Pulm/Renal - Histology - Urinary System Flashcards
What are some of the general functions of the kidneys?
Waste excretion;
BP regulation;
blood acid-base regulation;
hormone production;
vitamin D production
Name the relevant changes in artery from the renal artery to the glomerulus and subsequent capillary beds.
- Renal a. –>*
- segmental a. –>*
- interlobar a. –>*
- arcuate a. –>*
- interlobular a. –>*
- afferent arteriole –>*
glomerulus –>
efferent arteriole –>
peritubular capillaries (cortex)
+
vasa recta (juxtamedullary)
Describe what vessel changes occur after blood passes through the peritubular capillaries (cortical) and/or vasa recta (juxtamedullary).
Either:
Peritubular capillaries (cortical)
Or:
vasa recta (juxtamedullary)
- –>*
- interlobular v. –>*
- arcuate v. –>*
- interlobar v. –>*
- renal v.*
What section of tissue is shown here?
The renal cortex, medullary rays, and medulla
What is a renal corpuscle?
A histological section containing the glomerulus and Bowman’s capsule
What is the order of a nephron?
(See attached image for more detailed description)
Bowman’s capsule –>
PCT –>
Loop of Henle (descending and ascending) –>
DCT –>
Collecting duct
What cells form the visceral layer of the glomerular capsule?
What contractile cells are also found in this region?
Podocytes;
mesangial cells
What is the glomerulus in terms of type of blood vessel?
A bed of fenestrated capillaries
What is the parietal section of the glomerular capsule?
Bowman’s capsule
What is unique about the fenestrated capillaries of the glomerulus?
The lack of a fenestration diaphragm;
presence of a nephrin-containing glomerular slit diaphragm instead
What space can exists between podocyte foot processes (pedicles)?
Filtration slits
What are some major proteins and compounds found in the glomerulus basement membrane?
Collagen IV;
fibronectin;
laminin;
heparin sulfate (charge barrier)
True/False.
Albumin can easily pass through the fenestrations / fenestration slits of the glomerulus.
False.
Although albumin can fit through the slits, it is difficult, and the charge barrier helps prevent it from occurring.
How large is albumin in Daltons?
68 kDa
What size proteins can pass through the glomerular filtration slits?
Albumin (68 kDa) or smaller
What protein is essential to the glomerular filtration slit diaphragm?
Nephrin
A mutation in nephrin leads to what condition?
A mutation in collagen IV leads to what condition?
Congenital nephrotic syndrome;
Alport’s syndrome
In order, what structures must a substrate in a glomerulus pass to reach the lumen of the Bowman’s capsule?
The endothelial fenestrations;
the basement membrane;
the podocyte filtration slit;
the podocyte filtration diaphragm
Which limb of the loop of Henle (ascending or descending) has a thick portion?
Ascending
Describe the epithelial histology of the proximal convoluted tubule and any distinctive characteristics.
Where are they found?
Simple cuboidal layer with brush border,
luminal debris,
indistinct cellular outlines,
very eosinophilic;
the renal cortex and medullary rays
What type of renal tissue is this?
Proximal convoluted tubules
What effect does chronic renal disease (e.g. advanced polycystic kidney disease) have on the blood?
Decreased erythropoeitin release –> normocytic anemia
Where, specifically, is erythropoeitin produced?
By what type of cell?
The interstitium surounding the PCT and peritubular capillaries;
interstitial fibroblasts
Which portion of the nephron is involved in vitamin D activation?
Via what enzyme?
The PCT;
1-α hydroxylase
What enzyme is unique to the PCT?
What does it do?
1-α hydroxylase;
turns 25-hydroxy vitamin D3 into 1,25-hydroxy vitamin D3
1-α hydroxylase turns ___(OH) vitamin D3 into ___(OH) vitamin D3 in the ________________ of the kidney.
25-, 1,25-;
proximal convoluted tubule
Activation of 25-(OH) vitamin D3 into 1,25-(OH) vitamin D3 occurs in what organelle(s) of the PCT epithelium?
Via what enzyme?
The mitochondria;
1-α hydroxylase
What process occurs uniquely in the mitochondria of the renal PCT?
Via what enzyme?
Vitamin D activation
(25-(OH) vitamin D3 to 1,25-(OH) vitamin D3);
1-α hydroxylase
True/False.
The conversion of vitamin D from 1,25-(OH) vitamin D to 25-(OH) vitamin D occurs in the PCT via the enzyme 1-α hydroxylase.
False.
The conversion of vitamin D from 25-(OH) vitamin D to 1,25-(OH) vitamin D occurs in the PCT via the enzyme 1-α hydroxylase.
What type of epithelium is found in the loop of Henle?
Simple squamous cells
What type of epithelium lines the PCT?
What type of epithelium lines the loop of Henle?
What type of epithelium lines the DCT?
Simple cuboidal, brush border;
simple squamous;
simple cuboidal, no brush border
For what function are the pumps in the thick ascending loop of Henle responsible?
Pumping sodium out of the tubule
Describe the appearance of the loops of Henle vs. collecting ducts on H&E light microscopy.
After passing the loop of Henle, what mechanism is responsible for all further water and ion regulation in the DCT and collecting duct?
Hormonal action
(e.g. aldosterone, ADH)
How is the DCT different on H&E light microscopy when compared to the PCT?
Slightly smaller cuboidal cells;
no brush border;
little debris in lumen;
(still very eosinophilic, still indistinct cellular outlines, still simple cuboidal)
Identify an example of each of the following in this image:
Glomerulus
PCT
DCT
Glomerulus (Purple)
PCT (Blue)
DCT (Green)
The macula densa is on the _____ convoluted tubule and communicates with the ________ arteriole.
Distal;
afferent
The _________ arteriole interacts with the _______ _______ of the distal convoluted tubule.
Afferent;
macula densa