THE SKELETAL, MUSCULAR & INTEGUMENTARY SYSTEMSCHAPTER 36

CHAPTER 36.1THE SKELETAL SYSTEMHW: P. 925 #1-4

THE SKELETON• Functions: • Supports the body• Protects internal organs• Enables movement• Stores mineral reserves• Site for blood cell formation

• Axial: skull, vertebrae and rib cage

• Appendicular: bones of upper and lower limbs

Structure of Bones (Fig. 36.3)• Bones: solid network of living

cells and protein fibers surrounded by deposits of calcium salts

• Periosteum: tough layer of connective tissue that surrounds the bone

• Compact Bone: dense bone• Haversian Canals: tube

network for vessels and nerves

• Spongy Bone: lattice network of bone; adds support without mass

• Bone Marrow: soft tissue inside bone; yellow = fat; red = blood cell formation

BONE DEVELOPMENT• Ossification:

cartilage replaced by bone• Osteocytes: mature bone cells• Osteoblasts: produce bone (“blast off”)• Osteoclasts: break down bone

• Where can you find cartilage in your body?

TYPES OF JOINTS• Joints: where bones attach;

allow for movement without damage

• Types of joints:• Immovable: no movement

(i.e. skull bones)• Slightly movable: small,

restricted movements (i.e. vertebrae)• Freely movable: movement in

one or more directions• Ball-and-socket: most

movement (i.e. shoulder)• Hinge: back-and-forth motion

(i.e. knee, elbow)• Pivot: bones rotate (i.e. forearm)• Saddle: bones slide (i.e. thumb)

STRUCTURE OF JOINTS• Cartilage between

bones helps reduce friction

• Ligaments fuse with bone membranes and connect bone to bone.

• Synovial fluid allows for smooth bone movement

SKELETAL SYSTEM DISORDERS

• Arthritis: inflammation of joints

• Osteoporosis: severe bone loss (mostly in women)

CHAPTER 36.2THE MUSCULAR SYSTEMHW: P. 931 #1-5

TYPES OF MUSCLE TISSUE (Fig. 36-6)

• Skeletal muscle cells: long, slender, multi-nucleated and striated; voluntary (aka muscle fibers); attached to bones

• Smooth muscle cells: spindle-shaped, one nuclei and non-striated; involuntary; lines organs, vessels and digestive tract

• Cardiac muscle cells: striated with one or two nuclei; involuntary; only found in the heart

SKELETAL MUSCLE STRUCTURE (Fig. 36-7)

• Thin (actin) & Thick (myosin) filaments myofibrils (sarcomere) muscle fiber (cell) bundle of muscle fibers skeletal muscle

MUSCLE CONTRACTION (Fig. 36-8)

• Thick filaments: myosin protein

• Thin filaments: actin protein (“thin” and “tin”)

• Filaments arranged into a sarcomere (from Z to Z line)

• Sliding filament model: A muscle contracts when the thin filaments slide over the thick filaments.

• Energy for contraction supplied by ATP

• Neuromuscular junction: synapse between neuron and muscle cell

• Acetlycholine: neurotransmitter that binds to muscle fibers and causes calcium to release

• Calcium is KEY to muscle contractions (allows myosin to bind to actin)

• More muscle cells stimulated = stronger contraction

MUSCLES AND BONES• Tendons connect

muscles to bone.• Muscles contract and

tendons pull on bones, function like levers around a fixed point (joint)

• Regular exercise is important in maintaining muscular strength and flexibility.

CHAPTER 36.3The Integumentary SystemP. 936 #1-5P. 939 #1-10, 14, 16, 23

THE SKIN• Functions:•Protection—barrier against infection and injury (most important)•Regulates body temp.•Removes waste•Protection against UV rays

THE STRUCTURE OF SKIN (Fig. 36-13)

• Two layers:•Epidermis: outer layer; dead and living cells (inner cells divide constantly)• Keratin: tough, fibrous

protein• Melanocytes: cells that

make melanin (brown skin pigment)

•Dermis: inner layer; contains vessels, nerves, glands, etc…

HAIR AND NAILS• Hair: protection from

UV rays; insulation from cold; traps dirt and other particles; grow from hair follicles (pockets in the dermis)

• Nails: made of keratin; grow from the nail root; protects tips of fingers and toes

SKIN DISEASES

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