Renal - Lecture 3 Flashcards
What is the clearance of glucose in a normal/healthy person?
zero
Total-body balance of ___ and ___ has to be maintained to sustain normal blood pressure and life.
sodium and water
How is water lost every day (4)?
- skin and lungs (insensible loss)
- sweat
- in feces
- urine
How is NaCl lost every day (3)?
- sweat
- feces
- urine
How much can water output vary?
0.4 L to 25 L a day
How much can sodium chloride output vary?
0.05 g to 25 g a day
Is sodium and water secreted?
no
How much of sodium and water are reabsorbed?
99%
Where does the majority of sodium and water reabsorption occur?
in the proximal tubule
Where does the major hormonal control of reabsorption of water and sodium occur?
on the DCT and CD
What kind of process is the sodium reabsorption?
active
Where does sodium reabsorption happen? What is the exception?
in all tubular segments except the descending thin limb of Henle’s loop
How does water reabsorption happen?
by diffusion
What is water reabsorption dependent upon?
sodium reabsorption
What happens to sodium reabsorption on the basolateral membrane?
the ATPase pumps transports sodium out of the cells and keep the intracellular concentration of sodium low
What happens to sodium reabsorption on the apical membrane?
sodium moves downhill from tubular lumen into the tubular epithelial cells
Every tubular segment has different ___.
mechanisms
What is the transport protein in the cortical collecting duct cells that allows sodium to enter?
sodium channel
What are the transport proteins in the proximal tubule that allows sodium to enter?
Na+-H+ antiporter
Na+-glucose cotransporter
How is renal sodium regulated?
when sodium intake increases, urinary sodium increases
when sodium intake decreases, urinary sodium decreases
Sodium is the major ___ solute.
extracellular
Changes in total body sodium result in similar changes in ___ fluid volume.
extracellular
Total body sodium is sensed as ___ filling by baroreceptors in the cardiovascular system.
intravascular
How is total body sodium sensed?
by baroreceptors
Is plasma concentration of sodium a marker for total body sodium?
no
What does P(Na) only reflect?
the relative relationship of total Na and water
What is the formula for sodium excreted?
sodium filtered - sodium reabsorbed
Is sodium secreted in the tubules?
no
How is sodium excretion regulated by (2)?
- GFR (minor role)
- sodium reabsorption (most important)
What is the sensor of the kidney at the level of vascular filling?
renal sympathetic nerve
What happens to plasma volume and venous pressure when Na and H20 decrease due to diarrhea?
they both decrease
What increases the activity of renal sympathetic nerves?
the decrease in venous return, atrial pressure, ventricular end-diastolic volume, stroke volume, CO, arterial blood pressure
What happens to the afferent arterioles when the activity of the renal sympathetic nerves increases?
they constrict
What has a direct effect on the constriction of afferent arterioles?
the decrease in arterial blood pressure
What happens to the net GF pressure when the afferent arterioles constrict?
it decreases
What causes the decreases in excretion of Na+ and H20?
the decrease in GFR
What is the key hormone that regulates sodium by reabsorption?
aldosterone
Where does aldosterone stimulate sodium reabsorption?
in the DCT and CCD
How much of the filtered load is excreted when there is no aldosterone?
2%
How much of the filtered load is excreted when there is high aldosterone?
0%
How much Na is reabsorbed in the proximal tubule?
67%
How much Na is reabsorbed in the descending loop of Henle?
0
How much Na is absorbed in the ascending loop of Henle?
25%
How much na is absorbed in the distal tubule and cortical collecting duct?
DT: 4%
CCD: 3%
What is the final amount of Na excreted by aldosterone?
1%
What does aldosterone upregulate and activate?
ATPase pump, sodium channels and potassium channels
Aldosterone stimulates sodium ___ and ___.
reabsorption and secretion
What else does aldosterone increase the secretion of?
H+
What secretes aldosterone?
adrenal cortex
What causes the secretion of aldosterone?
angiotensin II
What converts angiotensin I to angiotensin II?
angiotensin converting enzyme
What converts angiotensinogen to angiotensin I?
renin
What is the rate limiting step in the renin-angiotensin system?
the amount of renin your body has
What other 3 thing stimulates aldosterone secretion?
plasma K+
ACTH
ANP
What is found around the afferent arterioles?
juxtaglomerular cells
Which cells secrete renin?
juxtaglomerular cells
What 3 components activate the juxtaglomerular cells?
- sympathetic nerve fiber
- macula densa cells
- vascular tension of afferent arteriole
The:
___ activity of renal sympathetic nerve
___ arterial pressure
___ GFR
___ flow to macula densa
___ NaCl delivery to macula densa
causes the increase secretion of renin by renal juxtaglomerular cells
increase
decrease
decrease
decrease
decrease
Does aldosterone stimulate H20 reabsorption directly in the CCD?
no
What does ANP stand for?
atrial natriuretic peptide
What kind of hormone is ANP?
peptide hormone
What cells secrete ANP?
cells in cardiac atria
Where does ANP act on?
the tubules
What does ANP inhibit?
sodium reabsorption
What stimulates ANP secretion?
increased total body sodium
Increased blood pressure ___ sodium excretion.
increases
When the plasma volume increases, the distention and ANP secretion in the cardiac atria ___.
increases
What happens to plasma aldosterone when the plasma ANP increases?
it decreases
What happens to the afferent arterioles and efferent arterioles when plasma ANP increases?
afferent: dilates
efferent: constricts
What happens to the Na reabsorption in the tubules when plasma ANP increases?
it decreases
When plasma volume increases, sodium excretion ___.
increases
