Anatomy of the Renal System Flashcards
Components of the renal system
Kidney, ureter, bladder, urethra
Kidney location
Lies behind the parietal peritoneum on posterior abdominal wall
Right kidney slightly lower than left
Lumbar vertebrae and rib cage partially protect the kidney - can be damaged through trauma
External anatomy of the kidney
renal capsule, adipose tissue, renal fascia
Renal capsule
fibrous connective tissue surrounding each kidney
Adipose tissue
engulfs renal capsule, acts as cushioning
Renal facia
thin layer loose connective tissue, anchors kidneys to posterior abdominal wall
Internal anatomy of the kidney
Hilum, renal sinus, ureter, cortex, renal columns
Hilum
renal artery and nerves enter, renal vein and ureter exit - most medial section
Hilum opens into renal sinus
Renal artery
blood from heart to kidney
Renal vein
blood from kidney to heart
Renal sinus
Cavity filled with fat and loose connective tissue
Ureter
exits at the hilum; connects to urinary bladder
Cortex
outer area
Renal columns
Part of cortical tissue that extends into medulla
Internal Anatomy
Medulla, renal pyramids, renal papilla, major calyces, pelvis
Medulla
inner area, surrounds renal sinus
Renal pyramids
cone-shaped, base is boundary between cortex and medulla
Apex of pyramid is renal papilla, points towards sinus
Major calyces
converge to form the renal pelvis
Pelvis
Enlarged chamber formed by major calyces
Nephron
Functional unit of the kidney; filter blood and produce urine
Nephron - structure
Renal corpuscle, proximal tubule, loop of Henle, distal tubule
- Blood enters the nephron for filtration. Filtrate/urine is produced
- Urine continues from the nephron to papillary ducts, minor calyces, major calyces, renal pelvis and ureter
Juxtamedullary nephron
- renal corpuscle located near the medulla
- Long Loops of Henle extending deep into medulla (15%)
Cortical nephron
- renal corpscule located nearer to the periphery of the cortex
- Loops of Henle don’t extend deep into medulla (85%)
Renal corpuscle
Bowman’s Capsule - enlarged end of the nephron, double walled chamber
- Filters blood/fluid which then enters the proximal convoluted tubule
Glomerulus - network/ball of capillaries
- Blood enters through afferent arteriole, exits through efferent arteriole
- Efferent arteriole is smaller than afferent; creates pressure
Bowman’s capsule
Parietal layer - outer layer
- simple squamous - becomes cuboidal in PCT
Visceral layer - inner layer
- Specialised podocytes that wrap around the glomerular capillaries; facilitate filtration
Filtration membrane
fenestrae, filtration slits, basement membrane
Fenestrae
window-like openings in endothelial cells of glomerular capillaries
Filtration slits
gaps between podocytes
Basement membrane
between endothelial cells of glomerular capillaries and podocytes
PCT
filtrate drains from Bowman’s capsule into PCT
- Simple cuboidal epithelium with many microvilli
- Active reabsorption of sodium, potassium and chlorine
Loop of Henle
ascending and descending limb
- Thick parts - simple cuboidal; thin parts - simple squamous (for osmosis/diffusion)
DCT
shorter than PCT
- Simple cuboidal, few microvilli
- Numerous mitochondria
Collecting duct
extends through medulla towards renal papilla to ureter
- Larger in diameter
- Simple cuboidal epithelium
Major renal arteries and veins
Blood enters kidney via abdominal aorta; left and right artery branch off
Deoxygenated blood removed via right and left renal vein, exits through inferior vena cava
Urine movement
Pressure forces urine through nephron
Peristalsis moves urine from renal pelvis in kidney through ureters to bladder (smooth muscle)
Ureters enter bladder obliquely through trigone
Pressure in bladder compresses ureter, prevents backflow - important to prevent kidney infection
Ureters
Bring urine from renal pelvis to bladder
Lined by transitional epithelium
transitional epithelium - mucosa - muscularis - adventitia
Bladder
Hollow, smooth muscle; allows for temporary storage of urine
Sits posteriorly to symphasis pubis
Volume can increase/decreasae
Transitional epithelium - lamina propria - submucosa - detrustor muscle
Trigone
interior of urinary bladder
Triangular area between the entry of the ureter and the exit of the urethra
Urethra
Transports urine from the bladder to outside the body
Internal urinary sphincter - elastic connective tissue and smooth muscle prevent urine continuously flowing out of the bladder
Transitional epithelium (top), stratified columnar epithelium (external opening)
External urinary sphincter - skeletal muscle surrounds urethra; extends through pelvic floor. Acts as a valve that controls the flow of urine
