Question | Answer |
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) |