Acid-Base balance

Question 1

why do need to keep pH level good?

Answer 1

• enzymes active site will denature if wrong pH

Question 2

is pH same throughout a cell?

Answer 2

No - varies in the different places

Question 3

what are the normal pH blood limits?

Answer 3

7.35 (venous) to 7.45 (arterial)

Question 4

what is name of when blood is too a) acidic? b) alakline?

is blood outside normal pH range compatible with life?

Answer 4

below 7.35: acidosis (acidaemia)

above 7.45: alkalosis (alkalaemia)

( outside pH range- can still exist, but leads to disturbance of body functions - disrupts enzymes and ECT in mito)

Question 5

which pH ranges lead to death?

Answer 5

Below 6.8 and above 8.0 = DEATH

Question 6

Where do most H ions originate from in normal human body?

Answer 6

H ions orignate from:

• cellular metabolism (aerobic resp = carbonoic acid, anaerboic resp = lactacte acid)
• breakdown of foods ( oxidation of sulfur contain amino acids in foods like protein = sulfuric acid, incomplete oxidation of fatty acid = acidic ketone bodies)

/

MAIN SOURCE OF H+ IS FROM AEROBIC RESP - C02 TURNING INTO CARBONIC ACID

even though disease states can produce even more (e.g. diabetic keto acidosis)

Question 7

what are the figures produced of co2, lactic acid and acid in diet per day?

Answer 7

• 15 mol/day of CO2 metabolically produced -> leads to carbonic acid
• 1.5 mol/day of lactic acid metaboliicaly produced
• 60 mmol/day produced by diet (posphoric and sulphuric) and metabolism (ketoacids)

Question 8

the concentation of hydrogen ions is regualted by which systems?

how long does it take for each system to regulate?

Answer 8

1. chemical buffer system in blood and ICF
   - immediate action
2. Respiratory centre in brain stem
   - acts within 1-3 minutes

3. kidneys

- hours to days

Question 9

(how does a buffer work?)

Answer 9

(bind or releases H+

consists of a weak acid and the salt of that acid functioning as a weak base)

Question 10

what are the three major chemical buffer systems in the body?

Answer 10

Bicarbonate (HCO3-) buffer system

Proteins (Hb and albumin) buffer system

Phosphate buffer system

Question 11

what is the equation for bicarbonate buffer?

what is the enzyme used?

Answer 11

Question 12

which proteins in blood can act as buffers? (2)

Answer 12

Haemoglobin, Albumin

(In alkaline env, a.a. acts as an and releases H+

In acidid medium amino acd acts as base and absorbs H+)

Question 13

where do you find each buffer?

Answer 13

Bicarbonate: Blood

Proteins: In / out cells

Phosophate: In the cell

Question 14

what is the normal anion gap?

how do you measure?

Answer 14

• measure the conc of Na, Cl and HCO3- in blood. - cations should be greater by anions by 8 to 12 mEq/L.
• (remember cations = anions)

[Na+] - ([Cl-] + [HCO3-]) = 8 to 12 mEq/L

Question 15

which is the second line of defense of blood pH?

Answer 15

the resp. centre in the lungs

Question 16

how does resp. centre change acid levels?

Answer 16

How? Eliminate or retain CO2

• CO2 transported into rbc as HCO3-
• HCO3 recombines to CO2 and H20 when in capil. next to lungs
• CO2 expelled via respiration - reduces the acid levels (increased CO2 in blood increases likelihood of acidosis)

centre only deals with volatile acids (CO2)

Question 17

how do you control acid / base balance (physiologically?) via resp. centre?

what controlled by?

how quick is change?

Answer 17

• alter rate and depth of respirations
• change incurred by Pons and medulla
• rapid change

Question 18

what are normal co2 levels/

Answer 18

35 to 45 mm Hg

OR

4.7-60 kPA