Week 1 Bioscience

Question 1

five functions of bone

Answer 1

1. Support: Bones provide a framework that supports the entire body
2. Protection: Bones surround and enclose body tissues and organs
3. Storage of minerals and triglycerides: Bones store minerals (e.g., calcium & phosphate) and triglycerides (fat)
4. Blood cell production: Bones produce red blood cells, white blood cells and platelets (haematopoiesis)
5. Movement: Bones act as levers to move body parts

Question 2

THE AXIAL SKELETON

Answer 2

Forms the longitudinal axis of the body and includes the bones of the:
* skull
- cranial and facial bones
* vertebral column
- cervical, thoracic, lumbar, sacral and coccyx vertebrae
* rib cage
- sternum and ribs

Question 3

THE APPENDICULAR SKELETON

Answer 3

Includes the the bones of the:
* upper limbs - arms, forearms and hands
* lower limbs - thighs, legs and feet
* shoulder (pectoral) girdles
* pelvic girdle

Question 4

BONE SHAPES

Answer 4

According to their shape bones are classified as:
* long bones
* short bones
* flat bones
* irregular bones

Question 5

OSSEOUS TISSUE

Answer 5

Is a connective tissue - contains specialised cells and an extracellular matrix (a.k.a. matrix).
The Matrix
* Consists of ground substance, collagen fibres, and calcium phosphate crystals
* Makes bones hard, slightly flexible and strong
- collagen fibres:
→ provide flexibility & tensile strength
- calcium phosphate crystals:
→ make our bones hard & provide compressive strength

Question 6

Specialised Cells

Answer 6

Osteoprogenitor cells
- stem cells that differentiate into osteoblasts
Osteoblasts
- bone “building” cells - produce & secrete collagen fibres & ground substance (matrix)
Osteoclasts
- bone “resorbing” cells that break down the matrix and release stored minerals
Osteocytes
- mature bone cells that maintain the matrix

Question 7

Compact Bone

Answer 7

• Osseous tissue is arranged into osteons
• Each osteon:
• runs parallel to the long axis of a bone (e.g., shaft of long bones)
• consists of:
  → a central canal - contains blood vessels & nerves
  → concentric circles (hollow cylinders) of matrix
  → osteocytes - lie in-between each layer of matrix
• acts as a tiny weight-bearing pillar → resist forces applied to the ends of a bone

Question 8

Spongy Bone

Answer 8

• Osseous tissue is arranged into an irregular lattice of thin needle-like structures called trabeculae - trabeculae are precisely orientated to resist forces from all directions and transfer weight without breaking
• Is lighter than compact bone - reduces the weight of the skeleton
  In long bones, mainly found the proximal & distal epiphysis

Question 9

INTERSTITIAL GROWTH

Answer 9

• Occurs at the epiphyseal plates of long bones

Question 10

APPOSITIONAL GROWTH

Answer 10

Occurs at the outer surface of all bones

Question 10

REGULATION OF BONE GROWTH

Answer 10

• During childhood bone growth is mainly controlled by growth hormone (GH) and thyroid hormone (TH)
• During adolescence bone growth requires GH, TH, testosterone (males) & estrogen (females)

These hormones:
1. Promote the adolescent growth spurt
2. End growth → induce epiphyseal plate closure
→ the rate of bone formation exceeds the rate of cartilage formation
→ cartilage eventually replaced entirely by bone
→ epiphyseal plate becomes epiphyseal line

Question 10

BONE REMODELLING

Answer 10

• Occurs throughout life
• Maintains bone mass and strength
• Replaces old matrix with new matrix
• Involves bone resorption and bone deposition
• In healthy young adults the rate of bone deposition equals the rate of resorption → bone mass remains constant
• With age, a decline in sex hormones results in a loss of bone mass as the rate of bone resorption exceeds the rate of bone deposition
• Loss of calcium phosphate crystals & collagen fibres = thin, weak, brittle bones

Question 10

comminuted fracture

Answer 10

bone fragments into three or more pieces

Question 10

compression fracture

Answer 10

bone is crushed

Question 11

greenstick fracture

Answer 11

bone bends and cracks - incomplete break

Question 11

spiral fracture

Answer 11

ragged break that occurs when excessive twisting forces are applied to a bone

Question 11

epiphyseal fracture

Answer 11

bone breaks along the epiphyseal plate

Question 12

transverse fracture

Answer 12

bone completely breaks across the diaphysis (shaft)

Question 13

depressed fracture

Answer 13

broken bone is pressed inwards

Question 14

avulsion fracture

Answer 14

tendon or ligament pulls off a fragment
of bone

Question 15

pathological fracture

Answer 15

caused by a disease that weakens bone
structure, e.g., osteoporosis

Question 16

Colles fracture

Answer 16

break at the distal end of the radius

Question 17

scaphoid fracture

Answer 17

common carpal bone fracture

Question 18

Pott’s fracture

Answer 18

a break in the medial malleolus of the
tibia and/or lateral malleolus of the
fibula

Question 19

FRACTURE REPAIR

Answer 19

1. Haematoma forms * torn blood vessels hemorrhage * clot forms * site swollen and sore 2. Fibrocartilaginous callus forms * fibroblasts produce collagen fibres * chondroblasts produce cartilage * fibrocartilaginous callus splints broken bone ends 3. Bony callus of spongy bone forms * fibrocartilaginous callus is replaced by spongy bone * bone ends firmly united 4. Bone remodelling * compact bone replaces spongy bone at the bone surface or diaphysis * osteoclasts remove excess bone * bone returns to normal shape

Question 20

CLASSIFICATIONS OF JOINTS

Answer 20

Based on the amount of movement, joints can be functionally classified as: * synarthrosis - immovable joint * amphiarthrosis - slightly movable joint * diarthrosis - freely movable joint Based on the connective tissue that connects the articulating bones, and the presence or absence of a joint cavity, joints can be structurally classified as: * fibrous * cartilaginous * synovial

Question 21

FIBROUS JOINTS

Answer 21

* Fibrous connective tissue unites articulating bones * Joint cavity absent * Are immovable (synarthrosis) or slightly movable (amphiarthrosis)

Question 22

CARTILAGINOUS JOINTS

Answer 22

* Cartilage (hyaline or fibrocartilage) unites articulating bones * Joint cavity absent * Are immovable or slightly moveable joints

Question 23

SYNOVIAL JOINTS

Answer 23

* Articulating bone ends are covered in articular cartilage * Joint cavity present * Are freely movable (diarthrosis) joints * Allow a wide range of body movements

Question 24

GENERAL STRUCTURE OF A SYNOVIAL JOINT

Answer 24

Articular capsule * surrounds entire joint and encloses joint cavity * two-layers: → tough outer fibrous layer - stabilises articulating bones → inner synovial membrane - produces synovial fluid Joint cavity * separates articulating bones & contains synovial fluid Synovial fluid * shock absorption * reduces friction * supplies oxygen and nutrients to articular cartilage cells (chondrocytes) and remove wastes Articular cartilage * covers the ends of each articulating bone * shock absorption * reduces friction Reinforcing ligaments * stabilise joint Sensory neurons & blood vessels * sensory neurons detect pain and monitor proprioception * blood vessels - mainly supply synovial membrane

Question 25

ADDITIONAL STRUCTURES OF A SYNOVIAL JOINT

Answer 25

Menisci - discs of fibrocartilage * stabilise joint * reduce friction * shock absorption Muscle tendons * stabilise joint Bursae and Tendon sheaths * bags of synovial fluid * reduce friction between adjacent joint structures Fat pads * mass of adipose tissue cushion & protect joint structures

Question 26

angular movements

Answer 26

increase or decrease the angle between articulating bones

Question 27

rotational movements

Answer 27

turn a bone around its own longitudinal axis

Question 28

1. Pivot joint

Answer 28

allows rotation e.g., proximal radioulnar & atlas-axis joints

Question 29

2. Plane Joint

Answer 29

allows gliding movements e.g., intercarpal & intertarsal joints

Question 30

3. Condylar joint

Answer 30

allows flexion, extension, adduction, abduction & circumduction e.g., metacarpophalangeal (knuckle) & wrist joints

Question 31

4. Saddle joint

Answer 31

allows flexion, extension, adduction, abduction & circumduction e.g., carpometacarpal joint of the thumb

Question 32

5. Hinge Joint

Answer 32

allows flexion & extension e.g., elbow, knee, ankle & interphalangeal (finger) joints

Question 33

6. Ball and Socket joint

Answer 33

allows flexion, extension, adduction, abduction, circumduction & rotation e.g., shoulder and hip joints