Bone Tissue

Question 1

Skeletal cartilages (3)

Answer 1

1. Hyaline Cartilages: provide support, flexibility, and resilience, MOST abundant, end of long bones (trachea, ribs)
2. Elastic cartilages: similar to hyaline cartilages, but contain elastic fibers (ear, epiglottis)
3. Fibrocartilages: collagen fibers –> have great tensile strength (invertebrate discs, knee caps)

Cartilage found in between joints which are where bones are connected for movement

Question 2

Growth of cartilage (3)

Answer 2

1. Appositional (grows from outside - width)
   - cells secrete matrix against external face of existing cartilage
2. Interstitial (grows from inside - length)
   - Chondrocytes divide and secrete new matrix, expanding cartilage from within
3. Calcification of cartilage occurs during normal bone growth, old age, and calcified cartilage is NOT BONE

Question 3

Classification of bones by shape (4)

Answer 3

1. Long bones: longer than they are wide
2. Short bone: cube shaped bones (wrist and ankles), sesamoid bones (within tendons, patella)
3. Flat bones: thin, flat, slightly curved (skull, scapula, sternum)
4. Irregular bones: complicated shapes (vertebrae, pelvis)

Question 4

How many bones in human body?

Answer 4

206 bones
- fetus has more bones but fuse as one bone as you grow

Question 5

Functions of bones (6)

Answer 5

1. Support for the body and soft organs
2. Protection for brain, spinal cord, and vital organs
3. Movement levers for muscle action
4. Storage: minerals (calcium + phosphorus) and growth factors
5. Blood cell formation (hematopoiesis) in marrow cavities
6. Triglyceride (energy) storage in bone cavities

Question 6

Bone markings

Answer 6

• Bulges, depressions, and holes serves as…
• sites of attachment for muscles, ligaments, tendons
• joint surfaces
• conduits for blood vessels and nerves
• helps you understand the function of many bones

Question 7

What are the sites of muscle + ligament attachment? (8)

Answer 7

• tuberosity: rounded projection
• crest: narrow, prominent ridge
• trochanter: large, blunt, irregular surface
• line: narrow ridge of bone
• tubercle: small rounded projection
• epicondyle: raised area above a condyle
• spine: sharpe, slender projection
• process: any bony prominence

Question 8

Projections that form joints (4)

Answer 8

1. Head: bony expansion carried on a narrow neck
2. Facet: smooth, nearly flat articular surface
3. Condyle: rounded articular projection
4. Ramus: armlike bar

Question 9

Depressions + openings (6)

Answer 9

• Meatus: canal-like passageway
• Sinus: cavity within a bone
• Fossa: shallow, basin-like depression
• Groove: furrow (bicipital)
• Fissure: narrow, sitlike opening
• Foramen: round/oval

Question 10

2 types of bone textures

Answer 10

1. Compact bone (10 years)
   - dense outer layer
2. Spongy cancellous bone (3-4 years)
   - honeycomb of trabeculae
   - more porous like a sponge

Question 11

2 membranes of bone

Answer 11

1. Periosteum
   - outer fibrous layer
   - inner osteogenic layer
   - osteoblasts (bone forming cells)
   - osteoclasts (bone destroying cells)
   - osteogenic cells (stem cells)
2. Endosteum
   - delicate membrane on internal surfaces of bone
   - also contains osteoblasts and osteoclasts

Question 12

Structure of short, irregular, and flat bones

Answer 12

• periosteum covered compact bone on the outside
• endosteum covered spongy bone within
• spongy bone called diploe in flat bones
• bone marrow between the trabeculae

Question 13

location of hematopoietic tissue (red marrow)

Answer 13

• red marrow cavities of adults
• trabecular cavities of the heads of the femur and humerus
• trabecular cavities of the diploe of flat bones

Question 14

Microscopic anatomy of bone and its 4 types

Answer 14

-cells of bones

1. osteogenic (osteoprogenitor) cells: stem cells in periosteum and endosteum that give rise to osteoblasts
2. osteoblasts: bone-forming cells, secrete bone matrix
3. osteocytes: mature bone cells, monitor/maintain matrix
4. osteoclasts: cells that break down (resorb) bone matrix

Question 15

Compact bone and 4 types

Answer 15

1. Haversian system (osteon): structural unit
   - Lamellae: concentric rings, weight bearing, column like matrix tubes (collagen)
   - arranged in diff directions to maintain strength
   - central (haversian) canal: contains blood vessels and nerves
2. perforating (volkmann’s) canals: at right angles to the central canal, connects blood vessels and nerves of the periosteum + central canal
3. lacunae: small cavities that contain osteocytes

4: canaliculi: hairlike canals that connect lacunae to each other and the central canal (adj. osteocytes communication)

Question 16

Spongy bone

Answer 16

Trabeculae
- align along lines of stress
- no osteons
- contain irrgularly arranged lamellae, osteocytes, and canaliculi
- capillaries in endosteum supply nutrients

Question 17

Organic composition of bone

Answer 17

• osteogenic cells, osteoblasts, osteocytes, osteoclasts

osteoid: organic bone matrix secreted by osteoblasts
- ground substance: proteoglycans, glycoproteins
- collagen fibers: provide tensile strength + flexibility

Question 18

Inorganic composition of bone

Answer 18

• hydroxyapatites (mineral salts)
• 65% bones by mass
• mainly calcium phosphate crystals
• responsible for hardness + resistance to compression