The Urinary System - Herron Flashcards
What is the pathway of urine?
The kidney produces urine.
Urine passes to the ureters.
Then to the bladder for storage until discharged through urethra.
What does the hilum consist of?
Renal artery
Renal Vein
Nerves
Renal Pelvis
What is the parenchyma of the kidney divided into?
Cortex (outer layer)
Medulla (Inner Layer)
Where are the pyramids located?
In the medulla
What is the apex of the pyramid?
Renal Papilla
What is the tissue between adjacent pyramids?
renal column
What is a lobe?
a medullary pyramid and the overlying cortex plus 1/2 of the renal columns on each side of the pyramid
What are calyces?
Extensions of the renal pelvis into the proper kidney
How many renal papilla does a minor calyx surround?
One
What is a major calyx?
The combination of two or more minor calyces
What is the function of the minor calyx?
Drains the urine from the papilla of the pyramid into the major calyx (beginning of renal pelvis)
How many lobes does each kidney have?
8-10
What does the structure of the kidney allow the kidney to do (functions)?
remove waste from the blood and excrete it as urine
regulate electrolyte balance (na, k, h, ca)
regulate plasma volume and bp
produce hormones
what hormones does the kidney produce?
EPO, for rbc formation
renin, involved in water retention for bp and volume regulation
converts vit d precursor to active form of vit d.
what is the structural and functional unit of the kidney
the nephron
what does the nephron consist of
renal corpuscle and its tubules
where does the renal corpuscle’s tubules end?
at the collecting duct
How many nephrons does the human kidney have?
800k to 1 mill
What percentage of cardiac output goes to the kidney?
25%
What are the four main segments of the nephron tubule?
Proximal thick segment
Thing segment
Distal thick segment
loop of henle
what are the segments of the proximal thick segment?
proximal convuluted tubule
proximal straight tubule
what are the segments of the thin segment?
thin limb
what are the parts o the distal thick segment
Medullary thick ascending limb (mtal)
cortical thick acscending limg (ctal)
macula densa (md)
disetal convoluted tubule (dct)
connecting segment (ct)what is the dividing point between the proximal and distal tubules?
the macula densa
What is the collecting duct?
NOT part of the nephron
Conducts urine from the nephron tubule to the renal papillae
Consists of the cortical collecting duct and the medullary collecting duct
what does the collecting duct consist of?
cortical collecting duct
medullary collecting duct
what are the ducts of bellini?
the papillary duct or collecting duct
how do you distinguish between different tubular segments and dcuts?
PCT are larger, have a lot of microvilli (increases the SA), which forms the distinctive brush border
DCT don’t ahve brush border, smaller, sharper luminal void and a higher [ ] of cells
How can you identify collecting ducts on histo?
they are like ice cube trays and you can see the border between adjacent cells
how can you identify the thin segment of the loop of henle?
seen by squamous cells, flattened with thin and small lumen
what type of cells do collecting ducts and thick segments both have? (in contrast to squamous cells of the thin segment of the loop of henle?
cuboidal cells
describe the shapes of the lumen of dct and pct
pct have a star shaped lumen, with a brush border
dct have a round lumen with a distinct border
describe the diameters of dct vs proximal tubules
the outside diameters of prox tubules are larger than those of distal tubules
do proximal or distal tubules have more nuclei in their cross sections?
the distal tubules have more, but have less than CDs.
describe the walls of the collecting ducts
they are cuboidal and smaller than those of proximal tubules. they also display a relatively larger number of nuclei than do comparable segmetns of proximal tubules.
what two cells types can make the walls of the thin segments?
low cuboidal cells or simple squamous
when looking at a histo slide near a corpuscle, will more of the visible areas be proximal or distal?
proximal
What is the beginning of the nephron?
the renal corpuscle
what brings blood directly to teh renal capillaries? away from them?
afferent arteriole efferent arteriole (STILL artery)
Is the afferent or efferent arteriole alrger?
afferent is always larger
What does the renal corpuscle consist of?
glomerulus ( a tuft of capillaries)
bowman’s capsule (two layers, visceral and parietal)
urinary space (between visceral and parietal layers)
where does the ultrafiltrate drain to WITHIN the renal corpuscle?
the urinary space
what and where are the mesangial cells?
that phagocytose debris, provide structural support, and secrete substances (il1) for repair of the glomerulus
they are located amongst the cappilaries
what are the different types of nephrons?
cortical nephrons
juxtamedullary nephrons
intermediate neprhons
what are cortical nephrons
have a short loop of henle, located near the surface of the kidney
what are juxtamedullary neprhons
close to the medullary boundary, and have long loops of henle
what are intermediate nephrons
those with intermediate loops of henle
what separates the cortex from the medulla?
the arcuate artery
what are the subdivisions of the cortex?
cortical labyrinths
medullary rays
what are the cortical labyrinths
one of the subdivisions of the cortex
consist of renal corpuscles, proximal convoluted and distal convoluted tubules
what are medullary rays?
subdivision of the cortex, consisting of aggregation of straight tubules and collecting ducts, lies between the cortical labyrinths.
on a histological slide, why are medullary rays so easy to identify?
they are multiple straight lines surrounded on each side by normal looking histology
what is a lobule?
consists of the medullary ray and adjacent half of labyrinths
parallels the organization of lobes (which are medullary pyramids and overlying 1/2 of renal columns)
where in the kidney does the majority of cardiac output go?
90% goes to the cortex
Which artery carries blood to the kidney?
the renal artery
what is the arterial pathway and divisions?
renal artery - lobar arteries - interlobar arteries - arcuate arteries - interlobular arteries - afferent arterioles - tuft of capillaries - efferent arterioles - peritubular capillaries -
explain the different formations of efferent arterioles in the cortical vs juxtamedullary areas?
those in cortical area produce the peritubular capillary network that surrounds local tubules
those in the juxtamedullary glomeruli descend into medulla to from arteriole rectae
LOOK UP EFFERENT ARTERIOLES MAKING PERITUBULAR CAPILLARY AND ARTERIOLE RECTAE
YEA….. DO IT
where are interlobular arteries?
between lobules…as the name implies
what are the three principal functions of nephrons?
filtration of blood making ultrafiltrate
reabsorption (mostly in pct)
secretion
where does filtration primarily occur
glomerulus, bc it contains the filtration apparatus
how much do the two kidneys filter per day
180 l/day or 125 ml/min
what are the three components of the filtration apparatus?
- fenestrated endothelium of glomerulus
- basement membrane of the glomerulus (loops of cpaillaries)
- basement membrane of the podocytes
what do podocyte processes form?
numerous secondary processes called pedicels (or foot processes) around glomerulus
what are the elongated spaces between pedicels called?
filtration slits
What part is considered the ultimate barrier?
the ultimate barrier is the lamina densa
why is the lamina densa considered such a good barrier?
only molecules that are neutrally charged and less than 70000 daltons can pass through the lamina densa
why and proteins generally excluded by the lamina densa?
the lamina densa is made of heparin, which is negatively charge. likewise most proteins are negatively charged. so albumin, which is small enough to pass through, will not because of the charge of the protein
How is the basal lamina different in diabetes mellitus?
it is thicker than normal and functionally leaky so an excessive amount of protein gets lost in the urine.
May lead to low blood albumin (leading to edema)
all of this together is called nephrotic syndrome
Where do reabsorption and secretion occur?
tubules
What is reabsorption?
when filtered products in the renal tubules are reabsorbed back into the peritubular capillaries
what is secretion?
when prodcues (h k nh3 etc) from peritubular capillaries are secreted into the provisional urine of the tubules and collecting ducts
what is the major site of reabsorption
proximal convuluted tubule (where most h20 and electrolytes and all glucose is reabsorped)
Where does secretion largely occur?
distal part of nephron (thin limb and distal tubules) and collecting ducts
what types of interactions largely manage reabsorption and secretion?
electrochemical reactions
what does the juxtamedullary apparatus consist of?
macula densa, juxtaglomerular cells (on afferent and efferent arterioles), and extraglomerular mesangial cells
what does juxtaglomerular apparatus do?
regulates blood pressure
how are the macula densa cells different from the adjacent tubule cells?
they are narrower, usually taller and more crowded
what do the macula densa cells do?
they monitor blood volume and sodium concentration
Under what conditions do jg cells activate a system for restoring homeostasis?
Under low sodium intake or decreased volume of circulating blood, jg cells active renin-angiotensin-aldosterone system.
Give an overview of regulation of blood pressure by jg cells
macula densa cells monitor physiological conditions and communicate with jg cells
jg cells contain granules of renin which is released when signaled to by macula densa cells.
where are the jg cells located?
they are located on the exterior of the afferent arteriole
what do all excretory pathways except the urethra contain in terms of general structure?
mucosa, muscularis, adventitia or serosa
all excretory passages except the lower part of the urethra are lined by ___________?
transitional epithelium
what is the lower part of the urethra lined with
stratified or pseudostratified columnar epithelium
Make sure you are practicing for the practical
yep
In the kidney, papillary ducts:
a. release urine into renal pelvis
b receive ultrafiltrate from urinary space
c release urine into minor calyces
d receive urine from distal convoluted tubules
e release urine into straight connecting ducts
c
what tubular segment contains the macula densa? proximal convoluted tubule distal convoluted tubule distal straight tubule proximal straight tubule thin limb
c
podocytes form?
the visceral layer of bowmans capsule
cells in which structure are responsible for the repair of the glomerulus?
mesangium
the macula densa is a specialized region of the
distal straight tubule
