Spring Exam 3 Flashcards
(169 cards)
1
Q
how is bilirubin eliminated
A
conjugated bili is added to bile in hepatic cells–> once in duodenum it is digested by bacteria into urobilinogen
2
Q
describe some characteristics of erythrocytes
A
- biconcave discs (large SA–> crucial for diffusion of oxygen)
- 120 day lifespan
- rely solely on glycolysis bc no mitochondria
3
Q
vasoactive substances important to renal fxn
A
Epi, NE, dopa, Angio II (vasoconstrictor), adenosine, NO (vasodilator)
4
Q
how do myoglobin and hemoglobin differ?
A
- 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%)
5
Q
how do natriuretic peptides promote NaCl and water excretion?
A
- 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
6
Q
describe the difference of Deoxy and Oxy shapes of Hgb
A
deoxy- taut form (low affinity for O2)
Oxy- relaxed form (15 degree deviation from axis- high affinity for O2)
7
Q
what is used to measure RBF and GFR
A
RBF–> PAH
GFR–> inulin
8
Q
A conduit that drains the cortex and extends through the medulla opening into the minor caylce
-serves to drain multiple nephrons
A
Collecting duct
9
Q
what is the fate of RBCs
A
- 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
10
Q
what ways can bicarb be reabsorbed cross the BM?
A
- 3Na/HCO3 symport
2. Cl/HCO3 antiport
11
Q
what is heme synthesized from?
A
glycine and alpha-keto gluterate to form a pyrrole
12
Q
does [PAH] affect its clearance
A
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
13
Q
describe how movement in filtration is dictated by the Staring forces
A
- HPcap. is driving force (outward) which is hindered by HPbowmens cap. (inward)
- pressure in renal artery dictates pressure in capillaries
14
Q
what does the diuertic Acetazolamide do?
A
inhibits CA
- Bicarb levels SORE in urine bc it is not being recaptured
- used to treat resp. alkalosis
15
Q
filtration takes place, fed by afferent arteriole, and exposed to standard cap. network, and blood leaves via efferent arteriole
A
Glomerulus
16
Q
all cellular elements come from what molecule?
A
SC: hemocytoblast
*Mainly cytokines that signal for certain cell production IL1 and IL6
17
Q
cyanosis is a clinical sign of what?
A
low pO2
18
Q
What is the Bohr Effect?
A
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
19
Q
describe what happens when O2 is released from Hgb (Bohr effect)
A
*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
20
Q
what is adult hemoglobin made from?
A
2 alpha chains
2 beta chains
4 heme groups
21
Q
Tiny blood vessels that travel alongside the PCT and DCT allowing reabsorption and secretion between blood and the inner lumen of the nephron
A
peritubullar capillaries
22
Q
Where is glucose, AA, and lactate reabsorbed?
A
the PCT only!
23
Q
an increase in vascular resistance has what impact on GFR and RBF
A
decrease GFR and RBR
*SmM. allows for a lesser drop in GFR by constricting/(creating more resistance) in efferent arterioles
24
Q
describe the difference in hemoglobin affinity in the fetus and adult
A
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
25
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
```
26
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
27
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
28
hemoglobin is represented exclusively in what cells?
RBCs and reticulocytes
| *some hgb does leak into circulation via hemolysis
29
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
30
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
31
how much plasma is filtered per day?
180L/day
*plasma volume is ~3L therefore, plasma is filtered ~60x per day!
32
the amount of substance that appears in the urine is a function of what?
1. glomerular filtration
2. tubular reabsorption (water, electrolytes, buffers, nutrients)
3. tubular secretion (H, K, organic A/B)
33
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
34
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
35
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)
36
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)
37
all transport mechanisms are ___
saturable!!
38
what nutrients are found in blood?
- glucose and other carbs
- AA
- lipids
- cholesterol
- vitamins
- trace elements
39
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)
40
how does 2,3 BPG affects Hgb affinity for O2?
it LOWERS Hgbs affinity for O2
41
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
42
when iron is in the ferric state what is it called?
Met-hemoglobin (cannot bind O2)
43
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)
44
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
45
why is there only positive NFP across glomerulus capillaries?
no reabsorption, only filtration
| no movement from Bowmen's capsule to capillaries
46
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
47
what does TIBC reflect?
transferrin concentration in the ECF
48
what are the functions of EPO
1. Maintain constancy of RBC mass in our systems –hematocrit (will increase in hemorrhage)
2. Maintain hemoglobin concentration
3. Ensure and speed recovery from hemorrhage
49
___ is KEY to proper hgb function
affinity!
50
what proteins are found in blood?
- albumin (Transports reversibly with many things, non-specific, contributes to oncotic pressure)
- globulins (immune)
- fibrinogen
51
why is inulin so important/useful?
Used to measure GFR bc:
1. freely filtered at glomeruli
2. not reabsorbed
3. not secreted
4. not metabolized by tubule cells
5. not synthesized by tubule cells
52
how does iron get into our system?
diet (1-2mg/day)
| -absorption in GI tract (duodenum) is controlled by signallying mechanism
53
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
54
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
55
where are the components of blood made?
depends on developmental stage:
fetal life- mainly liver and BM
adult life- mainly BM* and thymus
56
what is GFR?
the volume of blood that is filtered by the glomeruli per unit of time (units: volume/time)
57
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
58
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
59
describe the difference between intercalated A and B cells
A- transporter on apical membrane
| B-transporter on BM (can secrete HCO3 w/ alkalosis)
60
what substances decrease NaCl reabsorption?
- ANP (atrial natriuretic peptide)
- PGE
- bradykinin
*all in distal tubule collecting duct
61
How much oxygen is normally physically capable of binding with hemoglobin?
normally 1.34 per gram of hemoglobin (functional binding capacity)
62
___ levels are an indicator of hemolysis
haptoglobin
hemolysis occuring= low haptoglobin levels
63
describe the mechanisms of PO4 reabsorption
1. 2Na/HPO4 symport into the cell on apical membrane (where PTH inhibits)
2. Acid (in)/HPO4 antiport on BM
64
what progenitor cell do RBCs, Megakaryocyte/platelets, Mast cells, Myeloblasts come from?
common myeloid progenitor
65
what is the functional unit of the kidney?
a nephron
66
what 2 factors greatly contribute to filterability
1. charge (more neg. charge= less filterability, less neg. = more filterable)
2. molecular size
67
area of Cl- sensing via granula cells that will release renin
Macula densa cells
| in DCT- sits btwn afferent and efferent arterioles
68
what cells present in the late DCT
1. princple cells
| 2. intercalated cells (major site of acidification)
69
how does carbon monoxide affect Hgb affinity for O2?
- when CO is bound to Hgb, its affinity for O2 increases (harder to distribute O2)
- CO is a powerful competitive inhibitor of O2 binding on Hgb
70
how is HCO3 reabsorption different in the DCT and CCD compared to the PCT?
- only active pumping of protons into the filtrate and NO CA to help facilitate the rxn
* *rxn is MUCH slower!
71
marker for amount of iron that is being accumulated by cells
hemosiderin
72
major influences upon K+ secretion
1. Na/K ATPas activity
2. concentration gradient (increased K= increased secretion)
3. apical membrane permeability (aldosterone effects this)
*aldosterone-Na keeper,K secretor
73
an adult male has how many grams of iron in his body?
3.5 grams
74
when does physiological anemia of the newborn occur in full term and premature infants?
FT: 6-9 weeks
premature: 4-6 weeks
75
describe the permeability in TAL
- impermeabile to water
| - 20-25% of reabsorption of Na, Cl, K, HCO3- occurs here
76
hemoglobin stores what percentage of oxygen?
98.6% of oxygen
77
what do the intercalated cells do in the late DCT
- active secretion of protons into filtrate via ATPase
- Secretion of H+ and recapturing of HCO3
- major site of acidification
78
describe what happens to erythrocyte composition as it matures
as nuclear area/circumference decreases with maturation, RNA amount decreases and hemoglobin levels increase rapidly
79
describe the 3 basic renal processes that dictate urine composition
1. Glomerular filtration- movement from plasma to urinary space
2. Tubular secretion- movement from peritub. cap. into nephron
3. Tubular reabsorption- movement from nephron into peritub. cap.
80
how do we control ECV (effective circulating volume)
by regulating Na and CL excretion
| autoreg: myogenic response of vascular Sm.M/, and TGF
* resistance
81
Describe the 3 main roles of blood?
1. transport vehicle of nutrients
2. provides defense via: (1. B-cells (Ab production) 2. phagocytosis)
3. A homeostatic role: (1. buffering capacity (bicarb) 2. osmotic balance 3. heat distribution)
82
what is a filtered load?
the amount of substance that is filtered/time
FL= GFR x Psubstance
83
what is a means that you can promote charged chase reabsorption in the distal PCT?
acidification of the filtrate (organic base entering filtrate--> associate w/ free H+--> neutral compound can diffuse freely)
84
why can creatinine be used to estimate GFR?
- produced constantly from skeletal M. tissue
- filtered and secreted (actually overestimates GFR a little)
- as GFR decreases= increase in creatinine
*only an estimate bc creat. is complicated by body mass and ethnicity
85
what is the site of most reabsorption
PCT
86
increased ADH has what effects on H20 reabsorption and NaCl reabsorption
- increase H20 reabsor. by CD
- increase NaCl reabsorp. by Thick AL
- increase Na reabsorb by CD
87
- dictate the composition of the ECF compartment of the medulla
- main role is to create concentration gradient (maintain the osmotic gradient)
Vasa Recta
-branch off efferent arterioles of juxtameduallary nephrons
88
describe how loop diuertics work
- work on the TAL by inhibiting the reabsorption of NaCl and K (inhibits the Na/K 2 Cl symport).
- By keeping these charged electrolytes in the filtrate, when the filtrate reaches the DCT, water will stay in the filtrate instead of being reabsorbed leading to more water in the urine
89
what can be used to enhance water solubility of many substances?
UDP glucose
90
describe movement of solutes and water in vasa recta
- Descending: H20 out and Solutes in
| - Ascending: H20 in and solutes move out
91
how can renal failure result in anemia?
renal failure leads to decreased EPO which means less RBC production which leads to anemia (might see more reticulocytes)
92
In order to use a substance to measure GFR, it can only be ___
Ex. of that substance
filtrated and not secreted/absorbed
ex. inulin
93
what does a pulseox tell you?
% of Hgb bound with oxygen
| ex. pulseox 95% = 95% of Hgb is bound with oxygen. Therefore pO2 is 85-100mmHg (gas exchange is working efficiently)
94
as blood moves from arterial side to venous side, what happens to oxygen saturation?
- Oxygen is dissociating from the Hgb due to the pO2 diminishing
- oxygen will start dissociating from myoglobin at a much lower pO2 pressure (myo. has a lower p50%)
95
what is methemoglobinemia
- when Hbg is bound to ferric iron (Fe3+), which makes it unable to reversibly associate w/ O2
- high levels lead to RBC degradation
- caused by certain chemical exposure (low amounts do circulate in our bodies tho)
96
what is the fundamental driving force of filtration?
```
hydrostatic pressure
(depends on basement membrane permeability)
```
97
what are the effects of PTH
- stimulates shift from bone deposition to bone mobilization
- increase Ca++ reabsorption and decrease PO4- reabsorption
- promotes final hydroxylation of VitD3 (at level of kidney) to enhance Ca absorption from the Gut
98
where does PTH act on the nephron?
at DCT to enhance paracellular reabsorption of Ca and reduce PO4 reabsorption at PCT
99
where is the EPO receptor expressed?
on immature RBC forms in marrow
100
does [inulin] affect its clearance?
no bc its freely filtered
| -only depends on pressure at glomeruli and GFR
101
what are urobilinogen and urobilin?
digested bilirubin
- urobilinogen: colors stool
- urobilin: colors urine
102
when can heme reversibly associate with O2
- when iron is in ferrous state (Fe2+)
| - if we oxidize iron into ferric state (lose an electron), it cannot bind O2
103
what is transport?
amount filtered - amount excreted
104
describe the different types of nephrons
- Superficial and midcortical (short nephron loops, efferent arterioles supply peritubular caps.)
- Juxtamedullary (long loops, efferent arterioles supply peritub. cap. AND vasa recta)
105
where is transferrin synthesized and what does it do?
- synthesized in liver mainly (also in testes and CNS)
| - binds/transports 2 irons
106
describe what physiological anemia of the newborn is
prior to birth, babe is hypoxic= EPO high= RBC high
-after birth, O2 status improves, EPO/RBC drops, and breakdown of unnecessary RBCs and loss of stimulus to BM to make RBC
107
what 6 factors influence hemoglobin O2 saturation?
1. partial pressure of O2
2. oxygenation
3. effects of 2,3 BPG (less in babies)
4. pH
5. pCO2
6. age
108
how do you determine blood types?
lipids in membrane are glycosylated
A: agglutingoen-A, Antiglutins- anti-B
B: agglutingoen-B, Antiglutins- anti-A
O: agglutingoen-none, Antiglutins- anti-B, anti-A, anti-AB
AB: agglutingoen-A and B, Antiglutins- none
(agglutinogens- antigens that stimulates agglutinins/anti-Ab)
109
what mechanisms go on in prox. DCT
- reabsorption of Na/Cl (Na/Cl symport)
- filtrate is hypo-osmotic w/ respect to plasma
- not water permeable
110
how does altitude affect EPO
lower pO2 so EPO levels double compared to at sea level
111
the O2 carrying capacity of blood is a function of what?
1. amount of O2 dissolved in plasma (very small)
+
2. amount of O2 bound to Hgb
112
What is SaO2?
saturation of hemoglobin with O2 in arterial blood. This is a fxn of the degree to which hemoglobin is associated with O2 relative to the maximum amount of hemoglobin
113
increased SNS activity has what effect on GFR, renin secretion, and Na reabsorption
- decrease GFR
- increase renin secretion
- increase prox. tubule Na reabsorption
114
65-70% of reabsorption occurs in the PTC due to what?
brush border cells and large SA --> microvili
*have a lot of mito to provide energy for Na/K ATPase
115
describe Hgb w/ no 2,3 BPG present
- acts as myoglobin (high affinity for O2 and poor transporter of O2)
- shifts Hgb%sat. x pO2 curve to left and steeper
116
Increased ANP/BNP has what effect on GFR, renin secretion, Na reabsorption and ADH?
- increase GFR
- decrease renin secretion
- decrease aldosterone secretion
- decrease Na reabsorp. by CD
- decrease ADH secretion
117
Describe bilirubin conjugation
-UDP-glucuronic acid is added to bilirubin via UDP-glucuronsyl transferase to enhance its water solubilty
118
where are the glomeruli located?
ALL live in cortex
119
what molecule is an oxygen reservoir and what molecule is a an oxygen transporter?
oxygen reservoir- myoglobin
| oxygen transporter- hemoglobin
120
describe what happens when O2 binds to Hgb (Bohr effect)
*occurs mostly in lungs
Hgb changes shape and salt bridges break--> exposes His residue (pKa 6.1) w/ a proton on it --> proton dissociates (picked up by bicarb)
*Hgb acts as weak acid
121
describe tubuloglomerular feedback
helps regulate GFR and RBF by macula dense sensing
- high Cl---> signals to decrease GFR
- low Cl--> signals to increase GFR
122
what is Barts hemoglobin?
an alpha thalassemia where all 4 genes that make alpha chains are gone
- 4 gamma chains in utero results in high affinity for O2 (doesn't let it go)
- results in CHF and fetal hydrops (intense edema all over)
123
how does a pyruvate kinase deficiency affect Hgb affinity for O2?
leads to build up on intermediates including 2,3 BPG
| -Hbg will have a lower affinity for O2 and drop it off more readily (shift to right)
124
-the only barrier to filtration between vascular and urinary space
```
Basal lamina
(non-cellular. Made of collagen and protein w/ neg. charge)
```
125
kidneys recieve __% of cardiac output
20%-25%
- and always has a high flow rate through renal artery
- series resistance (AA--> glomerulus--> EA)
126
when are high levels of 2,3 BPG beneficial?
- when our bodies are hypoxic (ie. in utero)
| - less O2--> large + pocket in Hgb--> high affinity for 2,3 BPG--> lowers affinity for O2 and drops off O2 readily
127
how is K handled in the kidney?
- filtered, reabsorbed (PCT, TAL) and secreted (DCT, CCD)
| - typically excretes 15% of K+ filtered load but CAN excrete 80%
128
what are natiuretic peptides
-promotes NaCl and water excretion in response to increased pressure or ECV (ie. increase NaCl consumption or CHF)
129
explain how PAH is handled by the nephron
-some is filtered at the glomerulus
-ALL is actively secreted back into nephron (MAX secretion), and ALL is excreted in urine
(substance X)
130
what hormones influence potassium
insulin, epi, and aldosterone
* all stimulate the uptake of K+ via Na/K ATPase
* these are short term regulators
131
what cells in the DCT reabsorb HCO3:
```
intercalated cells
(secrete K and reabsorb HCO3)
```
132
describe the changes of oncotic pressure in the renal vasculature
- in RA and AA: constant at baseline
- at GC to EA: increase as fluid leaves vasculature and proteins stay
- in EA: no reabsorption, steady
- in PTC to SV: fluid reenters vasculature (reabsorption)
133
what gases found in blood?
- CO2 (most CO2 is in form of bicarbonate)
- O2 (10x Co2 dissolving than O2-O2 not readily dissolved in liquid medium)
- N2
134
does [glucose] affect its clearance?
Yes!-like in DM
increase [glucose]= increased clearance
-normally clearance is 0 bc all glucose that was freely filtered was reabsorbed and nothing shows up in uine
135
Venous blood comes back around __% oxygenated and leaves the lungs around ___% oxygenated
venous blood- 75%
| blood from lungs- 97.5%
136
explain how glucose is handled by the nephron
- some is filtered at the glomerulus
- 100% is reabsorbed into peritubular lumen (none excreted in urine)
(substance Z)
137
describe the filtrate in the PTC
- isosmotic w/ respect to plasma
| - therefore, we need electrolytes and water moving out in order to keep this balance
138
describe how oxygenations influences Hgb binding of oxygen
- Hgb changes shape w/ each binding of oxygen
- each O2 binding leads to greater affinity for the next oxygen
- p50 for each site decrease (p50 site 1=32, site 3=1.8)
139
define the concept of clearance
the clearance of a substance is the volume of plasma from which that substance is completely cleared by the kidneys per unit of time. (units: volume/time)
aka: it is a measure of the volume of plasma from which the substance would have to be completely removed to account for the mass in the urine.
140
describe Hct, RBC, Hb, fMCV, MCH, and MCHC in males and females
- Hct, RBC, and Hb are higher in males
- MCV: indicator of RBC well being (fL)
- MCH- gram weight of Hb per cell (pg)
141
how does pCO2 levels affect Hgb affinity for O2
high pCO2= lower affinity for O2
142
what happens when transferrin binds to its receptor on cell membrane of RBC precursors and hepatocytes?
binding of transferrin to receptor stimulates endocytosis of the complex-->acidic environment in the endosome--> iron dissociates from transferrin into ferrous state--> iron stored as ferritin
143
describe how hemoglobin composition changes with age
-Embryo: epsilon and zeta chains (drops off quickly)
-Fetus: alpha and gamma chains increase (HgbF)
-at birth: alpha stays high, gamma drops, beta increase (HgbA1) and alpha + delta chain = HgbA1 (low amounts)
*fetal gamma chains still present in low amounts throughout life
*
144
explain how electrolytes (Na, Cl, K, etc.) are handled by the nephron
- some is filtered at the glomerulus
-SOME is reabsorbed into peritubullar lumen, SOME is excreted in urine
(substance Y)
145
describe the circulating concentrations of EPO
- great individual variation (low concentration in normoxia)
| - diurnal fluctuations- lowest in the a.m.
146
how does pH affect K secretion?
acidosis causes:
- Na/K ATPase inhibition (takes away gradient to facilitate Na reabsorption and K secretion)
- reduction in membrane permeability
147
describe the p50% in myoglobin and hemoglobin and what that means
- low p50% in myo. (at low pO2 pressures, 50% of myo. will be sat. w/ oxygen)
- high p50% in hemo. (takes hight pO2 for it to become 50% sat. w/ O2)
* myo. releases O2 if SEVERELY hypoxic, hemo. release O2 if MILDLY hypoxic
148
what are the solutes and solvents in blood?
- plasma weight is 93% water
| - electryolytes (Na, K, Ca, Mg)
149
how does hexokinase deficiency affect Hgb affinity for O2?
-prevents glycolysis from proceeding forward--> no intermediates like 2,3 BPG
-Hgb will have a higher affinity for O2 and be a poor O2 transporter (symptomatic anemia)
(shift to left)
150
where is the iron distributed throughout the body?
70% in Hgb in RBCs
25% in ferritin in liver
4% in myoglobin in muscles
-some in BM, reticuloendothelial macrophages, cofactors (cytochromes, transferrin, catalase)
151
how does temperature affect Hgb affinity for O2?
elevated temperatures= lower affinity for O2
152
what stimulate PTH release
low [Ca]
153
describe Hgb w/ elevated 2,3 BPG present
- low affinity for O2 and drops off O2 readily
| - shifts Hgb%sat. x pO2 curve to right
154
how can an anemic person have a normal pulseox reading?
pulseox is not sensitive to overall [Hgb]. Their Hgb becomes 100% saturated at a lower pO2 bc they don't have very much Hgb present in the first place and it becomes oxygenated readily
155
why is a pulseox of 90% dangerous?
pO2 and O2 sat. of Hgb relationship is sigmoidal. At Hgb % sat. 90 (pulseox 90) the curve has a steep slope indicating severe drop in pO2 (pO2=60mmHg)
156
What does heme need to carry oxygen? and how is it delivered?
heme needs iron to carry oxygen
| -iron is delivered by transferrin (receptors live on immature RBCs)
157
describe how Hb A, Hb K, and Hb R mutations affect affinity and p50
Hb A: normal, p50=25mmHg
Hb K: (a/b contact) lower affinity, shifts curve to right, p50= 70mmHg
Hb R: (BPG site) higher affinity, shifts curve to left, p50= 10mmHg
158
how is p50 releated to O2 affinity?
inversely related
| low p50 = high affinity for O2
159
what is the main activity of the PCT?
reabsorption
160
describe the mechanisms of Ca reabsorption in the PCT and TAL
* 90% of Ca reabsorption
1. uptake of Ca via Ca ATPase
2. 3Na(in)/Ca exchange pump
3. Ca enters at apical membrane via [gradient]
4. paracellular route via tight jxns and [gradient]
161
what do the prinicple cells do in the late DCT
- reabsorb Na and Cl
- Actively secrete K (major site where K is being introduced into lumen)
- sensitive to aldosterone
162
why is it dangerous to give neonates too much oxygen?
their fetal Hgb that is still circulating will bind up the oxygen because it has a high affinity and will not let it go. High oxygen levels above 100mmHg damages the retina and causes blindness
163
where is most of the K+ stored?
tissue (muscle, RBC, liver, bone)
*90-95mEq excreted per day by kidneys
164
aka packed cell volume
hematocrit
165
what waste products are found in blood?
1. urea (from protein)
2. creatinine (from creatine-used to est. GFR)
3. uric acid (from nucleic acids)
4. bilirubin (from heme)
166
where is EPO synthesized?
- mainly in kidney by peritubular fibroblasts
| - also liver, spleen, lungs, brain
167
If filtered load exceeds the amount that was excreted= ____
If amount excreted exceeds the filtered load=_____
reabsorption
secretion
168
the amount excreted is equal to what?
filtered load - amount reabsorbed + amount secreted
169
what is iron lost from our system?
- the human body has not evolved a mechanism to clear excess iron
- 1-2mg/day of iron is loss via sloughed mucosal cells, menstruation, desquamation, other blood losses
