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96 Cards in this Set

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What are 5 fxns of the kidneys?
Removal of metabolic waste products
Removal of foreign chemicals & bioactive substances
Regulation of water & electrolyte balance
Gluconeogenesis
Production of hormones & enzymes
When is gluconeogenesis become a substantial amount in the kidneys? In this case where does glucose come from?
During a fast. Whenever the intake of carbohydrate is stopped for much more than half a day, our body begins to synthesize new glucose (the process of gluconeogenesis) from noncarbohydrate sources (amino acids from protein and glycerol from triglycerides).
What hormones & enzymes are produced in the kidneys?
EPO, Renin, & 1,25 dihydroxyviatim D
What is the indented surface of the kidney called?
The hilum
What penetrates the hilum?
By renal artery, renal vein, nn, & ureter
Fxn of the ureter?
Carries urine out of the kidney to the bladder
Each ureter w/n a kidney is formed from funnel like structures called ________ __________ w/c in turn, are formed from ___________ __________.
Major calyces, minor calyces
Cone shaped renal tissue where minor calyces fit over?
Pyramids
What is the tip of each pyramid called? This projects to what?
Papilla w/c projects into a minor calyx
What is the fxn of the calyces?
They act as collecting cups for the urine formed by the renal tissue in the pyramids
How are the pyramids arranged?
Radially around the hilum w/ the pipillae pointing toward the hilum
The _________ constitute the medulla of the kidney.
Pyramids
What covers the cortical tissue?
A very external surface of CT called the capsule
T/F: each kidney contains 1 million nephrons.
True
Each nephron consists of a spherical filtering component called the ___________ __________ and a long __________ w/c extends from the renal corpuscle.
Renal corpuscle, tubule
What constitutes the renal corpuscle?
Glomerulus & bowman’s capsule
The nephron is made up of what 3 things?
Renal corpuscle, renal tubule, collecting duct
What makes up the renal tubule?
PCT, henle’s loop, DCT
What is the primary job of the renal corpuscle?
To create a filtrate from blood that is free of cells & large proteins
What are the afferent & efferent arterioles?
Afferent is where blood arrives from the vasculature & efferent is where blood leaves from the gloemrulus
Juxtaglomerular apparatus or JGA is composed of what 3 things?
MD - macular densa, GC - granule cells, EGM – extraglomerular mesangial cells
The filtration barrier in the renal corpuscle through which all filtered substances must pass consists of 3 layers, what are they?
the capillary endothelium of the glomerular capillaries, a rather thick basement membrane, and a single-celled layer of epithelial cells.
Talk about the capillary endothelium & what is it composed of? What is it not permeable to?
the endothelial cells of the capillaries, is perforated by many large fenestrae ("windows"), like a slice of Swiss cheese, and is freely permeable to everything in the blood except red blood cells and platelets.
This is not not a membrane in the sense of a lipid bilayer membrane but is a gel-like acellular meshwork of glycoproteins and proteoglycans, with a structure like a kitchen sponge?
Basement membrane of the capillary
Describe the epithelial cell layer that makes up the filtration barrier? What are these epithelial cells called?
epithelial cells that rest on the basement membrane and face Bowman's space. These cells are called podocytes.
Describe the structure of the podocytes?
have an unusual octopus-like structure. Small "fingers," called pedicels (or foot processes), extend from each arm of the podocyte and are embedded in the basement membrane.
_______ from a given podocytes interdigitate w/ the pedicels from adjacent podocytes.
Pedicels for both
What is the fxn of spaces between adjacent pedicels?
constitute the path through which the filtrate, once through the endothelial cells and basement membrane, travels to enter Bowman's space.
The foot processes are coated by a _________ layer of _________ material, w/c partially occludes the slits, and extremely _______ process called _______ _______ bridge the slits between the pedicels.
Thick, extracellular, thin, slit diaphragm
These are widened versions of the tight jxn & adhering jxns that link all epithelial cells together?
Slit diaphragms
These are epithelial foot process that extend from each arm of the podocytes & are embedded in the glomerular BM.
Pediciles
Describe the make up of the tubule?
It’s made up of a single layer of epithelial cells resting on a BM
What is a common feature of the tubule epithelial cells?
The presence of tight jxns between adjacent cells that physically link them together like the plastic that holds a 6 pack together
What is the blood supply to the nephrons?
Renal artery -> arcuate artery -> interlobular artery -> afferent arteriole -> Bowman’s capsule -> efferent arteriole -> peritubular arteries (cortical glomeruli)-> interbundle plexus and descending/ascending vasa recta(juxtamedullary glomeruli
The 3 different names of nephrons according to position of their renal corpuscle?
Juxtamedullary, midcortical, & superficial nephrons.
Position of corpuscle often determines loop _________.
Length
What can be said about the anatomy of each nephron?
Each nephron is anatomically distinct until we get to the collecting ducts
Where do the peritublar capillaries come from in the kidneys & what happens to them?
Efferent arterioles subdivide to them. They are profusely distributed thruout the cortex then rejoin to form the veins by w/c blood ultimately leaves the kidney
w/c area of the kidneys receives less blood, medulla or cortex?
Medulla
T/F: gloumeruli can be found in both cortex & medulla?
False, medulla does not contain any glomeruli
What is special about the arterioles in the juxtameduallry glomeruli?
They do not branch into peritubular capillaries but descend downward into the outer medulla and form vasa recta
These vessels come from the juxtamedullary glomeruli, descend into medulla, divide many times to form bundles of parallel vessels that penetrate deep into the medulla?
Descending vasa recta
These are differentiated smooth mm cells in the walls of the afferent arterioles?
Granule cells or juxtaglomerular cells
Granule cells release what?
Renin
These cells are part of the JGA & they are continuous w/ those of Bowman’s capsule?
Extraglomerular mesangial cells
These cells are specialized thick ascending limb epithelial cells?
Macular densa cells
Function of macular densa cells?
Detect luminal content of the nephron at the very end of the tubule and contribute to the control of filtration rate and renin secretion. They are good Na sensors.
Describe the renal innervations?
sympathetic innervations of the kidneys is distributed between afferent and efferent arterioles, the JGA, and many portions of the tubule. In contrast to many systems, there is no significant parasympathetic innervations.
process by which water and solutes in the blood leave the vascular system through the filtration barrier and enter Bowman’s space.
Glomerular filtration
process of moving substances into the tubular lumen from the peritubular capillaries
Tubular Secretion
process of moving substances from the tubular lumen into the peritubular capillaries
tubular reabsorption
% of plasma that gets filtered thru the glomerulus?
20%
w/ the 3 renal processes for any substance, what is the formula?
Amount excreted = amount filtered + amount secreted – amount reabsorbed.
How many renal processes are there? What are they?
5 total. The major ones are filtration, secretion, & reabsorption. The other 2 are metabolism by tubular cells & production of substances by tubular cells
fraction of the blood volume composed of red blood cells.
Hematocrit:
total blood flow to the kidneys per unit time.
Renal blood flow:
amount of filtrate that enters the tubule system through Bowman’s space per unit time.
Glomerular filtration rate (GFR):
Typical hematocrit is about how much?
0.45 (or 45%).
Typical renal blood flow is
~1.1 L/min
what is the plasma flow to the glomeruli?
From these values we can calculate typical plasma flow to the glomeruli per unit time as
RBF * 0.55 = ~605 mL/min.
how much is GFR?
~125ml/min
Two primary factors set RBF (~1.1 L/min under normal conditions); what are they?
Mean pressure in the renal artery vs. mean pressure in the renal vein.
Resistance of the renal arterioles. This is the sum of the afferent & efferent arterioles of the 1 million nephrons in the kidney
since afferent and efferent arterioles of each glomerulus are in_________ , a given change in either arteriole will have an identical effect. When radius of both arterioles changes simultaneously, the effect on RBF is ___________
series, additive
Two main characteristics of molecules effect their ability to cross the filtration barrier and enter Bowman’s space, what are they?
molecular radius & shape, and electrical charge
Compare between molecular radius & shape of molecule to its filtration?
<7000 Da will freely pass, >66,000 Da will be blocked. Anything in between those #s will depend on the size, filtration rate increases as size decreases
What is the relationship between electrical charge & filtration rate?
For a given size, filtration rate increases with positive charge, negatively charged molecules are filtered less than neutral ones, and positively charged molecules are filtered more than neutral ones
What is the make up of each nephron?
it consists of a gloerulus, a PCT, loop of henle, DCT, & CT
where in the kidney is blood filtered?
in the glomerulus
what happens in the CT?
This is where water, electrolytes, & other substances are reabsorbed into the bloodstream while other, unneeded materials are secreted into the tubular filtrate for elimination
this is the functional unit of the kidney?
nephron
what is the vascular component of the nephron?
it consists of 2 arterioles closely associated w/ 2 capillary beds: the glomerulus & the peritbular capillaries
where do u find the peritubular capillaries?
surround the tubular structures
what happens in the tubular portion of the nephron?
it processes the glomerular filtrate (urine), facilitating the rabsorption of substances from the tubular fluid into the peritubular capillaries & the secretion of substances from the peritbular capillaries into the urine filtrate.
what are the 2 catergories of nephrons?
85% are nephrons that originate in the superficial part of the cortex called cortical nephrons.
15% are juxtamedullary nephrons.
these types of nephrons have short thick loops of henle that penetrate only a short distance into the medulla
cortical nephrons
these types of nephrons originate deeper in the cortex & have longer & thinner loops of henle that penetrate the entire length of the medulla
juxtamedullary nephrons
describe the pressure in the glomerulus? why is it this way?
the glomerulus is a high pressure capillary filtration system. b/c the arterioles are high resistance vessels Y the afferent arteriole has a larger diameter than the efferent, the BP in the glomerulus is extremely high & therefore easily forces fluid & solutes out of the blood into the GC along its entire length.
the peritubular capillaries originate from where?
efferent arteriole
describe the pressure of the peritubular capillaries?
low pressure vessels that are adapted for reabsorption rather than filtration.
in the deepest part o fthe renal cortex, the efferent arterioles serving the juxtaglomerular glomeruli continue into long thin walled looping vessels called __________?
vasa recta
along w/c part of the nephron do we see the vasa recta?
they accompany the long loops of henle in the medullary portion to assist in exchange of substances flowing in & out of that portion of the kidney.
blood flows into the glomerular capillaries from the ________ ________ & flows out of the glomerular capillaries into the _________ __________, w/c leads into the ___________ capillaries.
afferent arteriole, efferent arteriole, peritubular capillaries
fluid & particles from the blood are filtered through the capillary membrane into a fluid filled space in Bowman's capsule called __________ _________?
Bowman's space
T/F: the portion of the blood that is filtered into the capsule space is called the filtrate
true
what are the 3 layers of the glomerular capillary membrane?
1) capillary endothelial layer
2) BM
3) single celled capsular epithelial layer
In w/c of the 3 layers of the glomerular capillary memb do u find fenestrations?
they are found in the endothelial layer
These are small perforations found in the endothelial layer of the glomerular capillary?
fenestrations
this layer lines the glomerulus & interfaces w/ blood as it moves thru the capillary (fig 30-5)
endothelial layer
In w/c layer do u find the podocytes?
in the epithelial layer
The epithelial layer that covers the glomerulus is continuous w/ the ____________ that lines Bowman's capsule.
epithlium
Podocytes are embedded in what? what do they form?
they are embedded in the BM & form slit pores thru w/c the glomerular filtrate passes
what is the make up of the BM?
acullular meshwork of collagen fibers, glycoproteins, & mucopolysaccharides
what is primarily responsible for what gets filtered?
the spaces between the fibers that make up the BM represent the pores of a filter & determine the size dependent permeability barrier of the glomerulus
in some areas, the capillary endo thelium & the BM do not completely surround each capillary. What is there instead?
the mesangial cells
Two functions of mesangial cells?
1) phagocytic properties where they remove macromolecular material that enter the intercapillary spaces
2) they also can exhibit contractile properties & contribute to the regulation of blood flow
Describe the cells of the PCT?
they have fine villous structure that increases the SA for reabsorption & they are also rich in mitochondria