Acid/Base

Question 1

What is the ref range for blood conc?

Answer 1

35-45 nmol/L

Question 2

What is the Henderson-Hasslebach equation?

Answer 2

pH =pKa + Log ([A-]/[HA])
- the lower the pKa value the stronger the acid

Question 3

Describe Alkalosis

Answer 3

• condition where the body fluids have the excess base alkali
• decreased CO2 or increased bicarbonate in blood
• examples = respiratory, metabolic, hypokalemic

Question 4

Describe Acidosis

Answer 4

• when your body fluids contain too much acid
• it occurs when your kidney & lungs can’t balance pH
• types = respiratory & metabolic

Question 5

What is the first line of defence against a pH shift?

Answer 5

Chemical buffer system
- bicarbonate buffer
- phosphate buffer
- protein buffer

Question 6

What is the 2nd line of defence against pH shifts?

Answer 6

physiological buffers
- respiratory mechanism (CO2 excretion)
- renal mechanism
(H+ excretion)

Question 7

Describe Carbonic Anhydrase

Answer 7

• enzyme found in RBCs, gastric mucosa, pancreatic cells & renal tubules
• carbonic acid is converted into CO2 & H2O by this enzyme

Question 8

What regulates the elimination of CO2 in the lungs ?

Answer 8

the respiration rate

Question 9

What happens when there is a rise in CO2 levels?

Answer 9

• rise in CO2 = low pH which is detected by chemoreceptors in the medulla oblongata, carotid & aortic body

Question 10

What can a decreased ventilation efficiency result in?

Answer 10

• CO2 retention in blood
• along with increased in blood conc - acidosis may occur

Question 11

What the renal control of the acid base balance ?

Answer 11

1. filtration
2. reabsorption
3. secretion

Question 12

Describe filtration in renal control of acid/base balance

Answer 12

• blood plasma & other dissolved substances get filtered into the glomerular capsule
• glomerulus –> glomerular capsule

Question 13

Describe reabsorption in renal control of acid/base balance

Answer 13

• water, ions & other substances reabsorbed
• occurs in renal tubule & collecting duct
• goes from the renal tubule lumen –> peritubular capillaries
• ultimately back into the blood

Question 14

Describe Secretion in the renal control of acid/base balance

Answer 14

• wastes, drugs & excess ions are secreted from the peritubular capillaries into the renal tubule
• these substances eventually make their way to the urine

Question 15

What is the consequence of bicarbonate entering the lumen of the proximal tubule ?

Answer 15

• its unable to escape
• it can’t be reabsorbed directly

Question 16

What are the consequences of acidosis ?

Answer 16

• raised CO2
• Raised H+ in plasma

Question 17

Describe normal lung function

Answer 17

• expels CO2 & push equilibrium to the left
• greater formation of carbonic acid
• pH in plasma raised
• depletes H+ conc.

Question 18

What are some causes of metabolic acidosis ?

Answer 18

• increased production of H+
• ingestion of drugs metabolised to acids
• impaired excretion of H+ via kidneys
• loss of bicarbonate in urine or GI tract

Question 19

What are the lab findings for acute metabolic acidosis ?

Answer 19

pH = decreased
pCO2 = normal
[HCO3] = decreased

Question 20

What are the lab findings for compensated metabolic acidosis ?

Answer 20

pH = normal
pCO2 = decreased
[HCO3] = decreased

Question 21

What are the causes of metabolic alkalosis ?

Answer 21

• loss of hydrogen ions in vomit
• potassium deficiency
• large doses of an alkali-sodium bicarbonate

Question 22

What are the lab findings for acute metabolic alkalosis ?

Answer 22

pH = increased
pCO2 = normal
[HCO3] = increased

Question 23

What are the lab findings of compensated metabolic alkalosis ?

Answer 23

pH = normal
pCO2 = normal/slight increase
[HCO3] = marked increase

Question 24

Define COPD

Answer 24

Chronic Obstructive Pulmonary Disease
- flow of air into & out of the lungs is impaired

Question 25

What are the 3 mechanisms of airway obstruction?

Answer 25

1. lumen partially occluded by excessive secretions 2. causes in the wall of the airway 3. outside the airway destruction of the paranchyma may cause loss of elasticity & narrowing

Question 26

Describe acute cases of respiratory acidosis

Answer 26

- acute within minutes or hours - non-compensated as it can take 48-72 hours for bicarbonate reabsorption to occur - hypoventilation = an increase in pCO2 & H+ will rise in the blood

Question 27

What are the lab findings for acute respiratory acidosis ?

Answer 27

pH = low pCO2 = increased [HCO3] = normal/slight increase

Question 28

What are the lab findings for compensated respiratory acidosis ?

Answer 28

pH = normal pCO2= increased [HCO3] = increased

Question 29

Describe respiratory alkalosis

Answer 29

- less common - acute no renal compensation - hysterical over-breathing -hypoxia - raised intracranial pressure