Acid-Base

Question 1

pH

Answer 1

from 0 to 14
from Acid to Basic/Alkaling
7 is neutral
value can go beyond the scale

pH: potential of Hydrogen. Less H+ -> pH increase. More H+ -> pH decrease. pH inversely indicate hydrogen concentration.

Question 2

Henderson - Hasselbach equation

Answer 2

pH= pKa + log10([Base]/[Acid]) 
Ka: acid dissociation constant 
strength of acid: acid dissociate in solution and release H+
[] = concentrations
=> [HCO3]/[CO2] 
=> HCO3 up => pH up (less acid)
=> CO2 down => pH up (less acid)
Describes how a buffer can resist change

Question 3

Buffer

Answer 3

pH/Hydrogen buffer
Keep pH at nearly constant value regardless of the other things in the solution

blood kept between 7.35-7.45. outside range acidosis/alkolosis. Inside range does not mean no acidosis/alkolosis but then it is compensated !

H+ bind to buffer
equilibrium from strong acid & conjugate base

carbonic acid(H2CO3): raise pH, if dissociate into HCO3- it lower pH
bicarbonate(HCO3-): raise pH
hemoglobin
phosphate

Question 4

Hemoglobin

Answer 4

carry oxygen in red blood cells
CO2 -> HCO3- (bicarbonate)
Hydrogen buffered by hemoglobin to preserve pH
CO2 enters rbc -> combines with water -> H2CO3 (carbonic acid) -> dissociate H+, HCO3- (bicarbonate) -> uptake CO2 in blood

Question 5

Acid base balance

Answer 5

respiratory system contribute to blood levels carbonic acid(H2CO3), equilibrium CO2

Hold breath -> CO2 increase -> carbonic acid(H2CO3) -> pH down Resiration Rate up Depth up -> CO2 down -> pH up

Question 6

Mean Corpuscular Volume (MCV)

Answer 6

average volume of red blood cells

Hct x 10 / [RBC]

Hct: hematocrit, proportion of red blood cells

Question 7

Blood gazes

Answer 7

group measured to evaluate pH, O2, CO2 of blood
lung function evaluation & acid base balance

Acid blood gazes (ABG): measure acidity pH, O2, CO2, HCO3 (bicarbonate), O2 saturation, lactate levels. How well lung moves O2 and removes CO2. Taken from radial artery usually.

Venous Blood Gazeds (VCG): similar to ABG but O2/CO2 levels are a bit different

Question 8

Lactate

Answer 8

byproduct anaerobic respiration

Question 9

Oxygen saturation

Answer 9

oxygen saturated hemoglobin relative to total hemoglobin.

hemoglobin has 4 binding sites, saturated when all 4 are bound

Question 10

Acidosis/ Alkalosis
Respiratory/ Metabolic
Compensated or not

Answer 10

Acidosis: pH lower
Alkalosis: pH above
Respiratory: CO2 a lot outside range
Metabolic: HCO3- a lot outside range

Respiratory acidosis: CO2 above
Respiratory alkalosis: CO2 under
Metabolic acidosis: HCO3 under
Metabolic alkalosis: HCO3 above

Compensated respiratory acidosis: pH normal or slightly under and HCO3 above
Compensated respiratory alkalosis: pH normal or slightly over and HCO3 under
Compensated Metabolic acidosis: hyperventilation
Compensated Metabolic alkalosis: hypoventilation

Question 11

HCO3-

Answer 11

bicarbonate

binds H+, raise the pH

Question 12

Hypoventilation / Hyperventilation

Answer 12

hypo: increases the concentration of carbon dioxide in the blood and decreases the blood’s pH
hyper: decrease the concentration of CO2 which increase the pH

Question 13

Henry’s law

Answer 13

C (gaz pressure) = K(constant)*P(pressure)

can compute pH
respiration: predict how gazes dissolve in alveoli and bloodstream during gaz exchange
amount of oxygen that dissolve into the bloodstream -> directly proportional to the partial pressure of oxygen in alveolar air

low oxygen pressure in deoxygenated blood -> oxygen dissolve

Question 14

Partial pressure

Answer 14

fractional pressure: percentage the molecule occupy the solution
partial pressure: fractional concentration x total pressure

Question 15

Alveolar ventilation

Answer 15

rate at which new air reaches alveoli

goes up -> pCO2 goes down -> pH goes down

Question 16

Dead space air

Answer 16

air that don’t reach alveoli but only reach nose, pharynx, trachea
the air that is 1st exhaled

Question 17

Blood flow

Answer 17

BF goes up then -> Oxygen saturation goes down -> BF goes up

Question 18

Chemical control respiration

Answer 18

maintain O2, CO2, H+
CO2 and H+ have direct impact on strength

Respiratory center has a chemosensitive area: central chemoreceptors

There are periphereral chemoreceptors

Question 19

Central chemoreceptors

Answer 19

ventral surface of the medulla
sensitive to blood PCO2 & H+ -> excite rest of respiratory center
More sensitive to H+ but it hardly cross the blood brain barrier
CO2 cross easily -> water and carbonic acid (H2CO3) -> H+ and HCO3- (bicarbonate) then it reacts to this H+
PCO2 goes up -> pH goes down -> central chemoreceptors triggered

Question 20

Peripheral chemoreceptors

Answer 20

mostly in carotid bodies (gassopharyingeal nerve), some in aortic bodies (vagus nerve) -> only exposed to arterial blood
Detect O2 (and a bit CO2, H+)

PO2 down (or PCO2,H+ up) -> chemoreceptors stimulated -> fires vagus and glassopharyngeal nerve -> decrease HR, contractility. diaphragm faster and deeper.

respiratory center communicate with cardiovascular center !

faster than central chemoreceptors but less powerful