Topic 16: Urinary System Flashcards
what are the structures of the urinary system?
-2 kidneys
-2 ureters
-1 urinary bladder
-1 urethra
what are the functions of the urinary system?
-regulates
-eliminates
what does the urinary system regulate?
-blood volume + pressure
-pH (H+ and HCO3-)
-ion concentrations (Na+, Ca++, K+, Cl-)
-secretion of renal hormones
how does the urinary system regulate blood volume + pressure?
-more fluid=more pressure
-releases more fluids to regulate
what wastes does the urinary system eliminate?
-urea (waste)
-uric acid (waste)
-hormones
-drugs (antibiotics)
-toxins
what are the characteristics of the kidenys?
-retroperitoneal
-right is lower than the left
-supported + protected by 3 layers of CT
what are the 3 supporting CT layers of the kidney?
-fibrous capsule (outer)
-perirenal fat capsule (middle)
-renal fascia (inner)
what is the renal hilus?
-also called the hilum
-medial indentation
-entry point of multiple things
what is the renal hilus the entry point of?
-renal artery (superior)
-renal vein (inferior)
-ureter
-nerves
what is the internal anatomy of the kidneys?
-renal cortex (superficial)
-renal medulla
-renal pelvis
what is contained in the renal medulla?
-renal pyramids
-renal columns
what are the renal pyramids?
-contain parts of nephrons
-apex of the pyramid = renal papilla (to release filtrate)
what is the renal cortex?
-superficial layer
-contains parts of nephrons
-contains afferent and efferent arterioles
-contains capillary beds (glomeruli)
what are the renal columns?
-projections of the cortex into the medulla
-separate renal pyramids
-contain arteries, veins, and nerves that supply the cortex
what is a nephron? what is it composed of?
-functional unit of the kidney
-composed of the renal corpuscle and renal tubules
what is the renal corpuscle?
-in the cortex
-site of blood filtration
-is formed by the glomerulus, glomerular (bowman’s) capsule, afferent and efferent arterioles, and the filtration membrane
what is the glomerulus?
-capillary bed
-very leaky capillaries
-simple squamous (endothelium) with many pores (fenestrations) between cells
what is the glomerular (bowman’s) capsule?
-surrounds the glomerulus
-collects filtrate from the glomerulus
-has an outer and inner layer
what is the outer layer of the bowman’s capsule? why?
-simple squamous epithelium
what is the inner layer of the bowman’s capsule?
-cells called podocytes that wrap around glomerular capillaries
what are podocytes?
-cells that have many finger-like projections
-form a network of filtration slits
what is the filtration membrane?
-glomerular endothelium (capillaries)
-shared basement membrane (between the other 2)
-podocytes
what are the four parts of the renal tubule
-proximal convoluted tubule (PCT)
-nephron loop
-Distal Convoluted Tubule (DCT)
-Collecting Ducts
where is the PCT located? what type of tissue is it composed of? what is its function?
-in the cortex
-cuboidal epithelium with dense microvilli
-receives filtrate from the glomerular capsule
-reabsorbs most useful substances from the filtrate (glucose + amino acids)
-secretes waste products into the filtrate
where is the nephron loop located? what forms it?
-in the medulla
-descending limb (thin, simple squamous epithelium)
-ascending limb (thick, simple cuboidal epithelium)
where is the DCT located? what tissue forms it?
-in the cortex
-cuboidal epithelium
where are the collecting ducts located? what is their purpose?
-in the cortex + medulla
-drains filtrate from numerous nephrons into minor calyces
-contains cells that regulate water and Na+ reabsorption and acid/base balance of the blood
what are the 2 types of nephrons?
-cortical (majority)
-juxtamedullary (small amount)
what is special about cortical nephrons?
-renal corpuscles are near the kidney surface in the cortex
-short nephron loop (dips in the outer medulla)
-has peritubular capillaries that branch from the efferent arteriole and surround the DCT + PCT
what is the purpose of the juxtaglomerular complex?
-regulates filtrate formation (amount of salts + ions being removed)
-point of contact between the ascending limb, afferent + efferent arterioles at the renal corpuscle of the same nephron
what is special about juxtamedullary nephrons?
-renal corpuscles in the cortex near the medulla
-long nephron loops
-loops penetrate deep in the medulla
-has capillaries called vasa recta that branch from efferent arterioles and run parallel to the nephron loop
what are the two parts of the juxtaglomerular complex?
-tubular portion (macula densa)
-vascular (arteriolar) portion
what is the tubular portion of the juxtaglomerular complex?
-modified (tall + narrow) DCT cells
-monitors filtrate composition
what is the vascular (arteriolar) portion of the juxtaglomerular complex?
-afferent + efferent arteriole portion
-granular (juxtaglomerular cells)
-modified smooth muscle cells that monitor blood pressure
-secrete an enzyme/hormone that helps to regulate blood pressure and ion balance
what are retroperitoneal parts of the urinary system?
-kidneys
-ureters
-urinary bladder
what type of epithelium is the mucosa of the ureters?
-transitional epithelium (stretching)
do the ureters have a submucosa layer?
-no
-lamina propria is connected directly to the muscularis externa
what is the muscularis externa layer of the ureters?
-smooth muscle
-amount is dependent on location
do the ureters have an adventitia or a serosa?
-adventitia
-retroperitoneal
-connects ureter to the body wall
what type of epithelium is the mucosa layer of the urinary bladder?
-transitional epithelium with rugae (for stretching)
does the urinary bladder have a submucosa layer?
-no submucosa
-lamina propria is directly connected to the muscularis externa
what is the muscle called in the muscularis externa layer of the urinary bladder? what does the contraction of this muscle cause?
-detrusor muscle (smooth muscle)
-contraction causes urination
does the urinary bladder have serosa or adventitia?
-mostly adventitia
-serosa covers the superior surface
what are the 2 sphincters of the urethra? what do they surround?
-internal urethral sphincter
-external urethral sphincter
-the proximal end of the urethra
what is the internal urethral sphincter?
-thickening of detrusor muscle at the base of the bladder
-smooth muscle (involuntary)
what is the external urethral sphincter?
-in the urogenital diaphragm
-skeletal muscle (voluntary)
what does the urethra transport in females?
-transports urine
what does the urethra transport in males?
-transports urine + semen
how does the glomerular endothelium create the filtration membrane?
-fenestrations allow plasma through, but not formed elements or most large proteins
what is the role of the efferent arteriole in the nephron?
-exits the glomerulus
-drains into the peritubular (cortical nephrons)
-drains into the vasa recta (juxtaglomerular nephrons)
what is the role of the afferent arteriole in the nephron?
-enters the glomerulus
-carries blood delivered to the kidney from the renal artery
which parts of the nephron loop are water permeable/impermeable?
-descending = water permeable
-ascending = water impermeable
what do the long nephron loops of the juxtamedullary nephrons allow for?
-allows for different concentrations of urine depending on the need
-ex: conserving water for blood pressure and volume
what is the purpose of the ureters?
-transports urine from the renal pelvis to the bladder
what are the 3 histology layers of the ureters?
-mucosa
-muscularis externa
-adventitia
what is the purpose of the urinary bladder?
-short term storage for urine
what are the 3 histology layers of the urinary bladder?
-mucosa
-muscularis externa
-adventitia/serosa
what is the purpose of the urethra?
-drains urine from the urinary bladder
what are the 3 histology layers of the urethra?
-mucosa
-muscularis externa (smooth muscle)
-adventitia
what is the mucosa of the urethra?
-transitions from transition epithelium to stratified squamous epithelium
what is the filtrate/urine pathway?
-several DCT
-collecting ducts (exit at the renal papilla)
-minor calyx
-major calyx
-renal pelvis
-ureter
-urinary bladder
-urethra
