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
Why is it important that the macula densa (of the juxtaglomerular apparatus) interact with the afferent arteriole?
Filtrate flow is regulated according to the speed / concentration of Na+ in the DCT
What are the three portions of the juxtaglomerular apparatus?
The macula densa (DCT);
juxtaglomerular smooth muscle cells (afferent arteriole);
extraglomerular mesangial cells (outside the renal corpuscle)
Identify the macula densa and extraglomerular mesangial cells in this image.
(Note: both are part of the juxtaglomerular apparatus.)
Scenario: the macula densa senses a high concentration of NaCl in the DCT.
What does this indicate, and how does the juxtaglomerular apparatus respond?
The flow of filtrate is too rapid;
the afferent arteriole constricts, reducing bloodflow into the glomerulus
Scenario: the macula densa senses a low concentration of NaCl in the DCT.
What does this indicate, and how does the juxtaglomerular apparatus respond?
The flow of filtrate is too slow;
the afferent arteriole relaxes, increasing bloodflow into the glomerulus
What can juxtaglomerular cells (modified smooth muscle) release in response to low blood pressure?
Renin
What organ releases angiotensinogen?
What organ releases renin?
What organ releases angiotensin-converting enzyme?
What organ releases aldosterone?
Liver;
kidney;
lung;
adrenal zona glomerulosa
Describe the portions of the renin-angiotensin system released by each of the following:
Kidney
Lung
Adrenal zona glomerulosa
Liver
Renin
ACE
Aldosterone
Angiotensinogen
What main hormone-releasing functions does angiotensin II perform?
What main vascular and ionic functions does angiotensin II perform?
Stimulates aldosterone synthase in the zona glomerulosa of the adrenal gland;
stimulates ADH release;
stimulates AT1R receptors to cause arteriolar vasoconstriction;
stimulates NaCl reabsorption in the PCT
What main hormone-releasing functions does angiotensin II perform?
Stimulates aldosterone synthase in the zona glomerulosa of the adrenal gland;
stimulates ADH release;
What main vascular and ionic functions does angiotensin II perform?
Stimulates AT1R receptors to cause arteriolar vasoconstriction;
stimulates NaCl reabsorption in the PCT
What location(s) of the nephron is(are) targets for aldosterone?
The ascending limb of the loop of Henle;
the DCT;
the collecting duct
What three stimuli activate the tubuloglomerular feedback system (juxtaglomerular apparatus)?
- Hypovolemia
- Hypotension
- Decreased Na+ in the DCT
What process is the main regulator for the GFR?
Na+ reaching the macula densa
What location(s) of the nephron is(are) targets for ADH?
The collecting tubule (late DCT) and collecting duct
What are the two main cell types of the collecting ducts?
What general function does each perform?
Principal cells (light-staining) (more) - water reabsorption via aquaporin2 (ADH-regulated)
Intercalated cells (dark-staining) (fewer) - secrete H+ and absorb HCO3-
Describe the histology of the collecting ducts.
Simple cuboidal cells, becoming taller towards the papilla;
clear borders between cells (as opposed to PCT or DCT)
principal cells (light-staining);
intercalated cells (dark-staining)
Identify the renal structures in the image.
1 - Collecting ducts
2 - Loop of Henle
3 - Vasa recta
What is the name of the capillary bed feeding the nephron?
What is the name of the capillary bed surrounding the collecting duct?
What is the name of the capillary bed surrounding the PCT and DCT?
Glomerulus;
vasa recta;
peritubular capillaries
Describe the urothelium histology.
Transitional epithelium
+
2-3 layers of smooth muscle
+
connective tissue
What is the term used to describe the luminal layer of transitional epithelium in the ureters/bladder/urethra?
Umbrella cells
What three structures are characterized by urothelium (transitional epithelium + 2-3 layers smooth muscle + connective tissue)?
The ureters, bladder, and urethra
How long is the average female urethra?
How long is the average male urethra?
5 cm
20 cm
What structure is this most likely to be?
A ureter
True/false.
Both male and female urethras transition from urothelium to non-keratinized stratified squamous epithelium.
Female urethras are mostly stratified squamous epithelium.
True.
Identify structures A - D and the structure outlined by arrows in this micrograph.
A - Macula densa
B - Glomerular capillary
C - Urinary space
D - PCT
Arrows - Bowman’s (parietal glomerular) capsule
Identify the structures in the micrograph.
A - Medullary ray
B - Cortical labyrinth
C (and arrows) - Renal corpuscle
D - Proximal convoluted tubule
Identify tissue layers A and B.
A - Lamina propria (smooth muscle + connective tissue)
B - Transitional epithelium
Identify structures A - D in the micrograph.
A - Collecting duct
B - Thick limb of the loop of Henle
C - Vasa recta
D - Thin loop of Henle
Identify structures A - E in the micrograph.
A - Urinary pole
B - Urinary space
C - Proximal convoluted tubule
D - Distal convoluted tubule
E - Glomerulus covered by visceral layer of glomerular capsule
Identify the structures in this transmission electron micrograph of a portion of the kidney.
A - Podocyte
B - Lumen of capillary
Arrows - Pedicels of podocytes
Astericks - Glomerular basement membrane
Identify the structures in this transmission electron micrograph of a portion of the kidney.
A - Podocyte
B - Urinary space
C - Capillary with RBCs
Identify the marked structures in this micrograph of the kidney.
A - Medullary ray
B - Collecting duct
C - Thick descending limb of the loop of Henle
D - Thick ascending limb of the loop of Henle
Identify the renal structures in this transmission electron micrograph.
A - Process of podocyte
Arrows - Pedicels
Astericks - Glomerular basement membrane
Identify the structures in this micrograph.
(Renal corpsucle)
A - Urinary pole
B - Vascular pole
Arrowheads - Macula densa
Arrows - Parietal layer of glomerular capsule
Identify the organ in this micrograph.
A ureter
What are some examples of endocrine hormones produced by the kidney?
EPO,
renin,
prostaglandins
What are the two ends of the renal corpuscle?
The vascular pole (arterioles of the glomerulus)
and urinary pole (Bowman’s capsule leading into the PCT)
Where is the glomerular slit diaphragm?
Between podocyte foot processes
(NOT at the capillary fenestrations like you would expect)
Proteinuria is seen in __% of both types of diabetes mellitus, usually within 12 - 22 years following diagnosis.
Of what is this predictive as a prognosticator?
50;
chronic renal failure or ESRD within 4 -5 years
Describe some of the features of diabetic glomerulosclerosis.
- Thickened capillary basement membranes
- Diffuse glomerulosclerosis
- Nodular glomerulosclerosis (Kimmelstiel-Wilson lesions)
What kidney pathology is shown in this micrograph?
As a result of what?
What is another name for the hyaline nodule?
Diabetic glomerulosclerosis (diffuse and nodular);
type I or II diabetes mellitus;
a Kimmelstiel-Wilson lesion
What is the most common cause of most primary glomerulopathies?
Immune mechanisms
The following are examples of _____________ glomerulopathies.
- Acute diffuse proliferative glomerulonephritis (poststreptococcal)
- Rapidly progressive (crescentric) glomerulonephritis (RPGN)
- Focal segmental glomerulosclerosis (FSGS)
- Membranoproliferative glomerulonephritis (MPGN)
- IgA Nephropathy
Primary
(often immune mechanisms)
The following are examples of causes of __________ glomerulopathies.
- Systemic Lupus Erythematous
- Diabetes Mellitus
- Amyloidosis
- Goodpasture’s Syndrome
- Bacterial Endocarditis
- Fabry’s disease (X-linked inheritance, buildup of globotriaosylceramide)
Secondary
(often systemic vascular or metabolic conditions)
Is the PCT brush border ever visible on light microscopy?
Yes.
What is acute tubular necrosis?
What effect does it have on renal function?
A rapid destruction of proximal tubular epithelial cells due to a variety of causes - may be fully reversible if the basement membrane is intact;
rapid suppression (< 24 hours)
What are two examples of polycystic kidney disease?
When does each manifest?
ADPKD (between 30 and 40 years of age);
ARPKD (less common; shortly after birth)
Name two types of benign renal tumor.
Oncocytoma (incidental in the elderly);
angiomyolipoma (often in patients with tuberous sclerosis)
What is the most common form of renal malignancy?
In which gender is it more common?
Renal cell carcinoma
(clear cell being the most common subtype);
males (3:1)
Renal cell carcinomas may extend into what nearby hematogenous structure(s)?
The renal v. and vena cava
What renal disorder is shown in this micrograph?
Renal clear cell carcinoma
(clear cytoplasm and are arranged in nests with intervening blood vessels)
True/False.
Urothelial (transitional cell) carcinomas are the 8th most common malignancy in men and the 4th most common malignancy in women.
False.
Urothelial (transitional cell) carcinomas are the 4th most common malignancy in men and the 8th most common malignancy in women.
In what age group are urothelial (transitional cell) carcinomas most common?
What are the typical presenting S/Sy?
≥ 60;
painless hematuria; also infection or obstruction
Urothelial (transitional cell) carcinomas can occur in what organs?
The renal pelvis, ureters, bladder, urethra
Define renal lobe.
Pyramid + associated cortical tissue
Define renal lobule.
Medullary ray + associated cortical tissue
True/False.
The parietal layer of Bowman’s capsule is a simple squamous epithelial layer.
True.
