Urinary 2 Flashcards
Mastery
the sodium potassium pump is between what
what is its purpose
how does Cl- move
how does H2O move
how does glucose move
how does K+ move
H+?
lumen, across the cell, fluid, and then blood
3 membranes for the price of one
- creates a gradient across membranes, to facilitate absorption into the blood, so 100% of Na+ is brought back is.
Cl- gets a free ride into the blood with Na+. ELECTRICAL GRADIENT
H2O also moves with Cl- and Na+. OSMOTIC GRADIENT
glucose moves with sodium, and once in the fluid, need a carrier
K+ moves against Na+ at the start and it moves in
exchange with Na+
and exchange with K+ and reabsorb
Reabsorption of Glucose
Tubular maximum
Point where all the….
Renal threshold
…..
Eg. …
Tubular maximum
Point where all the glucose carriers are full
excess glucose stays in the tubules and is lost in the
urine
Renal threshold
Blood glucose level where the carriers are full and glucose is seen in the urine
Eg. Diabetes Mellitus
Tubule Area
% of Na+ reabsorbed
role of reabsorbtion
Proximal tubule
Ascending limb of the loop of Henle
Distal and collecting tubules
Urea Reabsorption
Urea - what is it
size? process? amount?
Urea - byproduct of protein breakdown
Small, diffusible
Passive process
To equilibrium - 50%
*TEST **Reabsorption
% - and how
Na+ (…%) - ….
Cl- (…%) - …..
Water (…%) - ….
Glucose (….%) - ….
Urea (….%) - ….
K+ (…..%) - …..
Reabsorption
Na+ (99.9%) - Na+/K+ ATPase pump
Cl- (99%) - Electrical gradient
Water (99%) - Osmotic gradient
Glucose (100%) - Carrier-mediated
- Sodium-linked glucose reabsorption in the
proximal tubule
Urea (50%) - Passive
K+ (80-90%) - secreted and reabsorbed
Aldosterone
Controls ….
Released if….
High Aldosterone
… speed of pump
… Na+ reabsorption
… water reabsorption
* … urine
Eg. …
Renin-Angiotensin-Aldosterone System
Regulates … and ….
Controls Na+/K+ ATPase pumps - receptors in cell
Released if blood volume is low
High Aldosterone
↑ speed of pump
↑ Na+ reabsorption
↑ water reabsorption
* Decreased urine
Eg. Dehydration
Renin-Angiotensin-Aldosterone System
Regulates Na+ and blood pressure/volume
Atrial Natriuretic Peptide (ANP)
what is it?
goes against?
inactivates….
Inhibits….
Secreted by … with
…
Atrial Natriuretic Peptide (ANP) - water loaded, increased stretch in left atria, sends out this ANP. sodium potassium pump to be inhibited, more sodium out in urine, slows osmotic gradient. More urine
Antagonist to Aldosterone - distal tubule
inactivates Na+/K+ pump
Inhibits Na+ reabsorption
Secreted by atria with
↑ BP
↑ Na+
↑ Stretch of atria (↑ volume)
Secretion
Transfer of….
… process
….+
how?
…. reabsorbed
…+
…. balance
….
biotransformed
KHLO
Transfer of molecules from extracellular fluid into tubule
Active process
K+
Na+/K+ pump
Later reabsorbed
H+
Acid-base balance
Large Organics biotransformed
Collecting Ducts
Site of….
Controlled by …
…. the urine
Requires … from…
Vasa Recta
Vessel following….
Osmotic gradient…
Collecting Ducts - salty outside of duct
Site of water reabsorption
Controlled by ADH
Concentrates the urine
Requires osmotic gradient
Loop of Henle
Vasa Recta
Vessel following loop of Henle
Similar Osmotic gradient in blood supply
Counter-Current Mechanism
Ascending loop of Henle
- Permeable to …
* reabsorb?
- Impermeable to …
- Filtrate becomes …
Loop of Henle
Creates a….in medulla
From 100 to 1200 mosm/litre
Descending loop of Henle
- Permeable to …
- Impermeable to …
- Filtrate becomes …
Descending loop of Henle
- Permeable to water
- Impermeable to salts
- Filtrate becomes more concentrated
Loop of Henle
Creates a large, vertical osmotic gradient in medulla
From 100 to 1200 mosm/litre
Ascending loop of Henle
because it is so salty, pump out salts.
- Permeable to salts
* Actively reabsorbed NaCl
- Impermeable to water
- Filtrate becomes less concentrated
Water reabsorption
ADH causes insertion of water pores….
ADH
Anti-diuretic hormone
Controls ….
Released if….
Low ADH
…. to water
…. urine
* … volumes
Eg. ….
High ADH
Due to….
makes collecting duct….
…. urine
* …. volume
Eg. ….
Water reabsorption
ADH causes insertion of water pores into the apical membrane
ADH
Anti-diuretic hormone
Controls permeability of collecting ducts
Released if blood osmolarity high
Low ADH
Impermeable to water
Dilute urine
* High volumes
Eg. Water loading
High ADH
Due to high blood osmolarity
makes collecting duct permeable to water
Concentrates urine
* Lower volume
Eg. Dehydration
TEST
Dehydration
….ADH
….Aldosterone
…. ANP
…. water reabsorption
…. urine
* more …
Behavioral Mechanisms
Drinking?
Low sodium stimulates….
…. help prevent dehydration
Desert animals….
TEST
Water Loading
…ADH
….Aldosterone
….ANP
…. Water reabsorption
…. urine volume
* More ….
Dehydration
↑ADH
↑Aldosterone
↓ ANP
↑ water reabsorption
↓ urine
* More concentrated
Behavioral Mechanisms
Drinking replaces fluid loss
Low sodium stimulates salt appetite
Avoidance behaviors help prevent dehydration
Desert animals avoid the heat
Water Loading
↓ADH
↓Aldosterone
↑ANP
↓ Water reabsorption
↑ urine volume
* More dilute
Proximal Tubule
…% of Na, Cl, and water reabsorption
….% glucose and amino acids are reabsorbed
K is …. (small amt)
Variable …. secretion occurs
Organic ion … (not controlled)
Phosphate and electrolytes controlled, variable reabsorption
Urea reabsorption to…
Distal Tubule
Variable Na reabsorption
- controlled by …
Variable water reabsorption
- controlled by…
Variable K secretion / reabsorption
- controlled by …
Variable H secretion
- depends on …
Collecting Ducts
Variable water reabsorption
- controlled by …
Variable H secretion
Variable Urea reabsorption
- related to ….
Proximal Tubule
67% of Na, Cl, and water reabsorption
100% glucose and amino acids are reabsorbed
K is secreted / reabsorbed (small amt)
Variable H secretion occurs
Organic ion secretion (not controlled)
Phosphate and electrolytes controlled, variable reabsorption
Urea reabsorption to equilibrium 50%
Distal Tubule
Variable Na reabsorption
- controlled by aldosterone and ANP
Variable water reabsorption
- controlled by aldosterone and ANP
Variable K secretion / reabsorption
- controlled by aldosterone
Variable H secretion
- depends on acid-base balance
Collecting Ducts
Variable water reabsorption
- controlled by ADH
Variable H secretion
Variable Urea reabsorption
- related to loop of Henle
Excretion
Excretion =
Clearance
Rate at which ….
Non-invasive way to measure GFR
* …
Renal Clearance
RC = UV/P
RC = …
U = …
V = …
P =…
Inulin Clearance
* Inulin clearance is equal to GFR. 100% excreted not secreted or absorbed
TEST
Glucose Clearance
Usually ….
UREA clearance
Excretion
Excretion = filtration – reabsorption + secretion
Clearance
Rate at which a solute disappears from the body
Non-invasive way to measure GFR
* Inulin and creatinine
Renal Clearance
RC = UV/P
RC = renal clearance rate (ml/min)
U = concentration (mg/ml) of the substance in
urine
V = flow rate of urine formation (ml/min; GFR)
P = concentration of the same substance in
plasma
Glucose Clearance
Usually Zero because of 100% reabsorption
UREA clearance of 50%
