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99 Cards in this Set

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At what concentration is the transport mechanism for glucose saturated?
300 mg/dL
Define effective renal plasma flow.
ERPF = U (PAH) x V/P (PAH) = C (PAH)
Define filtration fraction.
FF = GFR/ RPF
Define free water clearance.
C(H2O) = V- C(osm)
Define GFR.
GFR = U(inulin) x V/P (inulin) = C (inulin) GFR also equals the difference in (osmotic pressure of the glomerular capillary minus Bowman's space) and (hydrostatic pressure of the glomerular capsule minus Bowman's space).
Define renal blood flow.
RBF = RPF/1 - Hct
Define renal clearance.
Cx = UxV/Px The volume of plasma from which the substance is cleared completely per unit time.
Define urine flow rate.
V = urine flow rate C (osm) = U(osm)V/P(osm)
How are amino acids cleared in the kidney?
Reabsorption occurs by at least 3 distinct carrier systems, with competitive inhibition within each group.
How do NSAIDs cause renal failure?
By inhibiting the production of prostaglandins which normally keep the afferent arterioles vasodilated to maintain GFR
How high can the osmolarity of the medulla reach?
1200-1400 mOsm
How is ICF measured?
ICF = TBW - ECF
How is interstitial volume measured?
Interstitial volume = ECF - PV
How is PAH secreted?
Via secondary active transport
How is PAH transport mediated?
Mediated by a carrier system for organic acids
How much of the ECF is interstitial fluid?
Three-fourths
How much of the ECF is plasma?
One-fourth
How much of the total body water is part of intracellular fluid?
Two-thirds
How much of the total body water is part of the extracellular fluid?
One-third
If clearance of substance X is equal to GFR, what occurs?
There is no net secretion or reabsorption
If clearance of substance X is greater than GFR, what occurs?
Net tubular secretion of X
If clearance of substance X is less than GFR, what occurs?
Net tubular reabsorption of X
T/F. Secondary active transport of amino acids is saturable.
TRUE
What 3 layers form the glomerular filtration barrier?
1. Fenestrated capillary endothelium 2. Fused basement membrane with heparan sulfate 3. Epithelial layer consisting of podocyte foot processes
What actions does ADH have on the kidney?
-Increase water permeability of principle cells in collecting ducts -Increase urea absorption in CD -Increase Na/K/2Cl transporter in the thick ascending limb
What actions does AII have on the kidney?
-Contraction of efferent arteriole increasing GFR -Increased Na and HCO3 reabsorption in proximal tubule
What actions does aldo have on the kidneys?
-Increased Na reabsorption in distal tubule -Increased K secretion in DT -Increased H ion secretion in DT
What actions does ANP have on the kidney?
-Decreased Na reabsorption -Increased GFR
What actions does PTH have on the kideny?
-Increased Ca reabsorption -Decreased phosphate reabsorption -Increase 1,25-(OH)2 Vit D production
What activates 1 alpha-hydroxylase?
PTH
What are the 4 actions of angiotensin II?
1. Vasoconstriction 2. Release of aldo from adrenal cortex 3. Release of ADH from posterior pituitary 4. Stimulates hypothalamus to increase thirst
What are the 4 endocrine functions of the kidney?
1. EPO release 2. Vitamin D conversion 3. Renin release 4. Prostaglandins release
What are the consequences of a loss in the charge barrier?
-Albuminuria -Hypoproteinemia -Generalized edema -Hyperlipidemia
What competitively inhibits the carrier system for PAH?
Probenecid
What constricts the efferent arteriole?
Angiotensin II
What dilates the renal afferent arteriole?
Prostaglandins
What do the collecting ducts reabsorb in exchange for K or H?
Na ions
What does renin do?
Cleave angiotensinogen into angiotensin I
What does the anterior pituitary secrete?
-FSH and LH -ACTH -GH -TSH -MSH -Prolactin
What does the beta subunit do?
The beta subunit determines hormone specificity
What does the early distal convoluted tubule actively reabsorb?
-Na ions -Cl ions
What does the posterior pituitary secrete?
ADH and oxytocin
What does the secretion of prostaglandins from the kidney do?
Vasodilates the afferent arterioles to increase GFR
What does the thick ascending loop of Henle actively reabsorb?
-Na ions -K ions -Cl ions
What does the thick descending loop of Henle indirectly reabsorb?
-Mg ion -Ca ions
What effect does constriction of the efferent arteriole have?
-Decreased RPF -Increased GFR -FF increases
What effect does dilation of the afferent arteriole have?
-Increased RPF -Increased GFR - FF remains constant
What enzyme converts 25-OH Vit D to 1,25-(OH)2 Vit D?
1alpha-hydroxylase
What happens to glucose in the kidneys when glucose is at a normal level?
Glucose is completely reabsorbed in the proximal tubule.
What hormones act on the kidney?
1. ADH 2. Aldosterone 3. Angiotensin II 4. Atrial natriurtic Peptide 5. PTH
What inhibits constriction of the efferent arteriole by AII?
ACE inhibitors
What inhibits dilation of the afferent arteriole by prostaglandins?
NSAIDS
What is an important clinical clue to diabetes?
Glucosuria
What is angiotensin II's overall function?
To increase intravascular volume and increase blood pressure
What is passively reabsorbed in the thin descending loop of Henle?
Water via medullary hypertonicity (impermeable to sodium)
What is reabsorbed in the early distal tubule under the control of PTH?
Ca ions
What is the function of the early proximal convoluted tubule?
Reabsorbs all of the glucose and amino acids and most of the bicarbonate, sodium, and water
What is the oncotic pressure of Bowman's space?
Zero
What is the thick ascending loop of Henle impermeable to?
Water
What is the threshold for glucose reabsorption in the proximal tubule?
200 mg/dL
What may act as a 'check' on the renin-angiotensin system in heart failure?
ANP
What part of the nephron secretes ammonia?
Early proximal convoluted tubule
What part of the pituitary is derived from neuroectoderm?
Posterior pituitary
What percentage of the body is water?
0.6
What regulates the reabsorption of water in the collecting ducts?
ADH
What secretes renin?
JG cells
What stimulates ADH secretion?
-Increased plasma osmolarity -Greatly decreased blood volume
What stimulates aldosterone secretion?
-Decreased blood volume (via AII) -Increased plasma K concentration
What stimulates angiotensin secretion?
Decreased blood volume (via renin)
What stimulates ANP secretion?
Increased atrial pressure
What stimulates EPO release?
Hypoxia
What stimulates PTH secretion?
Decreased plasma ca concentration
What stimulates renin release?
1. Decreased renal arterial pressure 2. Increased renal nerve discharge (Beta 1 effect)
What subunit do TSH, LH, FSH and hCG have in common?
Alpha subunit
What symptom is present once threshold is reached?
Glucosuria
What type of tissue is the anterior pituitary derived from?
Oral ectoderm
What value is used clinically to represent GFR?
Creatinine clearance
What variables are needed to calculate free water clearance?
-Urine flow rate -Urine osmolarity -Plasma Osmolarity
Where
does
Primarily
the
Where
does
In
the
Where
is
Endothelial
cells
Where
is
Proximal
tubule
Which
barrier
Charge
barrier
Which
layer
Fused
basement
Which
layer
Fenestrated
capillary
Where does ACE convert AI to AII
Where does secondary active transport of amino acids occur
Where is EPO secreted
Where is paraaminohippuric acid secreted
Which barrier is lost in nephrotic syndrome
Which layer filters by negative charge
Which layer filters by size