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Phys. Exam 4 Renal Filtration
Renal Filtration
89
Physiology
11/16/2010

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Term
Kidney functions:
Definition
- Regulation of body fluid volume and composition
- Regulate acid-base balance
- Rid body of waste products and foreign substances
- Blood pressure regulation
- Endocrine function – renin, calcitriol, erythropoietin
Term
The __ is the functional unit of the kidney and is composed of the __ ___ and the ___ ___.
Definition
- nephron
- renal corpuscle
- renal tubule
Term
The renal corpuscle is made of the ___ and ___ ____.
Definition
- glomerulus
- renal capsule
Term
The renal capsule, which is one part of the renal corpuscle, has ___ layers. The inner layer surrounds the glomerulus capillaries.
Definition
two
Term
The space between the inner and outer layers of the renal capsule is called ____ ____. This area is continuous with the tubular lumen.
Definition
- Bowman's space
Term
Blood goes into glomerulus> water moves out of capillaries into Bowman's space> tubular lumen> proximal tubule> loop of Henle> distal tubule> collecting duct
Definition
Term
Theoretically, the ___ ___ is not part of the nephron, but its function is similar to that of the nephron, so it gets grouped in with it.
Definition
- collecting duct
Term
Urine formation and the adjustment of blood composition involves three major processes, list them.
Definition
- glomerular filtration
- tubular reabsorption
- tubular secretion
Term
There are two sets of capillaries in the kidneys, what are they?
Definition
- glomerulus
- peritubular capillaries that surround the renal tubules
Term
The glomerulus performs ___ ___ filtration, so there is only a very very small amount of ____ in filtrate, so small you can ignore it and call it __-free filtrate, aka ___ filtrate in Bowman's space.
Definition
- protein free filtration
- protein
- protein
- ultra-filtrate
Term
Once ultra filtrate goes into the tubular lumen, it is called ___ ___. In the renal tubules lots of water and electrolytes will be transported from the lumen back into the blood, this is called ____.
Definition
- tubular fluid
- reabsorption
Term
With filtration substances are going from the ___ in the ___ to ___ ____ and then the ___ ___.
Definition
- blood
- glomerulus
- Bowman's space
- tubular lumen
Term
With reabsorption, substances are going from the ____ to the ___ in the ____.
Definition
- from the tubular lumen to the blood in the peritubular capillaries
Term
With secretion substances go from ____ or _____ into the the ______.
Definition
- from blood or epithelial cells of the tubule to the tubule lumen
Term
Reabsorption and secretion are occuring at the same time.
Definition
Term
After filtration, reabsorption, and secretion, you have ____.
Definition
final urine
Term
Final urine is collected by the minor calyxes, where does it go from here?
Definition
- minor calyx> major calyx> renal pelvis> ureter
Term
Glomerular capillary pressure forces water and dissolved solutes into Bowman's space and produces a protein-free solution called, ____, which is very similar to ___ ___.
Definition
- ultrafiltrate
- blood plasma
Term
Main difference between plasma and ultrafiltrate is:
Definition
- plasma contains protein and ultrafiltrate does not, KNOW THIS

- but there is NO difference between concentrations of electrolytes between plasma and ultrafiltrate
- so plasma concentration of sodium is 140 mmol and ultrafiltrate sodium concentration is also 140 mmol
Term
Water passing from the glomerulus lumen to Bowman's space has to pass through what 3 barriers, going from innermost to outermost?
Definition
- endothelial cells of capillaries
- basement membrane
- podocytes
Term
Processes from podocytes form ___ ____, this is not a negative space b/c it is covered by a thin membrane called the ___ ___. This membrane has many perforations so water and substances can get through it.
Definition
- filtration slits
- slit diaphragm
Term
What makes up the glomerular filtration membrane aka glomerular filtration barrier?
Definition
- fenestrated capillary endothelium
- basement membrane
- slit diaphragm
Term
What are 2 determinants of filtration:
Definition
- mechanical property: based on size of substance and size of pore
- electrical property: the filtration membrane is negatively charged, so substances in the plasma that are negatively charged will not pass through it and will remain in the plasma
Term
The filtration membrane functions as a ____ and ____ filter.
Definition
- mechano
- electro
Term
Considering the filtration barrier, explain what happens with differently charged dextrins.
Definition
- neutral dextrin can filter
- negative dextrin won't filter
- positive dextrin filters the best
Term
4 components of Starling force:
Definition
- capillary pressure- favors filtration
- interstitial fluid colloid osmotic pressure- favors filtration
- plasma colloid osmotic pressure- againsst filtration
- interstitial fluid pressure- against filtration
Term
Interstitial colloid osmotic pressure ___ filtration because it needs to be diluted.
Definition
- favors filtration
Term
Plasma colloid osmotic pressure is ___ filtration b/c it needs to keep water and stay diluted.
Definition
- against filtration
Term
Interstitial fluid pressure aka ____ pressure is ____ filtration.
Definition
- interstitial hydrostatic pressure
- against
Term
Capillary pressure ___ filtration.
Definition
-favors
Term
Just remember interstial colloid favors filtration, interstitial fluid pressure is against.
Definition
ICF

IPA
Term
Why is the glomerulus more efficient than other capillary beds?
Definition
- its filtration membrane is much more permeable
- glomerular blood pressure is higher
- it has a higher net filtration barrier
Term
Plasma proteins are not filtered in the glomerulus and are used to maintain plasma ____ pressure in the blood.
Definition
- oncotic
Term
What starling force is lacking in the kideny and why?
Definition
- oncotic pressure in Bowman's space/interstial b/c filtrate is protein free
Term
The three pressures that determine glomerular filtration include:
Definition
- hydrostatic/fluid pressure in glomerulus
- oncotic pressure in glomerulus
- hydrostatic/fluid pressure in Bowman's space
Term
___ ___ ____ is the pressure responsible for filtrate formation. Equation for this value:
Definition
- Net Filtration Pressure

NFP= glomerular hydrostatic pressure - (glomerular oncotic pressure + Bowman's space hydrostatic pressure)
Term
Filtration is not constant throughout glomerulus, it decreases along the way, so NFP decreases along the way.
Definition
Term
average NFP:
Definition
17 mmHg
Term
NFP decreases along the way of a capillary b/c water is being reabsorbed so ____ ____ pressure is increasing, which is against filtration.
Definition
- glomerular oncotic
Term
Define Glomerular Filtration Rate:
Definition
- GFR
- the total amount of filtrate formed per minute by both kidneys together (about 125 ml/min)
Term
Factors governing GFR:
Definition
- total surface area available for filtration
- filtration membrane permeability
- Net Filtration Pressure (NFP)
Term
Glomerular filtration is driven by NFP, so a factor that affects NFP will also affect GFR. So if you have high NFP you will have a higher GFR.
Definition
Term
GFR assess the function of ___ ___.
Definition
all nephrons
Term
equation for GFR:
Definition
GFR= NFP x Kf

Kf = filtration by surface area and permeability
Term
formula for filtration fraction:
Definition
FF= GFR/RPF

RPF: renal plasma flow
Term
Filtration fraction can be used to assess GFR and affects GFR.
Definition
Term
factors that affect GFR:
Definition
- NFP- direct correlation
- RPF- direct correlation
- GFR- direct correlation
Term
parameters used to assess renal function:
Definition
- GFR
- RPF
- FF
Term
If both the afferent and efferent arterioles were constricted, pressure would be ___ and renal plasma flow would be ___, so GFR would be ___.
Definition
- high
- low
- low
Term
If the efferent arteriole is constricted, but the afferent is normal, resistance of the renal vasculature will ____, renal plasma flow will ____, glomerular pressure will ___, GFR will ___, and filtration fraction will ____.
Definition
- increase
- decrease
- increase
- increase
- increase
Term
If the afferent arteriole constricts, but the efferent does not, resistance ____, renal plasma flow ___, glomerular pressure ____, so GFR ___.
Definition
- increases
- decreases
- decreases
- decreases
Term
If the efferent arteriole is dilated, resistance will ____, renal plasma flow will ___, glomerular pressure will ___, GFR will ___, and filtration fraction will ____.
Definition
- decrease
- increase
- decrease
- decrease
- decrease
Term
If the afferent arteriole is dilated, resistance will ____, renal plasma flow will ____, GFR will ____, and filtration fraction will ____.
Definition
- decrease
- increase
- increase
- increase
- stay the same
Term
Define filtration fraction:
Definition
- percentage of water filtrated to total renal plasma flow in kidneys
Term
Three mechanisms that control GFR:
Definition
- renal autoregulation aka intrinsic system
- neural controls
- hormonal mechanism (renin-angiotensin system)
Term
Under normal conditions, ___ ____ maintains a nearly constant ___ ___ ___.
Definition
- renal autoregulation
- glomerular filtration rate
Term
Autoregulation entails two types of controls, list and define them.
Definition
- Myogenic- responds to changes in pressure in the renal blood vessels
- Flow-dependent tuboglomerular feedback- senses changes in the juxtaglomerular apparatus
Term
Above an arterial pressure of 100 mmHg, renal blood flow and GFR do not change much due to ____.
Definition
autoregulation
Term
Explain the renal autoregulation-myogenic response to increased pressure in the renal artery:
Definition
- increased pressure in renal artery> strethces walls of afferent arteriole> constriction of afferent arteriole> no change in the glomerular capillary pressure and renal plasma flow> no change in GFR
Term
components of the juxtaglomerular apparatus:
Definition
- ascending loop of henle/distal tubule with macula densa cells
- afferent arteriole with juxtaglomerular cells
- extraglomerular mesangial cells between the afferent and efferent arterioles
Term
The ___ cells in the ___ ___ make renin.
Definition
- juxtaglomerual cells
- afferent arterioles
Term
The __ ___ in the ___ ___ senses concentration of NaCl in tubular fluid.
Definition
- macula densa
- ascending loop
Term
Explain the autoregulation response that occurs with increased GFR:
Definition
- increased GFR> more sodium goes past the macula densa> macula densa senses high NaCl> macula densa sends signals to afferent arteriole causing it to contract> less blood flow in glomerulus> GFR goes back to normal

- this is an example of negative feedback
Term
Via what substances does the macula densa cause the afferent arteriole to constrict?
Definition
- ATP
- Adenosine
Term
Via what substances does the macula densa cause the afferent arteriole to relax?
Definition
- nitric oxide
- PGE2
Term
So if GFR is high, urine flow will be high, the macula densa will note lots of NaCl and send signals via ATP and Adenosine to the afferent arteriole causing it to constrict to decrease GFR
Definition
Term
If the GFR is low, urine flow will be low, and the macula densa will NOT note much NaCl and will send signals via nitric oxide and PGE2 to the afferent arteriole causing it to dilate so GFR will increase some
Definition
Term
List the local hormones that have intrinsic control over the kidneys:
Definition
- Endothelin-I
- Prostaglandins
- Nitric Oxide
- Adenosine
Term
Endothelin I is produced by the ___ and causes ____ of the afferent and efferent arterioles , thus decreasing ___ and ___.
Definition
- kidney
- vasoconstriction
- RBF and GFR
Term
Prostaglandins are produced by the ____ and increase ____ by antagonizing the effects of ___ and _____.
Definition
- kidneys
- renal blood flow
- antagonizing sympathetics and Ang II
Term
Nitric oxide is ___ produced and caused ___ of the afferent and efferent arterioles, thus increasing ____.
Definition
- locally
- dilation
- renal blood flow (RBF)
Term
Adenosine is produced in the ___ and causes ____ of the afferent and efferent arteriole, thus ___ GFR and RBF.
Definition
- kidney
- vasoconstriction
- decreasing
Term
When the sympathetic nervous system is at rest, the renal blood vessels are maximally ____ and ____mechanisms prevail.
Definition
- dilated
- autoregulation
Term
Under stress, the sympathetic nervous system releases ____ and the adrenal medulla releases ____. These cause the ___ arteriole to constrict which inhibits ___. The sympathetic nervous system also stimulates the ______ mechanism.
Definition
- norepinephrine
- epinephrine
- afferent
- filtration
- Renin-angiotension mechanism
Term
The sympathetic nervous system will trigger the ____ ____ mechanism.
Definition
renin-angiotension
Term
The renin-angiotension mechanism is triggered when the ____ cells release ___. These cells are stimulated to release this by the sympathetic nervous system.
Definition
- juxtaglomerular cells
- renin
Term
Renin acts on ____ to release _____.
Definition
- angiotensinogen
- Angiotension I
Term
Angiotension I (10 amino acids long) is not active yet. _____, which comes from the lungs, converts Ang. I to Angiotension II (8 amino acids, active form).
Definition
- Angiotension Converting Enzyme (ACE)
Term
Angiotension II causes vessel ____ to ____ blood pressure. It also further stimulates the ___ ___ to release ____.
Definition
- constriction
- increase
- adrenal cortex
- aldosterone
Term
Angiotensinogen is made in the ____.
Definition
liver
Term
Angiotension II cuases mean arterial pressure to ___ and stimulates the ___ ___ to release ___. As a result, both ___ and ____ ___ pressure rise.
Definition
- increase
- adrenal cortex
- aldosterone
- systemic
- glomerular hydrostatic
Term
Renin release can be triggered by 3 mechansims. List them.
Definition
- reduced stretch of the granular juxtaglomerular cells
- stimulation of juxtaglomerular cells via activated macula densa cells
- direct stimulation via beta1 adrenergic receptors by renal nerves
- angiotension II
Term
Atrial Natriuretic Peptide (ANP) is secreted by ___ ___ and is part of extrinsic control of kidneys.
Definition
- cardiac atria
Term
Brain Naturiuretic Peptide (BNP) is secreted by the ___ ___ and ___.
Definition
- cardiac ventricle
- brain
Term
ANP and BNP both ___ the afferent arteriole and ___ the efferent arteriole to ___ GFR without much change in RBF.
Definition
- dilate
- constrict
- incease
Term
List 3 vasoconstrictors to the kidneys:
Definition
- sympathetic nerves
- Angiotension II
- Endothelin
Term
List 3 vasodilators to the kidneys:
Definition
- prostaglandins (PGE2, etc. )
- nitric oxide
- bradykinin
- ANP
- BNP
Term
Intrinsic mechanisms are in control for pressures between:
Definition
80 and 180 mmHg
Term
Extrinsic mechanism kick in with pressures below ___.
Definition
80 mmHg