Bone & Skeleton

Question 1

What are the 6 functions of bones?

Answer 1

1) Protect soft parts
2) Support body
3) Fat Storage
4) Site of hematopoiesis
5) System of levers for movement
6) Mineral homeostasis

Question 2

What are the 4 different cells of bones

Answer 2

1) Osteogenic/ osteoprogenitor cells
2) Osteoblasts
3) Osteocytes
4) Osteoclasts

Question 3

Describe the role of osteogenic/ osteoprogenitor cells

Answer 3

Stem cells that differentiate into

Question 4

Describe the function of osteoblasts

Answer 4

Osteoblasts synthesise and secrete new bone

Question 5

Describe the function of osteocytes

Answer 5

Osteocytes are bone maintaining cells

Question 6

Describe the function of osteoclasts

Answer 6

Osteoclasts are bone reabsorbing cells

Question 7

What are lamellae?

Answer 7

Layers of bone - can help with age determination

Question 8

What is an osteon?

Answer 8

A structural unit of compact bone

Question 9

Describe the structure and function of the osteon

Answer 9

Function as pressure-resistant columns.
Collagen fibres spiral in each lamella
Angle of spiral is opposite in adjacent lamellae. This resists compression and twisting forces.

Question 10

What does axial mean (with reference to the skeleton)

Answer 10

Central column (spine and vertebrae)

Question 11

What does appendicular mean (with reference to the skeleton)

Answer 11

To do with the limbs (arms and legs)

Question 12

What is endochondral ossification

Answer 12

Bone development from hyaline cartilage

Question 13

What is intramembranous ossification?

Answer 13

Bone development from fibrous membranes.

Question 14

What is the medullary cavity?

Answer 14

Hollow space in the centre of a bone’s shaft that stores bone marrow and allows blood vessels to deliver blood throughout the bone.

Question 15

What are the 5 different shapes of bone?

Answer 15

1) Long
2) Short
3) Flat
4) Sesamoid
5) Irregular

Question 16

Describe the structure of a long bone (different vertical layers)

Answer 16

Proximal Epiphysis
Metaphysis (growth plate)
Shaft/ diaphysis
Metaphysis (growth plate)
Disal Epiphysis

(Remember Eat My Donuts Mr Eagle)

Question 17

Do long bones have a medullary cavity?
Are long bones compact and spongy?

Answer 17

Yes
Yes

Question 18

Describe the structure of short bones

Answer 18

About as long as wide. Can be different shapes (e.g., cylindrical, cubic)

Question 19

1) Do short bones have a medullary cavity?
2) Are short bones compact and spongy?

Answer 19

1) No
2) Yes

Question 20

Describe the structure of flat bones

Answer 20

Thin, flat and wide.
Compact bone surrounding spongy bone or air sinus.

Question 21

Describe the location and formation of sesamoid bones

Answer 21

Found under tendons, close to joints
Formation is sensitive to biomechanical forces.

Question 22

Describe irregular bones

Answer 22

Odd shapes. Jutting processes - sticking out bits to increase surface area for muscle attachment.

Question 23

Describe the 2 types of membrane found in bones - include layers, their function and location.

Answer 23

Periosteum - covers the outside of bone. Contains 2 layers (cellular and fibrous) Osteogenic (produces new bone). Site of sensory nerves, blood and lymphatics.

Endosteum. lines inside surface (medullary cavity). Single layer. Osteogenic and osteolytic to stop bone being too dense.

Question 24

How are bones well vascularised?

Answer 24

Arteries enter via nutrient foramen (holes in the surface), passing through the subchondral bone to supply the calcified part of cartilage.

Question 25

What is bone remodelling?

Answer 25

The continuous deposition and reabsorption of bone Influenced by hormones and forces (Wolff’s law - bone adapts to load).

Question 26

What hormones are influential in bone remodelling?

Answer 26

PTH and Calcitonin.

Question 27

What is ossification?

Answer 27

The process of bone formation. Can be either intramembranous or mesenchymal

Question 28

What are mesenchymal cells/ tissue?

Answer 28

Multipotent stem cells that differentiate into osteoblasts, osteocytes etc.

Question 29

What happens to the mesenchymal tissue in intramembranous ossification.

Answer 29

Mesenchymal tissue is converted to bone to form the flat bones of the skull and clavical.

Question 30

What happens to the mesenchymal tissue in endochondral ossification.

Answer 30

Mesenchymal tissue transforms into cartilage, then is replaced by bone. Forms the remainder of the axial skeleton and long bones.