Download Urinary System

Urinary System
Anatomy and Physiology
Turk
Urinary System
kidneys, urinary bladder, ureters, and
urethra
Kidney
renal hilus
renal sinus
adrenal gland
Internal Anatomy of Kidney
renal cortex
renal medulla
renal pyramids
renal columns
renal sinus
renal pelvis
major calyces
minor calyces
Blood and Nerve Supply
renal artery
five segmental arteries
renal plexus
Nephrons
collecting ducts
Glomerulus
glomerular (Bowman’s) capsule
renal corpuscle
parietal layer - simple
squamous epithelium
visceral layer consists of
podocytes that terminate in
pedicels
filtration slits or slit pores
capsular space
Nephron Continued
proximal convoluted tubule
cuboidal epithelial cells with microvilli
Loop of Henle
descending - simple squamous epithelium
ascending - cuboidal cells
distal convoluted tubule
cuboidal but lack microvilli
intercalated cells and principal cells
collecting duct
Nephrons Continued
cortical nephrons
juxtamedullary nephrons
medulla-cortex junction
important for producing concentrated urine
Capillary Beds of Nephron
glomerulus
afferent arteriole
Efferent arteriole
peritubular capillaries
vasa recta
juxtaglomerular apparatus
juxtaglomerular (JG) cells
Renin
macula densa
Filtration Membrane
the capillary endothelium (fenestrated)
podocytes of glomerular capsule
(visceral membrane)
the basement membrane
Kidney Physiology (Urine Formation)
filtrate contains everything the blood
did except the cells and proteins
180 liters (47 gallons) filtrated a day
1.5 liters (1 %) leaves the body as
urine
glomerular filtration rate is the amount
of filtrate formed per minute
filtration surface area, filtration membrane
permeability, and the net filtration pressure
Glomerular Filtration Regulation
Intrinsic Controls
renal autoregulation
regulating the diameter of the afferent
areteriole
Extrinsic controls
Sympathetic Nervous System Control
Glomerular Filtration Regulation
renin-angiotensin mechanism
aldosterone
reduced stretch of juxtaglomerular cells
also stimulates the hypothalamus to
release antidiuretic hormone and activates
the hypothalamic thirst center
Tubular Reabsorption
reabsorbing the contents of
the tubule and returning
them to the blood
if the kidneys are healthy
just about all of the
glucose and amino acids
are reabsorbed
the rate of water and ion
reabsorbtion is based on
hormonal signals
Tubular Reabsorption
Sodium Reabsorption
ATPase pump
Reabsorption of Water, Nutrients, and
other Ions
osmosis, diffusion, and facilitated diffusion
glucose, amino acids, lactate, vitamins, and
positive ions are reabsorbed by secondary
active transport
Nonreabsorbed Substances
lack of carriers
not lipid soluble
too large to pass through plasma
membrane pores of tubular cells
urea, creatinine, and uric acid
Absorptive Capabilities of the Different Regions
of the Renal Tubules
Proximal Convoluted Tubule
where the most reabsorption takes place
all of the glucose, lactate, and amino acids
60-70% of the sodium and water
90% of the bicarbonate, 50% of the
chloride, and 90% of the potassium
uric acid is absorbed here but will be
secreted back into the filtrate
1/3 of the filtrate remains afterwards
Absorptive Capabilities of the Different Regions
of the Renal Tubules
Loop of Henle
water can leave the
descending loop but not
the ascending
20-25 % of the salt and
water
Distal Convoluted tubule
and collecting ducts
aldosterone
atrial nautriuretic peptide
Tubular Secretions
hydrogen and potassium ions,
creatinine, ammonium ions, and some
organic acids
disposing of substances not already in
the filtrate
elimination of wastes which have been
reabsorbed
get rid of excessive potassium ions
control blood pH
Urine Concentration and Volume
Osmolality
Countercurrent Mechanism and the Medullary
Osmotic Gradient
medulla has more concentrated solution
descending loop of Henle is impermeable to
solutes but allows water to pass
ascending limb of the loop of Henle does not allow
water to pass but actively transports salt into the
surrounding interstitial fluid
collecting ducts deep in the medulla are
permeable to urea
Urine Concentration and Volume
Formation of Dilute Urine
as long as collecting ducts remain
impermeable no more reabsorption will
occur – result is dilute urine
Formation of Concentrated Urine
antidiuretic hormone increases the number
of water channels in the principal cells of
the collecting ducts
less urea means less water can be retained
Urine Concentration and Volume
Diuretics
chemicals which enhance urinary output
caffeine and most diuretic drugs inhibit
sodium reabsorbtion
alcohol inhibits ADH release
Urine Concentration and Volume
Renal Clearance
volume of plasma from which a substance
is cleared in a set time
used to determine glomerular filtration rate
RC=UV/P
U is concentration of the substance in the urine
V is the flow rate of urine formation
P is the concentration of the same substance in
the blood
Characteristics of Urine
Color and Transparency
clear and pale to deep yellow
Urochrome
Odor
pH
slightly acidic (about pH 6)
Specific Gravity
between 1.001 and 1.035
Composition of Urine
95% of the volume of urine is water
after water the largest component by weight
is urea
other nitrogenous wastes - uric acid and creatinine
sodium, potassium, phosphate, and sulfate
ions, calcium, magnesium, bicarbonate ions
may include glucose, blood proteins, red
blood cells, hemoglobin, white blood cells, or
bile pigments
Ureters
connect the kidneys and the bladder
mucosal lining
transitional epithelium
muscularis layer
inner longitudinal and out circular
lower 1/3 of the ureters there is a third muscle
sheet which is longitudinal
outer adventitia layer
Ureters continued
calcium, magnesium, or uric acid salts
in the urine can crystallize making renal
calculi (kidney stones)
frequent urinary tract bacterial infections,
urinary retention, high calcium conc., in
blood, and alkaline urine
Urinary Bladder
three opening in the bladder – two
ureters and the urethra - in the trigone
mucosa is transitional epithelium
detrusor muscle is smooth muscle fibers
arranged in inner and outer longitudinal
layers with a middle circular layer
adventitia layer
rugea (folds)
Urethra
mucosal lining is mostly pseudostratified
columnar epithelium
internal urethral sphincter
external urethral sphincter
urogenital diaphragm
urethritis – inflammation of the urethra
cystitis – inflammation of the bladder
pyelitis or pyelonephritis – renal inflammation
dysuria – painful urination
Proststic, membranous, penile (spongy)
Micturition
aka voiding or urinating
pelvic splanchnic nerves
detrusor muscle contract and the
internal sphincter relax
we choose when to relax the external
sphincter and levator ani
Incontinance
urinary retention
Renal failure and Dialysis
renal failure - not enough functional nephrons
repeated damaging infections of the kidneys
injury or trama to the kidneys
prolonged pressure on skeletal muscles causes
release of myoglobin which can clog the renal
tubules
chemical poisoning of the tubule cells by heavy
metals or organic solvents
inadequate blood delivery to tubule cells
dialysis