Functions of the Skeletal System • Movement: Muscles work on the foundation of the bones to allow for movement. • Support: The backbone is the main support center for the upper body. • Protection: The bones of your skull protect the brain. • Storage: Bones store minerals, such as calcium, for use by the body. • Blood Cell Formation: Red and white blood cells are formed by marrow.
Two Major Parts of Skeletal System • Axial: supports the central axis of the body; includes skull, vertebral column, ribcage. • Appendicular: consists of the bones of the arms, legs, pelvis, shoulder area *THERE ARE 206 BONES IN AN ADULT SKELETON
What are bones? • Bones: solid network of living cells and protein fibers that are surrounded by deposits of calcium salts.
Bone Structure • Periosteum: tough layer of connective tissue surrounding bone • Compact bone: thick, dense layer of bone containing Haversian canals – containing blood vessels • Spongy bone: strong layer found inside compact bone • Bone Marrow: soft tissue located inside bone cavities
Types of Bone Marrow • Yellow Marrow – made up primarily of fat cells • Red Marrow – produces red blood cells, some white blood cells, and platelets
Development of Bones • The skeleton of an embryo is composed almost entirely of cartilage • Cartilage: connective tissues with cells that are scattered in a network of protein fibers including collagen and elastin • Ossification: process of cartilage being replaced by bone • During adolescence/early adulthood, cartilage in growth plates are replaced by bone – stopping growth!
Joints • Joint: place where one bone attaches to another • Depending on its type of movement, a joint is classified as immovable, slightly movable, or freely movable
Types of Joints • Immovable: allow for no movement • Ex. Skull • Slightly Movable: small amount of restricted movement • Ex. joint between adjacent vertebrae
Types of Joints • Ball-and-Socket: Round end of one bone fits snuggly into another • Ex. Shoulder and Hip
Types of Joints • Hinge Joint: movement at joint occurs in one direction, like a door • Ex. Knee and Elbow
Types of Joints • Pivot Joint: bone resting atop another bone permitting free movement • Ex. Neck, Wrist, Ankle
Types of Joints • Saddle Joints: permit one bone to slide in two directions • Ex. knuckles
Structure of Joints • Ligaments: tough connective tissue that connects bone to bone • Synovial Fluid: a substance that enables joints to slide over each other smoothly
Skeletal System Disorders • Arthritis: Inflamed/stiff joints • Osteoporosis: weakening of bones, especially in women
Muscular System • More than 40% of the mass of a human is muscle • Muscular system includes large muscles displayed by some athletes • Muscular system also includes many tiny muscles used to help regulate blood pressure, move food, and power every movement of the body
Types of Muscle Tissue: Skeletal • Usually attached to bones • Responsible for voluntary movements: dancing, walking, typing • Referred to as striated muscle • Controlled by the central nervous system • Consists of muscle fibers, connective tissue, blood vessels, and nerves
Types of Muscle Tissue: Smooth • Usually not under voluntary control • Found in walls of hallow structures: stomach, blood vessels, intestines • Can function without nervous system stimulation
Types of Muscle Tissue: Cardiac • Found in the heart ONLY! • Cells may have up to two nuclei • Is not under control of the central nervous system
Muscle Tissue Makeup • Myofibril: smaller structures that make up a muscle; composed of two filaments • Myosin: the name of the protein that composes the thick filament • Actin: the name of the protein that composes the thin filament
Muscle Contraction • A muscle contracts when the thin filaments in the muscle fiber slide over the thick filaments • ATP is used to power muscle contractions • Large amounts of ATP are needed!
Muscle and Bone Interactions • Tendon: attaches bone to muscle • Origin: attachment of muscle to immovable bone • Insertion: attachment to bone that moves when muscle contraction • Muscles move from insertion point to origin
Exercise and Health • Muscle tone: result of skeletal muscles remaining in a state of partial contraction • Regular exercise is important in maintaining muscular strength • Aerobic exercise causes the body systems to become more efficient
Muscle Pain • Sprain: wrenching, twisting, stretching injury to a ligament • Strain: injury to muscle or tendon – often caused by overuse
Muscle Pain Shin splints • Shin splints is pain resulting from damage to the muscles along the shin. Pain is felt in different areas, depending on which muscles are affected. Shin splints represent an "overuse injury" and occur most commonly in runners.
Integumentary System Functions • Barrier against infection and injury • Regulates body temperature • Removes waste products from the body • Provides protection against ultraviolet radiation from the sun
Skin • Serves as a gateway through which sensations such as pressure, heat, cold, and pain are transmitted to the nervous system • Two main layers: epidermis, dermis • Below the dermis is a layer of fat and connective tissue to insulate the body
Skin: Epidermis • Epidermis has two parts: outside portion is made of dead cells, inside portion is made of living cells • As cells move from the inner layer towards the outer layer, they create keratin – a fibrous protein • Eventually the cells die and form a waterproof coating – skin • The outer layer of cells is shed every 4-5 weeks
Skin: Epidermis • Epidermis contains melanocytes – cells that produce melanin • Melanin protects skin from the damage of UV rays • Differences in skin color are due to the differences in the amount of melanin produced
Skin: Dermis • Dermis contains collagen, blood vessels, nerve endings, glands, smooth muscle, hair follicles • The vessels in the dermis help control body temperature: contracting and widening as needed
Skin: Dermis • Dermis contains two types of glands: • Sweat glands: produce perspiration; sweat contains salts, water, and other compounds; sweat helps get rid of waste • Sebaceous glands: produce an oily secretion called sebum; sebum helps keep the epidermis flexible and waterproof
Skin Cancer • Skin cancer = abnormal growth of cells in the skin • Excessive sun exposure can produce skin cancer • SPF 15 should be the minimum!!!
Hair and Nails • Keratin forms the basic structure • Hair • Functions: protect surface of the body from UV; prevent dirt/particles from entering body • Hair Follicles: tubelike pockets of epidermal cells that produce hair • Nails • Nail root: area of rapidly dividing cells from which nails grow • Grow at a rate of 3mm per month