Urinary System Flashcards
what type of gland is the kidney?
compound tubular
what are the major functions of the kidney?
- filtration
- secretion
- (re)absorption
Describe the organization of the kidney
- outermost capsule (CT)
- Outer cortex
- Inner medulla
what types of cells make up the kidney capsule?
fibroblasts and myofibroblasts
What makes up the kidney cortex?
- Renal corpuscle
- Renal columns
- Medullary Rays
What makes up the renal corpuscle?
- Capillary Glomerulus
2. Bowman’s capsule
what is the capillary glomerulus?
branched fenestrated capillary tube that is derived from and afferent arteriole and drained by an efferent arteriole (arterial portal system!)
What is a medullary ray?
straight portions of the 1. proximal and 2. distal tubules and the 3. collecting ducts as they extend into the medulla
What does the medulla of the kidney contain?
tubules + collecting ducts grouped into pyramids
what is a medullary pyramid?
cone shaped bundle of tubules that converge to form a papilla with a rounded apex that projects into a minor calyx
What does the renal sinus contain?
Renal Pelvis with its:
major/minor calyx, branches of renal arteries, veins, nerves, and fatty connective tissue
what is the renal pelvis
an expanded funnel shaped portion of the ureter
what defines a kidney lobe?
medullary pyramid + associated cortex tissue (humans have 8-18 per kidney); bound by interlobar arteries
What does premature birth cause with respect to kidney development?
can cause a decrease in the number of kidney lobes and thus develop into hypertension during the ADULT LIFE
what defines a kidney lobule?
medullary ray + associated cortex tissue (the lobule is centered around the medullary ray and bound by interlobular arteries)
What is a uriniferous tubule?
a nephron + the associated collecting tubule
What is a nephron
the function unit of the kidney, around 2 million per kidney
what is Bowman’s capsule?
blindly ending tubule indented by glomerular capillary
What makes up a thick segment of the nephron?
the convoluted and straight tubules (proximal or distal)
What makes up the Loop of Henle?
it is a loop that includes the entire U-shaped portion of the nephron with its hairpin turn; made of the THIN segment of a nephron
what are the two types of nephrons?
- cortical/supcapsular
2. juxtamedullary
Describe the cortical/supcapsular nephron? (the defining characteristic, location, function)
SHORT loops of Henle in the cortex and outer medulla ;
located in the outer cortex
function: do not concentrate urine significantly
Describe the Juxtamedullary nephron? (the defining characteristic, location, function)
LONG loops of Henle deep into the pyramids ;
renal corpuscle is located near the corticomedullary junction
function: significantly contribute to the concentration of urine
Regardless of nephron type, where are the straight portions of the neprhon/collecting tubules located?
in the medullary ray (WITHIN IN THE CORTEX, but extending into the medulla)
Describe afferent blood flow in the kidney
Renal artery to interlobar artery to arcuate artery to interlobular artery to afferent arterioles to glomerular capillary
Describe efferent blood flow in the subcapsular nephrons
from the glomerular capillary to the efferent arteriole to the PERITUBULAR CAP to the interlobular vein to the arcuate vein to the interlobar vein to the renal vein
Describe efferent blood flow in the juxtamedullary glomerulus
from the glomerular capillary to the efferent arteriole to the STRAIGHT ARTERY (VASA RECTA) to the VENOUS VASA RECTA to the arcuate vein to the interlobar vein to the renal vein
where are the interlobar arteries/veins located in the kidney?
between pyramids
where are the arcuate arteries in the kidneys located?
between the cortex and base of the pyramids
where are the interlobular vessels in the kidneys located?
run radially in the cortex between the medullary rays
How does the morphology of an efferent arteriole compare to that of an afferent arteriole? Why is this significant?
the diameter of the efferent arteriole is smaller than that of an afferent arteriole;
this allows for maintenance of the filtration pressure
what is the function of the renal corpuscle?
to filter plasma from the glomerular capillary
what is the renal corpuscle composed of?
bowman’s membrane + glomerulus
what type of capillary is the glomerulus?
branched fenestrated (w/open fenestrae)
what is the vascular pole of the nephron?
where the Afferent ateriole enters the renal corpuscle and the efferent arteriole leaves it
what is the urinary pole of the nephron
where the parietal layer of the bowman’s membrane is continuous with the beginning of a proximal convoluted tubule
What does Bowman’s space enclose?
the urinary space with contains provisional urine
what type of epithelium is found in the parietal layer of Bowman’s capsule?
simple squamous epithelium
what type of epithelium is found in the visceral layer of Bowman’s capsule?
podocytes
Describe podocyte morphology
have interdigitating pedicals (foot processes) separated by slit pores spanned by slit membranes
what makes up the filtration barrier of the nephron?
- glomerular endothelium
- glomerular basement membrane
- slit membrane
- glycocalyx of podocytes
How does the glomerular endothelium contribute to the filtration barrier of the nephron?
it has OPEN FENESTRAE that restrict the entry of molecules >70kD into the glomerular basement membrane; some fenestrae with diaphragms are also present
How does the glomerular basement membrane contribute to the filtration barrier of the nephron?
it contains type IV collagen, heparin sulfate, laminin and fibronectin;
the negative charge of the heparan sulfates limits the movement of negatively charged proteins less than 70 kD across the GBM although they may enter the GBM
What molecules does the glomerular basement membrane contain that contributes to the filtration barrier of the nephron
it contains type IV collagen, heparin sulfate, laminin and fibronectin
What is the slit membrane formed by?
nephrin (an adhesion protein) and its anchoring comoplex
where are the slit membranes located?
between the pedicels of a podocyte (in the visceral layer of the bowman’s capsule)