Exam 5: Chapter 20 Flashcards
what is sensible water loss?
urine & feces
what is insensible water loss?
skin & lungs
what is the medullary gradient? what is it created by?
created by the countercurrent exchange system
-as we go down the medulla, there is a higher concentration
what two tubules are apart of the countercurrent exchange system?
LOH & vasa recta
-close in proximity to eachother
-fluids move in opposite directions
what happens at the descending LOH in the countercurrent exchange system?
water leaves and enters vasa recta
-makes sure it doesn’t dilute the medulla
-LOH filtrate becomes more concentrated
what happens at the ascending LOH in the countercurrent exchange system?
solute leaves and stays in the interstitial fluid
-creates the medullary gradient
what are the collecting ducts permeable to?
BOTH water and solutes
-depends on situation
what is dilute urine?
large volume (more H2O), low solute
-solutes are reabsorbed
what is concentrated urine?
small volume (less H2O), high solute
-water is reabsorbed
what is diuresis?
increase water excretion
what is ADH/vasopressin released by?
posterior pituitary
what does ADH/vasopressin do?
stops water excretion (antidiuretic)
-promotes water reabsorption
-more concentrated urine
how does ADH/vasopressin act on collecting ducts?
- ADH binds to a receptor on collecting duct MB
- activates cAMP pathway
- aquaporins (AQP2) are inserted on apical MB
- water enters and exits on basolateral MB
- water goes into bloodstream
what triggers ADH/vasopressin release?
-low BP, low blood volume
-increase in osmolarity (high solute conc.)
what is the circadian rhythm of ADH/vasopressin?
increase ADH secretion at night
what happens to volume when osmolarity increases?
volume does not change
what happens when there is a high osmolarity?
too concentrated
-hypothalamus initiates thirst drive (bring osmolarity back down through dilution)
-initiate AHD/vasopressin release
what is aldosterone released by?
adrenal cortex
what are the effects of aldosterone release?
increase Na+ reabsorption
increase H2O reabsorption
increase K+ secretion
what are triggers for aldosterone release?
- high K+ (we need to get rid of it)
- low osmolarity (need more solutes)
- low BP (triggers RAAS)
how does aldosterone act on the collecting ducts?
- aldosterone is released and enters principle cells (P cell)
- aldosterone binds to cytoplasmic receptor
- creates new channels on the MB
- modifies existing channels on MB (increase opening time or speed of pumps)
- Na+ enters ECF to be reabsorbed into blood
- K+ enters nephron to be secreted
what is the renin-angiotensin-aldosterone system (RAAS)?
- decrease in BP
- sympathetic NS acts on granular cells of kidney
- constriction causes renin to release into the blood
- angiotensinogen -> angiotensin 1
- angiotensin 1 -> angiotensin 2 (enzyme: ACE)
- angiotensin 2 constricts vessels (increase R = increases blood volume)
- MULTIPLE FACTORS (next flashcards)
- increase BP
what is the impact of the medulla oblongata in RAAS?
increase symp NS
-constriction
what is the impact of the proximal tubules in RAAS?
increase Na+ reabsorption
increase water reabsorption
what is the impact of the adrenal cortex in RAAS?
release aldosterone
-increases Na+ reabsorption
-increases H2O reabsorption
-increase K+ secretion
what is the impact of the posterior pituitary in RAAS?
release ADH
-increase water reabsorption
what is the impact of the hypothalamus in RAAS?
initiate thirst drive
-increase H2O intake
initiate ADH release from the posterior pituitary
-increase water reabsorption
what are the two types of naturetic peptides?
ANP (atrial)
BNP (brain)
what is the process of ANP after it is released?
- increase BP = stretch
- ANP released
- MULTIPLE IMPACTS
- decrease BP
what is the effect of the hypothalamus due to ANP?
decrease ADH
-increase water secretion
what is the effect of the kidney due to ANP?
afferent arteriole dilates
-increase GFR
-decrease renin
proximal tubule
-increases Na+ secretion
-increases water secretion
what is the effect of the adrenal cortex due to ANP?
decrease aldosterone
-increase Na+ secretion
-increase water secretion
-increase K+ reabsorption
what is the effect of the medulla oblongata due to ANP?
decrease SYMP
-dilation
what hormone keeps K+ in it’s narrow range?
aldosterone
-increases K+ secretion if levels are too high
what is hypokalemia?
low K+
-muscle weakness, failure of respiratory muscles and heart
what is hyperkalemia?
high K+
-cardiac arrhythmias
what are the effects of dehydration?
low volume
low BP
high osmolarity
how does the body fix dehydration?
- decrease in BP
- increase SYMP NS
- constriction
- decrease GFR
- increase RAAS
- inhibit adrenal cortex (do not want to increase osmolarity)
what do buffers do?
binds to H+ if its too acidic, and lets go of H+ if too basic
-fast working and make small changes
what are the three molecules that use ICF mechanisms for buffers?
cellular proteins
phosphate ions
hemoglobin
what molecule uses ECF mechanisms for buffers?
bicarbonate
what two molecules are kidney/urine buffers?
phosphate ions
ammonia
what does the respiratory system do when the pH is too low? (too acidic)?
HYPERventilation
-need to decrease CO2 = decrease H+
-creates an alkaline state to increase pH
what does the respiratory system do when the pH is too high (too basic)?
HYPOventilation
-need to increase CO2 = increase H+
-creates an acidosis state to decrease pH
what does the kidney do when pH is too high (too basic)?
H+ reabsorption and HCO3- secretion
-overall decreases pH
what does the kidney do when pH is too low (too acidic)?
H+ secretion and HCO3- reabsorption
-overall increases pH
what does the proximal tubule do to H+ and HCO3-?
secretes H+
reabsorbs HCO3-
what does type A distal tubule cells do to H+ and HCO3-?
secretes H+
reabsorbs HCO3-
wants to make pH more basic
what does type B distal tubule cells do to H+ and HCO3-?
reabsorbs H+
secretes HCO3-
wants to make pH more acidic
what is respiratory acidosis caused by?
HYPOventilation
-CNS depressants
what is respiratory alkalosis caused by?
HYPERventilation
-anxiety
what is metabolic acidosis accompanied by?
HYPERventilation
-increased acid production in the body
what is metabolic alkalosis accompanied by?
HYPOventilation
-increased action of getting rid of acids (vomitting)
what is happening to H+, pH, and HCO3- during respiratory acidosis?
increase H+
decrease pH (more acidic)
increase HCO3- (high CO2 in the body)
what is happening to H+, pH, and HCO3- during metabolic acidosis?
increase H+
decrease pH (more acidic)
decrease HCO3- (low CO2 in the body)
what is happening to H+, pH, and HCO3- during respiratory alkalosis?
decrease H+
increase pH (more basic)
decrease HCO3- (low CO2 in the body)
what is happening to H+, pH, and HCO3- during metabolic alkalosis?
decrease H+
increase pH (more basic)
increase HCO3- (high CO2 in the body)
