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29 Cards in this Set
- Front
- Back
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What does Na+ regulation primarily respond to?
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This responds to changes in blood volume.
Driven by changes in blood pressure- (this effects the renin-angiotensin-aldosterone system) |
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What does Water regulation primarily respond to?
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This responds to changes in osmolarity and volume of ECH
the primary effector is ADH |
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What does Aldosterone do?
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Stimulates Na+ reabsorption in the late distal tubule and collecting duct (in principle cells)
also stimulates loss of K+ (as Na+ retention entails loss of K+) |
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What things stimulate aldosterone release?
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increase in Angitensin 2 OR plasma K+
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What are the Major effects of Angiotensin 2?
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powerful vasoconstrictor
stimulates aldosterone release stimulates Na+/H+ exchange in proximal tubule increases salt retention and elevation of BP |
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What controls Angiotensin 2 levels?
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Renin
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What controls Renin Release?
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Granula cells of the JGA- release of renin is inversely related to pressure in afferent arterioles.
Macula densa- Renin release inversely related to GFR Renal sympathetics- these directly stimulate renin release |
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How does ANP affect GFR?
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ANP increases GFR
this dilates the afferent arteriole, and constricts the efferent arteriole (forcing more fluid out via pressure) |
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How does ANP affect NaCl?
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this decreases NaCl reabsorption
it inhibits renin and aldosterone secretion directly inhibits Na+ uptake in medullary CD |
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What is the most important hormone in regulating water balance?
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ADH
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What does ADH do? What causes its release?
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This causes reabsorption of water.
it is released in response to an increase in osmolarity, or decrease in plasma volume. ADH has little effect on NaCl excretion |
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What part of the brain is sensitive to small changes in plasma osmolarity? what does it release?
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The hypothalamic osmoreceptors.
this stimulates ADH secretion NOTE: hypocolemia also stimulates ADH release, but is far less sensitive to change. |
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What does ADH specifically do to incrrease water retention?
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Increases Na+/K+/2Cl- cotransporters in the Loop of Henle
Increase permeability of CD to water Increase permeablility of inner medullary CD to urea |
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How does ADH respond to a pure water load?
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this will significantly decrease the levels of ADH in the body. this will lower the permeability of the CD to H2O
this leads to a water loss. |
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What is osmolar clearance?
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this is the ml/min of blood plasma cleared of osmotically active particles
Cosm= UosmV/Posm |
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What is the equation that estimates osmolarity?
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2Na+BUN2.8 + Glucose/18
This estimates plasma osmolarity |
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What things can causes a reduced Cosm
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this a positive osmolar balance- gaining osmoles.
A degressed GFR, increased aldosterone would all caused a reduced Cosm. This is due to solutes NOT getting filtered out |
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What things can cause an increased Cosm?
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this would be the dumping of osmolytes- a loss of ECF
diuretics, low aldosterone |
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How does urine production rate, relate to Cosm?
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IF V>Cosm, solute free water is being lost.
If V < Cosm, solute free water is being gained. USE Ch20= V- Cosm (this gives us the same water balance numbers) |
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What does a positive Ch2o, and a negative Ch2o mean?
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Ch2o= V- Cosm
a positive Ch20 means that solute free water is lost from the body a negative Ch2o means free water is being conserved by the body |
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What happens in Diabetes insipidus? causes?
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Polydipsia, polyuria.
High plasma osmolarity, low urine osmolarity ADH is very low or ineffective |
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What are the 2 Main causes of Diabetes Insipidus
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Neurogenic diabetes insipidus- Unable to secrete ADH
Nephrogenic diabetes insipidus- renal in origin, unable to respond to ADH. high plasma ADH |
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What is SIADH? what does it result in?
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syndrome of inappropriate ADH secretion: Excessive ADH.
this results in chronic ECF dilution. Hyponatermia, expanded ECF volume, excess sodium loss. |
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What is the Pathophysiology loop of SIADH?
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WAY high ADH-> excess free water retained-> Lowers aldosterone in response of hypervolemia-> increased salt loss-> Hyponatermia (low salt)
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What do changes in Na+ concentration of ECF often lead to?
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these often lead to changes in body water content rather than changes in Na+ content
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What defines hyponatremia?
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plasma Na+ of less than 135 mEq/L
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What are common causes of hyponatremia?
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blood volume depletion
SIADH excessive water intake |
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What dominates during bladder filling?
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sympathetics
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what dominates during bladder empyting?
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parasympathetics
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