Urinary System Histology (Shaw) - W1 Flashcards
What forms the outer and inner layer of teh connective tissue capsules of the kidney?
- Outer layer = fibroblasts that make collagen
- Inner layer = myofibroblasts
What structures are found in the cortex of the kidney parenchyma?
- Renal corpuscles
-
medullary RAYS that consist of
- straight tubules &
- collecting ducts
What structures are found in the medulla of the kidney?
- pyramids - straight tubules and collecting ducts
- Vasa recta - capillaries
- Renal columns - part of the CORTEX that spills into the medulla
What connects at the renal sinus (4 things)?
- Renal pelvis
- calyces - both MAJOR and MINOR
- nerves and vessels
- connective tissue (fat)
What are the features of a lobe of the kidney?
- see GROSSLY
- includes the medullary pyramid and surrounding cortical tissue
- will have as many lobes as there are pyramids
- human kidney has 8-18 lobes
What are the features of a lobule?
- see MICROSCOPIC
- includes the straight tubules from MEDULLARY RAYS and surrounding cortical tissue (multiple nephrons)
Where do the collecting ducts drain into and what area is surround it?
- drain into the renal papilla
- calyx surrounds renal papilla
What are 4 structures seen in a uriniferous tubule?
- Nephron
- collecting tubule
- Juxtaglomerular apparatus
- blood vessels
Functional components of a nephron:
-
Renal corpuscle
- Bowman’s capsule
- Glomerulus
-
Tubular portion
- proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
4 types of blood vessels that supply the kidney/nephron:
- Glomerular capillaries
- peritubular capillary networks
- Vasa recta
- larger supplying and draining vessels
What are the features of bowman’s capusle, part of the renal corpuscle of a nephron?
- 2 layers
- parietal - outside the space
- visceral- right along glomerulus
- 2 poles
- urinary
- vascular
- capsular space (Bowman’s space)
What are the features of the glomerulus, part of the renal corpuscle of a nephron?
- ENTIRELY arteriole vascular apparatus - afferent and efferent arterioles
- Fenestrated capillaries in the capsule
- Special cells
- podocytes - SLIT PORES in visceral layer of Bowman’s capusle - 1’ and 2’ processes
- Mesangial cells - many functions, similar to pericytes
What makes up the filtration apparatus of the glomerulus? - designed to limit filtration
- fenestrated capillary endothelium
-
basement membrane - has endothelial cells, podocytes
- rich in proteoglycans, glycoproteins
- Slit pores on podocytes- outer most barrier
What are the functions of the mesangial cells of the glomerulus?
- phagocytosis and endocytosis to CLEAN GBM and slits
- GBM TURNOVER
- Structural support - secrete matrix
- secrete IL-1, PGE2, PDGF - found in the matrix
- moderate glomerular distention by contracting
- can push blood through
Where are proximal tubules FOUND, what is their FUNCTION, and what are their DISTINGUISHING TRAITS?
- make up the bulk of CORTEX
-
Traits
- FUZZY BRUSH BORDER
- eosinophilic - cuboidal epithelium
- lateral membrane folding
- basal folds have mitochrondia
-
Function
- REABSORB water and NaCl (65%)
- glucose + amino acids
- protein absorption
What are the cells that make up the THIN SEGMENTS?
- SIMPLE SQUAMOUS EPITHELIUM
- NO brush border
- surrounded by capillaries - VASA RECTA
What are the features of the DISTAL STRAIGHT tubules?
- simple cuboidal epithelium
- less eosinophilic
- LARGE lumen
- NO brush border
- more nuclei around circumferance
- BASAL MEMBRANE FOLDS & mito
What are the features of the distal convoluted tubules and what do they respond to?
- begin at VASCULAR POLE of renal corpuscle
- have ARCHED and STRAIGHT PORTIONS
- terminal portions open at area cribosa into minor calyces
- cuboidal to columnar epithelium
-
TWO CELL TYPES
- LIGHT STAINING - collecting duct cells
- DARK STAINING - intercalaled cells
-
respond to ADH to increase tubule peremability to water
- helps form CONCENTRATED URINE
What cells make up the juxtaglomerular apparatus, where are they found, and what are its FUNCTIONS?
- CELLS
- Juxtaglomerular cells - modified SMOOTH MUSCLE - respond to degree of stretch
- macula densa - monitors Na+ concentration in distal tubule
- extraglomerular mesangial cells
- FOUND
- inside the afferent arteriole next to distal tubule (touches macula densa)
- FUNCTION - maintain normal blood pressure
Explain the NERVE supply to the kidneys
-
Sympathetic division supplies EXTRINSIC –> CONTRACTS vascular smooth muscle
- afferent arteriole - contraction –> REDUCED filtration rate (and urine output)
- efferent arteriole - contraction –> INCREASED filtration (and urine output)
- NO sympathetic innervation = increased urine output
- not necessary for renal function
What are the 3 layers of the ureter? (similar in the urinary bladder)
-
MUCOSA
- Transitional epithelium - only found in the urinary system
- lamina propria - loose CT, blood vessels, nerves
- MUSCULARIS - inner longitudinal, outer circular smooth muscle
- ADVENTITIA - fibrous connective tissue
What are the components of the female urethra?
- shorter than males
-
Mucosa
- transitional epithelium near bladder - pseudostratified columnar after
- lamina propria
- Muscular wall (mostly smooth muscle)
What are the components of the male urethra?
- 3 sections of mucosa
- Prostatic: transitional epithlium
- MEmbranous: pseudostratified columnar
-
Cavernous/spongy/penile:
- stratified or pseudostratified columnar - becomes stratified squamous distally
What is shown by the white arrows?
- Medullary ray - collection of straight tubules in the kidneys cortex
- straight tubules include: proximal straight tubules, distal straight tubules, thin segments of the loops of Henle, and collecting tubules
- medullary rays form core of kidney lobule
