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MC Bio 205 ch 24

urinary system

F/kidneys reg/blood ionic composition | reg/blood pH | reg/blood volume | reg/blood pressure | produce 2 hormones | reg/blood glucose | excrete wastes
organs of the urinary system kidneys (L and R) | ureters (L and R) | urinary bladder | urethra
L/kidneys just above the waist, between the peritoneum and the posterior wall of the abdomen | R kidney slightly lower (pushed down by liver)
A/kidneys 4-5 in long, 2-3 in wide, 1 in thick | concave borders face the vertebral column
renal hilum indentation through which the ureter leaves the kidney and blood vessels, lymphatic vessels, and nerves enter and exit
renal capsule layer of dense irreg CT that protects kidney against trauma | continuous w/ outer layer of ureter
renal columns the portions of the renal cortex that extend between renal pyramids
renal lobe a ----- consists of a renal pyramid, its overlying area of renal cortex, and one-half of each adjacent renal column
nephron the functional unit of the kidney | each kidney contains approx 1 million of them
path of filtrate/urine after leaving the loop of Henle collecting duct, papillary duct, minor calyx, major calyx, renal pelvis, ureter, bladder, urethra
renal sinus cavity that contains part of the renal pelvis, the calyces, and branches of vessels and nerves
arcuate arteries renal arteries at the point where they arch between the renal medulla and cortex
glomerulus the tangled, ball-shaped capillary network at the heart of a nephron
path of blood flow through the kidneys renal a, segmental a, interlobar a, arcuate a, interlobular a, afferent a, glomerular capillaries, efferent a, peritubular capillaries, interlobular v, arcuate v, interlobar v, renal v
two major components of the nephron renal corpuscle and renal tubule
two major components of the renal corpuscle glomerulus and glomerular capsule
flow of fluid through a cortical nephron glomerular capsule, proximal convoluted tubule, descending limb of the loop of Henle, ascending " ", distal convoluted tubule, collecting duct
podocytes modified ss ep cells in the visceral layer of the glomerular capsule
hist/proximal convoluted tubule simple cuboidal ep cells with microvilli to increase surface area for absorption and secretion
hist/ascending limb of the loop of Henle simple columnar epithelium
three basic processes of urine formation glomerular filtration, tubular reabsoroption, tubular secretion
glomerular filtration water and most solutes in blood plasma move across the wall of glomerular capillaries into the glomerular capsule and then into the renal tubule
tubular reabsorption as filtered fluid flows through the renal tubule, tubule and duct cells reabsorb about 99% of the filtered water and many useful solutes
tubular secretion as fluid flows through the renal tubule and collecting duct, materials in the peritubular capillary blood or tubule and duct cells (e.g. wastes, drugs, excess ions) are secreted into the filtrate
avg daily volume of glomerular filtrate 150 liters in females, 180 liters in males
avg daily volume of urine excreted 1-2 liters
C/filtration membrane endothelial cells of glomerular capillaries + podocytes, which completely encircle the capillaries
mesangial cells contractile cells that help regualate glomerular filtration
basal lamina a layer of acellular material between the endothelium and the podocytes; prevents filtration of larger plasma proteins
net filtration pressure = glomerular blood hydrostatic pressure - capsular hydrostatic pressure - blood colloid osmotic pressure
normal NFP 10 mm Hg
glomerular blood hydrostatic pressure blood pressure in the glomerulus; typically 55 mm Hg [filtration ceases if it falls below 45 mm Hg, because opposing pressures add up to 45]
capsular hydrostatic pressure the hydrostatic pressure exerted against the filtration membrane by fluid already present in the capsular space; typically 15 mm Hg
blood colloid osmotic pressure the osmotic pressure resulting from the presence of proteins in blood plasma; in glomerular capillaries, typically 30 mm Hg
glomerular filtration rate the amount of filtrate formed in all the renal corpuscles of both kidneys, per minute
normal GFR 125 mL/min in males, 105 mL/min in females
two modes of renal autoregulation of GFR the myogenic mechanism and tubuloglomerular feedback
the myogenic mechanism stretching (as from an increase in systemic blood pressure) causes contraction of smooth muscle cells in the afferent arterioles
tubuloglomerular feedback macula densa cells detect increased delivery of Na+, Cl-, and water (increased because of too-rapid filtrate flow through tubules); the juxtaglomerular apparatus decreases secretion of nitric oxide, which in turn causes constriction of afferent arterioles
neural regulation of GFR during exercise or hemmorhage, ANS promotes release of norepinephrine, which causes vasoconstriction of afferent arterioles
two hormones involved in hormonal regulation of GFR angiotensin II and atrial natriuretic peptide
angiotensin II's role in GFR regulation decreased blood volume or blood pressure stimulates production of angiotensin II, which causes vasoconstriction of afferent + efferent arterioles
atrial natriuretic peptide's role in GFR regulation promotes relaxation of the mesangial cells, which in turn increases surface area available for filtration
two basic routes of reabsorption paracellular reabsorption and transcellular reabsorption
five hormones that regulate tubular reabsorption and tubular secretion angiotensin II (PCT), aldosterone (collecting duct), antidiuretic hormone (collecting duct), atrial natriuretic peptide (PCT and collecting duct), parathyroid hormone (DCT)
negative feedback regulation of water reabsorption by ADH osmoreceptors in hypothalamus detected decreased water concentration in blood | posterior pit releases ADH | ADH stimulates principal cells to become more permeable to water, which increases facultative water reabsorption
two processes of water reabsorption obligatory and facultative
obligatory water reabsorption via osmosis, water follows solutes as they are reabsorbed into peritubular capillaries; 90% of water reabsorption happens this way
facultative water reabsorption occurs in collecting ducts, and is regulated by ADH; 10% of water reabsorption happens this way
vasa recta long loop-shaped capillaries that extend from the efferent arteriole and supply the tubular portions of the nephron in the renal medulla
formation of dilute urine filtrate becomes more dilute in the ascending limb of the LoH, because that region is not permeable to water | when ADH level is very low, DCT and collecting ducts are also not permeable to water
formation of concentrated urine under influence of ADH, cells in DCT and collecting duct become more permeable to water | urea recycling causes a buildup of urea in the renal medulla
L/transitional epithelium lines the deepest (mucosal) layers of the ureters and the urinary bladder
F/transitional epithelium cells can stretch, which allows them accommodate large inflows of fluid
the micturition reflex discharge of urine from the bladder into the urethra | internal urethral sphincter muscle relaxes involutarily, external "" relaxes voluntarily
fluid balance the body is in ----- when the required amounts of water and solutes are present and are correctly proportioned through the body
electrolytes inorganic compounds that break apart into ions when dissolved in water
why it's important to maintain body pH between 7.35 and 7.45 outside that range, proteins tend to lose their three-dimensional shapes
the phosphate buffer system dihydrogen phosphate ion acts as a weak acid, buffering strong bases | it can be formed in kidney tubule when H+ ions combine with monohydrogen phosphate | those ions then pass out of body in urine as part of dihydrogen phosphate
kidney excretion of H+ cells in PCT and collecting ducts secrete H+ ions into the filtrate | apical membranes of intercalated cells in collecting ducts include proton pumps | urine can be up to 1000 times more acidic than blood
diuretics substances that slow renal reabsorption of water and the thereby cause diuresis, an elevated urine flow rate, which in turn reduces blood volume
naturally occurring diuretics caffeine inhibits Na+ reabsorption | alcohol inhibits secretion of ADH
drug diuretics typically act by interfering with a mechanism for reabsorption of filtered NA+
hemodialysis directly filters the patient's blood, using an artificial kidney | the cleansed blood is passed through an air embolus detector to remove air and then returned to the body
peritoneal dialysis uses the peritoneum of the abdominal cavity as the dialysis membrane to filter the blood | a catheter is inserted into the peritoneal cavity and connected to a bag of dialysate
renal calculi kidney stones | insoluble crystallized salts that form in kidneys
why urinary tract infections are more common in females the urethra is shorter
cystitis inflammation of the urinary bladder
pyelonephritis inflammation of the kidneys
four types of urinary incontinence stress: results from weakness of the deep muscles of the pelvic floor | urge: in older people, an abrupt need to urinate followed by involuntary loss of urine; can be associated with infection, kidney stones, stroke, MS | overflow | functional
urinary retention a failure to completely or normally void urine | may be associated with obstruction in the urethra or the bladder, nervous contraction of the urethra, or prostate enlargement
C/urine contains wastes of metabolism but not wastes of digestion
F/fenestrated endothelial cells prevent red blood cells from passing into filtrate, but allow filtration of most solutes
detrusor muscle the muscularis of the urinary bladder
parasympathetic nerve impulses in the micturition reflex cause contraction of the detrusor muscle and relaxation of the internal urethral sphincter
specific gravity of urine the weight of a volume of urine divided by the weight of the same volume of distilled water | normally 1.001 - 1.035 | lower = more dilute
ca/cloudy urine microbes, pus, epithelial cells, crystals
pH of urine normally 4.6 - 8.0, with average of 6.0 | high-protein diets cause acidic urine | vegetarian diets produce alkaline urine
glucosuria glucose in urine | ca/diabetes mellitus, stress
hematuria erythrocytes in urine | ca/inflammation of urinary system organs, kidney stones, kidney disease, polyps or tumors in urinary system
albuminuria excess albumin in urine | ca/increase in filtration membrane permeability caused by high bp, kidney trauma, disease, or inflammation
ketonuria ketone bodies in urine | ca/ketosis, a metabolic condition in which cells do not have enough glucose to completely break down fatty acids (assoc w starvation, untreated diabetes mellitus)
Created by: dglenn34



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