Skeletal System

Question 1

6 functions of the skeleton

Answer 1

1. Supports the body
2. Permits flexible body movements
3. Protects soft body parts
4. Stores and maintains mineral homeostasis
5. Produces blood cells
6. Fat storage

Question 2

How does the skeletal system suppert the body

Answer 2

Provides a skeletal framework that can produce movement through the coordinated use of levers, muscles, tendons and ligaments

Question 3

Examples of skeletal system protecting soft body parts

Answer 3

• Cranium protects the brain
• Vertebral column protects the spinal cord
• Ribcage protects heart and lungs
• Pelvis protects urogenital organs

Question 4

How does the skeletal system produce blood cells

Answer 4

Haemopoietic stem cells present in red bone marrow

Question 5

How does the skeletal system store and maintain mineral homeostasis

Answer 5

• Bones contain 99% bodys calcium, 85% bodys phosphate, 50% bodys magnesium
• Bones release these in response to bodys demands
• Levels maintained and regulated by parathyroid hormone

Question 5

How does the skeletal system aid in fat storage

Answer 5

• Yellow bone marrow is a potential energy reserve for the body
• It consists of adipose tissue which stores triglycerides

Question 5

Bones of the appendicular skeleton include…

Answer 5

• Bones of the appendages
• The pectoral girdle
• The pelvic girdle

Question 6

The 2 divisions of the skeleton

Answer 6

1. Axial skeleton
2. Appendicular skeleton

Question 6

Axial skeleton includes…

Answer 6

• Bones of the skull
• Bones of the vertebral column
• Rib cage

Question 6

What are the first 7 bones in the rib cage

Answer 6

The true ribs

Question 7

What are the next 3 pairs of bones in tthe rib cage called

Answer 7

The false ribs

Question 8

What are the next 2 sets of bones in the rib cage called

Answer 8

The floating ribs

Question 9

The cervical vertebrae: function and structure

Answer 9

The cervical vertebrae is made up of the first 7 vertebrae. It forms a framework for the neck and supports the head

Question 10

The thoracic vertebrae: function and structure

Answer 10

Made up of the next 12 vertebrae. They form the rear anchor of the rib cage

Question 11

The lumbar vertebrae: function and structure

Answer 11

Made of the next 5 vertebrae. Supports most of the bodys weight.

Question 12

The sacrum: function and structure

Answer 12

The triangular bone located below the lumbar vertebrae. Forms the back wall of the pelvic girdle

Question 13

The coccyx: structure

Answer 13

3-5 bones fused together in adults

Question 14

What is between the vertebrae and what is its function

Answer 14

Intervertebral discs. They act as shock absorbers and allow the back to move

Question 15

The 5 types of bones

Answer 15

1. Long bones
2. Short bones
3. Flat bones
4. Sesamoid bones
5. Irregular bones

Question 16

Comment on long bones

Answer 16

• Longer than they are wide
• Work as levers
• Bones of the upper and lower extremities

Question 17

Comment on short bone

Answer 17

• Short
• Cube shaped
• Found in wrists and ankles

Question 18

COmment on flat bones

Answer 18

• Broad surfaces for protection of organs and attachment of muscles
• Sternum, cranial bones

Question 19

COmment on Sesamoid bones

Answer 19

• Small round bone that is embedded in a tendon
• Purpose is to decrease stress on the tendon
• In the knees, thumb and big toe

Question 20

Comment on irregular bones

Answer 20

• Others that dont fall into other catergories
• Varied shape, size
• Bones of the vertebrae and some in the skull

Question 21

3 components of bone matrix

Answer 21

1. 25% organic matrix: collagen fibres, other proteins 2. 50% inorganic mineral content (mineral salts): support structure hardened by calcium deposition 3. 25% water

Question 22

Composition of compact bone

Answer 22

* Highly organised * Composed of tubular units called osteons * Osteons contain osteocytes in lacunae which are organised in concentric rings arouns a central canal

Question 23

Composition of spongy bone

Answer 23

* Less dense, softer, weaker, less stiff than compact bone * Occurs at the ends of long bones * Frequently contains red bone marrow where haematopoiesis occurs * Arranged in trabeculae

Question 24

5 types of bone cells

Answer 24

1. Osteogenic cells 2. Osteoblasts 3. Osteocytes 4. Osteoclasts 5. Bone lining cells

Question 25

Comment on osteogenic cells

Answer 25

* Respond to traumas * Giving rise to bone forming cells and bone destroying cells

Question 26

COmment on osteoblasts (bone forming cells)

Answer 26

* Synthesis and secrete unmineralised ground substance * FOund in areas of high metabolism within the bone

Question 27

Comment on osteocytes

Answer 27

* Mature bone cells * Made from osteoblasts that have made bone tissue around themselves * Maintain healthy bone tissue by secreting enzymes and controlling bone mineral content * Control calcium release from bone tissue to blood

Question 28

Comment on osteoclasts

Answer 28

* Large cells that break down bone tissue * Important in bone growth, healing and remodeling

Question 29

Comment on bone lining cells

Answer 29

* Derived from osteoblasts * Regulate movement of calcium and phosphate into and out of the bone

Question 30

The 2 ways bone is formed by

Answer 30

1. Intramembranous ossification -> skull 2. Endochondral ossification -> bones of the trunk and extremities

Question 31

Steps of intramembranous bone formation

Answer 31

1. Increased vascularity of tissue (increased supple of blood vessels) 2. Active proliferation of mesenchymal cells (mesenchymal cells give rise to osteogenic cells which develop into osteoblasts) 3. Osteoblasts begin to lay down osteoid (osteoid is the organic part of the bone) 4. Osteoblasts either retreat or become entrapped as osteocytes in the osteoid 5. Osteoid calcifies to form trabeculae of spongy bone 6. Bone remodelling occurs (compact bone formed)

Question 32

Steps of endochondral ossification

Answer 32

1. Hyaline cartilage model develops in foetus and is replaced by bone as development proceeds 2. Cartilage breaks down in center of diaphysis which is now covered in periosteum 3. **Osteoblasts invade** and create a **primary ossification center** where **spongy bone is first laid down** 4. **Compact bone is then laid down** 5. Gradually the **osteoclasts create the medullary cavity** 6. After birth **secondary ossification centers appear at the epiphyses** of bones where spongy bone is laid down 7. A band of cartilage called a **growth plate** remains between the primary and secondary ossification centers, **as long as this remains the bones continue to grow** but once ossified the bones no longer grow

Question 33

Steps of bone repair

Answer 33

1. Haematoma forms from blood from ruptured blood vessels within 6-8 hours 2. Fibrocartilage fills the space in about 3 weeks 3. Osteoblasts produce the trabeculae of spongy bone that joins bone together after 3 months 4. Remodelling by osteoblasts of compact bone and osteoclasts create a new medullary cavity