Urinary System Flashcards
Organs of the urinary system
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Main Waste Products excreted in urine
- urea-comes from the breakdown of amino acids during recylcling of body’s proteins
- uric acid- results from the body’s turnover over of nucleic acids
- creatine- formed by the breakdown of creatine phosphate:
- a molecule in muscle that stores energy for the manufacture of ATP
Functions of the kidney
- dispose of wastes and excess ions
- regulate the volume and chemical makeup of the blood
- maintain the proper balance of water and salts and of acids and bases
Kidneys
- bean shaped
- lie retroperitoneal in lumbar region of the posterior abdominal wall
- from 3rd lumbar vertebrae to to 11th or 12th thoracic vertebrae
- avg=12cm high, 6cm wide and 3 cm thick
differences between left and right kidney
- right kidney is crowded by the liver
- right kidney lies slightly inferior to left kidney
hilum of kidney
- a vertical cleft on the medial (concave) surface
- site where vessels, ureters, and nerves enter and exit kidney
Fibrous capsule of kidney
- a thin, tough layer of dense connective tissue
- adheres directly to surface of kidney
- inhibits spread of infection from surrounding regions
perirenal fat capsule of kidney
- external to the fibrous capsule
- supportive tissue
- cushion the kidney against blows and holds it in place
renal fascia
- envelope between perirenal capsule and pararenal fat
pararenal fat
- external to and posterior to renal fascia
- cushions kidney against blows and helps keep kidneys in place
surgical approach to kidney
- Through posterolateral abdominal wall
- very few muscles, vessels or nerves need to be cut
- need to avoid t12 area to avoid puncturing pleural cavity and causing pneumothorax
two distinct regions of kidney tissue
- renal cortex:
- most superficial region
- light in color
- more granular appearance
- renal medulla:
- darker in color
- consists of cone-shaped masses called renal pyramids
renal lobes
- a single renal pyramid plus the cortical tissue that surrounds that pyramid
- each kidney has 5-11 lobes and pyramids
renal pyramids
- apex (papilla) points interiorly
- exhibit striations:
- roughly parallel bundles of tiny urine collecting tubules
renal sinus
- a large space within the medial part of the kidney opening to the exterior through the renal hilium
- a “filled space” full of:
- renal vessels and nerves
- some fat
- renal pelvis and calices
renal pelvis
- pelvis=basin
- a flat, funnel-shaped tube
- the expanded superior part of the ureter
- branches with major calices
- urine from calices flows into the pelvis and on to the ureter
major calices
- calyx singular
- 2-3 branching extensions of renal pelvis
- urine filled tubes
- divide further to form several minor calices
minor calices
- extensions from the major calices
- cup-shaped tubes that enclose the papillae of the pyramids
- collect urine during draining from papillae and empty it into the renal pelvis
pyelitis
- infection/inflammation of the renal pelvis and calices
pyelonephritis
- when pyelitis spreads to involve the rest of the kidney
- nephros=kidney
- results from
- spread of fecal bacterium (escherichia coli) from the anal region superiorly through the urinary tract
- bloodborne bacteria lodge in the kidneys and proliferate there
- kidney scars, abcesses form, and the renal pelvis fills with pus
- left untreated, the infected kidneys may be severely damaged
- antibiotics usually totally cures it
renal arteries
- offers rich blood supply to kidneys
- about 1/4 of heart’s systemic output reaches kidneys through here
- branch at right angles from the abdominal aorta
- right renal artery is longer than left (due aorta slightly off midline)
segmental arteries of kidney
- the five divisions of the renal artery
- enter the hilium
interlobar arteries of kidneys
- division of segmental arteries
- division occurs in renal sinus
- lie in the renal columns between renal pyramids
arcuate arteries
- the division of interlobar arteries at the medulla cortex
- “shaped like a bow”
- arch over the bases of the renal pyramids
cortical radiate arteries of kidneys
- division of arcuate arteries
- radiate outward
- supply the cortical tissue with blood
- more than 90% of the blood entering the kidneys comes through the cortex
glomerular arterioles of kidneys
- stem from cortical radiate arteries
- feed into peritubular capillaries
Peritubular Capillaries of kidneys
- surround the tubules in the kidney
- come from glomerular arterioles
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Veins of kidney
- trace the pathway of arteries in reverse
- blood leaving the renal cortex drains sequentially:
- cortical radiate
- arcuate
- interlobar
- renal veins (no segmental veins)
- renal vein exits at hilium and empties into inferior vena cava
- left renal vein is longer (about twice as long) because inferior vena cava lies on the right side of the vertebral column
renal plexus
- the nerve supply of the kidney
- a network of autonomic ganglia on the renal arteries
- offshoot of the celiac plexus
uriniferous tubule
(microscopic anatomy of kidneys)
- The main structural and functional unit of the kidney
- lined by simple epithelium adapted for production of urine
- more than a million in each kidney
- uriniferous=urine carrying
- two parts:
- urine-forming nephron
- collecting duct
Mechanisms of urine production
- filtration
- resorption
- secretion
filtration
mechanism of urine production
- filtered blood leaves kidney capillaries and enters uriniferous tubule
- filtrate resembles tissue fluid
- as it proceeds through the uriniferous tube the filtrate is processed into urine through resorption and secretion
resorption
mechanism of urine production
- most nutrients (water/essential ions) are recovered from filtrate and returned to blood of capillaries
- 99% of the volume of renal filtrate is resorbed
- remaining wastes and unneeded substances contribute to urine that eventually leaves body
secretion
mechanism of urine production
- moves additional undesirable molecules into the tubule from blood of surrounding capillaries
- active process
Nephron
(microscopic anatomy of kidneys)
- where filtration, resorption, and secretion occur
- Composed of:
- renal corpsucle
- tubular section
renal corpsucle
of the nephron
of uriniferous tubule
- the first part of the nephron
- where filtration occurs
- occur strictly in the cortex
- consist of:
- glomerulus
- glomerular capsule
glomerulus
of the renal corpsucle
of the nephron
of the uriniferous tubules
of the kidney
- a tuft of capillaries
- “ball of yarn”
- surrounded by glomerular capsule like a fist in an underinflated balloon
glomerular capsule
of the renal corpsucle
of the nephron
of the uriniferous tubules
of the kidney
- aka Bowman’s capsule
- cup-shaped
- hollow
capsular space
of the renal corpsucle
of the nephron
of the uriniferous tubules
of the kidney
- the hollow interior of the glomerular capsule
- large quantities of fluid passes from capillary blood into here
fluid of the capsular space
of the renal corpsucle
of the nephron
of the uriniferous tubules
of the kidney
- the filtrate that is ultimately processed into urine
- only about 20% of fluid leaves the glomerulus and enters the capsular space
- the remaining 80% remains in the blood
parietal layer
of glomerular capsule
of the renal corpsucle
of the nephron
of the uriniferous tubules
of the kidney
- Simple squamous epithelium
- plays no part in formation of filtrate
visceral layer
of glomerular capsule
of the renal corpsucle
of the nephron
of the uriniferous tubules
of the kidney
- clings to the glomerulus
- consists of branching epithelial cells called podocytes
podocytes
of the visceral layer
of glomerular capsule
of the renal corpsucle
of the nephron
of the uriniferous tubules
of the kidney
- unusual branching octopus-like epithelial cells
- end in foot processes, or pedicles, that surround the glomerular capillaries
- filtrate passes into capsular space through filtration slits or slit pores
- thin clefts between the foot processes
Filtration membrane
of the renal corpsucle
of the nephron
of the uriniferous tubules
of the kidney
- filter that lies between the blood in the glomerulus and the capsular space
- 3 layers:
- fenestrated endothelium (pores) of the capillary
- restrict the passage of largest elements like blood cells
- the filtration slits between the foot processes of the podocyte
- an intervening basement membrane composed of the fused basal laminae of the endothelium and the podocyte epithelium
- filtration slits and basement membrane hold back all but the smallest proteins. Allow passage of ions, water, glucose, amino acids, urea and small proteins
- fenestrated endothelium (pores) of the capillary
tubular section
of the nephron
of the uriniferous tubules
of the kidney
- filtrate comes here from renal corpsucle
- contains:
- proximal convoluted tubule
- the loop of henle
- the distal convoluted tubule
- ends by joining a collecting duct
- meandering nature of the nephron:
- increases length
- enhances its capabilities in processing the filtrate
proximal convoluted tubule
of the tubular section
of the nephron
of the uriniferous tubules
of the kidney
- confined entirely to renal cortex
- most active in resorption and secretion
- cuboidal epithelia with fuzzy microvilli to increase surface area for resorption
- contain many mitochondria which provide energy for resorption