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Support and Locomotion

Chapter 36

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Skin

The body’s protection

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Epidermis the outer layer

• Exterior layer 25-30 layers of dead, flattened cells– Constantly being shed– Keratin protective protein (elasticity)

• Interior layer living cells continually dividing– Melanin protective skin pigment

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Epidermis cont.

• Epidermal ridges• Fingers and palms• Toes and soles• Good for gripping give increased

friction

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Dermis the inner layer

• Blood vessels, nerves, nerve endings, hair follicles, sweat and oil glands

• Layer of fat underneath insulation and protection

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This picture shows a false-colored SEM of human skin. 

The lower portion is the living epidermis. As those cells die, they flake off and become the stratum corneum, which does most of the work creating a barrier between the body and the outside world.

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Functions of the skin

• Regulate body temperature• Sense organ• Vitamin D production• Physical barrier against damage and

microbial invasion

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Aging

• Drier glands decrease production• Skin loses it’s elasticity wrinkles• Accelerated by prolonged exposure to

UV rays

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The Skeletal System

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Axial skeletonIncludes the skull, vertebral column, ribs, and sternum

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Appendicular skeletonIncludes the bones of the arms and legs, and associated structures

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Joints

Places where bones are connected

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Ball-and-socket joint

• Allows for rotational movement

• Hips and shoulders

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Hinge joint

• Allows for back-and-forth movement

• Elbows, knees, fingers, and toes

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Pivot joint

• Allows bones to twist around each other

• Neck and elbows

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Gliding joint

• Allows bones to slide past each other

• Wrists and ankles

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Fixed joint

• Also called a fused joint

• Allows for no motion• Skull

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Cartilage

• Bones are cushioned by a thin layer of cartilage

• Flexible, elastic tissue• Nose, ears, trachea, between each

vertebrae

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Bursae

• Fluid-filled sacs between bones• Absorb shock

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Arthritis

• Inflammation of the joints• Wearing down of cartilage• Bone spurs splinters• Causes infections, aging, injury,

genetic

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Connective tissue

• Ligaments connect bone to bone– Sprain torn or stretched ligament

• Tendons connect muscles to bones– Tendonitis inflammation of the tendon

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Bone Structure

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Compact bone

• Very dense and strong• Outside of ends and along shafts• Osteocytes bone cells

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• Osteon systems (Haversian canals)– Openings which allow blood vessels and

nerves through bone

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Spongy bone

• Less dense, porous• Ends of bones

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PeriosteumOuter covering of bone shafts

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Osteoblasts potential bone cells

• Secrete a protein called collagen• Deposition of minerals turns them into

osteocytes ossification

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• Osteoporosis loss of bone mass• Growth

– Length: cartilage plates at ends– Width: outer surface

• After growth repair and maintenance

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Marrow found at the center of bones

Red marrow• Long bones only

– Production of blood cells

Yellow marrow• Most bones

– Stored fat

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Functions of the skeletal system

• Protects internal organs• Framework for body tissues• Attachment for muscles• Production of blood cells• Mineral storage

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Skeletal system

• Animation

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Muscles

3 types

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Smooth muscle

• Sheets of cells• Walls of internal organs and blood

vessels• Function squeezing (pressure)• Involuntary not under conscious

control

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Smooth muscle tissue

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Cardiac muscle

• Found in your heart• Interconnected bands of muscle fibers

striated• Adapted to generate and conduct

electrical impulses• Involuntary

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Cardiac muscle tissue

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Skeletal muscle

• Attached to bones• Controls movement• Work in opposing pairs 1 bends a limb

and the other extends the limb• Striated in appearance• Voluntary

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Skeletal muscle tissue

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Muscle and nerves

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Skeletal muscle contraction

• Contraction Animation

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Muscle strength

• The number of muscle fibers you have is fixed before birth

• Muscle fibers get bigger and more fibers contract as you increase your strength

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Muscle fatigue when muscles hurt after use

• Due to decreased available oxygen• Cells switch from aerobic to anaerobic• Lactic acid buildup toxic, causes pain• Cure rest• Not resting can result in permanent

muscle damage

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Comparative anatomy

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Amoeba

• Pseudopods “false feet”• Extensions of the cell membrane that

can reach in any direction• Locomotion

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Amoeba with pseudopods

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Paramecium

• Have cilia to propel them through the water

• Locomotion

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Paramecium with cilia

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Hydra

• Pull with tentacles• Glide on base• Somersaulting• Movement

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Hydra with tentacles

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Earthworm

• Setae bristles used as anchors• Longitudinal muscles shorten body• Circular muscles lengthen body

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Grasshopper

• Jointed appendages• Walking legs and jumping legs• 2 sets of wings• Exoskeleton made of chitin

– Attachment site for muscles

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