Urinary System Flashcards
what composes nephrons
- renal corpuscle
- PCT
- loop of Henle
- DCT
- connecting tubule
what are the organs of the urinary system
- kidneys - 2
- ureters - 2
- urinary bladder - 1
- urethra - 1
what are the layers of renal corpuscle (bowman’s capsule)
parietal-simple squamous
visceral - podocytes , pedicels
(urinary space between the two layers, receives filtered fluid from the capillaries)
what are the general functions of the urinary system
- regulate water and electrolyte balance
- excretion of nitrogenous wastes, water and electrolytes
- excretion of some other materials like drugs
- secrete renin
Describe the structure of the kidneys
- capsule - thin and fibrous made of dense irregular CT
- hilum-concave and medial- nerves in, ureters exit; blood and lymph enter and exit
- renal pelvis-widening of the ureter
- major calyces- broad spaces within kidney to collect urine and direct to renal pelvis, 2-3/kidney
- minor calyces - smaller collecting areas from each major calyx, contain renal papilla-tip of each renal pyramid
- renal sinus - area surrounding renal pelvis, major calyces and minor calyces containing adipose
what are the two general regions of parenchyma within the kidney
- cortex - contains renal corpuscles, tubules, medullary rays extending from medulla into cortex, contains primarily portions of the loop of Henle and collecting tubules
- medulla - contains renal pyramids (8-12/kidney), renal columns (area separating the renal pyramids)
what are podocytes
modified epithelial cells containing pedicels
what are pedicels
secondary podocyte cell processes covering the glomelular capillaries creating filtration slits
what are mesangial cells
special cells found within the renal corpuscles thought to replace regular CT cells many are pericyte like, often present in areas lacking podocytes, their functions include: capillary support
adjust capillary pressure for good filtration
phagocytosis of interfering materials (ie, proteins)
secrete various cytokines for immune defense and glomerulus repair
describe PCT
- epithelium - simple cuboidal with long microvilli
- located in cortex
- function a. reabsorption of nutrients, proteins, water, and electrolytes (actively and passively)
b. secretion of organic molecules like H+. ammonia, bile salts, and some drugs
describe the thin limbs of the loop of Henle
epithelium - simple squamous
location - medulla
function - reabsorb Na+ and Cl- (passively)
describe the thick ascending limb of the loop of Henle
epithelium - simple cuboidal (no microvilli)
location - medulla and medullary rays
function - reabsorb electrolytes (actively)
describe the DCT
- epithelium - simple cuboidal (shorter cells with fewer and shorter microvilli)
- location - cortex
- function - reabsorb electrolytes
- macula densa - special part of DCT at the vascular pole containing closely packed columnar cells, part of juxtaglomerular apparatus (JGA), gen function of JGA-regulate glomerular blood flow and glomerular filtrate
describe the Collecting Tubule
epithelium - simple squamous to simple cuboidal
function- connect nephrons to collecting ducts
describe Collecting ducts
not part of nephron
epithelium-simple cuboidal to simple columnar (in larger ducts)
2 cell types - 1. principle cells 2. intercalated cells
describe principle cells
light cells = collecting duct cells most common cell type location - medullary rays and medulla function - influence water and electrolyte movement and influence K+ secretion
describe intercalated cells
dark cells - fewer in number
location - medullary rays
function- secretion of H+ or HCO3- to maintain pH balance
none close to renal papillae
where do collecting ducts go
they lead to a papillary duct which leads to a renal papilla and finally to a minor calyx
describe ureters
2 each ~24-34 cm long function to transport urine to urinary bladder
describe the mucosa of the luminal wall
I. surface epithelium - urothelium or transitional, ~4-5 cell layers thick
3 layers:
a. 1 layer of basal cells
b. 1 to several layers of intermediate cells
c. 1 layer of superficial cells called umbrella cells, can be bi-nucleate, possess a free edge plasma membrane with placque
placque functions to protect cells and tissues beneath and to block water passage
II. LP rather dense irregular CT
where are placque and umbrella cells most developed
in the urinary bladder
describe the mascularis Externa
-smooth muscles mixed with CT
-Reverse Pattern - inner longitudinal layer, outer circular layer
Distal end has 3 muscle layers
-inner longitudinal
-middle circular
-outer longitudinal
describe the adventitia of the ureter
contains adipose, blood vessels and nerves
describe the connection of the ureter to the urinary bladder
- enters at an angle to create a valve
- as bladder fills entrance to ureters is closed
what is the function of urinary bladder
storage unit
describe the mucosa of luminal wall of the urinary bladder
- transitional epithelium - function to stretch and protect from hpertonic and toxic urine
- usually 6+ layers thick
- placque is well developed to fold at the thinner regions when bladder collapses - LP - rather dense irregular CT
Describe the mascularis externa of the urinary bladder
3 distinct smooth muscle layers = detrusor muscle
- inner longitudinal
- middle circular
- outer longitudinal
what is the Internal Urethral Sphincter
-circle of muscle around the urethral opening into the urinary bladder
-involuntary
-function - prevent backflow
this is important to stop the spread of infection to the kidneys
describe the nerve supply to the urinary bladder
a. sympathetics - to blood vessels
b. parasympathetics (from S2 to S4 travelling with Splanchic nerves) to ME and adventitia - function in micturition reflex
c. sensory -urinary bladder to sacral spinal cord
function - afferent fibers for micturition reflex
describe the urethra
fibromuscular tube
longitudinal folds in mucosa
describe the urethra in males
part of urinary and reproductive systems
3 sections
a. prostatic urethra - ~3-4 cm
in prostate
surface epithelium - urothelium
b. membranous urethra- ~1cm - passes thru external urethral sphincter - striated muscle.
-surface epithelium- stratified columnar andmpseudostratified columnar epithelium
c. spongy (penile) urethra: ~15 cm
-surrounded by erectile tissue (corpus spongiosum)
-surface epithelium - stratified columnar and pseudostratificed columnar and stratified squamous distally
describe the urethra in females
- urinary system only
- 4-5 cm long
- surface epithelium=transitional, stratified columnar/pseudostratified columnar (middle part) and stratified squamous distally
- external urethral sphincter is around the middle portion
describe the female glands within the wall
- proximal urethral glands - small and numerous and lead to lumen
- paraurethral glands - secrete alkaline fluid to paraurethral ducts into the sides of external urethral orifice
