Topic 9

Question 1

Functions of skeletal system

Answer 1

• support
• protection of vital organisms
• attached muscles and allows movement
• red marrow produces rbc and wbc
• stores Ca

Question 2

Before week 8 skeleton embryo constructed of..

Answer 2

fibrous membranes and hyaline cartilage

Question 3

Bone formation occurs

Answer 3

8 weeks to 20 years

Question 4

2 types of ossification

Answer 4

• intramembranous

- endochondral

Question 5

Intramembranous

Answer 5

flat bones (skull, mandible, clavicle), develop from fibrous CT membrane

Question 6

Process of intramembranous ossification

Answer 6

• oesteoblasts produce spongy bone alone CT fibres

- periosteum forms and then osteoblasts under it lay down and compact bone

Question 7

Fontanels

Answer 7

unossified membranes in the skill that remain at birth

Question 8

Endochondral

Answer 8

hyaline cartilage used as a model for bone construction then ossifies to form spongy bone. periosteum forms and the osteoblasts beneath lay down compact bone.

Question 9

articular cartilage and epiphyseal plates =

Answer 9

cartilage that has not been ossified

Question 10

Bone growth in length and process

Answer 10

=endochondral growth at epiphyseal plates
process: cartilage grows to matrix near diaphysis becomes bone then growth stops when epiphyseal plate ossifies into epiphyseal line

Question 11

Bone growth in diameter and process

Answer 11

= appositional growth
process: osteoblasts beneath periosteum secrete bone matrix. osteoclasts reabsorb bone on the endosteal surface so size of cavity keeps pace with growing bone

Question 12

Mechanical stress is due to

Answer 12

muscle action

Question 13

2 examples of of mechanical stress

Answer 13

• moderate exercise: increase osteoblast activity in areas of stress
• injury that restricts movement: decrease osteoblast activity and no change in osteoclast activity decrease bone mass

Question 14

Weights or electric currents may speed..

Answer 14

healing by increase osteoblast activity

Question 15

Ca and PO4 is required for

Answer 15

production of bone matrix

Question 16

Vitamin C

Answer 16

required for collagen production

Question 17

Vitamin D

Answer 17

increase absorption fof Ca from intestine (if lacking Vit D then rickets soft bone in tissue)

Question 18

Growth hormone and thyroid hormone stimulate

Answer 18

bone growth

Question 19

Estrogen and testosterone increase..

Answer 19

osteoblast activity

Question 20

Estrogen in both sexes does what

Answer 20

ossification of epiphyseal plate

Question 21

Calcitonin

Answer 21

inhibits osteoclast activity. increases Ca movement from blood to bone

Question 22

Parathyoid hormone (PTH)

Answer 22

osteoclast activity increases and osteoblast activity decreases therefore blood Ca increases

Question 23

Osteoporosis

Answer 23

decrease in bone mass

Question 24

Risk factors of osteoporosis

Answer 24

• increasing age
• post menopause
• inadequate diet
• illness, excess PTH
• too little/excessive exercise
• drugs or smoking

Question 25

Process of bone repair

Answer 25

• begins with formation of a blood clot
• clot replaced by a callus of fibrous network and fibrocartilage islets
• callus ossifies so intramembranous and endochondral ossification
• takes 4-6 weeks so cast required since movement can refractor new matrix