Chapter 5The Skeletal

System

Provides an internal framework for the body, Provides an internal framework for the body, protects organs by enclosure, and anchors protects organs by enclosure, and anchors

skeletal muscles so that muscle contractions skeletal muscles so that muscle contractions can cause movementcan cause movement

Types of Bone CellsTypes of Bone Cells Osteocytes

Mature bone cells

Osteoblasts Bone-forming cells

Osteoclasts Bone-destroying cells

Break down bone matrix for remodeling and release of calcium

Bone remodeling is a process performed by both osteoblasts and osteoclasts

Changes in the Human SkeletonChanges in the Human Skeleton

In embryos, the skeleton is primarily hyaline cartilage

During development, much of this cartilage is replaced by bone

Cartilage remains in isolated areas

Bridge of the nose

Parts of ribs

Joints

Bone GrowthBone Growth

Epiphyseal plates allow for growth of long bones during childhood

New cartilage is continuously formed

Older cartilage becomes ossified

Cartilage is broken down

Bone replaces cartilage

Long Bone Formation & GrowthLong Bone Formation & Growth

Bone RemodelingBone Remodeling

Bones are remodeled continually in response to changes in 2 factors

Calcium levels in the blood

Pull of gravity & muscles on the skeleton

Disease of the bones:• Thin, brittle bones with lots of holes• Bones are susceptible to fractures

• Especially, the hips, spine, & wrists• Usually strikes after age 60

Symptoms:• Broken bone after a fall• Back pain• Decreased height• Curved backbone

Cause:• Lack of bone strength or bone density

Risk Factors:• Age• Female gender• Menopause

• After menopause Reduced production of estrogen, which protects the body from bone loss

• Family history – Genetics• Slender body frame• Race European; Asian• Smoking• Lack of weight-bearing exercise• Alcohol• Lack of calcium & vitamin D in the diet

Osteoporosis Slideshow

Treatment:• Medication

• Fosamax: Reduces bone loss & build bone thickness•Calcium & Vitamin D supplements

• Diet• Eat dark green vegetables, yogurt, milk Calcium• Eat eggs, fatty fish, fortified cereal Vitamin D

• Exercise Weight bearing

Bone FracturesBone Fractures

A break in a bone

Types of bone fractures

Closed (simple) fracture – break that does not penetrate the skin

Open (compound) fracture – broken bone penetrates through the skin

Bone fractures are treated by reduction and immobilization

Realignment of the bone

Common Types of FracturesCommon Types of Fractures

* Know Table 5.2 page 137

Repair of Bone FracturesRepair of Bone Fractures

1. Hematoma (blood-filled swelling) is formed

2. Break is splinted by fibrocartilage to form a callus

3. Fibrocartilage callus is replaced by a bony callus

4. Bony callus is remodeled to form a permanent patch

Stages in the Healing of a Bone FractureStages in the Healing of a Bone Fracture

* KNOW Figure 5.5 page 138

JointsJoints

Articulations of bones

Functions of joints

Hold bones together

Allow for mobility

Joints are classified in 2 ways

Functionally

Structurally

Functional Classification of JointsFunctional Classification of Joints

Focuses on the amount of movement allowed by the joint

Synarthroses – Immovable joints Amphiarthroses – Slightly moveable joints

Immovable & slightly movable joints Restricted to the axial skeleton Firm attachments & protection of internal organs

Diarthroses – Freely moveable joints Predominantly in the limbs

Structural Classification of JointsStructural Classification of Joints

Fibrous joints

Generally immovable

Cartilaginous joints

Immovable or slightly moveable

Synovial joints

Freely moveable

Fibrous JointsFibrous Joints Bones united by fibrous tissue

Ex. Sutures of the skull Synarthroses (largely immovable)

Cartilaginous JointsCartilaginous Joints

Bone ends are connected by cartilage

Examples

Amphiarthrotic- Slightly movable

Pubic symphysis

Intervertebral joints

Synarthrotic

Immovable

True ribs & sternum

Synovial JointsSynovial Joints

Articulating bones are separated by a joint cavity

Synovial fluid is found in the joint cavity

Features of Synovial Joints- Features of Synovial Joints- DiarthrosesDiarthroses

Articular (hyaline) cartilage) covers the ends of bones

Joint surfaces are enclosed by a fibrous articular capsule

Have a joint cavity filled with synovial fluid

Ligaments reinforce the joint

Structures Associated with the Structures Associated with the Synovial JointSynovial Joint Bursae – flattened fibrous sacs

Lined with synovial membranes Filled with synovial fluid Not actually part of the joint

Common where ligaments, muscles, skin, tendons, or bones rub together

Tendon sheath Elongated bursa that wraps around a tendon

subject to friction

The Synovial JointThe Synovial Joint

Types of Synovial Joints:Types of Synovial Joints:

Based on ShapeBased on Shape

Types of Synovial Joints: Based on ShapeTypes of Synovial Joints: Based on Shape

Inflammatory Conditions Inflammatory Conditions Associated with JointsAssociated with Joints

Bursitis – inflammation of a bursa usually caused by a blow or friction

Tendonitis – inflammation of tendon sheaths

Arthritis – inflammatory or degenerative diseases of joints

Over 100 different types

The most widespread crippling disease in the United States

Clinical Forms of ArthritisClinical Forms of Arthritis

Osteoarthritis Most common form of chronic

arthritis Chronic degenerative condition

Probably related to the normal aging

processes “Wear-and-tear arthritis” Affects the articular cartilages

Most commonly affected joints Fingers, cervical & lumbar regions of the spine Large weight-bearing joints of the lower limbs (knees & hips)

Progression = slow & irreversible, but rarely crippling

Clinical Forms of ArthritisClinical Forms of ArthritisRheumatoid arthritis Chronic inflammatory disorder

Autoimmune disease- Disorder in which the body’s immune system attempts to destroy its own tissues Initial trigger = unknown

Usually occurs between the ages of 40 and 50 but it may occur at any age

Affects 3 times as many women as men Joints of the fingers, wrists, ankles, and feet are affected

at the same time and usually in a symmetrical manner Often leads to deformities

Clinical Forms of ArthritisClinical Forms of ArthritisGouty Arthritis “Gout”

Disease in which uric acid accumulates in the blood and may be deposited as needle-shaped crystals in the soft tissues of joints

Agonizing painful attack- typically affects the great toe

Most common in males