Diseases of Human Systems - connective tissue disease (bone) Flashcards
List the 3 key features of bone.
Load bearing
Self repairing
Dynamic - continuously adapting = can adapt to its environment
What are the functions of calcium?
It maintains nerve and muscle function
What is the role of the parathyroid hormone in relation to calcium? (2)
It regulates calcium
Ensures calcium is transported to the correct location.
Describe hypoparathyroidism
When there is low serum calcium from insufficient amounts of parathyroid hormone
Name the two types of hyperparathyroidism
Primary
Secondary
What causes primary hyperparathyroidism?
Problems with the glands themselves i.e. tumours
What is the outcome of primary hyperparathyroidism?
High serum calcium and inappropriate activation of osteoclasts to resorb bone
What causes secondary hyperparathyroidism?
Kidney failure
Vitamin D deficiency
- low sunlight exposure
- GI disease = poor absorption
- drug interactions
What is the outcome of secondary hyperparathyroidism?
where there is appropriate activation of osteoclasts which causes bone resorption in response to low serum calcium in order to raise it
What are sources of vitamin D?
Sunlight
Food - OJ and fish
Describe how sunlight produces vitamin D.
Cholecalciferol is produced by the skin absorbing sunlight.
Cholecalciferol is transported to the blood and then travels to the liver and kidneys where it is processed.
The processing creates the active form which can be absorbed by the gut; 1, 25 - dihydroxycolecalciferol.
what is the active and absorbable form of vitamin D?
1, 25 - dihydroxycolecalciferol.
What are the barriers to absorbing vitamin D?
Low sunlight exposure - housebound individuals, dark skinned people in northern countries.
Poor GI absorption - those with intestinal diseases such as crohns and UC.
Drug interactions - anti-epileptics such as carbamazepine and phenytoin
What is osteomalacia?
When healthy bone matrix is formed but it is not calcified properly after bone formation
What are the effects of osteomalacia? (3)
Vertebral compression and pain in the lower limbs
Muscle weakness
Nerve effects such as trousseau and Chvostek signs
