Histology Of Urinary System Flashcards
Bowman’s capsule (tissue slide)
- vascular pole
- urinary pole
- glomerular filtrate–>tubular filtrate–>urine(minor calyx)
What is the pathway of venous drainage of the kidney
1) interlobular vein
2) arcuate vein
3) interlobar vein
- -no segmental vein
4) renal vein
***lymphatic drainage most likely follows the veins
Loop of Henle
- made up of simple squamous epithelium, divided into 4 parts:
- thin descending limb
- thin ascending limb
- thick ascending limb
- cortical thick ascending limb
Filtration of blood (kidney)
- kidneys receive 21% of cardiac output
- each kidney filters 600 mL of blood every minute
- both kidneys filter the entire blood every 5 min
Urination (micturition)
-stretch receptors in bladder send impulses to spinal cord (200-400 mL of urine)
What kind of epithelium forms thick segments of loop of Henle
Simple cuboidal epithelium
Anti-diuretic hormone (ADH)
- makes the DCT, collecting tubule, & collecting duct permeable to water and urea
- stimulates reabsorption of water
- concentrates urine
Medullary rays
- loops of Henle
- collecting ducts
Internal urethral sphincter
- continuous with the middle muscular layer of the bladder near its neck
- involuntary
What is the effect of aldosterone on distal convoluted tubule
- it stimulates Na+/K+ ATPase pump to transport Na+ and Cl- from filtrate in lumen into renal interstitium
- K+ and H+ into lumen
- impermeable to water
Ammonia
Metabolic byproduct of aa metabolism
Mesangial cells
- specialized cells around the glomerulus that keep it free of debris
- provide physical support
- phagocytosis
- maintenance of basement membrane
- contraction of efferent arteriole in response to angiotensin II
Thin ascending limb of loop of Henle
- impermeable to water
- permeable to ions (solutes get reabsorbed)
Juxtamedullary nephrons
- have loop of Henle deep in medulla
- renal corpuscle is near medulla (juxtamedullary) but still in cortex
What 3 hormones act on the distal convoluted tubule
- aldosterone: stimulates reabsoption of Na+
- atrial natriuretic factor: inhibits aldosterone
- parathyroid hormone: stimulates reabsorption of Ca+
Vitamin D synthesis
1) UV converts precursor vit D to vit D3 in skin
2) liver converts vit D3–> 25OH vit D3 (precursor)
3) kidney converts it to 1,25-(OH)2 vit D3 (active form)
Glomerulus
- Capillary tuft that receives its blood supply from an afferent arteriole
- glomerular blood pressure is driving force for water and solutes out of blood and into bowman’s capsule
What happens with decrease in blood pressure
–>decreased glomerular filtration rate (GFR)–> decreased sodium concentration in fluid of DCT–> macula densa –> indirect release of renin
Macula densa
- tightly packed simple columnar epithelium (osmoreceptors)
- tall, narrow cells with centrally-located nucleus
- senses any increase in Na+ and Cl- concentration in the distal tubule of the kidney
- secretes paracrine vasopressor which acts on adjacent afferent arteriole to decrease GFR
- decreases renin release from juxtaglomerular cells of the afferent/efferent arterioles
Pathway of action of renin
- released by juxtaglomerular cells and converts angiotensinogen in blood to angiotensin I
- angiontensin I (blood) travels to lungs and is converted to angiotensin II by ACE
- angiotensin II is a potent vasoconstrictor
- renin also increases aldosterone secretion (increase in Na+ and Cl- reabsorption in DCT)
Components of urinary system
- 2 kidneys
- 2 ureters
- 1 bladder
- 1 urethra
- 2 renal arteries
- 2 renal veins
Thin descending limb of loop of Henle
- reasonable permeability: Na+, Cl-, and other ions
- high permeability: water (water channels) due to concentration gradient
- urea enters lumen of tubule
Renal cortex (tissue slide)
- skip pattern
- cortex= cortical labyrinth (renal corpuscles plus convoluted tubules) + medullary rays (straight part of tubules)
Renal capsule
- made of 2 layers
- outer: dense irregular CT; fibroblasts and collagen fibers
- inner: myofibroblasts
Uric acid
Formed from nucleic acid catabolism