Skeletal System

Question 1

What is the skeletal systems function?

Answer 1

Makes up 20% body mass, Provides mechanical support and protection for internal organs.

Question 2

What is the axial skeleton?

Answer 2

This is the central body that the appendages connect to. It includes the head, neck, torso which is the vertebral column and ribs.

Question 3

What is the appendicular skeleton?

Answer 3

This consist of 126 bones and includes the pelvic and pectoral girdle (hipbone), harms, hands, legs, feet.

Question 4

What is special about the skull bones?

Answer 4

The 8 cranial bones are seperated when we wre born so that they are more flexible allowing the head to pass through the birth canal and vagina. They fuse together at 2yo.

Question 5

What is the function of bones?

Answer 5

Osseous (bone) tissue consists of 50-70% mineral salts; 20-40% organic matrix which is 95% collagen; and 5-10% water.
They offer mechanical support, homeostatic regulation of some minerals, defence against toxins.

Question 6

What are the components of bone?

Answer 6

80% cortical bone (bone marrow) and 20% trabecular bone.
Diaphysis, Epiphysis, Metaphysis, Medullary cavity, Epiphyseal plate (growth), endosteum, periosteum.

Question 7

What is the diaphysis?

Answer 7

This is a tubular shaft (hollow) in the centre of the bone. The walls are made from dense, hard, compact bone.

Question 8

What is the medullary cavity?

Answer 8

Contains the yellow bone marrow (adipocytes)

Question 9

What is the epiphysis?

Answer 9

This is the wider section at the end of bones covered in articular cartilage (reducing friction and acting as a shock absorber). It is composed of spongy bone and red marrow fills the spaces within the spongy bone.

Question 10

What is the metaphis?

Answer 10

This is the region where the epiphysis and diaphysis meet, it contains the epiphyseal plate.

Question 11

What is the epiphyseal plate?

Answer 11

In growing bone, contains transparent cartilage. At 18-21 when it stops growing, the cartilage is replaced by osseous tissue, and the plate becomes the epiphyseal line.

Question 12

What is the endosteum?

Answer 12

region where bone growth, repair and remodelling occur.

Question 13

What is the periosteum?

Answer 13

Fibrous membrane consisting of blood vessels, nerves and lymphatic vessels. They are also the site that ligaments and tendons attach to bone.

Question 14

What is bones organic matrix made of?

Answer 14

• collagen fibres encrusted with crystalline hydroxyapatite
• glycosaminoglycans
• proteoglycans

Question 15

What are properties of compact bone?

Answer 15

Dense bone, withstands compressive forces, provides support and protection, cells are arranged in concentric circles/

Question 16

What are properties of spongy bone?

Answer 16

Open spaces make bone lighter, this supports shifts in weight distribution, cells are arranged in trabeculae, red marrow within the spongy bone is the site of haematopoiesis.

Question 17

What is collagen?

Answer 17

This forms the calcifiable matrix of bone. It gives the bone flexibility. It is a fibrous protein that is rich in AAs glycine, proline and hydroxyproline. they are made up of tropocollagen molecules which are made from three separate monomers that form a triple helix.

Question 18

What is the hydroxyapatite?

Answer 18

Region of bone where ions can be exchanged. It is a complex of calcium phosphate, carbonate and magnesium hydroxide. They absorb excess phosphate which can bind to water and form a hydration shell over the crystal allowing fir easier ion exchange.

Question 19

What is involved in bone metabolism?

Answer 19

Bone matrix is continually synthesised, secreted, organised, mineralised and destroyed.
- osteoblasts form new bone, synthesise and secrete collagen matrix and calcium salts.
parathoid hormone and calcitonin hormone…

Question 20

What are the three types of joint?

Answer 20

Fibrous - adjacent bones are connected directly to one another by fibrous connective tissue, there is no movement.
Cartilaginous - adjacent bones are directly connected by cartilage. cartilage is a tough connective tissue, there is no joint cavity.
Synovial - Most common joint. The joint cavity is filled with synovial fluid to prevent friction of the bones and them wearing each other down. Synovial joints therefore allow movement.

Question 21

What are the synovial joints?

Answer 21

Pivot - neck
hinge - elbow
saddle - between trapezium and metacarpal bones in the feet
plane - between tarsal bones
condyloid - in the wrist
ball and socket - hip joint

Question 22

What are the classifications of joints movement?

Answer 22

Synarthrosis - immobile e.g. the skull
Amphiarthrosis - slightly movable e.g. vertebrae
Diarthrosis - freely movable e.g. synovial joints