Studied by 4 peoplekidney functions (6)
ion homeostasis
waste excretion
regulate blood pH
produce hormones
gluconeogenesis
regulate blood volume, pressure & osmolarity
3 main passageways of urinary tract
ureter
urinary bladder
urethra
nephron
structural & functional unit of kidney
2 main parts of nephron
renal corpuscle
renal tubule
2 parts of renal corpuscle
glomerulus
Bowman’s capsule
renal corpuscle function
produce filtrate
4 components of renal tubule
proximal convoluted tubule
loop of Henle
distal convoluted tubule
collecting duct
proximal convoluted tubule function
reabsorption of water, ions/electrolytes & all organic nutrients
loop of Henle components
ascending & descending limbs
loop of Henle function
sets up concentration gradient
descending limb function
reabsorption of water
ascending limb of the loop of Henle function
active transport; reabsorption of Na & Cl
distal convoluted tubule function
secrete ions, H+, drugs & toxins
variable reabsorption
collecting duct function
variable water reabsorption
secretion of Na, K, HCO3-, H+ based on needs
Types of nephrons
cortical nephron (80-85%)
juxtamedullary nephron (15-20%)
cortical nephron characteristics
short loops of Henle
surrounded by peritubular capillaries
juxtamedullary nephron characteristics
long loops of Henle
surrounded by vaso recta
establishes concentration gradient
juxtaglomerular apparatus (2 main cells & characteristic/function)
juxtaglomerular cells of affarent arteriole (modified smooth muscle)
macula dense cells of distal convoluted tubule (detect filtrate osmolarity for tubuloglomerular feedback)
juxtaglomerular apparatus function
regulates blood entry into glomerulus (to be filtered into filtrate)
glomerular filtration rate
rate at which blood is filtered to produce filtrate per time
reabsorption
movement of substances from filtrate back into the blood
secretion
movement of substances from blood into filtrate
excretion
urine flow rate
excretion formula
excretion = filtration - reabsorption + secretion
filtration membrane components
glomerular endothelial cells with fenestrations
basal lamina
podocytes with pedicels
glomerular endothelial cells with fenestration function
present passage of large substances (RBC, WBC, platelets)
basal lamina function
filters out large proteins
slit membrane between pedicels of podocyte function
prevents passage of medium sized proteins
filtration depends on (4)
size of substances
surface area available for exchange
diffusional distance
pressure gradient
4 pressure components for net filtration
glomerular blood hydrostatic pressure
blood colloid osmotic pressure
capsular hydrostatic pressure
filtrate colloid osmotic pressure
glomerular blood hydrostatic pressure & value
blood pressure pushing out (promotes filtration)
55 mmHg
blood colloid osmotic pressure & value
pulls fluid into blood
30 mmHg
Capsular hydrostatic pressure & value
pressure of fluid pressing against capsule
15 mmHg
filtrate colloid osmotic pressure & value
protein in suspension in filtrate taht causes osmotic pressure
0 mmHg
net filtration pressure equation & normal value
net filtration pressure = glomerular blood hydrostatic pressure - blood colloid osmotic pressure - capsular hydrostatic pressure
10 mmHg
glomerulonephritis/renal failure
damaged capillaries allow proteins into Bowman’s space
increases filtrate colloid osmotic pressure, increasing net filtration pressure (increased filtration & decreased blood colloid osmotic pressure)
can lead to edema
3 regulators of glomerular filtration rate
renal auto regulation
neural regulation
hormonal regulation
renal auto regulation (2 types)
myogenic mechanism
tubuloglomerular feedback
myogenic mechanism
quick regulation of glomerular filtration rate
stimulus: increased systemic blood pressure
response: vasoconstriction of affarent arteriole
effect: decreased glomerular filtration rate
tubuloglomerular feedback of GFR
slow regulation of glomerular filtration rate
stimulus: increased glomerular filtration rate
response: inhibit release of NO from juxtaglomerular cells
effect: vasoconstriction of affarent arteriole & decrease blood in glomerulus
neural regulation of GFR
important for detecting extreme drops in blood pressure
sympathetic division (NE) used to vasoconstriction affarent arteriole
decrease GFR & urine output
increase blood flow to other tissue
hormonal regulation of GFR
angiotensin II (vasoconstriction affarent arteriole, decrease GFR)
atrialnatriuretic peptide (ANP) (relaxes mesangial cells, increase surface area available for diffusion & increases GFR)
reabsorption routes
paracellular reabsorption
transcellular reabsorption
paracellular reabsorption
reabsorption between cells
limited by tight junctions between cells
transcellular reabsorption
absorption across cell via transport proteins
transport maximum
max amount of substances transported per time due to transporter efficiency
3 P’s of diabetes mellitus
polyuria
polyphagia
polydipsia
proximal convoluted tubule (urinary transport processes)
reabsorption (65% obligatory water reabsorption, glucose, amino acid & ions)
glucose, amino acid & water soluble vitamins reabsorption in proximal convoluted tubule
set up Na+/K+ concentration gradient with primary active transporter
use secondary active transport/symport to bring Na+ & substance into cell
use facilitated diffusion to move substance into blood
H+ secretion/HCO3- reabsorption in proximal convoluted tubule
establish Na+/K+ concentration gradient with primary active transporter
use secondary active transport/antiport to bring Na+ in & pump H+ out
use facilitated diffusion to move HCO3- into blood
water reabsorption in proximal convoluted tubule
moves into cell via aquaporin I
moves into cell via aquaporin I
paracellular water reabsorption
thin descending limb of loop of Henle (urine transport process)
water reabsorption via aquaporin I
paracellular water reabsorption
thick ascending limb of loop of Henle (urine transport process)
impermeable to water
active reabsorption of Na+ & Cl- via NKCC (reabsorbs Na+ & 2 Cl-; secrete K+)
countercurrent multiplication
sets up concentration gradient at loop of Henle
countercurrent exchange
maintains established concentration gradient
late distal convoluted tubule/collecting duct (urine transport process); fxn & 2 cells it takes place at
fine tunes filtrate based on bodily need
principal cell & intercalated cell
principal cell (urine transport process)
reabsorbs Na+/secrete K+ (regulated by aldosterone)
water reabsorption (facultative water reabsorption; regulated by ADH)
intercalated cell (urine transport process)
reabsorbs HCO3- & secretes H+
regulated by acid/base balance
hormonal regulation (3 main hormones/process)
antidiuretic hormone (ADH)
renin angiotensin aldosterone (RAA) cascade
atrial natriuretic peptide
Antidiuretic hormone (reflex arc)
stimulus: increased blood osmolarity
receptor: osmoreceptor (hypothalamus)
control center: released by posterior pituitary gland
effector: ADH inserts aquaporin II in principal cells
effect: increased water reabsorption, decreased blood osmolarity & decreased urine output
Renin angiotensin aldosterone cascade
stimulus: decreased blood volume & blood pressure
receptor: juxtaglomerular apparatus (kidneys; produce renin); renin converts angiotensinogen (from liver) into angiotensin I ; lungs produce Angiotensin converting enzyme (ACE) to convert angiotensin I to angiotensin II
angiotensin effect: vasoconstriction of affarent arteriole (decreased GFR, decreased urine output, increased blood volume); increased systemic vasoconstriction, increased Na+, Cl- & water reabsorption; increased thirst; stimulate adrenal cortex to produce aldosterone
aldosterone effect: increased Na+ reabsorption & K+ secretion (increased water reabsorption & blood volume)
atrial natriuretic peptide (stimulus & effect)
stimulus: increased blood volume
atria detects & secretes atrial natriuretic peptide
decreased Na+ reabsorption, decreased water reabsorption, decreased aldosterone & ADH secretion, increased filtration rate
3 factors of medullary concentration gradient
countercurrent multiplication
urea recycling
countercurrent exchange
countercurrent exchange established by what & its specifics
established by loop of Henle
descending limb: obligatory water reabsorption
ascending limb: active Na+ & Cl- reabsorption
urea recycling
urea produced by deamination of proteins
collecting duct permeable to urea & concentrates in medulla
countercurrent exchange established by what & its specifics
vasa recta
increased blood concentration along gradient
urinalysis & its factors
volume (~1 mL/min)
transparency (typically clear)
specific gravity (1.001-1.035)
pH (4.6-8; varies by diet)
color (changes with dilution/concentration)
odor (can vary with diet)
urination/micturition reflex (stimulus, receptor, control center, effectors & effect)
stimulus: stretch of urinary bladder (200-400 mL)
receptor: stretch receptor
control center: micturition center @ spinal cord
effectors: parasympathetic nervous system
effect: contraction of detrusor muscle, relaxation of internal & urethral sphincter
osmolarity of kidney from cortex to medulla
300 mOSM
600 mOSM
900 mOSM
1200 mOSM
how does filtrate osmolarity change as it descends from cortex into medulla
descending limb of loop of Henle; water reabsorption (from 300 mOSM to 1200 mOSM)
how does filtrate osmolarity change as it ascends from medulla into cortex
ascending limb of loop of Henle; active Na/Cl reabsorption & impermeable to H2O
makes filtrate 200mOSM less than surrounding interstitial fluid (1200 mOSM to 100 mOSM)
filtrate osmolarity in distal convoluted tubule
100 mOSM
to produce hypotonic urine
low ADH
decreased water reabsorption in collecting duct
urine: 100 mOSM
to produce hypertonic urine
high ADH
aquaporin II inserted into principal cells of collecting duct
increased water reabsorption
urine: 1200 mOSM
total body mass made up of fluids
55-60%
2 main categories of bodily fluids
intracellular fluid (2/3)
extracellular fluid (1/3)
extracellular fluid made up of
interstitial fluid (80%)
blood plasma (20%)
interstitial fluid and plasma separated by
capillary endothelial cells
intracellular fluid & interstitial fluid separated by
plasma membrane
water balance equation
water gain = water loss
water gain (*main point of regulation)
ingested liquids*
ingested foods
metabolic waters
water loss (*main point of regulation)
kidneys (via urine) *
skin (sweat)
lungs (breathing)
GI tract (fecal formation)
dehydration (causes, overall effect & symptoms)
water loss > water gain
causes: excessive perspiration, inadequate water intake, alcohol, vomit/diarrhea, diabetes mellitus, diabetes insipidus
overall effects: increased blood osmolarity & decreased blood volume
symptoms: sunken eyes/cheeks, decreased skin tumor, sunken fontanelle, few/no tears, dry mouth/tongue, sunken abdomen
over hydration (causes, overall effects & symptoms)
water gain > water loss
causes: excessive drinking of hypotonic solution/water, inability to eliminate water, endocrine disorder
overall effect: decreased blood osmolarity & increased blood volume
symptoms: water intoxication
increased osmolarity will result in what corrections (and their effects)
increased thirst
increased ADH (increases aquaporin II on collecting duct = increased water reabsorption)
decreased blood volume will result in what corrections (and their effects)
decreased atrial natriuretic peptide (increased sodium reabsorption)
increased renin angiotensin aldosterone (increased angiotensin II leads to increased thirst, increased sodium reabsorption, increased aldosterone & decreased GFR)
decreased blood osmolarity will leads to what corrections (and their effects)
decreased thirst
decreased ADH (decreased water reabsorption)
increased blood volume will lead to what corrections (and their effects)
increased atrial natriuretic peptide (decreased sodium reabsorption)
decreased angiotensin aldosterone (decreased thirst, decreased sodium reabsorption, decreased aldosterone & increased GFR)
important electrolytes
sodium
potassium
chloride
calcium
phosphate
magnesium
sodium (function, in excess, depleted & regulated by)
function: carry action potential, fluid & electrolyte balance
in excess: hypernatremia
depleted: hyponatremia
regulated by: ADH, ANP & RAA
potassium (function, excess, depleted & regulated by)
function: establish resting membrane potential & repolarization of action potentials
in excess: hyperkalemia
depleted: hypokalemia
regulated by: aldosterone
chloride (function, excess, depleted & regulated by)
function: anion balance & HCl production
in excess: hyperchloremia
depleted: hypochloremia
regulated by: ADH
calcium (function, excess, depleted & regulated by)
function: bone & teeth formation, blood clotting, neutrotransmitter release & muscle contraction
in excess: hypercalcemia
depleted: hypocalcemia
regulated by: calcitonin, parathyroid hormone & calcitriol
phosphate (function, excess, depleted & regulated by)
function: bone & teeth formation, buffer
in excess: hyperphosphatemia
depleted: hypophosphatemia
regulated by: calcitonin & parathyroid hormone
magnesium (function, excess, depleted & regulated by)
function: bone formation, cofactor for enzymes
in excess: hypermangesemia
depleted: hypomagnesemia
regulated by: N/A
main extracellular electrolytes
Na+, Ca2+, Cl-
main intracellular electrolytes
K+, Mg2+, HPO42-
normal blood pH
7.35-7.45
more acidic blood found in
systemic veins (increased [CO2])
more basic blood found in
systemic arteries (decreased [CO2])
Note
Flashcard