Skeletal System

• What makes up the skeletal system?– Bones (& connective tissue) made up of living

and nonliving material– Cartilage-no blood vessels – Tendons (attach muscle to bone)– Ligaments (attach bone to bone)

Functions

• Support and shape• Protect organs• Provide a system of levers (mov’t) • Mineral reserve (Ca & P) store fat• Site of blood cell formation (marrow)

Bone Marrow

• Yellow Marrow– Blood vessels– Nerve cells– Fat cells

• Red Marrow– Produces red blood cells

• (erythrocytes)– Produces white blood cells

• (leukocytes-lymphocytes)– Other elements

• (platlets-thrombocytes)

Development of Bone• Chondrocytes- cartilage cells• Cartilage- connective tissue. Found where

needed. (nose, ears, voice box, windpipe, ends of bones, ribs)

• 3 Types of cartilage:– Elastic-flexible

• (ears)– Hyaline-loose collagen, not too strong

• (end of nose, ribs, bones, joints)– Fibrocartilage- densely packed, tough

• (Intervertebral disks, pubis symphasis)

Development continued• Replacement bone- cartilage model of

what bones will look like– Newborns are mostly cartilage– Cartilage is replaced by bones about two

months in utero. – Ossification is the process where cartilage is

replaced by bone.• Mineral deposits lay down near center• Bone tissues form OSTEOCYTES (bone cells) that

replace cartilage.

Growth of bones

Structure of Bones

• Bones are made up of living and nonliving material.

• Periosteum-– tough membrane surrounds the bone. (blood

vessels carry oxygen & nutrients to bone)

• Compact Bone-– thick layer beneath periosteum. – Dense (ivory texture)– Not solid; filled with marrow

• Spongy Bone-– Inside layer of spongy bone– Not soft or spongy– Strong (adds strength w/out adding mass)

Structure continued…

• Haversian canals-– Network of tubes that carry blood vessels &

nerves. – Supply bones with blood.

Types of Bones

• Short– carpals

• Long– femur

• Irregular– sphenoid

• Flat– skull

Factors Affecting Bone Growth

• Mechanical Stress-weight lifting • Nutrition• Hormones

Body Positions

• Anatomical Position- arms by side, thumbs up, feet slightly apart.

• Superior/Inferior• Anterior/Posterior• Ventral/Dorsal• Proximal/Distal• Medial/Lateral• Cephalic/Caudal

Anatomical Planes

• Sagittal- separates Right and Left• Frontal- separates Front and Back• Transverse- separates Top and Bottom

How do bones move?

• Bones move by using a system of levers called JOINTS.

• Joints-– Where two bones meet– Permit movement– Hold bones in place

Joints• Immoveable Joints-

– Fixed, allow no movement– skull

• Slightly Moveable Joints-– Small amount of mov’t– Tibia, fibula, and vertebral column

• Freely Moveable Joints-– Most joints, ends of bones covered with cartilage– Synovial fluid-thin lubricant over joint– Small pockets of synovial fluid (BURSAE)

Freely Moveable Joints

• Ball and socket- permits circular mov’t: widest range of motion. – (shoulder and hip)

• Hinge-back and forth mov’t – (Elbow and knee)

• Pivot- allow rotation around a fixed point– (atlas and axis) and (radius and ulna)

More Freely Moveable Joints

• Gliding-Sliding of one bone over another– (Wrist, ankles, clavicles)

• Saddle-permit movement at 2 planes– (Thumb)

• Ellipsoid- hinge type mov’t in 2 directions– Fingers to palms and toes with soles.

Muscles

• Muscles make up ½ of the body’s weight.

Mrs. Hinzman in College

Three types of Muscles

• Skeletal- voluntary – Attaches to bone

• Smooth- involuntary– Alimentary canal, keeps eyes focused,

arteries• Cardiac-involuntary

– Found only in the heart

Muscles

• Skeletal– Striated, multinucleated

• Smooth– Spindle shaped, single nucleus

• Cardiac– Striated, single nucleus

Muscle Tone

• Muscles are kept in partial contracted state by a steady flow of nerve impulses from the spinal cord.

• If muscles lose nerve supply, what happens?– Shrinks, muscles lose about 2/3 bulk w/in

months– Muscles can repair themselves

• Origin– Muscle attachment on stable bone

• Insertion– Muscle attaches to one or more moveable

bones.

Muscle STRENGTH

• Depends on muscle shape:– Most powerful muscle is where?

• Spine-maintain posture and lifting– Hand muscles-dexterity– Eye (sphinctor) muscles- dialate, open and

close like a valve.

How Do Muscles Contract?

• Myosin- thick filaments• Actin- thin filaments• Cross Bridges- knoblike projections that

form in each myosin filament when actin and myosin come together.

Sliding Filament Theory• 1. When muscles contract, CROSS BRIDGES

move pulling the ACTIN and MYOSIN passed each other.

• 2. After CROSS BRIDGES move as far as it can, they release ACTIN to its natural position.

• Muscle work against each other (antagonist)• Flexing-makes angle small (biceps)• Extending-makes the angle bigger (triceps)

The Return of ATP• ATP

– Gives us energy (how do we get ATP in our bodies?)

– Aerobic process (required oxygen)-cellular respiration

– Anaerobic process (no oxygen needed)-fermentation (glycolysis)

– ATP makes and breaks contractions of actin and myosin. (enzyme, acetylcholinesterase, terminates a muscle contraction)

Questions???

• Do muscles push, pull, or do both?• What would take longer to heal?

– Muscle, tendon, or ligament. Why?

AnteriorTemporalisDeltoidPectoralis major/minorBicepsSternocleidomastoidFrontalisObicularis occuli/ orisQuadricepsSartorisMasseterGracilisObliques

Anterior Posterior

• Occipitalis• Trapezius• Hamstring• Latissimus Dorsi• Gastrocnemius• Triceps• Gluteus maximus• Gluteus medius

Integument (SKIN) System• Skin is the largest organ in the body• Self repairing• How does skin repair itself? What

process occurs?• What pigment determines the color of

skin?

Functions• Protect body from injury or infection• Helps regulate body temperature

– How?• Removes waste

– How?• Protects from UV rays

– How?

EPIDERMIS– Outer most layer of skin, NO BLOOD

VESSELS, but has NERVES– Cells undergo rapid division (MITOSIS)– As new cells are produced, old cell are

pushed to surface become Keratin– Keratin is tough fibrous protein that forms

hair, nails, and calluses– Keratin waterproofs our skin– New outer layer of skin is renewed every

14-28 days

DERMIS• Inner most layer under the epidermis• Contains blood vessels and nerves,

sense organs, smooth muscle, and hair follicles

Hot or Cold?• What does our body do to conserve

heat?– Blood vessels constrict to limit the heat

lost…keeps us warmer• What does our body do to cool down?

– Blood vessels open up, increases heat loss

Glands in Dermis• 1. Sweat gland-

– Produces sweat (salt and water)– Nerve impulses stimulate when body temp.

rises• 2. Sebaceous gland-

– Produces oily secretion called SEBUM– Keeps skin flexible and waterproof

Hypodermis• Layer beneath the dermis• Composed mostly of fat

– Insulates the body– Protects – Energy storage