principles of the skeletal system

Question 1

What is the function of the skeletal system?

Answer 1

• protection of organs
• supports the body
• movement
• metabolic reservoir
• production of new red blood cells

Question 2

What are the two divisons of the skeletal system?

Answer 2

axial and appendicular

Question 3

What is part of the axial division of the skeletal system?

Answer 3

• cranium
• thoracic cage
• spine
• sacrum

Question 4

What is part of the appendicular division of the skeletal system?

Answer 4

• shoulders
• hips
• limbs

Question 5

What are the 3 layers of the embryonic disc?

Answer 5

• ectoderm
• mesoderm
• endoderm

Question 6

What are the two types of tissues in the skeletal system?

Answer 6

cartilage and bone

Question 7

Describe the cartilage

Answer 7

• forms skeleton in parts where flexibility is required
• avascular
• connective tissue

Question 8

What are the two types of bone?

Answer 8

compact and spongy

Question 9

Describe bone

Answer 9

• hard form of connective tissue
• provides rigid framework
• vascular

Question 10

What is ossification?

Answer 10

the process by which bone is formed

Question 11

What is the process by which bone is formed called?

Answer 11

ossification

Question 12

What are the two methods through which ossification can occur?

Answer 12

• intramembranous
• endochondral

Question 13

What is mesenchyme?

Answer 13

embryonic connective tissue

Question 14

Describe the steps of intramembranous ossification?

Answer 14

• mineralisation of mesenchyme
• cells divide and condense around capillary network (grows radially, fusing together and replacing connective tissue)

Question 15

What is the starting point in intramembranous ossification called?

Answer 15

primary ossification centre

Question 16

What does undifferentiated mesenchyme become in intramembranous ossification?

Answer 16

bone marrow

Question 17

Give examples of bones arising from intramembranous ossification

Answer 17

• skull
• mandible
• clavicle

Question 18

What is endochondral ossification?

Answer 18

where a cartilaginous template made from the mesenchyme is replaced by bone

Question 19

What 2 cells is the bone made up of?

Answer 19

• osteoprogenitor cells
• osteoclasts

Question 20

What 2 cells types can osteoprogenitor cells become?

Answer 20

osteoblasts and osteocytes

Question 21

What are osteoclasts derived from?

Answer 21

blood monocytes/macrophages

Question 22

Which 2 bone cell types are responsible for the constant remodelling of bones?

Answer 22

osteoclasts and osteoblasts

Question 23

Which things we eat regulate bone maintenance?

Answer 23

• calcium
• phosphorous
• vitamin A, C, D

Question 24

What role does vitamin A have in bone maintenance?

Answer 24

bone remodelling

Question 25

What is vitamin C essential for in bone maintenance?

Answer 25

connective tissue

Question 26

What is vitamin D essential for in bone maintenance?

Answer 26

calcium absorption

Question 27

Which hormones control bone development?

Answer 27

- parathyroid hormone - growth hormone (GH)

Question 28

What is spongy bone also known as?

Answer 28

- cancellous bone - trabecular bone

Question 29

Describe spongy bone?

Answer 29

- irregular bony plates called trabeculae - surrounded by red marrow - highly vascuralised

Question 30

How can bone be classified?

Answer 30

- long bones - flat bones - irregular bones - short bones - sesamoid bones

Question 31

How many bones are we born with?

Answer 31

270

Question 32

How many bones do we have by adulthood?

Answer 32

206

Question 33

What are the 3 classes of joints?

Answer 33

- synovial - fibrous - cartilaginous

Question 34

Describe synovial joints?

Answer 34

- have a joint capsule and synovial cavity - permit movement

Question 35

What are the types of synovial joints?

Answer 35

- plane - saddle - ball and socket - hinge - pivot - condyloid

Question 36

Describe fibrous joints?

Answer 36

- connected by collagen - do not permit movement

Question 37

Give an example of fibrous joints?

Answer 37

sutures of skull

Question 38

Describe cartilaginous joints?

Answer 38

- connected by cartilage - allow some movement

Question 39

What is the mesoderm layer?

Answer 39

middle layer of embryonic disc from which all connective tissue develops

Question 40

What is a foramen?

Answer 40

a hole within a bone through which neurovascular structures may pass

Question 41

When does bone development start and finish?

Answer 41

- starts at 8 weeks - ends at around 20 years

Question 42

What is the name of the connective tissue that covers skeletal system (except at articulation)?

Answer 42

periosteum

Question 43

What is the connective tissue surrounding cartilage called?

Answer 43

perichondrium

Question 44

How is compact (cortical) bone arranged?

Answer 44

usually in lamellae (called concentric layers)

Question 45

How do the lamellae in compact bone get arranged?

Answer 45

they are laid down by osteoblasts

Question 46

How do the osteoblasts often become osteocytes?

Answer 46

- osteoblasts get trapped in osteoid matrix - turn into osteocytes occupying their own lacunae

Question 47

How do osteocytes communicate between each other if they are trapped in their lacunae?

Answer 47

- canaliculi radiate from each lacunae - this is how nutrients travel to them

Question 48

What contains the neurovascular supply in compact bones?

Answer 48

the Haversian canal

Question 49

In what group of people are bone fractures the most common?

Answer 49

- over 50s - cis-women

Question 50

What are the most commonly fractured bones?

Answer 50

- distal radius - ankle - metacarpals - proximal femur - proximal humerus

Question 51

Why can bones heal so well?

Answer 51

because they are a vascularised tissue