Mechanisms of obtaining acid base balance Flashcards Preview

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Flashcards in Mechanisms of obtaining acid base balance Deck (21):
1

Where in the tubule does resorption of bicarbonate happen?

PCT

 

TALLH

 

Collecting duct

2

How is bicarbonate resorption important in controlling acid base balance in the body?

Bicarbonate resorption determines the acidity or alkalinity of the blood

 

Bicarbonate is freely filtered by the glomerulus

 

Needs to be reabsorbed

3

Is bicarbonate resorption an active process?

Yes - uses a lot of energy

4

What is the normal concentration of bicarbonate in the urine?

40 mmol/L

5

What causes proximal renal tubular acidosis?

Disease in PCT

 

Means there is innapropriate reabsorption of bicarbonate ions

 

Bicarbonate will be present in the blood at low concentrations

6

What causes acute respiratory acidosis?

Decreased CNS stimulation - sedative drugs

Neuromuscular ventilatory failure

 

Structural/ mechanical ventilatory failure

 

Airway obstruction - asthma and inhaled foreign object

7

What causes chronic respiratory acidosis?

Decreased CNS stimulation - cerebral disease

 

Neuromuscular ventilatory failure - ALS, DMD

 

Structural/ mechanical ventilatory failure - obesity, thoracic deformities

 

Chronic airway obstruction - COPD

8

What causes acute respiratory alkalosis?

Increased CNS stimulation - anxiety or drugs

 

Subarachnoid haemorrhage

 

Mechanical over-ventialtion of an intubated patient

9

What causes chronic respiratory alkalosis?

Increased CNS stimulation - stroke

 

Increased hypoxic drive - high altitude

10

How does the PCT reabsorb bicarbonate?

Apical surface - NHE transporter (sodium hydrogen exchanger)

Sodium enters and hydrogen leaves the cell

Hydrogen is pumped out and combines with bicarbonate ions at the brush border

Carbon dioxide is formed from the carbonic acid produced

 

Carbon dioxide formed enters the cell

 

Carbon dioxide combines with the water to form protons and bicarbonate ions

 

Protons are transported out via NHE

 

Bicarbonate ions are reabsorbed into the basolateral membrane

11

What catalyses the breakdown of carbonic acid into carbon dioxide and water?

Carbonic anhydrase

12

What powers the sodium hydrogen exchanger (NHE)?

Sodium potassium ATPase

 

Sodium enters down its concentration gradient

13

How does the blood maintain its acid base balance?

Via the intercalated cells

14

What are the two cells that form the collecting duct called?

The principal cell

The intercalated cell

15

What is the role of the principal cell in the collecting ducts?

To regulate salt and water concentration

16

What is the role of intercalated cells?

To maintain acid base balance

17

How does the alpha intercalated cell work?

Carbon dioxide inside the cell is hydrated by carbonic anhydrase to form protons and bicarbonate ions

 

Protons are pumped out in an energy-dependent manner by ATPase into the urine

 

Bicarbonate ions are pumped into the blood via anion exchanger 1

18

What does the anion exchanger 1 do?

Exchanges bicarbonate inside the cell for chlorine inside the blood

19

What is distal renal tubular acidosis caused by?

Pathology to any of the two transporters in the alpha intercalated cells

20

Draw process bicarbonate reabsorption in PCT 

21

Draw process of bicarbonate reabsorption in the collecting duct