Body Plan 07: Bone

Question 1

Bone/bones. Which one is the organ and which one is the tissue?

Answer 1

Bone is the tissue. Bones are organs

Question 2

Functions of bone

Answer 2

1) maintain shape of body
2) transmit and amplify muscular forces
3) Reservoir for calcium and mineral phosphates
4) Phosphate homeostasis
5) Houses bone marrow for hematopoiesis

Question 3

What is the main constituent of bone tissue?

Answer 3

Extracellular matrix

Question 4

What type of collagen is usually found in bone tissue?

Answer 4

Type 1 collagen

Question 5

Osteoblasts

Answer 5

Cells that secrete bone tissue material and differentiate from osteoprogenitor cells. They are arranged in the epithelium of the bone surface and flatten when inactive

Question 6

Bone apposition

Answer 6

Osteon is laid down and then mineralized on the surface of previously existing bone

Question 7

Osteon

Answer 7

Unmineralized bone tissue secreted by osteoblasts

Question 8

How are osteons mineralized?

Answer 8

Osteoblasts secrete calcium salts into osteon

Question 9

Bone Lining Surface

Answer 9

Inactive cells that line the epithelium of the bone. They participate in the regulation of bone formation and resportion

Question 10

Osteocytes

Answer 10

Osteoblasts and laid down bone around themselves, surrounding the lacunane they live in

Question 11

What are the functions of osteocytes?

Answer 11

They monitor bone strains, detect microdamage, and maintain bone mineral

Question 12

Osteoclasts

Answer 12

Large, multi-nucleated cells that originate from macrophages and work to eat away bone. They work in coordination with osteoblasts through calcitonin and parathyroid hormones

Question 13

Hydroxyapatite

Answer 13

A calcium salt that is used to mineralize bone tissue

Question 14

What bones rise from the paraxial mesoderm?

Answer 14

Axial skeleton, ribs, skull base

Question 15

What bones rise from the lateral plate mesoderm?

Answer 15

Limbs

Question 16

What bones rise from the neural crest?

Answer 16

Bones of pharyngeal arches (mandible, maxilla, hyoid, ear ossicles)

Question 17

Ossification

Answer 17

The process of creating bone. Can be intramembranous or endochondral

Question 18

Intramembranous Ossification

Answer 18

Mesenchym cells differentiate into osteoblasts, which then secrete and mineralize osteon directly into the mesenchyme membrane

Question 19

What bones are formed from intramembranous ossification?

Answer 19

Bones of the skull, including the mandible

Question 20

Endochondral ossification

Answer 20

Forming bone on pre-existing hyaline cartilage. Chondrocytes hypertrophy, mineralize cartialge, and die. Osteoblasts lay down the bone tissue network

Question 21

Periosteum

Answer 21

A membrane that covers the outer surface of all bones, except at the articular surfaces of long bones

Question 22

Endosteum

Answer 22

A thin vascular membrane of connective tissue that lines the inner surface of the bony tissue that forms the medullary cavity of long bones

Question 23

In endochondral ossification, what cartilage is not replaced?

Answer 23

The articular cartilage remains on the surface of the epiphysis

Question 24

What are the zones of the epiphyseal growth plate?

Answer 24

Resting zone
Proliferation Zone
Maturation zone
Hypertrophic and cartilage calcification zone
Cartilage degeneration zone
Ossification zone

Question 25

What are the two general steps of ossification?

Answer 25

1) Laying down osteon

2) Mineralization at the edge of the seam closest to the bone already mineralized

Question 26

Cortical bone

Answer 26

Also known as compact bone; it’s the outer layer of bone that is more compact

Question 27

Trabecular bone

Answer 27

Also known as cancellous bone; it’s the inner network of bone tissue that has more gaps than cortical bone

Question 28

Subchondral bone

Answer 28

A type of cortical bone that rests under the cartilage of joints

Question 29

Epiphysis

Answer 29

The ends of the bone

Question 30

Diaphysis

Answer 30

The stem of the bone

Question 31

Metaphysis

Answer 31

The middle section between the ends and the stem

Question 32

Epiphyseal growth plate

Answer 32

Borders the epiphysis and the metaphysis; the site of endochondral ossification

Question 33

Woven Bone

Answer 33

Also known as primary bone; First bone laid down during development and in fracture healing; irregular array of collagen fibers

Question 34

Lamellar Bone

Answer 34

Also known as secondary bone; Replaces primary bone by remodeling and modeling. Starts occurring in age 2/3

Question 35

Osteon

Answer 35

A unit of bone remodelling; circumferential layers of bones consisting of a Haversian canal, osteocytes in lacunae, and canaliculi connecting the lacunae

Question 36

Haversian Canal

Answer 36

A canal in the middle of an osteon containing blood vessels and nerves

Question 37

Canaliculi

Answer 37

Connections between lacunae of an osteon

Question 38

Volkmann’s canals

Answer 38

Channels that connect Haversian canals

Question 39

Bone Modelling

Answer 39

The formation of bone during development. Large scale movements

Question 40

Bone Remodelling

Answer 40

The reformation of bone on a local, small scale

Question 41

Osteoporosis

Answer 41

A disorder that hyperactivates osteoclasts resulting in diminished bone mass

Question 42

Matrix vessicles

Answer 42

Vessicles secreted by chondrocytes and osteoblasts where crystals first form

Question 43

What are some natural causes of decreased bone mass?

Answer 43

Pregnancy, lactation, lack of exercise, menopause

Question 44

What are the effects of parathyroid hormone on bones?

Answer 44

It promotes bone resportion to increase blood calcium levels