T3 L8 Regulation of homeostasis in the kidney: acid-base balance Flashcards Preview

Module 104 - Nutrition, metabolism & excretion > T3 L8 Regulation of homeostasis in the kidney: acid-base balance > Flashcards

Flashcards in T3 L8 Regulation of homeostasis in the kidney: acid-base balance Deck (34)
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1
Q

What is the definition of renal dysfunction?

A

Inability to maintain salt and water balance & acid-base balance

2
Q

What is the role of the kidney in volume regulation?

A

Fluid balance - amount of water gained by the body = amount lost
Electrolyte balance - ion gain = ion loss

3
Q

Why is pH control important?

A

Alterations outside the normal range can cause coma, cardiac failure & circulatory collapse
pH < 6.0 or >8.0 leads to death

4
Q

What do acids do?

A

Release H+ into solution

5
Q

What do bases do?

A

Remove H+ from solution

6
Q

What is pH?

A

Potential of hydrogen

Specifies the acidity or basicity of an aqueous solution

7
Q

What are buffers?

A

Resist changes in pH
When H+ is added, the buffer removes it
When H+ is removed the buffer replaces it

8
Q

What are some types of buffers?

A

Carbonic acid / bicarbonate
Protein
Phosphate

9
Q

What is the acid-base balance reaction?

A

CO2 + H2O H2CO3 H+ + HCO3-

10
Q

Why is carbonic acid volatile?

A

It can be converted to CO2

11
Q

What is the pH of human blood?

A

7.4

12
Q

What is the pH of urine?

A

6.0

Slightly more acidic as you get rid of acids through the urine

13
Q

What does urine osmolality depend on?

A

The hydration status

14
Q

What is the relationship between pH and bicarbonate/CO2?

A

pH is inversely proportional to (HCO3-) / (pCO2)

HCO3- is a physiological buffer regulated by the kidney
pCO2 is a potential acid that is regulated by the lungs

15
Q

What happens to pH when pCO2 increases?

A

pH decreases as the extra CO2 reacts with water to form carbonic acid

16
Q

What detects changes in pH?

A

Peripheral chemoreceptors which act on the respiration centres in the brain to adjust respiration rates

17
Q

What is the most effective regulator of body fluid pH?

A

Renal system

18
Q

When does renal tubular acidosis occur?

A

When the kidneys don’t effectively reabsorb HCO3- and secrete H+

19
Q

What happens if the pH of the extracellular fluid increases?

A

Alkalaemia –> secretion of H+ into filtrate & reabsorption of HCO3- decreases –> extracellular pH decreases

20
Q

What happens if the oH of the extracellular fluid falls?

A

Acidaemia –> more secretion of H+ into filtrate & reabsorption of HCO3- back into the extracellular fluid –> causes pH to increase

21
Q

What is acidosis?

A

When the pH of the body fluid falls below 7.35

Too much H+

22
Q

What is the solution to acidosis?

A

Get rid of H+ out of the body
Excreted via the lungs as CO2 or via the kidneys as H+
Generate more buffer in the kidneys

23
Q

What is alkalosis?

A

pH of body fluids goes above 7.45

24
Q

What the solution to alkalosis?

A

Increase H+ levels in the body
Reduce excretion of CO2 via the lungs to increase blood CO2
Increase excretion of HCO3- buffer via the kidneys
Increase generation of H+ by the kidneys

25
Q

What is respiratory acidosis?

A

Caused by inadequate ventilation

Acute or chronic

26
Q

What is the treatment for respiratory acidosis?

A

Restore ventilation
Treat underlying dysfunction or disease
Give IV lactate solution which is converted to HCO3- buffer in the liver

27
Q

What is metabolic acidosis?

A

Results from all conditions that decrease pH apart from respiratory
Always chronic

28
Q

What is the treatment for metabolic acidosis?

A

Give IV isotonic HCO3-

Give IV lactate solution - converted to. HCO3- buffer in liver

29
Q

What are some ways to gain H+?

A

CO2 in the blood - combines with H2O to form carbonic acid
Non-volatile acids from metabolism such as lactic acid
Loss of HCO3- in diarrhoea or non-gastric GI fluids
Loss of HCO3- in urine

30
Q

What is respiratory alkalosis?

A

Caused by hyperventilation

Acute or chronic

31
Q

What is the treatment for respiratory alkalosis?

A

Treat underlying cause
Breathe into paper bag to increase pCO2
Give IV Cl- containing solution which increases HCO3- excretionn

32
Q

What is metabolic alkalosis?

A

Results from all conditions that increase pH apart from respiratory
Always chronic

33
Q

What is the treatment for metabolic alkalosis?

A

Give electrolytes to replace those lost
Give IV Cl- containing solution
Treat underlying disorder

34
Q

What are the reasons for a loss of H+?

A

Use of H+ in metabolism of organic anions
Loss of H+ in vomit
Loss of H+ in urine
Hyperventilation