Chapter 36

Skeletal System

Skeleton

• Supports the body• Protects internal

organs• Provides for

movement• Stores mineral

reserves• Provides site for

blood cell formation

• 206 bones in the adult human body

• Axial- supports central axis– Skull, vertebral column and rib cage

• Appendicular– Arms, legs, pelvis and shoulder area

Structure of bones• Network of living cells and protein fibers

surrounded by deposits of calcium salts• Periosteum- tough connective tissue layer

surrounding bone • Compact bone- dense outer bone with

Haversian canals that contain blood vessels and nerves

• Spongy bone- found closer to center than compact bones and the ends of long bones and middle of short, flat bones

Development of Bones

• Early in development the structure is cartilage- a protein fiber network of collagen and elastin with no blood vessels

• Ossification- process of bone replacing cartilage

• Osteoclasts- break down bone

• Osteoblasts- produce new bonethese both are found lining Haversian canals

• Bone Marrow- soft tissue– Yellow- made up of fat cells– Red- produces red blood cells, some white

blood cells and cell fragments called platelets

Types of Joints• Joint- where one bone

attaches to another bone• Immovable Joints

– Interlocked and held together by connective tissue or fused ex) skull

• Slightly Movable Joints– Allow small restricted

movements ex) tibia/fibula

• Freely Movable Joints– Move in one or more

directions

Freely Movable Joints

• Ball and socket- widest range of motion– Ex) shoulder

• Hinge- back and forth motion – Ex) knee

• Pivot- one bone to rotate around another– Ex) elbow

• Saddle- one bone to slide in 2 directions– Ex) finger

More Joint Information

• Ligaments- bone to bone

• Tendons- bone to muscles

• Synovial fluid- forms a thin film on cartilage in joint capsule to lubricate movement

• Bursae- sacs of synovial fluid- reduce friction and act as a shock absorber

36-2 Muscular System• 3 types of muscle tissue: skeletal, smooth

and cardiac• Skeletal

– Attached to bones– Responsible for voluntary movements– Also called striated muscle

• Smooth– Not under voluntary control– Found in hollow structures like the stomach,

blood vessels and intestines– Function without nervous stimulation

• Cardiac

– Found in the heart– Shares characteristics of both skeletal and

smooth muscle– May have two nuclei in the cells– Usually not under the direct control of the CNS

Muscle Contraction• Myosin-protein found in the thick filaments

of the muscle cells

• Actin- protein found in the thin filaments

• These filaments are arranged into a muscle fiber called a sarcomere

• The ends of the sarcomeres are called Z lines

36-3 Integumentary System

• Means “to cover”

• Includes skin, hair, nails, and glands

• Function: serves as a barrier against infection and injury, helping to regulate body temp, remove waste products from the body and provide protection against UV rays from the sun

• Skin– Epidermis-outer layer of skin– Dermis– Subcutaneous layer of fat and loose

connective tissue that help insulate

• Epidermis-outer layer of skin– Outer layer- made up of flat, dead cells

• Begin making keratin (a tough, fibrous protein)

– Inner layer is make up of living cells• Undergo rapid cell division

– Melanocytes• Produce melanin- a dark brown pigment that

protects the skin from damage caused by UV rays

• Dermis– Contains collagen fibers, blood vessels, nerve

endings, glands, sensory receptors, smooth muscles and hair follicles

– Regulates body temperature– Two types of glands: sweat and sebaceous