Topic 16 -Urinary System Flashcards
Structures of the urinary system
2 kidneys
2 ureters
1 urinary bladder
1 urethra
functions of the urinary system
what does it regulate?
regulates: blood volume blood pressure pH ion concentrations
functions of the urinary system
what does it eliminate?
eliminates urea, uric acid, hormones and drugs
kidneys external anatomy
retroperitoneal
right is lower than left
supported and protected by 3 layers of CT
what are the 3 protective CT layers of the kidney?
fibrous capsule
perirenal fat capsule
renal fascia
renal hilus (hilum) of the kidney
medial indentation entry point of: renal artery (superior) renal vein (inferior) ureter nerves
internal anatomy of the kidney
renal cortex (superficial) renal medulla
what does the renal medulla of the kidney contain
renal pyramids -apex of pyramid =renal papilla
renal columns -separate pyramids, contain blood vessels
Nephron
functional unit of kidney (microscopic)
composed of renal corpuscle and renal tubules
what makes up the renal corpuscle of a nephron, what does it do?
in cortex, site of blood filtration (first step in urine formation)
parts: glomerulus
Bowmans capsule
filtration membrane
Glomerulus
capillary bed
Bowmans capsule
what are the two layers
surrounds glomerulus collects filtrate from glomerulus 2 layers: outer= simple squamous epithelium inner= podocytes => wrapped around glomerulus capillaries
filtration membrane
consists of:
glomerular endothelium (capillaries) -simple squamous with pores =fenestrations
basement membranes
podocytes (of bowmans capsule) -simple epithelium
-projections cling to glomerulus
renal tubules 4 parts:
proximal convoluted tubule (PCT) -in cortex
loop of henle -descending + ascending limbs
-in medulla
distal convuluted tubule (DCT) -in cortex
collecting ducts -in cortex and medulla
-connect nephron to ureter (via calcyes/renal pelvis)
2 types of nephrons
Cortical (85%)
Juxtamedullary (15%)
cortical nephrons
renal corpuscle near kidney surface in cortex
short loop of henle in outer medulla
juxtamedullary nephron
renal corpuscles in cortex near medulla
- long loops -penetrate deep into medulla
- allow concentration of urine, depending on need
kidney and nephron blood supply
flow of vessels
aorta -> renal arteries -> segmental arteries -> interlobar arteries (up columns) -> arcuate arteries (medulla/cortex junction) -> cortical radiate arteries -> afferent arteriole -> glomerulus -> efferent arteriole -> peritubular capillaries OR vasa recta (capillaries in medulla -juxtamedullary nephrons) -> cortical radiate veins -> arcuate veins -> interlobar veins -> renal veins -> inferior vena cave
Juxtaglomerular complex
regulates filtrate formation
point of contact between end of ascending limb, afferent and efferent arterioles at the renal corpuscle of the same nephron
parts of the juxtaglomerular complex
tubular portion -modified (tall and narrow) ascending and limb cells =macula densa
arteriolar portion
-afferent and efferent arteriolar portion= granular (juxtaglomerular cells)
monitor blood pressure
modified smooth muscle cells => contain renin (enzyme+ hormone)
Ureters histology
mucosa -transitional epithelium
NO submucosa -lamina propria directly connected to muscularis externa
muscularis externa -smooth muscle ~3 layers
adventitia/serosa -retroperitoneal
Urinary Bladder histology
mucosa -transitional epithelium with rugae
No submucosa -lamina propria directly attaches to muscularis externa
muscularis externa =detusor muscle -smooth muscle ~3 layers
adventitia/serosa -adventitia =anterior, posterior and inferior
serosa =superior
internally of bladder
triangle formed by opening of 2 ureters (posteriorly) and urethra =trigone
-lacks rugae (smooth) -allows opening to remain in fixed position
urethra histology
mucosa -transitional to stratified squamous
muscularis externa -smooth muscle
urethra 2 sphincters
both surround proximal end of urethra
internal urethral sphincter (smooth muscle)
-thickening of detrusor muscle at base of bladder
external urethral sphincter (skeletal muscle)
-in urogenital diaphragm
urethra transports
urine in females
urine and semen in males
filtrate moves from
several DCTs ->collecting ducts (exit at renal papilla -fluid now=urine) -> minor calyx -> major calyx -> renal pelvis -> ureter -> urinary bladder -> urethra -> exits body
