L10- consequences of electrolyte imbalance

Question 1

Substances or ions that give off an electric charge (negative or positive)

Answer 1

electrolytes

Question 2

What would someone with electrolyte imbalance present with?

Answer 2

• Muscle spasms, weakness, twitching or convulsing.
• Irregular heartbeat, confusion, blood pressure changes, nervous disorders
• Respiratory imbalances

Question 3

Significance of Na+ ion

Answer 3

– Integral to action potentials and therefore neuron
function.

– Exerts significant osmotic pressure in extracellular
fluid (ECF).

– Water follows salt – a change in plasma Na+ affects plasma volume, blood pressure,
intracellular fluid volume (ICF) and interstitial fluid
(IF) volumes.

Question 3

What does hyperaldosteronism imply?

Answer 3

hypernatremia and
hypokalemia

Question 3

Cause of Addison’s disease

Answer 3

Reduced aldosterone production by adrenal glands.

Low aldosterone implies implies hyponatremia and hyperkalemia

Question 4

What are the 3 causes of hyponatraemia with respect to volume status?

Answer 4

1. HYPOVOLAMIC
   Both water and sodium are reduced
   CAUSES: Renal losses or
   excessive diuretic use
   GI losses: vomiting,
   diarrhea Burns
   Addison’s disease
2. EUVOLEMIC
   Water is high, but sodium is normal
   CAUSES: Water intoxication
   SIADH- Syndrome of Inappropriate ADH secretion
3. HYPERVOLEMIC:
   Both water and Sodium are increased
   CAUSES: Heart failure,
   Liver failure, Kidney injury/failure

Question 4

What are the consequences of hyponatraemia?

Answer 4

Na<135
- Headache
- Lethargy
- Dizziness
- Nausea & vomitting
- Abdominal cramps
- Muscle weakness

Na<120 (severe hyponatraemia)
- cerebral oedema,
- irreversible
neurological damage,
- coma,
- seizures,
- respiratory arrest,
- brainstem herniation,
- death

Question 5

What causes hypernatraemia? (Na>147)

Answer 5

Caused by net water loss. No water to dilute sodium salt

Question 6

What are the consequences of hypernatremia?

Answer 6

1. MILD (145-150mmol/l)
   Thirst
   Decreased urine output
   Headache
   Increased body temperature
2. Moderate (151-154mmol/l)

decreased reflexes,
agitation, headache

3, SEVERE >155
Coma
Seizures

Question 6

Why do potassium content decline with age?

Answer 6

Coz ~ 65 - 75% of potassium is in the muscle. And it is mainly due to a decrease in muscle
mass

Question 7

What are the 3 causes of hypernatraemia with respect to volume status?

Answer 7

1. HYPOVOLEMIC
   Both water and sodium are high
   CAUSES:
   Excessive sweating
   Burns
   Diarrhea
   Renal losses

2 EUVOLEMIC
Water decreased, sodium normal
CAUSES: Diabetes insipidus
Respiratory losses

3. HYPERVOLEMIC:
   Total body water ↑
   Total body Na+ ↑ ↑
   CAUSES:
   Sodium gains
   Primary
   hyperaldosteronism
   Cushing’s syndrome
   Hypertonic dialysis
   Hypertonic NaHCO3
   NaCl tablets
   Causes of hypernatremia

Question 7

What are the roles of potassium?

Answer 7

• Regulates excitability of the nerve and muscle cells, as well as
• contractility of
  cardiac, skeletal and smooth muscle tissue

Question 8

What is the effect of reduced potassium in resting membrane potential?

Answer 8

makes the resting potential more negative

*Stimulus needed to reach thresh hold needs to be greater than normal

Question 9

How the body educes excess potassium ions?

Answer 9

• excretion (urine, GIT, skin-sweat)
• Potassium shifts into cells from cell exterior

Question 10

Name the 3 causes of potassium shift into cells

Answer 10

• alkalosis
• hypothermia
• Drugs (insulin, verapamil)

Question 11

What is the effect of hypokalaemia on cardiac muscle?

Answer 11

cardiac irritability

Question 12

What are the effects of having low potassium levels?

Answer 12

• weakness
  -palpitations
• changes on ECG

*Low potassium cn be asymptomatic

Question 13

What are the effects of having high potassium?

Answer 13

cardiac arrest

Question 14

What is the importance of ionized calcium?

Answer 14

Ionized calcium is present in ~50% ECF

• important in membrane potential
• neuronal excitability
• cardiac contractility

Question 15

Why would too much calcium cause constipation?

Answer 15

Coz it decreases smooth muscle activity of the GIT

Question 16

What is the role of calcium in neuromuscular excitability?

Answer 16

Is to stabilize the neuromuscular activity. But if there is less of calcium available for this action, there’s increased excitability since more sodium channels are available’

If there is too much calcium, sodium channels are blocked and there is no excitation of neurons or muscles. Hence reduced activity of stomach smooth muscle»constipation.