• Skeletal and Muscular

Systems

Functions of the Skeletal System

• Framework

• Protection

• Movement (with

muscular system)

• Maintain calcium

balance

Bone • Connective tissue hardened by calcium

Types of Bone Tissue

• Compact: Dense, solid – forms outer shaft of long bones

• Spongy: Looks “lacy” – found inside shaft

Bone Development

• Start with cartilage

model

• Osteoblasts = bone

forming cells

• Ends separated

from shaft by

cartilage until

growth stops (late

adolescence)

• Bones are constantly being “remodeled”

• Load-bearing exercise important!

• Osteoporosis – Loss of bone density

Normal bone tissue After the onset of osteoporosis

Basic Bone Types • Long: Weight-bearing, structural

• Short: Allow wide range of movement

• Flat: Protective

• Irregular: Provide attachment sites

Human Skeleton

• Axial skeleton: Center axis

• Appendicular skeleton: “hanging”

• Bones connected by ligaments at joints

• Muscles attached to bones by tendons

Axial Skeleton

• Supports and

protects

• Made of:

- Skull

- Vertebral column

(backbone)

- Sternum

(breastbone)

-Ribs

Skull

• 28 bones!

• Brain case protects

the brain

• Facial bones

support & shape

the face

Vertebral Column

• 33 vertebrae

stacked with

intervertebral

disks between

most

• Intervertebral

disks = shock

absorbers, flex

points

Ribs / Sternum

• Ribs attach to vertebral column in back,

sternum in front

• Protect heart, lungs, other organs

• Important for breathing

Appendicular Skeleton

• “Hanging” skeleton

• Made of: - Arms / hands - Legs / feet - Pectoral girdle (shoulders) - Pelvic girdle (hips)

Pectoral Girdle

• Scapula (shoulder

blade)

• Clavicle (collar bone)

connects scapula to

the sternum

• Loose muscle

attachment

Arm Bones

• Humerus = upper arm

• Radius, Ulna = lower arm

• Carpals = wrist

• Metacarpals = hand

• Phalanges = fingers

Pelvic Girdle / Leg Bones

• Femur = thigh

• Tibia, Fibula =

lower leg

• Tarsals = ankle

• Metatarsals = foot

• Phalanges = toes

• Patella = kneecap

Functions of the Muscular System

• Allow us to stand

upright

• Movement

• Blood circulation

• Digestion & waste

removal

• Regulation of body

temperature

Types of Muscle

• Skeletal: connects

to skeleton & moves

parts, striated

• Smooth: found in

walls of hollow

organs and blood

vessels, not striated

• Cardiac: only found

in heart, striated

“Slow” Fibers

• Sustain long, repeated

contractions

• Many mitochondria

• Lots of myoglobin

“Fast” Fibers

• Generate quick bursts

of power

• Few mitochondria

• Little myoglobin

Types of Skeletal Muscle

Structure of Skeletal Muscles

• Bundles of muscle cells (fibers) covered by connective tissue

• Attached to bones by tendons

• Origin – attached to bone that moves little

• Insertion – attached to bone that moves most

Many Muscles Arranged in Pairs or Groups

• Antagonistic: work in opposition

• Synergistic: work together

Basic Types of Muscle Contractions

• Isotonic: Muscles shorten to move a load

• Isometric: Muscles develop tension but don’t shorten