The Skeletal System

The Skeleton Supports the body Protects internal organs Aids in movement Stores minerals Make blood cells The Skeleton

The Skeleton 206 bones Bone is living tissue Contains living bone cells, blood vessels and nerves. Bone marrow stores fat and makes blood cells Bone starts out as cartilage and ossifies into bone. The Skeleton

Figure 36-3 The Structure of Bone Section 36-1 Spongy bone compact bone Periosteum Bone marrow Haversian canal Compact bone Osteocyte Artery Vein

Joints Elastic ligaments hold bones together at joints. Cartilage protects bones at joints. Hinge joints – elbow and knee Ball and socket joint – shoulder and hip Pivot joint – neck Gliding joint – wrist and ankle Joints

Section 36-1 Muscle Tendon Femur Patella Bursa Ligament Synovial fluid Cartilage Fat Fibula Tibia

Skeletal Disorders Arthritis – inflammation of joints Osteoporosis – mineral loss; weakening Sprains – ligaments are stretched or torn. Skeletal Disorders

Muscular System

Muscular Tissue The only tissue that contracts. Three types: Skeletal = attached to bones; voluntary Cardiac = in the heart; involuntary Smooth = make up digestive tract, blood vessels and other organs; involuntary Muscular Tissue

Section 36-2

Protein fibers called actin and myosin slide over each other. This requires lots of energy. Muscle cells have lots of mitochondria, like nerve cells. Muscle Contraction

Muscles contract when nerves tell them to. Muscle Contraction

Movement Inelastic tendons attach muscle to bone. Muscles can only pull, not push. Muscles work in opposing pairs to move a bone. One muscle bends the joint and another muscle straightens the joint. Movement

Movement Movement Section 36-2 Biceps (relaxed) Biceps (contracted) Triceps (contracted) Triceps (relaxed)

Regular exercise keeps the muscles in a partial state of contraction called muscle tone. This is important to survival. Muscle Tone

Integumentary System Hair, skin, nails

Skin First line of defense against disease. Helps regulate body temperature. Aids in waste removal (excretion). Protects against UV radiation. Skin

Section 36-3

UV radiation can cause mutations in skin cells resulting in abnormal growth. The tendency towards skin cancer is hereditary. Skin Cancer

Hair provides protection from UV radiation and filters particulates from the nose, ear and eyes. Hairs as well as attached skin cells are used as forensic evidence. Nails grow from the base called the root. Some nails get invaded by a fungus and look nasty. Hair and Nails