Lecture 19 - Urinary System Flashcards
Functions of kidneys
- > regulation of blood composition, specifically ions
- > regulation of blood pH, osmolarity, pressure and glucose
- > regulation of blood volume by conserving/eliminating water
- > excretion of wastes and foreign substances
Urinary system vs urinary tract
the urinary system is what fiters blood and creates urine and the urinary tract is the body’s drainage system for removing urine
External anatomy of the kidneys
- > has concave hilum where blood vessels, nerves and the ureters enter and exit
- > the transparent membrane which maintains organ shape is called the renal capsule (fibrous capsule)
- > adipose tissue tisssue surrounding kidney protects it from trauma (paranephric fat)
location of the kidneys
- > found just above the waistline between the peritonium and posterior wall of abdomen (retroperitoneal along with adrenal glads and ureters)
- > kidneys are held against body wall by dense, irregular connective tissue called renal fasica
Internal anatomy of the kidneys
- > the parenchyma of the kidney is where the process of waste excretion takes place and is made up of the renal cortex and renal medula
- > the renal pyramids (humans have 8-15 per kidney) make up the renal medulla and are separated by the renal columns (part of cortex)
- > renal papila are the point of the renal pyramids that point towards the center of the kidney
Regions of the kidneys
- > inner renal medulla
- > outter renal cortex
- > renal columns (extensions of renal cortex that subdivide medulla)
- > corticomedullary junction (where wide base of ren.pyr. meets cortex)
- > renal pyramid (apex/tip of renal papilla)
How is urine drained from kidney
- > the drainage system fills the renal sinus cavity
- > the minor calyces collect urine from the papillary ducts of the papilla
- > minor and major calyces empty into the renal pelvis which empties into the ureter
Explain the path of oxygenated bloodflow through the kidneys
- > blood enters kidneys through the renal arteries
within the renal sinus, renal arteries - > segmental arteries - > interlobar arteries - > arcuate arteries - > interlobular arteries
- > interlobular arteries lead into afferent arterioles - > glomerulus *blood is filtered* - > efferent arteriole
The Nephron
*Kidney has over 1 million nephrons*
made up of 2 pieces
- > renal corpuscle
- > renal tubule
Renal copruscle
*SITE OF PLASMA FILTRATION*
- > made up of glomerulus and its capsule
- > glomerulus are capillaries where filtration occurs
- > Bowman’s (glomerular) capsule is double walled (parietal and visceral layers)epithelial cup that collects filtrate
Renal tubule
- > collecting ducts and papillary ducts drain urine to the renal pelvis and ureter
made up of…
- Proximal convoluted tube
- Loop of Henle (crosses over into medulla)
- Distal convoluted tubule
*P/D conv. tubules are lined with microvilli which will retain/ absorb certain substances from filtrate*
Structure of renal corpuscle
- has vascular and tubular pole
- Bowman’s capsule surrounds capsular space:
- > podocytes cover capillaries to form the capsules visceral layer
- > simple squamous cells form parietal layer of capsule
• glomerular capillaries arise from afferent artierole and form a ball before exiting via the efferent arteriole
Filtration membrane
- > made up of filtration slits and the fenestrated capillary wall
- > uses podocytes to cover the fenestrated endothelium of the capillaries to stop all cells, platelets, large plasma proteins, medium size proteins passing through
- > allows small proteins which will go through renal tubule to be filtered/processed
podocytes
- > similar to astrocytes but instead of perivascular feet, they have perdicels that wrap around the glomerular capillaries but do not completely surround it
- > perdicels are separted from eachother by thin spaces called filtration slits
Vascular pole vs tubular pole
vascular pole
- > receives the afferent and efferent arterioles
tubular pole
- > leads into the proximal tube and collects the initial urine
Cortical nephron
- > 80-85% of neprons are Cortical nephrons
- > renal corpuscles are in outer cortex and loop of Henle lies mainly in cortex
Juxtamendullary nephron
- > 15-20% of nephrons are JN
- > renal corpuscles close to medulla and long loops of Henle extend into deepest medulla enabling excretion of dilute or concentrated urine
position of ureter
- > extends from renal pelvis to bladder
- > enters posterior wall of bladder obliquely
- > urine flows through the ureters using peristalsis, gravity and hydrostatic pressure
Layers of the ureters
- Mucosa
- > transitional epithelium - Muscularis
- > inner longitudinal & outter circular smooth muscle layers
- > initiates peristalsis - Adventitia layer of loose connective tissue
*does not have submucosa, doesn’t need them, doesn’t need glands*
Trigone of bladder
a smooth flat area bordered by two ureteral openings and one urethral opening
Layers of the wall of the bladder
- Mucosa
- > transitional epithelium that lines internal surface of the blader - Submucosa
- > supports bladder wall - Muscularis
- > three layers of smooth muscle called detrusor muscle that run in 3 directions but they aren’t distinct. - Adventitia
- > outer layer of areolar connective tissue
Transitional epithelium of the urinary bladder and ureters
- > the epithelium is transitional because it appears cuboidal when relaxed and squamous when distended
- > transitional epithelium is needed to protect the underlying tissues from toxic urine, as well as being easily stretched
Sphincter of the urethra
- Internal urethral sphincter (smooth muscle; involuntary)
- External urethral sphincter (skeletal muscle; voluntary)
Functions and segements of the male urethra
2 functions…
- > urinary function to transport urine
- > reproductive function to transport semen
3 segments…
- Postatic urethra
- Membranous urethra
- Spongy urethra
