Urinary System - Downing Flashcards
(27 cards)
What are the five functions of the urinary system?
- Elimination of wastes (urine production)
- Fluid balance
- Salt balance
- Acid-base balance
- Endocrine
What are the three components of the Renal Parenchyma?
- Parenchyma
- Cortex
- Renal corpuscles
- Medullary rays
- Medulla
- Renal pyramids
- Area cribrosa
- Renal columns (cortical material)
- Cortex
What is the difference between a lobe and a lobule of the kidney?
- Lobe
- Grossly visible
- Medullary pyramid and surrounding cortical tissue
- Lobule
- Microscopic
- Straight tubules in medullary rays + surrounding cortical tissue
What defines the outer border of a lobule in the kidney?
Interlobular arteries & veins
What are medullary rays?
- collections of straight running tubules in the center of lobes of the kidney
- converge at the medulla
What does a nephron consist of?
- Renal corpuscle
- Bowman’s capsule
- Glomerulus
- Tubular portion
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
- (hooks up to collecting duct)
What kind of blood vessels are associated with the Glomerulus?
ARTERIES!
- Vascular apparatus; entirely arterial
- Afferent and efferent arterioles
- Fenestrated capillaries within capsule
What are podocytes?
- Visceral layer of Bowman’s capsule
- continuous with parietal layer
- Primary and secondary processes
- Slit pores
What is the function of mesangial cells?
- Cleaning GBM
- GBM turnover
- if blocked
- Support
How do you distinguish between the cortex and medulla of the kidney?
- Cortex
- Outer darker area
- Contains renal corpuscles and medullary rays
- Medulla
- Appears lighter, inner area
- Contains 6-18 medullary pyramids
- Bases of pyramids lie adjacent to cortical tissue
- Tips of pyramids (renal papillae) point toward the minor calyces of the renal pelvis
What is the vascular supply to and from the kidney?
- Renal Artery
- Interlobar Arteries
- Arcuate Arteries
- Interlobular Arteries
- branches to afferent arterioles
- efferent vessels
- peritubular vascular network
- Vasa recta (from efferent near corticomedullary junction)
- Arteriolae rectae (descending)
- Venae rectae (ascending)
- drains into Arcuate Vein
How do you distinguish between major & minor calyces of the kidney?
minor calyces converge to form several major calyces which in turn converge to form the renal pelvis
How do you identify Proximal tubules on histologic slides?
- Bulk of cortex
- Fuzzy (striated/brush) luminal border
- Eosinophilic
- Apical canaliculi (tiny invaginations)
- Lateral membrane folding
- Basal folds containing mitochondria
How do you identify a Distal straight tubule on histologic slides?
- Abrupt transition to simple cuboidal epithelium
-
Less eosinophilic and larger lumen than proximal tubule
- ‘cleaner’ apical and lateral borders
- More nuclei around circumference of tubules
- Basal membrane folds & mitochondria
What is the function of the collecting tubules?
- Water resorption; under influence of ADH
- Acid-base balance
What are the three components of the Juxtaglomerular Apparatus?
- Juxtaglomerular cells
- Macula densa
- Extraglomerular mesangial cells
What are the mechanisms that allow for the Juxtaglomerular apparatus to maintain normal blood pressure?
- JG cells respond to degree of stretch
- Macula densa cells monitor Na+ concentration in the distal tubule
- Low plasma Na+ stimulates renin release
- Sympathetic nerve fibers can terminate on JGA cells => release renin when stimulated
What is the nerve supply of the kidney?
- Sympathetic division of autonomic nervous system (extrinsic supply)
- Contraction of vascular smooth muscle
- Afferent arteriole contraction reduces filtration rate (and urine production)
- Efferent arteriole contraction increases filtration rate (and urine production)
- Loss leads to increased urinary output
- Contraction of vascular smooth muscle
- Extrinsic nerve supply not essential
What are the four components of a Ureter?
- Mucosa
- Submucosa?
- Muscular coat
- Adventitia
What are the four layers of the Urinary Bladder?
- Mucosa
- Submucosa?
- Muscular coat
- Adventitia
What is the difference between the male and female urethra?
- Female
- Mucosa
- Transitional epithelium near bladder; stratified squamous thereafter
- Lamina propria
- Muscular wall (mostly smooth)
- Mucosa
- Male
- Mucosa
- Prostatic: transitional epithelium
- Membranous: stratified columnar
- Cavernous: stratified or pseudostratified and becoming stratified squamous at end
- Mucosa
What is the area cribrosa?
- Name given to the tip of the papilla (tip of renal pyramids)
- Perforated by 10-25 small openings where the terminal segments of the uriniferous tubules open into a minor calyx
What is the macula densa?
- Elliptical disc of densely packed elongated cells in wall of ascending limb where it contacts afferent arteriole
- at the transition to the distal convoluted tubule
- Immediately adjacent to juxtaglomerular cells in wall of afferent arteriole at the vascular pole of the glomerulus
- Golgi apparatus is reversed in position in the macula densa cells
- Positioned between nucleus and base of cell rather than in apical cytoplasm
What is the function of the macula densa?
Function not completely clear.
Thought to monitor the Na+ concentration in the distal tubule
