test 4 Flashcards
6 functions of urinary system
o Filter blood to remove wastes/toxic substances
o Production, storage and elimination of urine
o Regulates fluid and electrolyte balance
o Regulates blood PH
o Regulates blood volume and blood pressure
o Regulates erythropoiesis
kidney functions
filter blood and produce urine
ureter
move urine from kidneys to bladder
urethra
moves urine from bladder to exterior
urinary bladder
stores urine
Kidney location and structure
retroperitoneal-outside/behind abdominal cavity
Renal cortex
Renal Medulla
kidneys surrounded by three external layer
renal fascia
adipose capsule
renal capsule
Nephron: definition and structure
major functional unit of the kidney. Urine production begins here. Empties into collecting system.
o Renal corpuscle: filters blood
o Renal tubule: collects filtrate
Collecting system
series of tubules that receive filtrate from nephron and further modify it
parts of collecting system
Cortical and medullary collecting ducts and papillary collecting ducts and papilla and minor calyx
Types of nephrons
Cortical nephron and Juxtamedullary nephron
what’s the difference between the types of nephrons
Cortical nephron: primarily in cortex. Branch into peritubular capillaries. And Juxtamedullary nephron: extend into medulla. Peritubular capillaries connected to long straight capillaries
which nephron is more abundant
Cortical nephron
Urine production
eliminates metabolic waste products while minimizing loss of water and nutrients
urea
most abundant organic waste from protein catabolism
creatinine
product of creatine phosphate catabolism
uric acid
product of nucleic acid catabolism
renal failure
results in buildup of toxic wastes
dialysis
medical process for those who have lost kidney functions. Machine that filters blood.
Filtration
kind of transport: passive movement of fluid and solutes direction of movement: blood in glomerular capillaries to filtrate inside renal corpuscle (blood to filtrate). Driven by hydrostatic pressure
Reabsorption
active or passive movement of water solute from filtrate in renal tubule back to blood in peritubular capillaries
Secretion
active transport of water and solutes from blood in peritubular capillaries to filtrate in renal tubule
Paracellular route
substances pass between adjacent tubule cells
Transcellular route
substances must move through tubules cells
diffusion and osmosis are examples of
passive transport
active transport requires
an energy input
facilitated diffusion and active transport are examples of
carrier-mediated transport and require protein pumps
Carriers (channels) are specific and can be saturated (what happens if channels get saturated
all binding sites are filled and can start seeing the substance in urine
transport maximum
maximal blood solute levels that can be transported
renal threshold
plasma concentration at which a specific compound appears in urine because the TM has been reached
Renal corpuscle
Glomerular (Bowman’s) capsule and the glomerulus
What are podocytes
cells that form the visceral layer of the capsule of the renal corpuscle
what are filtration slits
between podocytes and part of filtration membrane. Must fit in these area in order to filter.
how filtration works
it is only selective based on size: only small particles filtered (proteins and cells are not filtered)
Components of filtration membrane
made of pores of fenestrated capillaries, basal lamina, and filtration slits of podocytes
Hydrostatic pressure
pressure in glomerulus
GHP and filtration
favors filtration
CHP and filtration
opposes filtration
GCOP
osmotic pressure and pulls water into capillaries, so it opposes filtration
Net filtration pressure equation
= GHP – CHP-GCOP
o 0 or negative =no filtration
o Positive number = filtration
What is GFR
amount of filtrate produced by both kidneys per minute
what does GFR depend on
GFR depends on blood pressure (higher BP means higher GFR)
Autoregulation
ability of neprhons to adjust their own blood flow and GFR
myogenic
stretch receptors in afferent arteriole detect pressure changes and respond to adjust GFR
tubuloglomerular mechanisms
the glomerulus receives feedback on the status of downstream tubular fluid and adjusts filtration rate accordingly
changes in the afferent and efferent arterioles control
blood pressure in the glomerulus and therefore GFR
BP low/GFP low
= dilate arteriole/constrict efferent arteriole. Goal: high BP and high GFR
BP high/GFP high
= constrict afferent arteriole/dilate the efferent arteriole. Goal: low BP/low GFR
JGA
macula densa of DCT + smooth muscle of arterioles
JGA Hormonal regulation
JGA cells secrete rennin and EPO
Renin-angiotensin-aldosterone system
renin converts angiotensinogen to angiotensin I and then ACE converts angiotensin I to Angiotensin II
renin is released in response
low BP (low GFR) and low filtrate concentration in DT
low BP causes
low GFR, causes release of renin, causes activation of angiotensin II, causes increase in blood volume, causes increase in BP and therefore increase in GFR.
ANP
released in response to high BP and GFR
high BP causes
ANP/ BNP release, which causes an increase in GFR, which leads to more fluid loss and therefore less blood volume and less blood volume means lower BP.
recycling urea
helps pull water by osmosis
the countercurrent exchanger in the vasa recta
blood and filtrate go in opposite directions. Descending vasa recta absorbs NaCl, and the ascending vasa recta absorbs water
DT and collecting duct secretion
depending on needs substances can be secreted. Potassium, HCO3, and ammonium ions
DT and collecting duct selective reabsorption
body has a choice (selective based on needs). Na+, Ca2+, HCO3, water, urea. 85% of water and 90% of sodium reabsorbed.
aldosterone causes
more Na reabsorption and K loss
ADH causes
more water reabsorption (by increasing the number of aquaporins in membrane of DT and collecting duct
in collecting duct urine gets?
concentrated and its volume is reduced
Obligatory water reabsorption
85% in Proximal tubule and loop, through osmosis driven by medullary concentration
Facultative water reabsorption
(15 %, controlled by ADH, in Distal Tubule and collecting duct and requires aquaporins) more aquaporins means more reabsorption, which produces a smaller amount of concentrated urine. No ADH= no aquaporins, which means no water reabsorption and large amounts of diluted urine.
slit like opening in ureter
prevents back flow
rugae
series of ridges produced by folding of the wall the bladder
detrusor muscle
around the bladder
urethra is longer in
males
pH scale
low H+=high PH=basic. High H+=low PH=acidic
acid
dissociates to release H+
base
reduces the amount of free hydrogen in solution
Strong acid
completely dissociates in solution
Weak acid
does not dissociate completely
Strong base
dissociates completely
Weak base
do not dissociate completely
Volatile acids
can move from liquid to gas
carbonic acid is a
volatile acid
Fixed acids
only stay in solution. Remain in body until excreted
Organic acids
byproducts of metabolism
Normal range of ECF pH
7.35-7.45
Sources of H+ gains
from GI tract and metabolism
Sources of H+ losses
kidneys and lungs
Chemical Buffer systems
combination of weak acid and its anion. Are the first response, but a temporary solution
Protein buffer systems
know that amino group accepts H (base) and carboxyl group can donate H (acid) and act as buffer; know that only free or terminal amino acids can do that; know that hemoglobin is a buffer
Phosphate buffer systems
you only need to know that it’s the major ICF (intracellular fluid) buffer
Carbonic-acid bicarbonate buffer system
most important ECF buffer
how does the Carbonic-acid bicarbonate buffer system work?
prevents PH changes caused by fixed and organic acids
the 2 limitations to the Carbonic-acid bicarbonate buffer system
only works if respiratory system works and need enough bicarbonate
Carbonic-acid bicarbonate buffer system equation
CO2+H2O — H2CO3 — H+ + HCO3-
what will drive forward reaction? what will drive reverse?
too basic- forward reaction. too acidic= reverse reaction.
most important factor affecting pH
pCO2
relationship between H+, pH and pCO2
high pCO2=high H+=low ph. low pCO2=low H+=high Ph
Acute phase
ph moves rapidly out of normal range/ no compensation
compensated phase
adjusted back to normal pH but constant compensation
normal phase
normal pH and no compensation, source of problem is removed
what happens to ph and pCO2 during Respiratory acidosis
low Ph, high CO2.
causes of respiratory acidosis
respiratory problems, emphysema, CNS injury, heart failure
compensation for acidosis
respiratory compensation- increase RR; renal compensation- excretion of H+; reabsorption of HCO3-
what happens to ph during metabolic acidosis
low ph
causes of metabolic acidosis
diarrhea, loss in bicarbonate, unable to get rid of acid, producing too much acid
what happens to Ph and CO2 during respiratory alkalosis
high Ph and low CO2
causes of respiratory alkalosis
hyperventilation, pain, anxiety
compensation for alkalosis
decreased RR, excretion of HCO3-; reabsorption of H+
what happens to Ph during metabolic alkalosis
high ph
causes of metabolic alkalosis
vomiting, diuretics, too much bicarbonate
compensation for metabolic alkalosis
decreased RR, excretion of HCO3-; reabsorption of H+
what fluids make up the ECF
fluid outside cells. Includes plasma of blood, interstitial fluid, and other body fluids
ICF
intracellular fluid (cytosol)
how ECF and ICF are different
more than half fluid is inside cells and ICF contains more water
Major ICF ions
potassium, magnesium, proteins, sulfate, hydrogen phosphate
major ECF ions
sodium, chloride, calcium, bicarbonate
basic principles of regulation
o All receptors in ECF not ICF
o Receptors monitor plasma volume and osmotic concentration
o Cells cannot move water by active transport only passively by osmosis – water follows salt
Main sources of water gains
from drinking, eating, and metabolism
water losses
urine, feces, exhaled air, insensible and sensible perspiration
fluid shifts
rapid movement of water between ECF and ICF
hypertonic ECF
(low fluid, high concentration), shift is out of cells (from ICF to ECF)
hypotonic ECF
(high fluid, low concentration), shift is into cells (from ECF to ICF)
Osmoreceptors
in the hypothalamus respond to angiotensin 2 and rise in osmolarity of ECF. Regulates thirst and urination sensation
ADH
secreted by posterior pituitary upon stimulation from osmoreceptors. Stimulates you to drink more/excrete less
Aldosterone
secreted by adrenal cortex in response to too much potassium or not enough sodium or in presence of Ang 2. Stimulates to drink more/excrete less
Angiotensin II
Activated after renin is released by kidneys in response to low BP and blood volume. Stimulates us to drink more/excrete less
ANP/BNP
secreted by cardiac muscle excreted in response to high BP and increased volume. drink less/excrete more
how to get Dehydration
Sweating too much, diarrhea, vomiting, diabetes, too many diuretics
Dehydration results in
hypertonic ECF (hypernatremia), low plasma volume and low BP
Response mechanisms to dehydration
water shift out of cells (from ICF to ECF); roles of renin-angiotensin, ADH, aldosterone: increase volume (increase thirst and decrease excretion)
What is the difference between hypovolemia and dehydration
hypovolemia is loosing water and solute (bleeding) no fluid shift because no change in concentration and dehydration is only losing is water. Concentration goes up.
causes of overhydration
Renal failure, too much IV fluid, too much water, low or no ADH
over hydration results in
hypotonic ECF (hyponatremia), increased plasma volume and BP
Response mechanisms to overhydration
water shift into cells (from ECF to ICF); role of ANP/BNP (decrease thirst and increase excretion)
What is the difference between hypervolemia and over hydration
hypervolemia is both water and electrolytes gained. Results in edema. No fluid shift because no change in concentration and overhydration is water gain and concentration change
difference between total amount and the concentration of an ion
o Total amount of ions= how much solute
o Concentration of ions = total amount/ amount dissolved in
o fluid balance is critical factor that determines
electrolyte balance
Sodium imbalance is, while potassium imbalance is
sodium balance is more common while potassium balance is more dangerous
sources of Na gains
absorption though GI tract
sources of Na losses
excretion by kidneys and perspiration
water follows
salt
fluid loss and gain affects the concentration of electrolytes
fluid gains lower concentration and fluid losses increases concentration
Hypernatremia
higher than normal concentration of sodium. caused by fluid loss. Detected by osmoreceptors stimulates same mechanisms as response to dehydration
Hyponatremia
lower than normal concentration of sodium caused by overhydration or rapid loss of sodium. Detected by osmoreceptors in brain and stimulates same mechanisms as response to overhydration.
sources of K gains
absorption through GI
sources of K losses
excretion by kidneys
Hyperkalemia
lower than normal potassium concentration. caused by- inadequate intake, diuretics causes more negative resting membrane potential, which leaves cells less responsive to stimuli
Hypokalemia
higher than normal potassium levels caused by pH or ECF, renal failure, burns. Results in more positive resting membrane potential or excitable cells, such as cardiac arrhythmias.
Calcium balance. what is it important for and what hormones do you need to stay in balance?
important for muscle contractions. PTH and Vit. D are important for balance
what causes hypercalcemia
higher than normal calcium concentration. caused by hyperparathyroidism, excess vitamin D, bone disorders, and renal failure
hypocalcemia
lower than normal calcium concentration. caused by Ca and Vitamin D dietary deficiency, PTH deficiency, chronic renal failure
where is the JGA located
between the renal corpuscle and the afferent/efferent arteriole
what does the JGA do?
regulates blood flow to the glomerulus and secretes EPO and renin
effects of low level neural stimulation
causes increase in GFR
effects of high level neural stimulation
causes constriction of afferent arterioles and decrease in GFR. Ex: warm weather and exercise
parts of renal tubule
proximal tubule, nephron loop, and distal tubule
what happens to the filtrate as it travels through the tubule?
the filtrate changes as it travels through the tubule.
proximal tubule function
some secretion but mainly reabsorption.
what is reabsorbed in the proximal tubule
sodium, potassium, Cl-, PO4-, HCO3-
difference between thick and thin nephron loop
thick: reabsorption of ions: sodium chloride, calcium, and magnesium. thin: reabsorption of water
during Medullary concentration gradient concentration is higher in
medulla, because of countercurrent mechanisms and urea
what needs to be present for urine concentration at the collecting duct
ADH
