A&P ch. 6

Describe the structure, function, and location of skeletal cartilage

Structure: made mostly of water; cartilage tissue

Function:Support, cushioning, reduces friction

Location: joints, nose, ears, ribs

describe the structure, location and function of hyaline cartilage

Structure: contains only collagen fibers

Location: Joints, ribs, larynx, nose tip

function: provide support and flexibility

describe the structure, location and function of elastic cartilage

Structure: collagen and elastic fibers

Location: external ear and epiglottis

function: provide support and flexibility

describe the structure, location and function of fibrocartilage

Structure: thick collagen fibers

Location: meniscus of knee, vertebral discs

Function: great tensile strength

Describe the two ways that cartilage grows

Appositional growth: addition of new layers to the existing structure

Interstital growth: expands existing tissue

describe the 7 basic functions of the skeletal system

Support: the body and soft organs

Protection: protect brain, spinal cord, and vital organs

Movement: leaves for muscle action

Mineral growth and growth factors: calcium and phosphorus and growth factors resevoir

Blood cell formation: Hematopoiesis occurs in red marrow cavities of certain bones

Triglyceride (fat) storage:fat, used for an energy source, is stored in bone cavities

Hormone production: secretes hormone to help keep levels balanced

Describe the four shapes that bones are classified into, and location

Long bones: longer than they are wide

• location: limb bones

Short bones

• cube-shaped bones (wrist and ankle)

• Sesamoid bones form within tendons (patella)

Flat bones: thin, flat, slightly curved

• location: sternum, scapulae, ribs, most skull bones

Irregular bones: complicated shaped

• location: vertebrae and hip bones

Describe the structure of compact bone

dense outer layer on every bone that appears smooth and solid

describe the structure of smooth bone

made up of honeycomb of small, needle-like or flat pieces of bone called trabeculae

describe the structure of short, irregular, and flat bones

• consists of thin plates of spongy bone covered by compact bone

• compact bone is wedged between connective tissue membranes

• bone marrow is scattered throughout spongy bone; no defined marrow cavity

describe the structure of typical long bone, including diaphysis, epiphysis, and epiphyseal plate

• Long bones: shaft (diaphysis), ends (epiphyses), and membranes

• Diaphysis: tubular shaft; compact bone surrounds the medullary cavity

• Epiphyses: bone ends; compact bone outside, spongy bone inside

• Epiphyseal plate: cartilage where bone growth occurs

describe the structure, function, and location of the periosteum

• Structure: Outer fibrous + inner osteogenic layers

• Function: Supplies nerves/blood vessels, produces cells,anchors tendons/ligaments

• Location: Outer bone surface

describe the structure, function, and location of the endosteum

• Structure: Connective tissue membrane + osteogenic cells

• Function: Produces bone cells

• Location: Internal bone surfaces

describe the function and location of red marrow

Function: produces blood cells (hematopoiesis

Location: found in spongy bone and diploë of flat bones; in adults, mainly the heads of the femur and humerus and certain flat/irregular bones

describe the functions of the three types of bone marking

• Projection: Attachment points for muscles, ligaments & tendons

• Depression: Grooves/cutouts for vessels, nerves, or joints

• Opening: Holes/canals for blood vessels & nerves

describe the location and function of osteoblasts, osteocytes, osteoclasts, osteogenic cells, and bone-lining cells

Osteoblasts: bone-forming cells

Location: in growth zones

Osteocytes: mature bone cells in lacunae

• respond to stimuli and communicates info

Osteoclasts: reabsorption (breakdown of bone) and in depressions

Osteogenic cells: active sells in periosteum and endosteum

• when stimulated, they divide into osteoblasts/ bone-lining cells

Bone-lining cells: flat cells on bone surface w/ no active growth

• help maintain matrix

describe the structure and function of osteon

Structure: the structural unit of compact bone

function: withstands stress and resists twisting

describe the structure and function of canals and canaliculi

Canals

Structure: lined with endosteum

Function: connects blood vessels and nerves , medullar cavity, and central canal

Canaliculi

Structure: hairlike canals that contain blood vessels and nerve fibers

Function: connect lacunae to each other and central canal

describe the structure and function of interstitial and circumferential lamellae

Interstitial lamellae

Structure: lamellae that are not part of osteon

Function: fill gaps between forming osteons

Circumferential lamellae

Structure: layers surround surface of diaphysis

Function: helps long bone to resist twisting

describe the functions of the organic and inorganic components that make up bone

Organic

Function: high resilience and flexibility in bone

Inorganic

Function: reisists tension as strong as steel does

describe the five steps of endochondral ossification

• Begins around month 2 of development

• Uses hyaline cartilage models that break down

• Bone formation starts in the shaft (primary ossification center)

• Blood vessels enter → perichondrium becomes periosteum

• Mesenchymal cells → osteoblasts

describe the four steps of intramembranous ossification

1. Ossification center forms → cells become osteoblasts

2. Osteoid forms → hardens into bone

3. Trabeculae form → periosteum develops

4. Mature bone forms → lamellar bone + red marrow develops

describe the resting, proliferation, hypertrophic, calcification and ossification zone of the epiphyseal plate

1. Resting zone → Inactive cartilage; stores cells

2. Proliferation zone → Cells divide and push the bone longer

3. Hypertrophic zone → Cartilage cells enlarge and break down

4. Calcification zone → Cartilage hardens; cells die

5. Ossification zone → New bone replaces cartilage → spongy bone

describe how bones grow in length as well as diameter

• Length: Cartilage grows and is replaced by bone

• Diameter: Bone widens through oppositional growth

• Thickening: Bone responds to muscle activity and added weight/stress

describe the role of growth hormone, thyroid hormone, testosterone and estrogens on bone growth

• Growth hormone: Stimulates bone growth in children

• Thyroid hormone: Helps regulate growth hormone

• Testosterone & estrogen: Cause puberty growth spurt and close growth plates

describe bone remolding, including how resorption and deposit occur

• Remodeling: Bone is broken down and rebuilt.

• Resorption: Osteoclasts break down bone.

• Bone deposit: Osteoblasts build new bone.

describe the role of calcium, vitamin D, parathyroid hormone, calcitonin, leptin, and serotonin on bone remolding

• Calcium: Strengthens bones and maintains density

• Vitamin D: Helps absorb calcium

• PTH: Increases bone breakdown → raises blood calcium

• Calcitonin: Lowers blood calcium

• Leptin: Helps regulate bone density

• Serotonin: Affects mood, sleep, and bone-building cells

describe Wolf’s law and explain how bones respond to mechanical stress

Wolf’s Law: bones grow or remodel in response to demands

-How bone respond to mechanical stress: the bones bend

describe the six ways bone fractures are classified

1. Nondisplaced: ends retain normal position

2. Displaced: ends are out of normal alignment

3. Complete: broken all the way through

4. Incomplete: not broken all the way through

5. Open (compound): skin is penetrated

6. Closed (simple): skin is not penetrated

describe the six common types of bone fractures

• Comminuted: Bone breaks into 3+ pieces

• Compression: Bone is crushed

• Spiral: Bone twists and breaks

• Epiphyseal: Epiphysis separates from shaft

• Depressed: Broken bone is pushed inward

• Greenstick: Bone partly breaks and bends

describe the four stages of bone repair

• Hematoma: Broken vessels → blood clot

• Fibrocartilaginous callus: Collagen + cartilage connect bones

• Bony callus: Spongy bone forms

• Remodeling: Extra bone removed → bone regains shape

describe osteomalacia and rickets and explain the consequences of having them

• Osteomalacia: Poorly mineralized → soft, weak bones; often caused by vitamin D deficiency

• Rickets: Osteomalacia in children → bowed legs and bone deformities

• Both: Can cause bone pain and weakness

describe osteoporosis, including the risk factors and explain the consequences of having it

• Osteoporosis: Weak, fragile bones

• Risk factors: Age, menopause, low calcium/Vit. D, inactivity

• Effects: Fractures, pain, height loss, curved spine

describe how osteoporosis is prevented and how it’s treated

Prevention: lots of calcium in diet

• reduce consumption of carbonated beverages and alcohol

• plenty of weight-bearing excercises

Treatment: calcium, vitamin D, weight-bearing excursuses, hormone replacement therapy

describe Paget’s diseases and explain the consequences of having it

• cause bone to grow fast and develop poorly

• Consequence: bone fractures and deformities

describe the developmental aspects of bones

• 8 weeks: Bone formation begins

• 12 weeks: Main ossification centers form

• Birth: Most bones are formed

• Childhood: Growth plates allow bones to lengthen

• ~25 years: Growth ends

describe the changes that occur to bone as you age

• Children/teens: Bone formation > breakdown

• Young adults: Formation = breakdown

• Adults: Bone breakdown > formation

• Genetics: Major factor in bone density

• Aging: After ~40, bone mass and healing decrease