Physiology: Pulmonary Block, Chapter 8

Front 1

do changes in pH represent a small or large change in the concentration of H+ ions?

Back 1

small changes in pH represent a huge change in h+ concentrations - note that to go from 7.4 to 7.7 is a HALF CUT of ion concentration, despite moving only .3 pH units.

Going from 7.4 to 7.1 = a DOUBLING of H+ concentration.

Front 2

what are the different sources of acid in the body? how are they gotten rid of?

Back 2

most comes from metabolic activity, of which most is Co2. This is combined with water to form carbonic acid (h2Co3), which can disassociate into H+ and HCO3-.

This is then sent to the lungs, reversed, and expelled.

Carbonic acid is VOLATILE - breathable.

Other acids (sulfuric, hydrochloride, keto, etc) are removed by the kidney VERY SLOWLY and represent only 0.2 % of total body acid.

Front 3

what's the main buffer in the body? what needs to happen for it to work?

Back 3

Bicarbonate - you need to be breathing, getting converstion back to Co2 and water, otherwise it'll all get used up.

Front 4

carbon acid and CO2 - both represent Co2, which form is more common in the blood?

Back 4

dissolved Co2 is 1000x more common than carbonic acid.

Front 5

as the concentration of blood proteins rises (say, more Hb), what happens to the amount of bicarbonate around as Co2 concentrations go up?

Back 5

Hg and phosphate and other proteins are buffers which can absorb the H+ ion that comes off carbonic acid, meaning an increasing amount of bicarbonate will be around.

Front 6

in addition to Hb and bicarb, what are other important buffers in the body?

Back 6

phosphate compounds (glucose 1 phosphate and ATP in particular).

imidazol groups in the histidine residues of peptide chains!

Front 7

what happens to change Hb's affinity for the H+'s given off by Co2's disassociation?

Back 7

Remember that Hb's acid/base characteristics change based on how many O2's are bound.

Think in the tissues - want to accept H+'s to allow the formation of bicarbonate, meaning that in the DEOXY STATE, HB is a better BASE.

in the lungs, oxyhemoglobin acts as a stronger ACID, which makes the H+ fall off so it can convert bicarbonate back into Co2.

Front 8

what's the big buffer in the interstitial fluid?

Back 8

bicarb. there's more IF than plasma in the body, so this matters.

Front 9

what does chronic high acidosis do to bones?

Back 9

degrades them - the Ca and phosphate in bones acts as a buffer - if they're constantly being used for buffering isntead of being bones, bad news.

Front 10

what about intracellular buffering?

Back 10

mostly things like ATP and glucose-1-phosphate - intracellular proteins.

in red blood cells, have lots of Hb, so that does it.

Front 11

in simple respiratory acidosis, what happens to the concentration of bicarb? what about the ratio of bicarb to Co2?

Back 11

the total bicarb concentration increases - think that the extra Co2 that happens during depressed breathing and respiratory acidosis is going to force an H+ off carbonic acid, which will generally be absorbed by another buffer (Hb, etc).

This leaves our bicarbonate floating around.

however, the ratio of bicarb to Co2 decreases (lots more Co2 floating around overwhelms the relative increase in bicarb creation)

Front 12

simple respiratory acidosis - how does the buffer line/position on the buffer line change? what about the isobar?

what about metabolic acidosis?

Back 12

stay on the original buffer line, but move backwards to make a NEW isobar (isobar reflects Co2 concentration) (reflecting a drop in pH and a rise in bicarb).

in metabolic acidosis, move on the ISOBAR, making a new BUFFER line. In acidosis, move down the isobar.

Front 13

respiratory alkalosis - what's up?

Back 13

move down the same buffer line to a new isobar, reflecting an increase in pH, decrease in H+, and a decrease in bicarbonate. Note that the bicarb to Co2 ratio is INCREASING here, which again seems weird.

think that the bicarb to co2 ratio does the opposite of the absolute bicarb concentration. Or, imagine that you can cause alkalosis by administering bicarb - the ratio to Co2 increases.

Front 14

what are some causes of repiratory alkalosis?

Back 14

hyperventilation, high altitude, anxiety, progesterone, ASPRIN, asthma (they usually hyperventilate)

Front 15

metabolic acidosis - what happens to the amount of bicarb? what about the ratio of bicarb to Co2?

Back 15

the ratio for acidosis will always DECREASE in acidosis - again, think that bicarb is your buffer and that without it, more acidosis will happen.

the amount of bicarb is different here than in respiratory - imagine that the cause of metabolic acidosis is the LOSS of bicarbonate (alkalosis happens from eating too many tums) - so where as bicarb rose in respiratory acidosis, it FALLS in metabolic acidosis.

Front 16

what are common causes of metabolic acidosis?

Back 16

alcohol, methanol, aspirin overdose (causes first met acidosis, then resp alkalosis).

possible loss of bicarb ions (diarrhea, renal dysfunction)

lactic acidosis, ketoacidosis, shock,

Front 17

metabolic alkalosis - how does this affect the bicarb and bicarb to co2 ratio?

Back 17

metabolic alkalosis will raise the amount of bicarb (think that this is one way you can GET metabolic alkalosis, eat lots of tums). the ratio of bicarb to Co2 will always RISE in alkalosis.
For ratio, again imagine that what's important is the Co2 concentration - in alkalosis, it's decreasing so there's more bicarb, relatively.

Front 18

what are some causes of metabolic alkalosis?

Back 18

vomiting up all your gastric bicarb, diuretic therapy, overproduction of steroids, antacid overdose.

Front 19

if experiencing metabolic acidosis, what fixes it? what about respiratory acidosis?

what does renal compensation control?

Back 19

respiratory compensation. also, renal compensation.

if respiratory, problem with breathing - so kidneys alone step in. this take a while longer.

kidneys can control the amount of bicarb kept in the blood and H+ filtered out into the urine.

Front 20

pH, Co2, and bicarb - how can you tell what the problem is by looking at their relative movements?

Back 20

look at pH - this tells you if it's acidosis/alkalosis.

look at Co2 - if its value explains the condition (pH is low, Co2 is high, this makes sense), you're done.

for example, if pH is low and pCo2 is unchanged, we're talking metabolic acidosis.

if they don't jive (pH is low but Co2 is low), then you're talking compensation - here, it'd be compensated respiratory.

quick note - if pH and bicarb point opposite directions, dealing with both respiratory and metabolic.

Front 21

what is the anion gap and how is it calculated?

What is it useful for?

Back 21

Na+ - [Cl- + HCo3-]

should be around 12 meq/L

idea is that there is more Na+ than these other ions, so there's a gap to be made up.

good for helping guess where acidosis/alkalosis is coming from.

in acidosis, H+'s are made that bind with bicarb, which is then blown off, meaning that you're loosing your big anion, so the GAP increases.