to promote sodium retention (create a concentration gradient), and chloride passively, as well as secrete potassium
