2.1 Electrolyte Balance

Question 1

What can vomiting lead to? and what are the consequences ?

Answer 1

Electrolyte imbalance
Loss in H+,K+ + H2O

Consequences:

• Acid/base balance (metabolic alkalosis)
• Electrolyte balance
• Nerve + muscle function

Question 2

What can diarrhoea lead to and what are the consequences?

Answer 2

Losses in Na+ +H2O
Dehydration

Leads to
- Reduction in blood pressure (fluid loss)
Muscle weakness/ cramps (electrolytes)
Reduced levels of consciousness (electrolytes)
Heart failure (electrolytes)
Convulsions (electrolytes)

Question 3

What can an excess amout of urine loss lead to ?

Answer 3

Variable fluid loss

Hig K+, low Na+

Question 4

Why is electrolytes important for maintaining fluid balance ?

Answer 4

Controls the swelling and srinkage of cells

Alterations in electrolyte balance across the membrane has effects on nerve impulses and conduction of electrical impuse across heart: irregulatar heart rate.

Low Na+ can cause lethargy, seizures and respiratory problems

Question 5

What is the most abundant extracelullur cation ?

Answer 5

Na+

Question 6

What does osmotic activity of ECF depend on ?

Answer 6

The relative proportion of Na+ and H2O

Question 7

What is the exctretion of Na+ and H2O excretion in the kidney regulated by?

Answer 7

Vasopression and aldosterone

Question 8

What is hyponatraemia?

Answer 8

Low sodium levels in the blood

Question 9

What does hyponatraemia cause and how does this occur and how would this be treated ?

Answer 9

Fluid retention which causes renal failure and heart faliure

H2O into cells–> cerebral odema–> nausea,vomiting –> coma–> death

H2O restriction and increase salt intake

Question 10

What does MDMA/Ecstasy cause?

Answer 10

Need to drink excess water and stimulates vasopressin secretion- water retention

This causes hyponatraemia

Question 11

What is hypernatraemia and what is it due to?

Answer 11

High levels of sodium in the blood due to a decrease in H20

H2O moves out of cell —> decrease cell volume —> decrease brain size —> coma

Question 12

How does diabetes relate to hypenatraemia ?

Answer 12

Diabetes —> increased urination —> increased H2O loss

Question 13

What is hyper and hypokalaemia and what can it cause ?

Answer 13

Mucle weekness in both
Hyperkalaemia- ECG changes arrythmias

Hypokalaemia- ECG changes

These can alter membrane potential affecting AP and calcium channels etc

Question 14

What is acidosis and what can it cause ?

Answer 14

Drop in pH meaning H+ into cell and K+ out of cell. This causes hyperkalemia (decreased losses im urine)

Question 15

What is alkalosis and what can it cause ?

Answer 15

Rise in pH increasing entry of K+ into cells- Hypokalaemia (and increases loss in urine)

Question 16

What is hypokalaemia due to?

Answer 16

Decrease intake 
Alkalosis 
Increase losses- vomiting 
Increased urinary losses- diuretics 
Impared renal function

Question 17

What is hyperkalaemia due to?

Answer 17

Decreased excrertion- renal failure
Acidosis
ACEi with K+ supplements