Musculoskeletal - Physiology

Question 1

3 types of bone cells & their functions

Answer 1

• Osteoblasts
  
  • bone building cells that produce the bone matrix
  • work in 2 stages - ossification - formation of pre-bone, calcification - deposition of calcium in the bone tissue (makes bones solid)
• Osteoclasts
  
  • bone chewing cells that function in re-absorbtion of bone (phagocytic cells)
• Osteocytes
  
  • mature bone cells
  • involved in bone matrix maintainance
  • found in lacuna (fluid filled spaces in bone) & arranged in layers (lamellae)

Question 2

Parathyroid Hormone

Answer 2

• regulates calcium & phosphate levels in the blood
• increases number & activity of osteoclasts
• prevents serum calcium & phosphate levels falling below or rising above normal range
• initiates calcium release from bones
• conserves calcium in the kidneys
• activates VitD to enhance GIT absorption

Question 3

Calcitonin

Answer 3

• reduces number & activity of osteoclasts
• works with PTH to control how many osteoclasts we have & how hard they are working to reduce bone loss
• inhibits release of calcium from bones
• reduces renal re-absorption of calcium & phosphate
• reducing osteoclasts reduces calcium released from “chewed up” bone

Question 4

Vitamin D

Answer 4

• controls calcium levels in the blood
• increases calcium absorption in the GIT (from diet)
• promotes affect of PTH on resorption of calcium & phosphate from bone

Question 5

Joints

Answer 5

• site where 2 or more bones are attached
• synarthroses - immovable joints
• diarthoses - freely movable joints (synovial joints)
• fibrous - skull
• cartilaginous - intervertebral discs
• synoval - hip