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Renal Phys 4: Controlling Renal Function Guyton ch 27?
Pasley 4/25/11 lecture 1 hr
50
Physiology
Undergraduate 4
04/20/2011

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Term
secreted by zona glomerulosa, enhances sodium resorption(decreases sodium excretion), and K+ excretion
Definition
where is aldosterone secreted and what does it do (overall effect)?
Term
a decrease in sodium is detected by the macula densa and so angiotensin 2 is increased, leading to aldosterone secretion
Definition
what is the main thing that stimulates aldosterone secretion?
Term
1) late DCT & cortical collecting tubule: the principal cells increase Na+ resorption and increase K+ secretion

2) intercalated cells of the collecting tubule: increase H+ secretion and HCO3 reabsorption
Definition
where are the 3 places aldosterone acts?
Term
it makes it worse because it causes K+ secretion
Definition
what does aldosterone do to hypokalemia?
Term
1) it enhances ENaC synthesis on the luminal side

2) it enhances the Na+/K+ pump on the basolateral side of the cell

3) it increases the K+ channels to the lumen
Definition
what does aldosterone do to specific pumps on the principal cells?
Term
excess aldosterone production
Definition
What causes Conn's syndrome?
Term
Conn's syndrome
Definition
Na+ retention
hypOkalemia
alkalosis
hypertension

what disease is characterized by these things?
Term
aldosterone is secreted and it causes excess aldosterone secretion: Conn's syndrome
Definition
what disease is associated with a benign tumor in the zona glomerulosa?

(hint: what is secreted here?)
Term
aldosterone deficiency
Definition
what causes Addison's disease?
Term
Addison's disease
Definition
what disease is characterized by:

Na+ wasting
hypERkalemia
hypOtension
Term
Addison's disease
Definition
what disease is caused by an adrenal insufficiency, usually autoimmune?
Term
1) angiotensin 2 - stimulates adrenal cortex directly and constricts efferent arteriole

2) increased plasma K+

3) ACTH - stimulates ALL adrenal function, mostly cortisol from fasiculata though
Definition
what are the 3 things that stimulate aldosterone secretion?
Term
1) atrial naturiuretic factor (ANF/ANP)

2) increased Na+ concentration (osmolarity)
Definition
what 2 things decrease aldosterone secretion?
Term
1) PCT
2) LoH
3) DCT
4) collecting tubules
Definition
where does angiotensin 2 increase Na+ reabsorption?
Term
1) increases filtration fraction (GFR) which increases peritubular oncotic pressure

2) decrease peritubular capillary hydrostatic pressure
Definition
what does angiotensin 2 constricting the efferent arteriole do?
Term
Asp-Arg-Val-Tyr-Ile-His-Pro-Phe it is an octomer
Definition
what is the sequence of Angiotensin 2?
Term
ACE inhibitors & A-II receptor antagonists
Definition
Term
the -prils!

1) captropril
2) benazipril
3) ramipril
Definition
what are the ACE inhibitors?
Term
the -artans

1) losartan
2) candesartin
3) irbesartan
Definition
what are the A-II receptor antagonists?
Term
1) decrease aldosterone
2) directly inhibit Na+ reabsorption
3) decrease efferent arteriolar resistance (decrease GFR)

ultimately: natriuresis and diuresis to decrease blood pressure
Definition
what does ACE inhibitors/ A-II receptors antagoinists do (3 things)? ultimately?
Term
increases Na+ excretion
Definition
what does ANF/ANP do to Na+?
Term
cardiac atria, in response to stretch (high blood volume)
Definition
where in ANF/ANP secreted?
Term
1) Na+ reabsorption
2) renin release
3) aldosterone formation
Definition
what does ANF inhibit? (3 things)
Term
increase GFR by dilating the afferent arteriole

counteracts renin/angiotensin to minimize blood volume expansion
Definition
what does ANF do to GFR? how?
Term
basically aldosterone loses effect over time because ANP compensates to prevent the blood volume(and pressure) from getting to high
Definition
what is aldosterone escape?
Term
causes increased reabsorption
Definition
what does the sympathetic nervous system do to sodium?
Term
decreases both, which stimulates renin release, and stimulates Na+ retention
Definition
what does sympathetic stimulation do to GFR and renal blood flow?
Term
sympathetic nervous system effects (increase sodium retention)
Definition
what is the response to heart failure that is the opposite of ANF?
Term
sympathetic nervous system effects (increase sodium retention)
Definition
what is the response to heart failure that is the opposite of ANF?
Term
when the atria sense high pressure, they 1) increase peritubular hydrostatic pressure

2) decrease renin and aldosterone

3) increase release of intrerenal natiuretic factors such as prostaglandins


--> sodium excretion
Definition
what does pressure natiuresis do?
Term
neither, it is independent of both

it is a protective mechanism to prevent overexpansion of the total blood volume
Definition
Is renal pressure natiuresis dependent on hormones or the sympathetic nervous system?
Term
volume: Na + retention
osmolarity: H2O retention
Definition
volume sensing controls ____, whereas osomolarity sensing controls ______
Term
1) albumin excretion
2) plasma concentration of waste products (BUN, creatinine)
3) urine specific gravity
4) imaging methods
5) Isotope renal scans
6) biopsy
7) clearance methods (24hr creatinine clearance)
Definition
what are 7 ways to assess kidney function?
Term
clearance
Definition
concept that describes RATE at which substances are removed from the plasma
Term
renal clearance
Definition
the VOLUME of plasma completely cleared of a substance PER MINUTE by the kidneys
Term
Cs = (Us x V) / Ps

Cs =clearance of a substance
Ps =plasma concentration of substance
Us =urine concentration of substance
V =urine flow rate
Definition
what is the clearance equation?
Term
GFR
Definition
for a substance that is freely filtered but not reabsorbed or secreted, renal clearance = ?
Term
amount excreted
Definition
for inulin, 125-I-iothalamate, and creatinine amount filtered = ?
Term
the clearance of inulin (urine conc. of inulin * urine flow rate)/plasma conc. of inulin
Definition
what does GFR = ?
Term
inverse relationship, high creatinine in the blood means low GFR

why? because creatinine is secreted at about a constant rate by skeletal muscle and so is cleared at a constant rate. Clearance failure = fail kidney
Definition
what is the relationship between plasma creatinine and GFR?
Term
filtration - excretion
Definition
what is the equation for tubular reabsorption?
Term
plasma concentration of the substance
Definition
filtration = GFR * ?
Term
urine flow rate
Definition
excretion = Urine concentration of a substance x ?
Term
urine concentration of the substance
Definition
reabsorpbtion = (GFR - plasma concentration of substance ) - ( ? x urine flow rate)
Term
excretion
Definition
secretion = ? - filtration
Term
renal plasma flow
Definition
if a substance is completely cleared from the plasma, what does it's clearance rate equal?
Term
PAH clearance, it is freely filtered, and secreted so it is almost completely cleared from the plasma
Definition
what is used to estimate effective renal plasma flow? why?
Term
it is reabsorbed
Definition
if a substance's clearance is less than inulin, what does that mean?
Term
it is secreted
Definition
if a substance's clearance is greater than inulin, what does that mean?
Term
inulin - 125 ml/min
PAH - 600 ml/min
glucose- 0 ml/min
sodium - 0.9 ml/min
urea - 70 ml/min
Definition
what are the clearances of inulin, PAH, glucose, sodium, urea?
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