9. bone

Question 1

Answer 1

Question 2

what is in the ECM of bone

Answer 2

Ground substance​​​

• GAGs (Osteocalcin,sialoprotein)
• Minerals Ca⁺⁺ PO₄^{2- -} Hydroxyapatite
• Fibres*
• Type I collagen

Question 3

osteoprogenitor cells

Answer 3

stem cells that form osteoblasts

Question 4

obsteoblast

Answer 4

immature bone cells that secrete organic components of the matrix

Question 5

osteocyte

Answer 5

mature bone cells formed from osteoblasts

Question 6

osteoclasts

Answer 6

multinucleated macrophages acting as scavengers of unwanted material.

Question 7

canaliculi

Answer 7

join lacunae together

filled with extracellular fluid

Question 8

lacunae

Answer 8

spaces that hold osteocytes

Question 9

Volkmann’s canal

Answer 9

connect Haversian canals

Question 10

Haversians canals

Answer 10

gaps for blood vessels

Question 11

periosteum

Answer 11

dense layer of vascular connective tissue surrounding bones

determines healing process

source of precursor cells: chondroblast and osteoblast

Question 12

compact bone

Answer 12

dense bone organised into haversian systems

shaft of long bones corticol

Question 13

spongy bones

Answer 13

bone organised into 3D netowrk of spicules with spaces- marrow cavity and ends of long bones- medullary

makes it lighter

Question 14

what is needed for growth and maintenance of bone

Answer 14

mineralised matrix impermeable to water and small molecules

needs blood supply

growth by appositional (adding)

Question 15

growth of lamellar bone, what is it formed from

Answer 15

osteoid-> woven-> lamellar

Question 16

osteoid

Answer 16

newly formed matrix before mineralisation

Question 17

woven

Answer 17

bone matrix with collagen arranged in random orientation

repair

Question 18

lamellar bone

Answer 18

bone with collagen fibres arranged in parallel in alternating layers- adult bone

Question 19

Intramembranous ossification

Answer 19

Bone islands - begin as bone in embryonic connective tissue (mesenchyme) from mesenchymal stem cells which differentiate into osteoprogenitor cells

These cells differentiate into osteoblast which start to form bony trabeculae

Trabeculae, which as they develop trap blood vessels, join together to form spongy bone, with osteoblasts at the surface laying down compact bone

Question 20

endochondral ossification

Answer 20

Question 21

Answer 21

Question 22

Answer 22

Question 23

which bones have endochondral ossification

Answer 23

Base of skull

Long Bones

Question 24

Factors Influencing Bone Growth

Answer 24

mechanical forces

Nutrition

• Vitamin deficiencies
• Vitamin D reduced calcification
• Vitamin C collagen disrupted
• Vitamin A endochondral growth reduced

Hormones

• Growth hormone growth plate increases
• Adrenal androgens prepubertal growth spurt
• Gonadal steroids closure of epiphyses
• Thyroxine essential for osteogenesis
• Parathormone Ca from bone to plasma
• Oestrogen maintains bone density

Bone-derived Growth Factors: bone morphogenic protein

Question 25

disease of bone

Answer 25

osteoporosis- loss of bone mass

reduced weight bearing, reduced oestrogen (menopause), reduced gravity (astronauts)

osteomalacia- bone softening

vit D deficiency and rickets

Paget’s disease: ucontrol of resorption and formation uncoupled, woven bone produced

Osteogenesis Imperfecta - brittle bone, type I collagen defect