Chapter 6 - Skeletal System

Skeletal Function

1. Supports - weight bearing

2. Protection (ribs, spine, brain)

3. Body Movement

4. Store Inorganic Salts (Calcium/Phosphorus)

5. Blood Cell Formation

If Low Blood Calcium (Ca+2)

1. parathyroid hormone (neck) stimulates osteoclasts break down bone tissue

2. activates Calcium to be reabsorbed from kidneys

3. then absorbs Calcium from intestine

If High Blood Calcium (Ca+2)

1. hormone Calcitonin from thyroid gland stimulates osteoblasts

2. osteoclasts are inhibited (Ca+2 won’t rise)

3. stores excess Calcium

Red Blood Marrow

froms erthyrocytes (RBC), leukocytes (WBC), & platelets

• as you age red marrow is replaced w/ yellow marrow

Yellow Blood Marrow

• stores fat

• inactive in blood cell production

Long Bone

femur

Short Bone

Carpals/tarsals

Flat Bone

Scapula/Rib

Irregular Bone

Vertebral, Facial Bone

Diaphysis

→ shaft of the bone

→ compose of compact bone

→ within has medullary cavity

• filled with marrow, artery, vein, nerve

Epiphysis

→ ends of bone

→ articulates join w/ other bones

→ composed of spongy bone

→ interconnecting rods called trabeculae

• gives strength

Irregular space within the bone

→ help reduce weight

→ filled w/ marrow

Articular Cartilage

covers the articulating portion of the epiphysis

Periosteum

vascular tissue that encloses the bone

• continuous w/ tendons and ligaments

Endosteum

connective tissue that lines with the medullary cavity

Epiphyseal Plate (growth plate)

→ located between diaphysis and epiphysis

→ location of growth (length) in the bone

→ growth stops, it turns into epiphyseal line

Bone Ossification

→ formation of bone tissue

• involves preexisting tissue

→ first few weeks of prenatal development, skeletal system begins to develop

(Bone Growth) Diaphysis Side

(1 ossification center)

• osteoblasts turn cartilage to bone

(Bone growth) Epiphysis side

(2 ossification center)

→ new cartilage is being made by chondrocytes through rapid mitosis

• length the bone

• form cartilage

• allow bone growth

During bone growth on the epiphysis side does the plate grow longer?

No the shaft grows but the plate remains the same

Homeostasis of Bone

osteoclasts and osteoblasts continuously remodel bone that’s regulated by hormones

Bone Repair (Broken bone)

→ clot forms in damaged area where blood vessels and cells invaded it

→ produces fibers and callus (cartilage) between bone fragments

→ osteoblasts enter the callus

→ form spongy bone which eventually goes to compact bone

Factors affecting Bone Growth

1. Genetics

2. Nutrition

3. Hormone

• Growth Hormone

• Thyroid Hormone

• Estrogen/Testosterone

4. Exercise

Flexion vs Extension

decreases angle vs. extend angle

Abduction vs. Adduction

away from midline vs. toward midline

Rotation

movement around axis

Protraction vs. Retraction

bring forward vs. bring back (ex: jaw)

Hyperextension

beyond 180 degrees

Plantar Flexion vs. Dorsiflexion

toes down vs. toes up

Pronation vs. Supination

face down vs. face up (ex: hands)

Circumduction

360 degrees

Elevation vs Depression

goes up vs. goes down

Opposition

thumb touching digits

Inversion vs Eversion

soles of feet in vs. soles of feet out