Spring Exam 3 Flashcards
how is bilirubin eliminated
conjugated bili is added to bile in hepatic cells–> once in duodenum it is digested by bacteria into urobilinogen
describe some characteristics of erythrocytes
- biconcave discs (large SA–> crucial for diffusion of oxygen)
- 120 day lifespan
- rely solely on glycolysis bc no mitochondria
vasoactive substances important to renal fxn
Epi, NE, dopa, Angio II (vasoconstrictor), adenosine, NO (vasodilator)
how do myoglobin and hemoglobin differ?
- myoglobin is hydrophilic and hydrophobic
- myo. has 1 binding site for oxygen (myo. 1 heme group, hemo. 4 heme groups)
- myo. located in muscle not blood
- myo. has higher affinity for oxygen (low p50%)
how do natriuretic peptides promote NaCl and water excretion?
- vasodilate AA and EA = increase GFR= increase filtered load
- inhibit renin secretion= decrease angio II
- inhibit aldosterone= decrease NaCl reabsorp. in DCT
- inhibit NaCl reabsorp. in CD
- inhibit ADH secretion
describe the difference of Deoxy and Oxy shapes of Hgb
deoxy- taut form (low affinity for O2)
Oxy- relaxed form (15 degree deviation from axis- high affinity for O2)
what is used to measure RBF and GFR
RBF–> PAH
GFR–> inulin
A conduit that drains the cortex and extends through the medulla opening into the minor caylce
-serves to drain multiple nephrons
Collecting duct
what is the fate of RBCs
- eaten by spleen/macrophages–> heme separated from globin protein
- heme broken down into iron and biliverdin–> free Fe3+ binds to transferrin for transport elsewhere, biliverdin reduced into bilrubin–> associates w/ albumin and transported to liver
- globin protein–> recycled via breakdown into AA
what ways can bicarb be reabsorbed cross the BM?
- 3Na/HCO3 symport
2. Cl/HCO3 antiport
what is heme synthesized from?
glycine and alpha-keto gluterate to form a pyrrole
does [PAH] affect its clearance
Yes
increase [PAH]= decrease clearance
-at low levels PAH is completely cleared from plasma in a single pass through the kidney via filtration and secretion
-used to measure RPF
describe how movement in filtration is dictated by the Staring forces
- HPcap. is driving force (outward) which is hindered by HPbowmens cap. (inward)
- pressure in renal artery dictates pressure in capillaries
what does the diuertic Acetazolamide do?
inhibits CA
- Bicarb levels SORE in urine bc it is not being recaptured
- used to treat resp. alkalosis
filtration takes place, fed by afferent arteriole, and exposed to standard cap. network, and blood leaves via efferent arteriole
Glomerulus
all cellular elements come from what molecule?
SC: hemocytoblast
*Mainly cytokines that signal for certain cell production IL1 and IL6
cyanosis is a clinical sign of what?
low pO2
What is the Bohr Effect?
Allows Hgb to act as a buffer (weak acid or base) as consequence of O2 binding/dissociating
- Hgb acts as weak acid when O2 binds
- Hgb acts as weak base when O2 is unbound
describe what happens when O2 is released from Hgb (Bohr effect)
*occurs in periphery
Hgb drops off O2–> picks up a proton–> creates large pocket of + charge–> Hgb going to bind in taut state 2,3 BPG –> stabilizes a low affinity for Hgb to O2
*Hgb acts as weak base
what is adult hemoglobin made from?
2 alpha chains
2 beta chains
4 heme groups
Tiny blood vessels that travel alongside the PCT and DCT allowing reabsorption and secretion between blood and the inner lumen of the nephron
peritubullar capillaries
Where is glucose, AA, and lactate reabsorbed?
the PCT only!
an increase in vascular resistance has what impact on GFR and RBF
decrease GFR and RBR
*SmM. allows for a lesser drop in GFR by constricting/(creating more resistance) in efferent arterioles
describe the difference in hemoglobin affinity in the fetus and adult
fetal hemoglobin (alpha and gamma) has a HIGHER affinity for oxygen than adults. Therefore, hypoxic fetus steals O2 from mother and releases it into their body
how does pH affect Hgb affinity for O2?
*think about effects during exercise
low pH (aka increase [proton]) = lower affinity for O2 -anerobic exercise creates lactic acid--> lowers pH--> lower Hgb affinity for O2--> drops off O2 more readily here
what affect does a drop in GFR have on filtered load?
drop in GFR= drop in filtered load bc it puts a strain on reabsorption mechanisms
what is the process of inducing RBC production?
low local pO2 is detected by HIF (hypoxia-inducible factor)–> produces/releases EPO from peritubular fibroblasts in the kidney–> stimulates SC to produce reticulocytes/RBCs
*takes about 1 week to see results
hemoglobin is represented exclusively in what cells?
RBCs and reticulocytes
*some hgb does leak into circulation via hemolysis
describe how autoregulation helps maintain GFR and RBF
- autoregulation influences restistance
- stretch receptors on myocytes become activated as pressure increases–> increase Ca influx into cell–> increased resistance–> maintain flow over a higher pressure
describe the pO2 in utero and very early on in life
fetal arterial blood: 20-30mmHg
one hr after birth: 60mmHg
24 hrs after birth: 80-90mmHg
*shift from HgbF to HgbA
how much plasma is filtered per day?
180L/day
*plasma volume is ~3L therefore, plasma is filtered ~60x per day!
the amount of substance that appears in the urine is a function of what?
- glomerular filtration
- tubular reabsorption (water, electrolytes, buffers, nutrients)
- tubular secretion (H, K, organic A/B)
what is the recommended daily iron intake for newborns
- born w/ 75mg/kg of iron which is adequate storage until birth weight doubles then add supplement
- RBC mass doubles at 1st year of life
- 1mg of additional iron needed per 1ml of blood
why do newborns often have high bilirubin levels?
- the UDP-glucuronsyl transferase enzyme in the liver is not fully mature, so they have a hard time getting rid of the bili bc its not water soluble.
- tx w/ phototherapy
how is phosphate handled by the kidney
80% of filtered phosphate is reabsorbed at PCT
- 10% is reabsorbed at DCT
- see 10-20-25% excreted in urine (higher w/ PTH)
what does a transport of 0, +, and - mean?
0: all that is filtered is urinated out
(+): filtered amount is greater than urinated amount (REABSORPTION is occurring)
(-): filtered amount is less than urinated amount (SECRETION is occurring)
all transport mechanisms are ___
saturable!!
what nutrients are found in blood?
- glucose and other carbs
- AA
- lipids
- cholesterol
- vitamins
- trace elements
give examples of when you would see increased or decreased TIBC
Increased: iron def. anemia (liver produces more to bind whatever iron is available) and pregnancy
Decreased: anemia of chronic diseases (diseased liver produces less)
how does 2,3 BPG affects Hgb affinity for O2?
it LOWERS Hgbs affinity for O2
what is a good indicator for renal blood flow and why
PAH bc only a little is filtered and ALL is secreted (MAX secretion) and then all is excreted in urine
-PAH is freely filtered
when iron is in the ferric state what is it called?
Met-hemoglobin (cannot bind O2)
what happens when a free proton associates with a weak acid and a weak base in the PCT
weak acid: neutralizes the compound and allows it to freely diffuse
weak base: gives compound a + charge and now it is impermeable (proton trapping in the lumen)
what are the hematocrit levels in males, females, and newborns and why are there differences?
males: 40-50%- test. induces RBC production
females: 35-40%-estrogen inhibits/menstrual loss
newborns: 45-60%-low pO2 in utero engages in RBC production via Epo
why is there only positive NFP across glomerulus capillaries?
no reabsorption, only filtration
no movement from Bowmen’s capsule to capillaries
describe the osmolarity of the filtrate in the ALH w/ respect to plasma.
hypo-osmotic w/ respect to plasma bc reabsorbing electrolytes but not water
what does TIBC reflect?
transferrin concentration in the ECF
what are the functions of EPO
- Maintain constancy of RBC mass in our systems –hematocrit (will increase in hemorrhage)
- Maintain hemoglobin concentration
- Ensure and speed recovery from hemorrhage
___ is KEY to proper hgb function
affinity!
what proteins are found in blood?
- albumin (Transports reversibly with many things, non-specific, contributes to oncotic pressure)
- globulins (immune)
- fibrinogen
why is inulin so important/useful?
Used to measure GFR bc:
- freely filtered at glomeruli
- not reabsorbed
- not secreted
- not metabolized by tubule cells
- not synthesized by tubule cells
how does iron get into our system?
diet (1-2mg/day)
-absorption in GI tract (duodenum) is controlled by signallying mechanism
triggers for synthesis of EPO
- low pO2 (hypoxia)
- anemia of any cause
- factors that promote high-affinity states of Hgb (contributes to low pO2)
- Synthesis driven by hypoxemia-inducible transcriptional factors
describe what happens to the concentration of Na, Cl, Pi, and HCO3, glucose/AA/lactate across the PTC
[Na]- relatively stable
[Cl]- increased due to reabsorption of H20 and less Cl
[Pi] decrease
[HCO3]- decrease the greatest
[glucose, AA, lactate]- decrease greatest to 0
where are the components of blood made?
depends on developmental stage:
fetal life- mainly liver and BM
adult life- mainly BM* and thymus
what is GFR?
the volume of blood that is filtered by the glomeruli per unit of time (units: volume/time)
what causes oncontic pressure to change?
- fluid leaving vasculature in GC as protein stays due to filtration barrier= increases pressure
- reabsorption of fluid in PCT decreases pressure
how are protons used to recapture bicarb?
- actively pumped into filtrate
- exchanged w/ Na+
*protons in the filtrate then bind w/ HCO3 to form H2CO3–> CA–> H20 + CO2–> diffuses across and binds w/ H20–> CA –> H+ + HCO3
describe the difference between intercalated A and B cells
A- transporter on apical membrane
B-transporter on BM (can secrete HCO3 w/ alkalosis)
what substances decrease NaCl reabsorption?
- ANP (atrial natriuretic peptide)
- PGE
- bradykinin
*all in distal tubule collecting duct
How much oxygen is normally physically capable of binding with hemoglobin?
normally 1.34 per gram of hemoglobin (functional binding capacity)
___ levels are an indicator of hemolysis
haptoglobin
hemolysis occuring= low haptoglobin levels
describe the mechanisms of PO4 reabsorption
- 2Na/HPO4 symport into the cell on apical membrane (where PTH inhibits)
- Acid (in)/HPO4 antiport on BM
what progenitor cell do RBCs, Megakaryocyte/platelets, Mast cells, Myeloblasts come from?
common myeloid progenitor
what is the functional unit of the kidney?
a nephron
what 2 factors greatly contribute to filterability
- charge (more neg. charge= less filterability, less neg. = more filterable)
- molecular size
area of Cl- sensing via granula cells that will release renin
Macula densa cells
in DCT- sits btwn afferent and efferent arterioles