Moving the Body

Muscles and Bones

I. Bones

A. Functions

- site of formation of red blood cells

- offers support and structure for the body

- protection of internal organs (brain, heart, lungs)

- aids in locomotion (movement)

Bones (contd.)

B. Parts of Bone- bone is made of both living

and non-living materials1. Periosteum - thin, living

membrane covering the outer surface of bone

- has many blood vessels in it to carry nutrients and oxygen to the living parts of the bone

- bone cells are called osteocytes

Bones (contd.)

- bone is also made of non-living components - calcium and phosphorous

- give bones strong, rigid, structure

- not enough calcium in diet can cause rickets (in children) and osteoporosis (in older people)

Bones (contd.)

2. Spongy Bone - bone with many open spaces

- found towards the ends of long bones

- made of a hard network of minerals

3. Compact Bone- made of minerals, osteocytes, blood vessels, nerves, and elastic fibers

- dense, hard, inner part of bones

Bones (contd.)

4. Bone Marrow - found at center of bone

- gel-like material - makes red blood cells- 2 types of bone marrowa. yellow marrow - found in

long part of the bone, mostly made of fat

b. red marrow - found in spongy bone

- where red blood cells are made

Bones (contd.)

5. Cartilage - connective tissue that serves as a cushion and lubricant where bones meet

C. Bone Strength- bones are able to resist

high amounts of pressure- are lightweight, but strong

due to minerals- spongy bone serves as a

natural shock absorber

Bones (contd.)

D. Bone Development- most bones start off as

cartilage (when you are a baby)

- as you grow older, the process of ossification occurs - converting cartilage into bone

- eventually, almost all of the cartilage in your skeleton is replaced by bone

Bones (contd.)

- some animals have skeletons composed almost entirely of cartilage

- cartilaginous fishes - sharks and rays

- only bones that are fully formed whn you are born are the three small bones in the inner ear (hammer, anvil, and stirrup)

II. Joints

A. Joint - a place where two or more bones meet

- 6 types of joints1. Ball and Socket - allows

for circular movement (ex.: hip, shoulder)

2. Hinge Joint - allows for back and forth movement (ex.: elbow, knee, fingers)

Joints (contd.)

3. Pivot Joint - allows one bone to pivot past another

- allows for rotating movement (ex.: radius and ulna in forearm)

4. Gliding Joint - allows bones to glide past one another

- relatively little movement (ex.: vertebrae (backbone))

Joints (contd.)

5. Fused (Immovable) Joint - no movement (ex. Skull, pelvis)

6. Saddle Joint – allows for side to side and back and forth motion

(ex.: thumb)

Joints (contd.)

B. Connecting Bones- bones are connected to one

another by ligaments- like rubber bands - type of

connective tissue- in between bones, there is a

layer of synovial fluid - which cushions and lubricates the joint

- secreted by cartilage- cartilage covers ends of

bones to keep them from rubbing together

III. Muscles

- help to move bones like levers

A. 3 Types of Muscle1. Skeletal Muscle (Striated

Muscle)- voluntary - under your

direct, conscious control- controls, walking, talking,

etc- cells have no visible

nucleus

Muscles (contd.)

2. Smooth Muscle

- involuntary muscle

- no direct, conscious control

- controls body functions that always need to keep running

ex.: breathing, digestion

Muscles (contd.)

3. Cardiac Muscle - heart muscle

- only found in heart

- involuntary muscle - not under direct, conscious, control

- controls heartbeat

Muscles (contd.)

B. Muscle Movement1. Flexors and Extensors- muscles always occur in

pairs- muscles can only

shorten, or contract - need a partner muscle

moving in an opposite direction to stretch muscle out after it has been contracted

Muscles (contd.)

- like Newton's 3rd Law - for every actions, there is an equal and opposite reaction

a. flexor - the muscle that contracts and causes movement to occur at a joint

b. extensor - muscle that extends the muscle and bone

Muscles (contd.)

- causes bone to straighten out after they have been moved at the joint

muscles contract and relax in pairs

- important pairs of muscles in the body:

ex.: biceps and triceps (in upper arm)

quadriceps and hamstrings (in thigh)

Muscles (contd.)

2. Muscle Organization- muscles are made of

bundles of string-like tissue called fibers

- fibers are made of smaller tissues called filaments

- 2 types of filamentsa. actin b. myosin

Muscles (contd.)

- filaments make and break chemical bonds

- what causes muscles to be able to shorten (contract) and lengthen (extend)

- muscles are connected to bones by tendons