renal final Flashcards
volume
L, mL, microliter, gallon
velocity
distance/time
meters/second
km/hr
pressure
force
mmHg
cmH20
area
size
cross sectional area
- internal diameter
surface area
-walls of cylinder
blood flow
volume/time
ml/min
vascular conductance
inverse of vascular resistance
the ease of blood flow through a vessel
high conductance= high flow
what 2 things affect conductance
- viscosity
- density
- pipe length
- pressure difference between both ends
3 main functions of circulatory system
- transport nutrients to tissues
- transport waste products away from tissues
- transporting hormones
the greater the resistance…
the less flow
what does the brain use to drive brain blood flow
cerebral perfusion pressure
high conductance ->
high flow
what do the kidneys release to low MAP
renin released by juxtaglomerular cells
system in parallel ->
more pathways -> lower overall resistance
how does a larger cross sectional area affect blood flow in each individual tube?
lower velocity of blood flow
ex: capillaries (high cross sectional area) vs aorta
what are the 2 high resistance vessels
small arteries
*arterioles
what are the targets for pressers?
small arteries and *arterioles made of smooth muscle
why doesn’t BP decrease after the capillaries?
veins
-thin walls
- compliant
- decreased resistance
what is the BP from end of capillaries -> RA
10 mmHg
what does pressure drive?
blood flow
what does resistance drive?
Pressure
kidneys have how much blood flow and percentage of cardiac output
22% CO
1100 mL/min
why do the kidneys need extra blood flow?
filtration
large pressure difference in a vessel beginning to end ->
lots of flow
if you constrict vessel in half of its diameter ->
decrease flow by 16 fold
if you dilate the vessel twice its original size ->
increase flow by 16 fold
what vessel controls blood flow through capillaries
arterioles
describe small arteries and arteriole vessels and thickness
4 layers of smooth muscle
20 micrometers thick
UNITARY SMOOTH MUSCLE
how many capillaries in our body
10+ billion
capillary nutrient delivery includes (4)
glucose
fats
cholesterol
oxygen- exchange for CO2
describe capillary vessels and thickness
1 cell layer endothelial
1 micrometer thick
good for nutrient exchange
name 3 proteins of capillary oncotic pressure (in decreasing order)
albumin
globulins
fibrinogen
what is the other circulatory system in the body
lymphatics
what proteins make up the ISF colloid osmotic pressure
matrix proteins
- proteoglycan filaments
- hyaluronic acid
- collagen
how much can lymphatics increase activity in a health person
20-40x of fluid
what is the capillary filtration coefficient?
how permeable the capillaries are to FLUID
increased surface area in capillary means…
more permeation
what do lymphatics contain? like veins do
one way valves which rely on skeletal muscles to pump fluid back into circulation
where do lymphatics empty into?
lymphatic ducts into subclavian veins ontop of thorax
In systemic circulation, why is the overall capillary pressure 17.3 mmHg and not 20 mmHg
because capillary diameter gets larger on the venous end
Epithelial cells in a general capillary, the larger the ______ the LESS permeable the compound
molecular weight
what regulates GFR in the kidney
efferent arterioles
how much plasma is filtered in the kidney????
1/5th
whats the average GFR of ALL the glomerular capillaries combined?
125 mL/min
auto regulation controls what 2 things in the nephron?
blood flow
filtration
auto-regulation of renal blood flow is _____ as tight as it is in the brain
NOT
that’s why renal auto regulation is slanted
50-150 mmHg
what happens to proteins if they get in the tubule?
whats their pressure?
they get tethered to the cell membrane of tubule
no osmotic pressure associated with them
what vessel in kidney has the highest vascular resistance?
efferent arteriole
what percent of what gets filtered gets reabsorbed?
99% of filtrate
what cells are in the tubule
endothelial
what 3 things get secreted?
larger waste compounds/toxins
K+
what regulates renal blood flow in the kidney?
what regulates GFR?
afferent arteriole
efferent arteriole
constriction of efferent or afferent arterioles will…
decrease renal blood flow
3 conditions that make you unable to dilate your vessels
chronic HTN
sick (ICU)
DM
MAP range of renal autoregulation
50-150 mmHg
*except for people unable to dilate thier vessels
an example of something that’s filtered and PARTIALLY absorbed
Na+
an example of something thats filtered and COMPLETE absorption
glucose in non-diabetic
what is freely filtered and is FULLY secreted?
para aminohippuric acid
its actively secreted
diagnosis renal blood flow
* not present in renal vein means high renal blood flow
high clearance rate
inner, middle, outter layers of the glomerular capillaries
endothelium
- more permeable due to fenestrations
- contain negative charges
basement membrane
- big connective tissue
- contain negative charges
epithelium
- podocytes, structural reinforcement
where are podocytes located
epithelium
outer glom cap layer
provides structural reinforcement
what type of solutes are more likely to be filtered?
small, positive or neutral charged
what synthetic exogenous compound is used for finding GFR, more sensitive than creatinine
inulin
injected then check blood and urine levels
freely filtered NOT reabsorbed
what structural component provides support in the brain capillary
astrocytes
what are the “foot” processes of podocytes called which are littered with negative charges
slip pores
how does kidney regulate pH
produces and reabsorbs bicarbonate
excretes excess protons
where in the kidney regulates RBC hematocrit levels
what does kidney release
O2 sensors in deep medullary renal interstitium
releases erythropoietin
what does erythropoietin do?
stimulates bone marrow to produce more RBC
what vitamin is activated in the kidneys? why is this important?
vitamin D (calcitrol)
important for calcium absorption
how do drugs gets cleared
drugs metabolized in liver (P450) to more water soluble form, then filtered/secreted by kidney
what is a nitrogenous waste product of the kidney
urea
increased osmolarity means what?
hypernatremic
what in the brain cause ADH to be released
osmoreceptors
what does the macula densa do?
where is it located?
autoregulation of GFR
- comes into contact with juxtaglomerular apparatus
thick ascending LOH
at birth how many nephrons in EACH kidney
1 million
- start loosing nephrons at age 40
what makes up the nephron
afferent arteriole, efferent arteriole, peritubular capillaries, glomerular capillaries, tubules
cortical nephrons
more superficial
- LOH and peritubular capillaries extend into the outer medulla
90-95% of total nephrons
medullary nephrons
extend deep into the inner medulla… after the peritubular capillaries
- depending vasa recta
- ascending vasa recta (more)
why is it important that the ascending vasa recta has more split points than the descending vasa recta?
to decrease flow -> maintain normal concentration of solutes in the deep medullary interstium
if flow too fast it washes out the interstitium
what does angiotensin 2 constrict
another effect of angiotensin 2
efferent arteriole
increase Na reabsorption
what supplies blood to the kidneys
mesenteric arteries
what gland is onto of kidneys and what does it produce
adrenal glands
- glucocorticoids
- mineralocorticoids
- androgens
what two things form the ureter
minor calyx and major calyx
who was the chemist that took vitamin C (antioxidant) for prostate cancer
linus pauling
20,000 units vit C
what nerve controls bladder and rectum
where is it located
pudendal nerve
comes off spinal nerves
* S2, S3, S4
external sphincter and bladder
what is renal clearance
quantity of plasma that is cleared of a substance per measured time
ml/min
rate of filtration
rate of reabsorption
urine output
125 ml/min
124 ml/min
1 ml/min
if we reabsorb 100% of what was filtered (glucose) what is the clearance?
zero
(low clearance)
dL to mL conversion
1 dL = 100 mL
why is creatinine not as accurate for GFR?
its slightly secreted from the peritubular capillaries… therefore its a slight over estimate of GFR
what is creatinine a by-product of?
skeletal muscle metabolism
bad measurement of GFR:
bed bound pt. has low skeletal mass -> low creatinine production -> not accurate GFR
complications of chronic HTN on kidney
- arteriolosclerosis of afferent arteriole due to constant constriction
- glomerulus weakened podocytes, widened split pores/fenestrations, fibrosis
*glomerulus suffers most
hypotension in the tubule effects on filtration and reabsorption
less filtration and more reabsorption b/c fluid in tubule longer
*reabsorption also less selective
3 drugs that favor afferent arteriole
beta blockers
calcium channel blockers
pressors
how do pressers work on the kidney
vasoconstrict both arterioles
*more afferent though
where is the macula dense located
what does it monitor
thick ascending limb
monitors Na* and Cl TOAL NUMBERS not CONC.
monitors filtration rate
where are juxtaglomerular cells located
afferent and efferent arterioles
release renin
what do ACEi do?
prevent angiotensin 2 from being synthesized from angiotensin 1
2 causes of increased Na reabsorption
hyperglycemia
elevated amino acids
both lead to decreased numbers of Na and Cl reaching the macula densa… and macula dense thinks GFR is low even though its not (bad)
glucose threshold in the kidney
what does threshold mean
160 mg/dL
when glucose transporters begin to MISS glucose… glucose starts to be excreted in the urine
glucose transport maximum glucose level
300 mg/dL
transport maximum:
all glucose is excreted into urine
transporters can’t change their confirmation change fast enough to transport the glucose
secondary and tertiary effects from macula densa sensing low BP
nitric oxide mediated vasodilation of afferent arteriole
proximal tubule NaCl reabsorption via angiotensin 2
laminar flow
normal, efficient, non-turbulent
middle of vessel blood is the fastest
disorderly flow
turbulent flow
- inefficient
- can remodel vessels over time (calcifications , plaque build up)… calcium and cholesterol
- often caused by plaque or clot to begin with -> chokepoint
- initial velocity of flow through chokepoint is HIGH
- occurs in lungs too
- Reynold’s equation
what vessels do we take blood pressure?
large arteries… proximal to the resistance
- brachial artery, femoral artery
Why the drop in BP that happens between large arteries and capillaries?
VASCULAR RESISTANCE
not* the fact that it has multiple pathways to take
what is the total surface area of all capillaries combined
500-700 sq meters
LANGE BOOK AUTHOR
mohrman
where are endothelial cells located (4 places)
inner heart chambers
veins
arteries
capillaries
delta P of capillary
30 mmHg arteriolar/arterial end
10 mmHg venous end
DELTA P= 20 mmHg
why is the hydrostatic pressure in ISF negative
-3 mmHg
lymphatic system creating vaccum of negative pressure pulling ISF
liver failure and hemorrhaging cause a ________ in plasma osmotic pressure
decrease
if membrane becomes porous (sepsis) why does the plasma osmotic pressure decrease?
because the osmotic pressure is associated with a SEMIPERMEABLE MEMBRANE
*secondary problem is that the proteins can leak out
what are the collection area for the lymphatics
lymph nodes
ex: inguinal nodes
what is the average BP in a systemic capillary?
17.3 mmHg
what are 2 examples of measuring how much excretion there is?
mLs (volume)
mol or mg (quantity)
normal renal blood flow
1100 mL/min
normal filtration fraction
20%
bladder is controlled by ______ and ______ nervous systems
PNS and SNS
kidney filters substance “X” and reabsorbs ONLY the fluid that substance “X” was dissolved in. This means clearance is _____
HIGH
what is an exogenous compound that is freely filtered but NOT reabsorbed or excreted…. gold standard for measuring GFR
inulin
clearance rate = 124 mL/min
given IV, 2 measurements of urine and plasma at 2 different times
2 things freely filtered but not reabsorbed at the PT
creatinine
urea
conc. increases throughout the tubule
2 effects from angiotensin 2
- increase GFR
- Increase water retention via increased salt reabsorption
glucose is ONLY reabsorbed at the ______
proximal tubule
the filtered load of glucose is dependent on what 2 factors?
what does filtered load mean?
*plasma conc. of glucose
and GFR
filtered loads means quantity of glucose filtered
