Kidney Histology Flashcards
What are the capsules of the kidney?
there are three of them:
innermost is a CT capsule immediately on the surface
middle capsule is relatively thick layer of tat
outermost capsule is CT that binds the kidney to surrounding structures
WHat is the indentation on the medial side of the kidney that leads into the renal sinus?
the hilus
What enters at the hilus and what exits as the hilus?
the renal artery enters, the renal vein and ureter exit
plus nerves and lymphatics
Within the kidney parenchyma, what is the outer part and what is the inner part/
cortex is outer (darker staining)
medulla is inner (lighter staining)
What are the groupings of the medulla called?
medullary pyramids (6-18 per kidney)
WHat is contained in the cortex?
renal corpuscles and medullary rays
Bases of the medullary pyramids lie adjacent to the cortical tissue while the tips of the pyramids (renal papillae) point towards what?
minor calyces of the renal pelvis
What is the tip of the papilla called? Describe it.
Area cribrosa - it’s perforated by 10-25 small openings where the terminal segments of the uriniferous tubules open into the minor calyx
What areas extend between the medullary pyramids?
the renal columns
The renal sinus is basically just a potential space - what does it contain?
renal pelvis
major and minor calyces
arteries, veins, nerves, lymphatics
loose CT and fat
What is a medullary pyramid and the surrounding cortical tissue called?
a lobe
What does a lobule consist of?
straight tubules in medulla ray and the cortical substance immediately surrounding those tubules
What are the major components of a nephron?
- renal corpusle: with bowman’s capsule and glomerulus
- Tubular portion: proximal convoluted tubule, LOH (proxima; straight, thing seg, distal straight), and distal convoluted tubule
What does the distal convoluted tubule drain into?
the collecting tubules, which carry the urine to the renal pelvis
Bowman’s capsule has two distinct layers which are?
the parietal layer (simple squamous epithleium)
the visceral layer (composed of modified cells called podocytes)
WHat are the two distinct poles of the corpuscle?
urinary pole where the parietla epithelium is continuous with the cuboidal epithelium of the proximal convoluted tubule
vascular pole where the visceral epithelium reflects off the afferent and efferent arteriolsand becomes continuous with th eparietal epithelium
What lies between the visceral and parietal epitheliual layers of the capsule?
the lumen of the tubule, or Capsular (Bowman’s) space
What type of blood vessels make up the glomerulus?
it’s entirely arterial = an afferent arteriole and an efferent arteriole
Once within the capsule, the afferent arteriole quickly gives rise to what?
fenestrated capillaries that comprise the glomerular tift and form a complex anastomosing capilarry entwork
What do podocytes do?
they form the visceral epitheliual layer of bowman’s capsule
there are primary and secondary processes. the secondary processes (the feet) interdigitate with neighboring podocytes and then attach to the basal lamina of the capillary endothelium
What space is formed between the interdiitated podocyte food processes?
slit pores
What makes these fenestrated capillaries differnet from other fenestrated capillaries in the body?
these fenestrations lack the thin pore diaphragm
Since the endothelial pores only block large celllar components of blood and plasma, what else holds back molecules from the filtrate? How?
hte basal lamina. It has a large negative charge, so it repels things that ar enegatively charged and will block large molecules
Where are mesangial cells located?
occur where adjacent capillaries are soo close to each other that the podocytes cannot totally surround them - they’re probably very similar to pericytes
What do the mesangial cells do?
keep the glomerular filter free of debris
provide additional support at sites where basement membrane is lacking
help with basmenet membrane turnover
What part of the nephron makes up the bulk of the renal cortex?
the proximal convoluted tubule and proximal straight tubule
What type of epithelium comprises the tubules?
simple high cuboidal or two-columnar epithelium
How does the body increase surface area in the proximal tubules?
has a brush border composed of long regularly oriented and closely packed microvilli
What is the relationship between adjacent epithelial cells in the proximal tubules?
the lateral cell membranes are highly folded and interdigitate extensively with adjacent cells
Where are mitochondria located in high numbers in the epithleial cells of the proimal tubules?
they’re mostly found in the basal half of the cell - elongated and rod-like