Bone lectures 13 and 14

Question 1

Name the bones of the axial skeleton

Answer 1

Skull
Vertebral column
Ribs
Sternum
Coccyx
Sacrum

Question 2

Name the bones of the appendicular skeleton

Answer 2

Shoulder girdle
Upper limbs
Lower limbs
Pelvic girdle

Question 3

What is the function of the axial skeleton?

Answer 3

To support the weight of the torso and provide protection to the major internal organs.

Question 4

What is the function of the appendicular skeleton?

Answer 4

Consists of appendages, which are comprised of the arms and legs.

Question 5

How is bone a living tissue?

Answer 5

Bone is always remodelling.

Question 6

How is bone formed in the uterus?

Question 7

How does bone undergo remodelling?

Answer 7

Bone is always remodelling.
1. Osteoclasts makes a wide tunnel in the bone and reabsorb old bone.
2. Osteoblasts deposit new bone.
3. Osteocytes can act as both within bone tissue to recycle bone.

Question 8

What are the mechanical functions of bone?

Synthetic functions?

Metabolic functions?

Answer 8

Protecting important and delicate tissues and organs.
Framework for shape of human body.
Form the basis of levers involved in movement.

Haemopoiesis - holds and protects bone marrow.

Mineral storage (calcium and phospherous).
Fat storage (yellow bone marrow).
Absorbs or releases alkaline salts to help regulate blood pH.

Question 9

What are the two types of bone?

Answer 9

Cancellous bone - spongy bone. Network of columns or plates called trabeculae. Spaces are filled with bone marrow.

Compact - corticol bone. Forms external surfaces. 80% of skeletal mass.

Question 10

Describe the composition of bone in terms of its cells and extracellular matrix.

Question 11

What is osteoid?

Answer 11

Unmineralized, organic content of bone (90% collagen; 10% ground substance).

Question 12

What are Haversian canals and Volkmann’s canals and where are they found?

Answer 12

Haversian canals:
Longitudinal canals that carry nutrient-providing blood vessels, lymphatic vessels and nerves between lamellae.
Found in compact bone.
They communicate with marrow cavity, periosteum Volkmann’s canals.

Volkmann’s canals:
Canals with the same function as Haversian canals, but run in the transverse direction.

Question 13

Describe the structure of compact (cortical) bone.

Answer 13

Outer portion of bone formed of external circumferential lamellae parallel to the long axis of the bone. Between the lamellae are Haversian canals. Volkmann’s canals (transverse) connects these Haversian canals (longitudinal).
Composed of osteons.

Question 14

Describe the structure of spongy (cancellous/trabecular) bone.

Answer 14

Inner portion is formed of internal circumferential lamellae which the spongy bone attaches to. It is an extension of compact bone, but composed of trabeculae (beams of bone) instead of osteons.

Question 15

What is an osteon?

Answer 15

The Haversian system.

Question 16

How is bone maintained?

Answer 16

Osteoblast lay down oseoid that contains collagen, enzymes, and ground substance with a prolactin that binds calcium, called osteocalcin.
Osteoblasts secrete alkaline phosphatase which changes the osteoid pH and adds H+ ions and bicarbonate ions, resulting in the deposition of calcium crystals of hydroxyapatite.
This causes mineralisation to extracellular matrix and osteoid is turned into bone tissue.

Question 17

What are osteocytes?

Answer 17

Osteoblasts that have become trapped in the bone lamellae during the process of new bone tissue formation.

Question 18

Explain the importance of vitamin D in normal bone stability.

Where is vitamin D obtained?

Answer 18

Vitamin D produces calcitriol which aids calcium absorption.

It is either absorbed from the gut or synthesised in the skin.

Question 19

What is the importance of vitamin C?

Answer 19

Synthesis of collagen.

Question 20

What is the importance of vitamins K and B12?

Answer 20

Synthesis of bone proteins.