Skeletal(Bones), Muscular(Muscles), and Integumentary(Skin) Systems

Skeletal System Functions - support the body - movement - protection of internal organs - storing minerals - blood cell formation 206 bones in an adult human body Two divisions: 1. Axial skeleton – skull, vertebrae, and rib cage 2. Appendicular skeleton – arms, legs, pelvis and shoulders

Bones

Bones are a solid network of living cells and protein fibers that are surrounded by calcium deposits Cartilage is tough connective tissue that forms or ossifies (ossification) into bone Periosteum is the tough layer of connective tissue that surrounds the bone Haversian canals – network of tubes that run through the bone containing blood vessels and nerves Bone marrow – soft tissue found inside the cavities of the bone - yellow marrow – primarily fat cells - red marrow – contains red blood cells, white blood cells, and platelets

Joints Joint – place where bones attach to one another Types of Joints: a. Ball –and-socket – full rotational range or circle Ex: shoulder and hip b. Hinge joint – up and down or back and forth movement Ex: knee and elbow c. Pivot joint – up and down, side to side, rotate in a circle Ex: neck d. Gliding joint – rotational, limited side movement, up and down Ex: ankle and wrist Ligaments – connective tissue that meets at joints; attaches bone to bone

Muscular System Function - movement is the main function of the muscular system Three types of muscle: 1. Skeletal 2. Smooth 3. Cardiac

Type of Muscle Skeletal muscle – usually under conscious control -attached to bones and responsible for voluntary movements of the body

Types of Muscle Smooth muscle – spindle shaped with a nucleus - usually not voluntary or under conscious control - found in the digestive tract, or blood vessels near the heart, muscles of the pupil

Types of Muscle Cardiac muscle – found only in the heart - can have 1 or 2 nuclei - smaller and striated - not under voluntary control

Muscle Man

Muscle Contraction Myofibrils are smaller units of muscle fibers Filaments make up a myofibril 2 types of filaments: 1. actin – thin filaments that slide over thick ones to contract muscle; slide back to relax 2. myosin – thick filaments that form the sarcomere Sarcomere – muscle fiber unit that runs Z-line to Z-line Contraction of muscle shrinks distance of sarcomere and requires ATP Tendons – strong connective tissue that attach muscle to bone at the joint

Muscle Contraction

Integumentary System Largest single organ of the body Functions: 1. serve as barrier against infection and injury 2. regulate body temperature 3. remove waste products 4. protect against ultraviolet radiation from the sun Two main layers: - Epidermis - Dermis

Layers of Skin

Epidermis – outer layer of the skin - 2 layers that contain both dead and living cells - protective covering to prevent infection and prevent water loss - also contains melanocytes which release a pigment called melanin (skin and hair) to protect against ultraviolet rays

Layers of the Skin Dermis – inner layer of the skin that contains blood vessels, nerves, glands, smooth muscles, and hair follicles - helps regulate body temperature - eliminates waste products