Renal acid-base balance

Question 1

Acid:

Answer 1

Substance that donates protons

Question 2

Base:

Answer 2

Substance that accepts protons

Question 3

pH of extracellular fluid =

Answer 3

7.4

Question 4

pH of blood is between

Answer 4

7.35 - 7.45

Question 5

Acidosis pH

Answer 5

< 7.35

Question 6

Alkalosis pH

Answer 6

> 7.45

Question 7

Buffers are usually:

Answer 7

• Weak acid and conjugate base

- Weak base and conjugate acid

Question 8

pH of blood is regulated by what systems?

Answer 8

• Chemical (milliseconds)
• Respiratory (minutes)
• Renal system (hrs-days)

Question 9

Why are acids being constantly created in the body?

Answer 9

Diet: aminoacids, fatty acids
Metabolism: Co2, H2O, lactic acid, uric acid, ketone bodies

Question 10

Important respiratory buffers:

Answer 10

• HCO3-

Question 11

Important blood buffers:

Answer 11

• HCO3-
• Phosphate
• Proteins (Hb, albumin)

Question 12

Important kidney buffers:

Answer 12

• HCO3-
• Phosphate
• Ammonia

Question 13

Phosphate buffer system:

Answer 13

H2PO4- H+ + HPO4 2-

Question 14

Alpha intercalated cells can:

Answer 14

Secrete H+ and form new HCO3-

Question 15

How is ammonia formed?

Answer 15

Breakdown of glutamine

Question 16

Glutamine can be broken down into …

Answer 16

HCO3- and NH3+ (which can act as a buffer)

Question 17

H+ secretion ceases when …

Answer 17

Urine pH falls to 4.5 - so any additional H+ must be buffered in the filtrate

Question 18

Accumulation of CO2 in the blood stream.

Answer 18

Respiratory acidosis

Question 19

Decreased pCO2 in blood:

Answer 19

Respiratory alkalosis

Question 20

Normal p(CO2)

Answer 20

35-40 mmHg

Question 21

Causes of respiratory acidosis:

Answer 21

• Obstruction
• Reduced gas exchange (pneumonia, emphysema)
• CNS disease and depression
• Depression of respiratory centers (narcotics, anesthetics)
• Respiratory muscle problems (e.g. MG)

Question 22

Causes of respiratory alkalosis:

Answer 22

• Hyperventilation due to anxiety
• Over ventilation on ventilator (iatrogenic)
• High altitudes
• Fever

Question 23

Metabolic acidosis:

Answer 23

Gain of acid, loss of bicarbonate

Question 24

Metabolic alkalosis:

Answer 24

Loss of acid, gain of bicarbonate

Question 25

Causes of metabolic acidosis:

Answer 25

- Taking acids: aspirin, alcohol, protein, antifreeze - Excercise - Ketone bodies in T1D - Diarrhoea

Question 26

Causes of metabolic alkalosis:

Answer 26

- Ingestion of base: antacid, fruits - Vomiting - K+ loss from diuretic abuse (thiazide, loop)

Question 27

Compensatory mechanisms of the lungs:

Answer 27

- Acidosis --> ventilate more | - Alkalosis --> ventilate less

Question 28

Compensatory mechanisms of the kidneys:

Answer 28

- Acidosis --> secrete more H+, generate more HCO3- | - Alkalosis --> not reabsorbing HCO3- from PCT

Question 29

3 questions to ask when interpreting ABG:

Answer 29

- Acidosis or alkalosis? - Respiratory or metabolic? - Compensatory state?

Question 30

How to determine which system is primary problem:

Answer 30

p(CO2) abnormal only -> resp | HCO3- abnormal only -> metabolic

Question 31

You will never have a case with p(CO2) and HCO3- ...

Answer 31

One is high and the other is low.

Question 32

Acid pH High p(CO2) High HCO3-

Answer 32

Respiratory acidosis

Question 33

Acid pH Low p(CO2) Low HCO3-

Answer 33

Metabolic acisosis

Question 34

Basic pH High p(CO2) High HCO3-

Answer 34

Metabolic alkalosis

Question 35

Basic pH Low p(CO2) Low HCO3-

Answer 35

Respiratory alkalosis

Question 36

Why are infants at a greater risk of acid-base imbalance?

Answer 36

- Lower lung volume - Inefficient kidney - Excessive fluid shift - High rate of water loss - High metabolic rate

Question 37

What are elderly people at greater risk of acid-base imbalance?

Answer 37

- Not responsive to thirst queues | - Decrease in total body volume - slow homeostasis