Renal Physiology and AKI (Week 2): Normal Renal Physiology Flashcards
What is a good indicator of good kidney function?
Concentrated Urine, remember though that the mechanism to dilute and concentrate are intertwined
Glomerulus makes an ultra-filtrate that has the same solute concentration as the ______
blood
Where does the ultra-filtrate become diluted?
In the Thick loop of Henle
- continues in the distal tubule
What happens if there is no ADH present?
- The ultrafiltrate is going to stay approximately the same concentration as when it left at the distal tubule
- Excreting a Dilute Urine
What happens if there is ADH present?
- ADH is going to put aquaporins into the membrane and this is going to allow water to leave the ultra-filtrate and move into the Interstitium
- Concentrates the Urine
The ultra-filtrate gets _____________ on the way down, it gets ___________ on the way up and then the change is variable in the collecting duct depending on the presence or absence of ___________
concentrated, diluted, ADH
What regulates blood pressure?
Heart
Kidneys
Brain
Vessels
How does the kidney have the long term control of blood pressure?
By regulating sodium and water
Kidneys are key players in maintaining homeostasis of numerous substances like:
Potassium
Phosphorus
Acid-base
What are the two organs that play a big role in detoxifying and eliminating substances?
Kidneys
Liver
If dehydration is so severe that the blood volume is decreased, the kidneys may not get enough blood flow to filter all the waste. Creating waste build up in the blood, even though the kidneys are still doing their job of concentrating the urine. This situation is known as?
pre-renal azotemia
Filtration in the glomerulus is based on what?
Balance of hydrostatic and oncotic (protein) pressure in the glomerular capillary and Bowman’s space
The renal artery feeds the _____________, which branch off to the nephron
arcuate arteries
What plays a role in the concentrating and diluting of the urine?
Vasa recta
The filtration barrier is composed of 3 layers:
- Capillary Endothelium
- Glomerular Basement Membrane
- Visceral Epithelial Cells (called Podocytes)
The filtration barrier is composed of 3 layers:
- Capillary Endothelium
- Glomerular Basement Membrane
- Visceral Epithelial Cells (called Podocytes)
What things can NOT get into the ultra-filtrate of the glomerulus?
- Proteins
- Cells
- Other Large things
Is the rate at which substances are removed from the blood
Clearance
Is determined by hydrostatic pressure in the glomerular capillary and opposed by colloid oncotic pressure in the glomerular capillary
GFR
Are the combination of hydrostatic pressure and colloid oncotic (protein) pressure that control movement of fluid out of a capillary
Starling Force
What are the Two main mechanisms for renal auto-regulation ?
- Myogenic Mechanism
- Tubuloglomerular Feedback
is an automatic response to stretching the vessel
Myogenic Mechanism
Affects the tone of the afferent arteriole, using the renin-angiotensin-aldosterone system
Tubuloglomerular feedback
is a key part of controlling sodium, water, and blood pressure
RAAS
Where does much of the action of the RAAS occurs?
Juxtaglomerular Apparatus
RAAS is big part of ________________ feedback
tubular glomerular
These cells are cuboidal which allows them to fit in lots of mitochondria to make energy.
These cells also have an extensive brush border with lots of microvilli so there is plenty of luminal surface area for all this reabsorption to take place.
Proximal Tubule Cells
Water is reabsorbed in the _______________ part, and since that is passive, those cells are thin as they don’t have as many mitochondria as some of the more energy-intense parts of
the nephron
descending
The __________________ of the loop of Henle is very metabolically active, reabsorbing sodium, chloride, potassium, along with other things like calcium and magnesium
ascending thick limb
What helps blunt changes in pH and are fast-acting but limited incapacity?
buffers like bicarbonate or proteins
can buffer volatile acids (i.e. those in gas form), but it requires kidneys to excrete fixed acids (non-volatile) which come from diet and normal metabolism
respiratory system
What is another thing the kidney must be able to do, other than reabsorbing all the bicarbonate?
- Kidneys must also be able to secrete Hydrogens into the ultra-filtrate
- The secreted hydrogen is buffered by phosphate or ammonia in the urine.
about 65% of the Sodium is reabsorbed, along with 65% of the Chloride, and 65% of the Water. This is happening in the?
Proximal Tubule
Does the osmolality in the proximal tubule change when the volume is reduced to about 1/3 of what it was?
The osmolality doesn’t change
NaCl reabsorbed, water stays, diluted
Ascending thick loop
NaCl reabsorbed, water stays, further dilution
Distal tubule
The interstitium, which is the space outside the tubular lumen and outside the tubular epithelial cells, is what compared to the tubular lumen?
Hyperosmolar
In a dog, we would consider a urine specific gravity over __________ to be well concentrated
1.030
It needs to be over _________ to be considered well concentrated in a cat
1.035
Concentrating is an _________ process
active
AKI impairs ____________ ability
concentrating
Diluting is an __________ process
active
Hyposthenuria takes _____________ kidneys
functional
What is it called when the kidney can minimize ups and downs in the renal blood flow, which keeps GFR fairly constant?
Renal Autoregulation
What is known as a automatic response to stretching the vessel?
Myogenic Mechanisms
What are the two mechanisms for renal autoregulation?
- Tubuloglomerular Feedback
- Myogenic Mechanisms
What causes the Afferent Arteriole to dilate, delivering more blood to the glomerular capillary, which increases RBF, and it causes the Efferent Arteriole to constrict, which increases glomerular capillary pressure, thus preventing a drop in GFR?
Tubuloglomerular Feedback
___________________ in the glomerulus drains into the proximal tubule, and that tubule loops around, and when it turns into the distal tubule, it is nestled in an angle between the afferent and efferent arterioles of its glomerulus.
Bowman’s space
renal sensor elements that detect changes in distal tubular fluid composition and transmit signals to the glomerular vascular elements
Macula Densa Cells
A decrease in arterial pressure initially leads to a decrease in ________ pressure
glomerular
The decrease in glomerular pressure decreases _________.
GFR
The decreased GFR will decrease delivery of ________ to the macula densa.
NaCl
What decreases flow to the macula densa, other than the decreased GFR?
Increased proximal tubule NaCl absorption
What stimulates the release of renin, which leads to formation of angiotensin II, which increases resistance in the Efferent Arteriole?
Decreased flow in the Macula Densa
Increased resistance in the _______________ helps to increase glomerular hydrostatic pressure.
Efferent Arteriole
What also happens when there is decreased flow in the macula densa?
It decreases resistance in the Afferent Arteriole
What stimulates the
renin-angiotensin-aldosterone (RAAS) system to cause
VasoConstriction of the
Efferent Arteriole to maintain adequate hydrostatic pressure
to maintain GFR and it
causes VasoDilation of the Afferent Arteriole to restore blood flow to the kidney?
Low blood flow
It accounts for about 50% of autoregulation
Myogenic control
is a key regulator of Sodium, volume, and pressure.
RAAS
How much blood would need to be filtered to remove a substance if the kidneys were 100% efficient, describes?
Clearance
The Na+K+ATPase pump uses energy to move sodium inside the _____________ cell into the blood, decreasing the sodium concentration in the cell compared to the ultrafiltrate in the lumen
tubular
The concept of autoregulation is:
The glomerulus can maintain a fairly constant renal blood flow over a wide range of systemic blood pressure
What is the end result of RAAS activation?
Restoration of renal perfusion by increasing Sodium and water retention and increasing Blood Pressure
