The Skeletal System

Question 1

What are the 5 functions of the skeletal system?

Answer 1

1) Support the body’s structure
2) Protects internal organs
3) Leverage for movement
4) Stores Calcium
5) Produces blood cells

Question 2

What are the 2 bone functions?

Answer 2

1) Hard, yet brittle

2) Strong, yet flexible

Question 3

What compound is responsible for the bone’s function of hard, yet brittle?

Answer 3

HYDROXYAPATITE (inorganic) - this compound contains mineral salt deposits (calcium carbonate and calcium phosphate)

Question 4

What compound is responsible for the bone’s function of strong, yet flexible?

Answer 4

OSTEOID (Organic) - this compound contains collagen and protein complexes

Question 5

What are the 4 types of cells contained in bones?

Answer 5

1) Osteogenic stem cells
2) Osteoblasts
3) Osteoclasts
4) Osteocytes (mature bone cells)

Question 6

What are osteogenic stem cells?

Answer 6

Contained in the epistem and peristem. Responsible for new bone growth.

Question 7

What are osteoblasts?

Answer 7

They secrete osteoids to become osteocytes. They deposit minerals.

Question 8

What are osteoclasts?

Answer 8

They remove minerals from bones and release into the circulation. Important for bone remodelling.

Question 9

What are the osteocytes?

Answer 9

Mature bone cells that are found in the lacunae (nests) of bones and they maintain the matrix

Question 10

What percentage do cells make up out of the whole bone mass?

Answer 10

2%

Question 11

What are the 2 difference types of tissue which make up bones and what is their role?

Answer 11

1) Compact Bone (around the outside) - needs to be able to resist stresses
2) Cancellous Bone (inside) - needs to be able to be light so you can move around

Question 12

What are the 2 components of compact bone?

Answer 12

1) Osteons (functional unit)

2) Lamellae (rings of flat sheets around the osteons)

Question 13

What are the 3 types of lamellae?

Answer 13

Concentric - around osteons
Interstitial - between the osteons
Circumferential - around all the osteons

Question 14

What is the importance for the osteons to be positioned in the same direction?

Answer 14

It will increase unidirectional strength

Question 15

What are the 2 components of cancelleous bone?

Answer 15

1) Trabeculae (tissue elements)

2) Bone marrow (contained within the spaces between the trabeculae)

Question 16

What are the 2 types of bone marrow?

Answer 16

1) Red bone marrow (aka myeloid tissue) = (located in the spaces at the heads of long bones) produces red blood cells
2) Yellow bone marrow (aka fatty tissue) = can no longer produce red blood cells

Question 17

Who has more red bone marrow in the heads of their long bones?

Answer 17

Children as they require more RBC’s to grow.

Question 18

What are the advantages are disadvantages of yellow bone marrow?

Answer 18

Advantage = in severe anaemia - the yellow bone marrow can convert back to red in order to produce RBC's
Disadvantage = Pieces of fatty tissue can break off and cause an embolism

Question 19

What are the 2 names given to bone formation?

Answer 19

Either: Ossification or osteogenesis

Question 20

What are the 2 types of bone formation and where so they occur?

Answer 20

1) INTRA-MEMBRANEOUS OSSIFCATION (in clavicles and flat bones)
2) ENDO-CHONDRIAL CLASSIFCATION (in cartlidge)

Question 21

What occurs in INTRAMEMBRANEOUS OSSIFICATION?

Answer 21

1) MESENCHYMAL CELLS secrete osteoid.
2) They differentiate into osteoblasts and then become osteocytes (mature cells).
3) Calcium deposits (calcification)
4) Blood vessels grow in the area to supply O2 and nutrients.
5) Bone remodelling occurs - to form compact bone.

Question 22

When does bone modelling occur?

Answer 22

All throughout life the bones will deposit calcium into the circulation and reabsorb it again.

Question 23

What occurs in Endochondrial classification?

Answer 23

1) Cartlidge model is laid down.
2) The outer cell differentiate into osteoblasts and forms a thin layer of bone.
3) The cells in the shaft (diaphysis) differentiate into osteoblasts (forming the: primary ossification centre).
4) Osteoclasts will erode away the osteoblasts forming bone marrow cavities.
5) Cells at the ends of the cartlidge model (epiphyses) will differentiate into osteoblasts (forming the: secondary ossification centre).
6) When the epiphyses are completely occified = forms the Epiphysgeal Plate.

Question 24

How do bones grow after endochondrial classifcation?

Answer 24

1) Cartlidge models will continue to be placed down on epiphsgeal plate.
2) Endochondrial classification repeats.
3) Cells in the shaft (diaphysis) will differentiate into osteoblasts.

Question 25

What does the continuation of endochondrial classification rely on?

Answer 25

As long as cartlidge growth is faster than osteoblast activity, the bones will continue to grow!

Question 26

When does bone growth stop?

Answer 26

At puberty. 1) As sex and thyroid hormones will increase. This causes the osteoblast activity to increase at a rate higher than cartlidge growth. 2) Therefore, bone growth stops. 3) No more cartlidge is laid down on the epiphsgeal plate. 4) The epiphsgeal plate will narrow and errode away.

Question 27

Why do fractures occur?

Answer 27

1) Excessive load 2) Sudden Impact 3) Unusual direction

Question 28

How are different types of fractures classified?

Answer 28

Type: 1) Compound (in contact with the outside world) & 2) Simple and Nature: Spiral, Transverse, Comminuted, Linear, Oblique, Greenstick

Question 29

Which fracture is the worst?

Answer 29

Comminuted - as it results in 2 types of bones

Question 30

Which fracture is most common in children?

Answer 30

Greenstick

Question 31

What are the steps that are involved in bone formation?

Answer 31

1) When a bone has been fractured, blood vessels are torn. 2) Bleeding will show that a HEAMATOMA has formed. 3) 5 things will invade the area in order to form aSOFT CALLUS: 1) Osteogenic stem cells 2) osteoblasts 3) fibroblasts 4) macrophages 5) cappilaries 4) A HARD CALLUS will be formed when calcium phosphate and calcium carbonate deposit 5) Osteoclasts will remodel the bone and the hard callus is removed.

Question 32

What can be seen on an X-ray?

Answer 32

Soft Callus

Question 33

What factors promote healing?

Answer 33

1) Good blood supply | 2) Free from infection

Question 34

What occurs to encourage the bone healing process?

Answer 34

1) Alignment | 2) Immobilisation (using cast or pins)

Question 35

What things discourage bone healing?

Answer 35

1) Poor blood supply 2) Infection (either won't heal or painful) 3) Tissue fragments between bones so can't heal together 4) Poor alignment (either won't heal or shortened limb - will need to rebrake and realign) 5) Too much mobility 6) Age 7) Medication 8) Malnutrition 9) Systemic infection

Question 36

What is a 'joint'?

Answer 36

Where 2 bones meet

Question 37

What are the 2 ways to classify a joint and what are they each concerned with?

Answer 37

1) Functional Classification - How much movement occurs in that joint 2) Structural Classification - What is contained in that joint

Question 38

What are the 3 ways to functionally classify a joint?

Answer 38

1) Synarthrosis = Little or no movement 2) Ampharthrosis = Slightly moveable 3) Diarthrosis = Freely moveable

Question 39

What are the 3 ways to structurally classify a joint?

Answer 39

1) Cartilaginous = cartilage makes the joint in between the 2 bones 2) Fibrous = collegen fibres makes the joint in beween the 2 bones 3) Synovial = bones are seperated by a synovial cavity containing synovial fluid

Question 40

What are the 2 problems that are associated with Synovial joints?

Answer 40

1) Inflammation of the synovial cavity = arthritis | 2) Easily dislocated

Question 41

What are the components of the synovial joint?

Answer 41

Synovial cavity containing synovial fluid, lined by synovial membrane. Lining the bones is = articular cartlidge Around the synovial membrane is = articualar capsule

Question 42

What are the 6 different Synovial joint:

Answer 42

1) Ball and Socket 2) Pivot 3) Sliding 4) Ellipsoid 5) Saddle 6) Hinge

Question 43

What are the 6 different movements of the Synovial Joints:

Answer 43

``` Flexion and extension Abduction and adduction Circumduction Rotation Pronation and suprination Dorsiflexion and Plantar Flexion ```