Renal Flashcards
what are the components of the renal system
- Kidney
- Ureter
- Urinary bladder
- Urethra
what are Renal System Functions
Filtering of blood to produce urine - filtration, reabsorption, secretion Regulation of; - blood volume & pressure - conc ions & electrolytes - red blood cell synthesis - via erythropoietin production Synthesis vitamin D
describe the peritoneum
Peritoneum = serous membrane of abdomen
- Many abdominal organs contained within e.g. stomach and liver
Other organs lie against abdominal wall = Retroperitoneal
Only covered by peritoneum on one surface considered behind the peritoneum
- Kidneys & adrenals,
- pancreas, duodenum,
- rectum, bladder,
- ascending & descending colon
describe position/location of kidneys
¥ Bean shaped
¥ Size of clenched fist (~130g)
¥ Retroperitoneal
¥ on posterior abdominal wall
¥ either side of vertebral col.
¥ Right kidney slightly lower than left as liver above it
¥ Lumbar vertebrae and rib cage partially protect kidneys
¥ 11th & 12th ribs on L but only 12th on R
¥ Renal fascia = thin layer connective tissue, anchoring kidneys & surrounding adipose to abdominal wall
Pararenal fat - engulfs kidney and acts as cushioning
describe External Anatomy of Kidneys
¥ Renal capsule = fibrous connective tissue surrounding each kidney
¥ Hilum = medial side
Ð Renal artery & nerves enter
Ð Renal vein & ureter exit
Ð Opens into renal sinus (cavity filled with fat and loose connective tissue)
describe internal anatomy of kidneys
¥ Kidney = cortex + medulla
¥ Cortex: outer area
¥ Medulla: inner area; surrounds renal sinus
¥ Calyces = funnels connecting medulla to renal pelvis
Ð Minor: medulla pyramid extend into funnel of minor calyx; converge to form major calyces
Ð Major: 2-3 per kidney, converge to form renal pelvis
¥ Renal Pelvis: enlarged chamber formed by major calyces, narrows to form ureter
¥ Ureter: exits at the hilum; connects to urinary bladder
describe Blood vessels of the kidneys
- Renal blood flow relatively constant despite changes in blood pressure
- Autoregulated by kidneys
- Sympathetic stimulation constricts arterioles
- Set up of BVs within kidneys allows exchange of materials
describe arterial supply of kidneys
• Renal arteries from abdominal aorta
• Segmental arteries
• Interlobar arteries ascend toward cortex
• Arcuate arteries arch over pyramid base
• Interlobular arteries project into cortex
Ð give rise to afferent arterioles
Ð Take blood into glomerulus
Ð Efferent arterioles take blood out of glomerulus
describe venous supply of kidneys
• Peritubular capillaries arise from eff art Ð Run around convoluted tubules • Drain into interlobular veins • Arcuate & interlobar veins • Renal veins • Inferior Vena Cava
describe urine production
• Kidneys sort compounds from blood for removal into urine or return to blood
• Carried out by nephrons
1. Filtration – blood pressure forces water & small mols out of glomerular capillaries into Bowman’s capsule = filtrate
2. Tubular Reabsorption – nephron specifically returns some water & useful mols to blood. Remaining water & waste in filtrate = urine
3. Tubular secretion – when nephron selectively transports solutes from blood in peritubular capillaries into filtrate
describe The part of circulation involved with urine formation
¥ Afferent arterioles supply blood to glomerulus
¥ Glomerulus capillaries
¥ Efferent arterioles exit the renal corpuscle
Give rise to Peritubular capillaries which form a plexus around the proximal and distal tubules
describe Renal corpuscle
¥ Renal corpuscle = Bowman’s capsule + glomerulus
¥ Bowman’s capsule = double walled chamber
¥ Glomerulus = network of capillaries, sitting in capsule
Ð Blood enters glomerulus through afferent arterioles
Ð exits through efferent arterioles
Ð Fluid filtered from blood flows through glomerulus into Bowman capsule
Ð Fluid then flows into proximal convoluted tube
¥ becomes urine!
describe Glomerulus Characteristics
¥ Glomerulus capillaries allow blood filtration
¥ Openings in endothelial cells lining capillaries (fenestrations)
- Gaps between cells lining Bowman’s capsule
- Basement membrane between capillary endothelium & Bowman’s capsule = filtration membrane
- 1st step in urine formation when fluid filtered from blood in glomerulus to Bowman’s capsule
describe nephrons
¥ Nephron = Functional unit - 1.3 million per kidney - 50 mm long ¥ Parts of the nephron: - Renal corpuscle (Glomerulus + capsule) - proximal tubule - loop of Henle - distal tubule
what happens to urine concentration when you Drink lots of water
kidneys produce lots of dilute urine to eliminate excess without losing too many electrolytes etc
what happens to urine concentration when you dont drink enough
kidneys produce small volume concentrated urine
describe Urine collecting and expelling structures
¥ Urine flows from nephrons > papilla > minor calyx > major calyx > renal pelvis > Ureter > Bladder > Urethra
¥ Flow in the calyces is slow
Ð stones ('calculi') can develop
Ð especially if urine concentration high
Ð Painful when stones pass into ureterdescribe the ureter
One for each kidney carrying urine to bladder
Thin tubes, ~25 cm, leave each renal pelvis
Descend retroperitoneal & cross pelvic rim
enter posterolateral corners of bladder
Run medially in posterior bladder wall then open into interior
oblique entry prevents backflow
Three locations where ureter diameter decreases:
Ð ureteropelvic junction
Ð pelvic inlet
Ð bladder
Ð Kidney stones can become lodged here causing sever pain & block passage
describe histology of the ureter
Three main layers:
o Mucosa - transitional epithelium, stretches when ureters fill
o Muscularis - smooth muscle contract when urine in ureter
¥ peristaltic waves propel urine to bladder
o Adventitia - fibrous connective tissue with nerves & blood vessels
describe the urinary bladder
hollow collapsible muscular sac
Ð empty: bladder lies within pelvis, shaped like upside-down pyramid
Ð full: bladder spherical, extends upward into abdominal cavity
can hold 1L but uncomfortable after 0.5L
Lies on pelvic floor posterior to pubic bones
Males: anterior directly to the rectum
Females: anterior to vagina & uterus
Stores urine & expels it into urethra
Very thick muscle wall – contract expel urine
describe the urethra
Transports urine from bladder outside body
Male: about 20 cm long; prostatic, membranous, & penile parts
Female: 3-4 cm long
location of opening & short length why females have more UTIs than males: risk of ascending bacteria from stool contamination
Urethral sphincters control urine flow
Males have internal sphincter which contracts to keep semen entering bladder;
- smooth muscle
Females don’t have this
External sphincter in males & females
skeletal muscle surrounding urethra as extends through the pelvic floor
describe control of urination
• Flow of urine from kidneys to bladder relatively constant
• Stretch of urinary bladder by increasing volume urine stimulates micturition reflex
Ð Involves autonomic NS
Ð bladder contracts
Ð urinary sphincters open
Ð Higher brain centres in pons & cerebellum can control micturition reflex
¥ Conscious need to urinate
¥ Develops around 2-3 yrs old
¥ Irritation of bladder/urethra by bacteria can initiate urge to urinate even if bladder almost empty
describe urinary incontinence
= inability to hold urine
sphincter function compromised
mostly elderly female persons & pregnancy
describe urinary retention
= difficulty of urination e.g. prostatic hyperplasia by elderly males
what is Oliguria
low urine output
what is anuria
= almost absent urine output
e.g. kidney failure, blocked urine passage, etc
describe polycystic kidneys
enlarged kidneys with fluid-filled cysts
causes renal failure, genetic
describe bladder cancer
common, good survival if early diagnosis
Smoking major risk factor
describe Glomerulonephritis
inflammation of glomeruli, increases permeability of filtration membranes
protein & blood in urine, low blood protein levels and anaemia
describe Renal failure
can result from any condition affecting kidney function
Acute – damage to kidneys is rapid & extensive
Chronic – damage to so many nephrons that remaining nephrons cant cope
E.g. trauma to kidneys, tumours, kidney stones, etc
what are reasons for use of Urinary Catheters
- obstruction in the tube that carries urine out of the bladder (urethra) – e.g. prostate enlargement
- bladder weaknessor nerve damage
- drain bladder before, after & during surgery
- drainbladder during childbirth especially if you have an epidural
- to deliver medication directly into the bladder e.g. chemotherapy for bladder cancer
- treatment forurinary incontinence
