10. Changes in plasma Mg2+-concentration

Question 1

The function of magnesium in the body

Answer 1

Required for the activity of many enzymes (oxidative phosphorylation)

Question 2

Intestinal magnesium absorption is influenced by…

Answer 2

The amount of Ca²⁺, P and K⁺ in the diet

Question 3

Give the causes of magnesium deficiency

Answer 3

• Primary deficiency
• Secondary deficiency
• Stress

Question 4

Primary deficiency of Mg in the body

Answer 4

Limited Mg intake (young grass)

Question 5

Causes of secondary deficiency of Mg in the body

Answer 5

K⁺ excess

Question 6

List the consequences of Mg²⁺ deficiency in the body

Answer 6

• Tetany
• Neuromuscular hyperirritability

Question 7

Tetany as a consequence of Mg²⁺ deficiency

Answer 7

Condition marked by a prolonged involuntary contraction of muscles

Question 8

Give the pathway of Mg²⁺ deficiency causing tetany

Answer 8

1. ↑ AcCh release
2. ↓ Acetylcholinesterase activity
3. ↑ Muscle contractions

Question 9

List the types of tetany caused by Mg²⁺ deficiency

Answer 9

• Grass staggers (grass low in Mg²⁺)
• Transport tetany
• Winter tetany
• Whole milk tetany

Question 10

Give the causes of excess Mg²⁺ in the body

Answer 10

Can be primary, but mainly secondary (relative)

Question 11

Give the consequences of excess Mg²⁺ in the body

Answer 11

• Diarrhoea
• Decreased irritability

Question 12

Diarrhoea as a consequence of excess Mg²⁺ in the body

Answer 12

A local effect in the GI tract

• MgSO₄ used to fight constipation
• However, it was used for euthanasia in large doses when given IV

Question 13

Decreased irritability as a consequence of excess Mg²⁺ in the body

Answer 13

Curare-like effect (prevention of impulses to muscle)

(as a general effect)