Term
| What are sources of acid from the diet? |
|
Definition
| Meats, grains and dairy products |
|
|
Term
| What is the henderson-hassalbach equation? |
|
Definition
| pH = 6.1 + log(HCO3-)/.03(PCO2) |
|
|
Term
| how is the HCO3-buffer system different from other buffer systems of the body? |
|
Definition
| It's controlled by lungs and kidneys via carbonic anadydrase |
|
|
Term
| What is the chloride shift and where does it occur? |
|
Definition
Bicarbonate in the red blood cell (RBC) exchanging with chloride from plasma
CO2 that enters RBC gets converted to bicarbonate and H+ by CA. Bicarb is secreted to maintain maintain blood pH |
|
|
Term
| which is a better buffer: Hemoglobin or plasma proteins? |
|
Definition
| Hemoglobin (more histidine) |
|
|
Term
| Why is albumin such a good plasma protein buffer? |
|
Definition
It has 16 Histine bindings sites
Histidine is a good buffer because it has a dissociable proton |
|
|
Term
| What is the affect of chronic acidosis bone? |
|
Definition
| Increase ostoclastic function to increase Ca2+ release from bone |
|
|
Term
| How much bicarb appears in urine? |
|
Definition
None! It is all reabsorbed to the blood.
80% reabsobtion occurs in the proximal tubule |
|
|
Term
| Which part of the nephron has an apical carbonic anahydrase? |
|
Definition
|
|
Term
| How is bicarb reabsorbed in the early proximal tubule? In the TAL? In the a-intercalated cells? |
|
Definition
Proximal tubule: Na/3HCO3- symport and HCO3/Cl- antiport
TAL: HCO3/Cl- antiport
Intercalated: HCO3/Cl- antiport |
|
|
Term
How is H+ secreted once dissociates from H2CO3 in the early proximal tubule?
In the TAL? In the a-intercalated cells? |
|
Definition
Proximal Tubule and TAL: Na/H+ antiport or H+ atpase
a-intercalated cell: H+ atpase or H+/K+ antiport |
|
|
Term
| what is the difference between a-intercalated and b-intercalated cells in regard to Cl/HCO3 exchangers? |
|
Definition
a-intercalated cells: Cl/HCO3 exchanger located on basolateral membrane so HC03- released into blood
b-inercalated: located on apical membrane so HCO3- is secreted in responce to an alkine load setting |
|
|
Term
| synthesis/reabsorption of new HCO3- is linked to what metabolism? What happens is this metabolism doesn't occur? |
|
Definition
NH4 metabolism in proximal tubule (from glutamine)
Metabolic acidosis occurs if NH4 is failed to be produced |
|
|
Term
| How does ECF volume depletion alter H+ secretion? |
|
Definition
| increased Na+ reabsorption due to ECF volume depletion can lead to increased H+ secretion |
|
|
Term
| Bodies responce to respiratory acidosis? |
|
Definition
Increase ventilation
Acute increase in CO2 directly stimulates proximal tubule cells to increased renal H+ excretion |
|
|
Term
| what cell will increase in activity in responce to metabolic alkalosis? |
|
Definition
B-intercalated cells of collecting duct
Have apical Cl/HCO3 transporters so HCO3- secretion with increase |
|
|
Term
| how much of body weight is total body water? |
|
Definition
2/3
60-40-20
60% total body weight is water
40% is ICF
20% is ECF |
|
|
Term
| why do woman have less body water than men? |
|
Definition
| woman have higher fat content (more water in muscle than fat) |
|
|
Term
| what is the affect of adding isotonic saline to ECF? |
|
Definition
| only ECF volume will rise, ICF will remain the same |
|
|
Term
| what is the affect of adding hypotonic saline to ECF? |
|
Definition
| After osmotic equilibrium, osmolalities of ICF and ECF will be equal, but lower than before the infusion, and the volume of both compartments will increase bc water will move into ICF |
|
|
Term
| what is the affect of adding pure water to ECF? |
|
Definition
Fluid will shift from ECF to ICF => ICF osmolality will decrease
After osmotic equilibrium, added water will be distributed between ICF and ECF according to the initial ICF/ECF ratio of 60%/40% => more fluid will end up inside the cell |
|
|
Term
| What is be best to give a patient whose vascular volume (ECF) needs to be increased? |
|
Definition
Isotonic solution with 5% albumin
albumin molecules in the infused solution will generate colloid osmotic pressure causing fluid to be retained in the vascular compartment. |
|
|
Term
| where are baroreceptors located? |
|
Definition
| glomerular Afferent arterioles and carotid sinus |
|
|
Term
| long term regulation of effective circulating volume involves altering what? |
|
Definition
Na+ excretion via renin (low volume) or ANP (high volume)
When Na is retained, water is retained
When Na is excreted, water is excreted |
|
|
Term
| Short-term regulation of effective circulating volume involves changing what? |
|
Definition
| Arterial Pressure via changes in HR, cardiac contractility, and vascular resistance by the sympathetic nervous system |
|
|
Term
|
Definition
|
|
Term
| Renin is released in responce to what changes? |
|
Definition
Decreased ECF
decrease stretch of JG cells, decreased NaCl sensed by macula densa cells, increased sympathetic activity |
|
|
Term
| Describe the pathway caused by Renin release |
|
Definition
Renin (released when low circulation volume)
activated Ang II which causes ADH release from hypothalamus and Aldosterone release from adrenal gland
leads to... decreased Na and H20 excretion |
|
|
Term
| How does renin effect proximal tubule activity? |
|
Definition
Increased Na/H antiport
Increase Na/K atpase |
|
|
Term
| how does Ang II affect arteriole resistance? |
|
Definition
| It inreased resistance of efferent arteriole more than afferent arteriole so filtration fraction is incrased (increased reabsorption of Na and water) |
|
|
Term
| How does alosterone affect nephron activity? |
|
Definition
Increases activity in principal cell
Increase Na/K atpase and ENaC channels and increase K conductance
decreased Na and water excretion |
|
|
Term
| too much renin can cause what problem? |
|
Definition
|
|
Term
| What is the bodies responce to increased effective circulating volume? |
|
Definition
Increase ANP (decrease renin)
increase GFR
increase excretion of Na and water |
|
|
Term
| how do u calculate plasma osmolality? Effective plasma osmality? |
|
Definition
P osm = 2(plamsa Na) + (glcuose/18) + (BUN/2.8)
leave out BUN for effective P osm |
|
|
Term
| what does too much water rention cause? |
|
Definition
Hyponatremia (cells swell and burst)
brain swelling |
|
|
Term
| what causes hypernatremia? |
|
Definition
| water loss in excess of solute |
|
|
Term
| where are the CNS osmalality receptors located? |
|
Definition
Circumventricular organs: subfornical organ and OVLT
contol ADH synthesis |
|
|
Term
| what is the brains responce to increased plasma osmolality? |
|
Definition
CNS osmoreceptors shrink, depolarize and produce AP (stretch inactivated cation channels)
ADH is released |
|
|
Term
| what are the effects of ADH? |
|
Definition
inserts aquaporins in distal tubule and collecting ducts making them water permeable
increase N/K/Cl in TAL
increase ENaC in principal cells
Increase IMCD permeability to urea
overall: decrease free water clearence |
|
|
Term
| what is the affect of SIADH? |
|
Definition
| water rention, ANP release, hyponatremia from increased Na lost in urine |
|
|
Term
how do u calculate clearence?
When can it be used to estimate GFR? |
|
Definition
Clearance= (UIn x V )/ PIn
when you use inulin or creatinine concentration |
|
|
Term
| how to you calculate renal plasma flow? |
|
Definition
|
|
Term
| how do you calculate filtration fraction? |
|
Definition
|
|
Term
| How to you calculate free water clearence? |
|
Definition
urine flow rate - C osm
C osm = (Urine osm x urine flow rate) / plasma osmolality |
|
|
Term
| what provides the driving force for Na+ reabsorption in the early proximal tubule? |
|
Definition
| Low intracellular [Na+] va Na/K atpase |
|
|
Term
| what is reabsorpted with Na+ in proximal tubule? |
|
Definition
Glucose
Amino Acids
-carboxylates
Phosphates |
|
|
Term
| what is secreted with Na reabsorption in the proximal tubule? |
|
Definition
|
|
Term
| how does Na+ reabsorption affect the lumen charge in the early proximal tubule? |
|
Definition
creates seperation of charge with NEGATIVE voltage
leads to paracellular Cl- reabsorption |
|
|
Term
| where does glucose reabsorption occur? |
|
Definition
|
|
Term
| above what concentration does glucose appear in urine? what concentration do SGLTs become saturated? |
|
Definition
appears in urine above 200 mg/dL
SGLTs saturated around 380 mg/dL |
|
|
Term
|
Definition
| heterogeneity of renal tubules |
|
|
Term
| where does most bicarb reabsorption occur? |
|
Definition
|
|
Term
| where does most Ca2+ reabsorption occur? |
|
Definition
late proximal tubule
Due to Na backleak and lumen positive voltage leading to paracellular reabsorption |
|
|
Term
| what does in increased BUN/creatinine ratio mean? |
|
Definition
Dehyrdation
Urea is reabsorbed with water so increased urea means increased water reabsorption due to dehydration
creatinine and GFR are inversely related |
|
|
Term
| what is the osmalality of loop of Henle? why? |
|
Definition
| Hyperomsmotic compared to plasma because water is reabsorbed in the thin descending limb |
|
|
Term
| where does passive NaCl reabsorption occur? |
|
Definition
|
|
Term
| where is most Mg2+ reabsorbed? |
|
Definition
Thick ascending limb
linked w/ K+ recycling and claudin 16 tight junction |
|
|
Term
| what drives paracellular reabsorption of Na, K, Ca, and Mg in the TAL? |
|
Definition
K+ recycling creates lumen POSTIVE voltage
(K+ recycling inhibited whan ATP is high and when Ca2+ is high) |
|
|
Term
| how does hypercalcemia affect TAL? |
|
Definition
| inhibits Na/K/2Cl activity so lumen becomes less postive and paracellular Ca is inhibited ==> Decrease NaCl reabsorption |
|
|
Term
| what cation's reabsorption is hormonally mediated in TAL? |
|
Definition
Ca2+
via PKC, PKA, PTH, and Vit D |
|
|
Term
|
Definition
Thick Ascending limb
Inhibits Na/K/Cl => no K+ recycling
Lumen becomes less postive => no electrolyte reabsorption
Decreased osmalality => inablity to concetrate urine |
|
|
Term
| where do thiazide diuretics work? how? |
|
Definition
Distal convoluted tubule
Inhibits Na/Cl cotransporter
loss of K+ |
|
|
Term
| How is Na+ reabsorbed in the princibal cells of the collecting tubules? |
|
Definition
ENaC
generates lumen Negative voltage
Enhances K+ secretion |
|
|
Term
| where does amiloride act? how? |
|
Definition
Principal cell of collecting tubule
Inhibits ENaC => inhibits K+ secretion
(K+ sparring diuretic) |
|
|
Term
| what part of the nephron contributes to acid-base balance and how? |
|
Definition
intercalted cells of collecting tubule
responcible for K+ reabsorption in exchange for H+ secretion
HCO3 reabsorption via HCO3/Cl antiport in a-intercalated cells
HCO3 secretion via apical HCO3/Cl antiport in b-intercalated cells |
|
|
Term
| what hormones are produced in the kidney |
|
Definition
| Renin, erythropoitin, Vit D |
|
|
Term
| how much of the total cardiac output does the kidneys recieve? |
|
Definition
20%
most blood flow supplies the cortex |
|
|
Term
what hormone estimates RPF?
how do you calculate RPF? |
|
Definition
|
|
Term
| where does elevated hydrostatic pressure lead to filtration? |
|
Definition
|
|
Term
| what are the major barriers to glomerular filtration? |
|
Definition
Molecular weight and radius (<5500 daltons)
Electrical charge (postively charged glycoprotein) |
|
|
Term
| what prevents large molecules and proteins from entering bowmans space? |
|
Definition
|
|
Term
| How would you know if your glomerular filtration barrier is intact or not intact? |
|
Definition
| Proteins present in urine = not intact basement membrane |
|
|
Term
|
Definition
| loss of negative charge glycoproteins or absence of nephrin |
|
|
Term
| what are the consequences of proteinuria? |
|
Definition
causes hypoalbuminemia which causes decreased plasma colloid osmotic pressure which allows fluid to leak out of capillaries
=> Edema |
|
|
Term
| What is the function of mesangial cells? |
|
Definition
| provide structural support for glomerular capillaries (Important in regulating glomerular volume and pressure), secrete ECM, phagocytotic activity and secretes cytokines |
|
|
Term
| autoregulation affects with arteriole resistance the most? |
|
Definition
| Afferent arteriole resistance |
|
|
Term
| What are the two mechanisms responcible for autoregulation? |
|
Definition
1. Myogenic stretch
2. Tubuloglomerular feedback |
|
|
Term
| how does autoregulation (myogenic responce) respond to sympathetic stimulation? |
|
Definition
Increase arterial pressure
Increase arterial stretch
Stretch activated Ca2+ channels open
Ca2+ enters cell
Afferent arteriole constricts
Increase resistance to flow
=> RBF and GFR returns to normal |
|
|
Term
| How does the tubuloglomerular apparatus respond to sympathetic stimulation |
|
Definition
Increased GFR and RBF
increased NaCl to macula densa
increase ATP use, Adenosine production
Adenosine binds a1 receptor
Afferent arteriole constricts
Increase resistance to flow
RBF and GFR return to normal |
|
|
Term
| at what pressure does passive pressure circulation take over autoregulation? |
|
Definition
|
|
Term
| How does ANP affect arterioles? |
|
Definition
dilates afferent
constricts efferent |
|
|
Term
| what hormones constrict efferent arteriole? |
|
Definition
|
|
Term
| what hormones constrict afferent arteriole? |
|
Definition
|
|
Term
| what hormones dilate arterioles? |
|
Definition
| Nitric oxide and prostaglandins |
|
|
Term
| what substances can be used to determine GFR? |
|
Definition
|
|
Term
| what are the characteristics of a GFR marker? |
|
Definition
Freely filtered through the glomerulus
Not reabsorbed
Not secreted
Not synthesized/metabolized by renal cells
Not toxic
Concentration can be measured in plasma and urine |
|
|
Term
| what are some errors with using creatinine to estimate GFR? |
|
Definition
10% secreted
measurments overstimate plasma creatinine by 10% |
|
|
Term
| how do you convernt ml/day into ml/min? |
|
Definition
|
|
Term
| how do GFR and plasma creatinine relate to each other? |
|
Definition
|
|
Term
| what factors shift K+ into cells? |
|
Definition
Epinephrine
Insulin
Aldosterone
ECF alkalosis |
|
|
Term
| how does High plasma [K+] affect the adrenal gland? |
|
Definition
Deplorizes glomerulosa cells and opens volage gated Ca2+ cells
Ca2+ influx ==> Aldosterone sysnthesis
Aldosterone increases Na/K atpase on all cells and all activity of principal cells |
|
|
Term
| what are the affects of aldosterone on principal cells? |
|
Definition
Increases number and open probability of ENaC => enhances Na+ reabsorption in exchange for K+
increase Na + influx leads to a lumen negative potential
increase K+ conductance of the apical K+ channels which increases K secretion |
|
|
Term
| How does alkalosis affect K+? |
|
Definition
| promtes K+ influx in exchange for H+ leading to hypokalemia |
|
|
Term
| What causes hyperkalemia? |
|
Definition
Hyperosmolality
Insulin deficiency
Aldosterone deficiency
Beta receptor blockade
Mineral acidosis
Tissue injury
Exercise
Drugs
Increased dietary intake |
|
|
Term
| how does increased plasma osmolality cause hyperkalemia? |
|
Definition
| water leaves the cell until osmotic equilibrium is reached => cells shrink and intracellular [K+] increase => increase driving force for K+ efflux => increase K+ efflux => increased ECF [K+] (hyperkalemia) |
|
|
Term
| how does acidosis cause hyperkalemia? |
|
Definition
| Inhibits Na/K atpase so K+ remains outside cell |
|
|
Term
| what happens with increased K intake? |
|
Definition
| increased secretion of K+ in principal cell |
|
|
Term
| what happens with a decreased intake of K+? |
|
Definition
| K+ is reabsorpted via H/K antiport in a-intercalated cell |
|
|
Term
| what affect to tubular flow rate have on K+? |
|
Definition
Increased flow = increaed K+ secretion (diuretics) and increased Na+ reabsorption
decreased flow = decreased K+ secretion (hemmorage, fluid loss) |
|
|
Term
| Which hormone is most likely responsible for returning plasma potassium back to its normal pre-exercise levels? |
|
Definition
|
|
Term
| what hormone is most important and regulating K+ levels after a meal? |
|
Definition
|
|
Term
| what drugs can induce hypterkalemia? |
|
Definition
Ace inhibitor
B2 blocker
Amiloride
K+ suplements |
|
|
Term
| what is the role of vasa recta's countercurrent exchange mechanism? |
|
Definition
| To maintain a HYPERtonic medulla |
|
|
Term
| how does kidney produce concentrated urine? |
|
Definition
| by using osmosis to dive water out of distal tubule and cortical tubule (via ADH) |
|
|
Term
| how does kidney produce dilute urine? |
|
Definition
| by pumping salts out of lumen, leaving water behind |
|
|
Term
| what is the affect of Addison's disease (decreased aldosterone) on K+ levels? |
|
Definition
|
|
Term
| how does pressure in the bladder change as its filling? |
|
Definition
|
|
Term
| what factors stimulate ADH release? |
|
Definition
Increased plasma osmalality
Decreased effective circulating volume
Thirst
Stress
Pregnancy, vomiting |
|
|
Term
| where does ADH insert aquaporins? |
|
Definition
| Principal cells (apical and basolateral membranes) |
|
|
