Gross Anatomy of the Urinary System Flashcards
components of the Urinary System
- paired kidneys
- ureter for each kidney
- urinary bladder
- urethra
main functions of urinary system
- kidneys filter blood to keep it pure
- dispose of nitrogenous wastes from blood
- regulate the balance of water and electrolytes, acids and bases
What substances do kidneys filter out of the blood?
toxins
metabolic wastes
excess water
excess ions
nitrogenous wastes disposed from the blood
urea
uric acid
creatinine
position of the kidneys
retroperitoneal
T12 - L3
margins of the kidneys
lateral = convex medial = concave medial = hilum cleft
what is the hilus?
where vessels, ureters and nerves enter and leave
what lies superior to the kidneys
adrenal glands
describe the difference between the left and right kidneys?
the right is lower and slightly shorter than the left
measurement of kidney
10 x 5 x 2.5
anterior relations of right kidney
liver hepatorenal recess duodenum right colic flexure ascending colon
anterior relations of left kidney
stomach spleen pancreas left colic flexure jejunum
posterior relations of kidneys
subcostal, iliohypogastric + ilioinguinal nerves
superior relations of kidney
- diaphragm
2. T12
posterior inferior relations to kidneys
quadratus lumborum
posterior medial relations of the kidney
psoas major
posterior lateral relations of kidney
transversus abdominis
kidneys are derived from?
intermediate mesoderm - urogenital ridge
consequence of renal and reproductive systems being derived from the same mesoderm?
The kidney may never migrate during development & remains in the pelvis
- Look in the pelvis if there is a missing kidney
- Do not remove any pelvic tumours until you know they are not pelvic kidneys
what are the internal structures of the kidney?
cortex medulla pyramids papillae columns calyces pelvis
what are the 2 regions of the kidney?
cortex and medulla
describe the cortex?
outer region of kidney
- columns of cortex divide medulla into “pyramids”
describe the medulla?
- inner region of the kidney
- darker, cone-shaped medullary or renal pyramids
- parallel bundles of urine-collecting tubules
what are the lobes of the kidney?
renal pyramid + cortical tissue surrounding it
describe the renal pelvis?
- expanded, funnel shaped, superior part of ureter
- formed from major calices
function minor calices
collect urine from papillae of pyramids and send it to major calices
what structures surround the kidney?
renal fascia
adipose capsule
renal capsule
describe renal fascia?
- outermost layer - most external membrane
2. anchors kidney to peritoneum & abdominal wall
describe adipose capsule?
- second layer - contains perirenal fat
2. cushions kidney
describe the renal capsule?
- inner most layer - dense connective tissue
2. protects kidney from trauma & infection
describe the lymphatic drainage of the kidneys?
aortic (lumbar) lymph node
describe the nerve supply of the kidneys?
renal plexus
describe the arterial supply of the kidneys?
aorta > right + left renal arteries > segmental arteries > lobar arteries > interlobar arteries > arcuate arteries > cortical radiate arteries > glomerular afferent arterioles > glomerulus capillaries
describe the venous drainage?
glomerulus capillaries > efferent arteriole > peritubular capillaries and vasa recta > interlobular vein > arcuate vein > interlobar vein > renal vein > inferior vena cava
how is the vasculature of the kidney different?
- arterioles going both to it and away from it (afferent and efferent), instead of a vein going away as most
- two capillary beds in series (one following the other)
clinical correlations of the left renal vein?
the longer left renal vein crosses midline anterior to abdominal aorta and posterior to superior mesenteric artery therefore it can be compressed by an aneurysm in either of these tissues
importance of afferent and efferent arterioles associated with glomerular capillaries?
allows high pressure for forcing filtrate out of blood
function of peritubular capillaries?
absorb solutes and water from tubule cells
what is the vasa recta?
is a portion of the peritubular capillary system which enters the medulla where the solute concentration in the interstitium is high
function of vasa recta + loop of Henle?
concentrate the urine
arterial supply of the ureter
- branches of internal & external iliac arteries
2. renal, testicular or ovarian arteries
venous drainage of the ureter
- tributaries of internal & external iliac vein
2. testicular or ovarian veins
lymph drainage of ureter
internal iliac + external iliac lymph nodes
nerve supply of ureter
renal plexus supplied by thoracic splanchnic nerves
3 constrictions along their course of the ureter where stones or calculi are likely to lodge
- ureteropelvic junction - just inferior to the kidney
- where the ureters cross the common iliac vessels at the pelvic brim
- uterovesicle junction - where the ureters enter the wall of the bladder (narrowest of all)
pain from urinary tract stones radiate how?
from the infra-scapular region into the groin and even into the scrotum or labia majora
what is the urinary bladder?
collapsible muscular sac that stores and expels urine
describe the position of the urinary bladder?
Lies on pelvic floor posterior to pubic symphysis
describe the relations of the urinary bladder in both genders?
- males - anterior to rectum
2. females - anterior to vagina and rectum
3 layers of the bladder
- outer layer - loose connective tissue
- middle layer - smooth muscle + elastic fibres
- inner layer - transitional epithelium
what are the 3 openings of the bladder
2 ureters + urethra = trigone
4 histological layers of urinary bladder
- mucosa with rugae + lamina propria
- submucosa
- muscularis - detrusor muscle
- fibrous adventitia
describe the muscularis of the bladder
detrusor muscle
- 3 layers of highly intermingled smooth muscle
- squeezes urine out
describe the bladder when it is full?
bladder is spherical and extends into abdominal cavity (holds about 500 ml or 1 pt)
describe the bladder when its empty?
bladder lies entirely within pelvis with shape like upside-down pyramid
what is the trigone?
inside area between ureters and urethra - prone to infection
why is the trigone prone to infection?
urine stays there the longest
relations of the ureter
runs medial to and parallel with the internal iliac artery
which structure crosses over the ureter
uterine artery
water under the bridge
layers of the urethra
smooth muscle + inner mucosa
- epithelium changes from transitional through stages to stratified squamous near end
functions of urethra?
drains urine out of the bladder and body
length of urethra in males and females
- male - about 20 cm (8”) long
2. female - 3-4 cm (1.5”) long
consequence of a short urethra in females
short length is why females have more urinary tract infections than males - ascending bacteria from stool contamination
what is the internal urethral sphincter?
involuntary sphincter of smooth muscle
what is the external urethral sphincter?
skeletal muscle inhibits urination voluntarily until proper time
- levator anni muscle also helps voluntary constriction
3 regions of the male urethra
- prostatic urethra
- membranous urethra
- spongy/penile urethra
structure of female urethra
- external urethral orifice - between vaginal orifice and clitoris
- internal urethral sphincter - detrusor muscle thickened, smooth muscle + involuntary control
- external urethral sphincter - skeletal muscle + voluntary control
what is micturition?
voiding
urinating
emptying the bladder
what is the micturition center of the brain?
pons
how do higher centres influence micturition?
- parasympathetic - to void
2. sympathetic - inhibits micturition