CHAPTER 30

How Animals Move

Locomotion

• water: provides support against gravity but allows for a high frictional resistance

• air: provides little support for gravity but allows for low frictional resistance that requires us to have balance

- active travel from place to place- requires us to overcome friction & gravity

Sect 30.1

Skeleton

Axial Skeleton:- skull (protects brain)- backbone (protects

spinal cord, supports appendages, gives body structure, s-shaped to help balance biped body)

- rib cage (protects lungs & heart)

Appendicular:- bones of the

appendages (arms, legs)

- bones that link appendages to axial skeleton (shoulder girdle, pelvic girdle)

- 3 functions: support, movement, protection

Sect 30.3

p. 610

Joints

•Ball-and-Socket - allows for rotation of arms and legs and moving in several planes

- ex: scapula-head of humerus (shoulder); pelvis-head of femur (hip)

p. 611

• Hinge - allows for movement in single plane

- ex: humerus-head of ulna (elbow)• Pivot - allows for rotation

- ex: forearm at elbow, wrists

Bone Composition

•Outside Surface - covered w/fibrous connective tissue (when bones break or crack, this tissue is able to form new bone)

•Ends - cartilage replaces connective tissue to form cushions

Sect 30.4

p. 611

• Bone Shaft - compact bone w/dense matrix surrounding a hollow cavity called yellow bone marrow (stored in fat)

- but at the end of the shaft is an inner layer of a spongy bone matrix called red bone marrow

- bone matrix: noncellular matrix of calcium salts (which resist compression) & protein fibers (which resist cracking) surround the cells secreting these materials

• bones begin to form about 1 month after conception and stop growing at about 18 yrs for women and 21 yrs for men

Skeletal Disorders•Arthritis - inflammation of joints - affects 1 out of 7 in U.S. - joints become stiff & sore, swell

as cartilage between bones wear down or bones thicken at the joints (produces crunching noises when bones rub together & restrict movement)

Sect 30.5-30.6

- rheumatoid arthritis: joints become highly inflamed & the jointed tissues are destroyed by body’s immune system

* begins between 30-40 yrs old, usually more in women

* no cure, fitted w/artificial joints

• Osteoporosis

- bones become thinner, more porous, easily broken

- most common in women after menopause due to the decrease in estrogen (bone density starts decreasing between 30-35 yrs old)

- prevented by calcium intake and bone density exercises (running, walking)

Muscles

•found in antagonistic pairs•connected to bones by tendons•have a site of origin and insertion

p. 613 - ex: origin - biceps muscle

attached to shoulder insertion(place of work) -

attached to forearm

Characteristics for Skeletal Muscles

Sect 30.7

• muscles can only contract, must be extended passively by antagonistic pair

• is a bundle of long fibers running the length of the muscle

•each fiber is a single cell w/many nuclei and mitochondria

Muscle Contraction

•Parts of the muscle fiber: - each fiber is a bundle of smaller

myofibrils arranged lengthwise - a myofibril consists of repeating

units called sarcomeres * produce the light & dark bands on

muscle (this is what gives skeletal muscle its striated appearance)

Sect 30.8

Sarcomere

•Z lines (made of thin microfilaments) are borders

•Light bands - made of thin filaments on edges of sarcomere

- thin filaments consist of a double strand of the protein actin & 1 strand of a regulatory protein

• Dark bands - made of thick filaments in the middle of sarcomere

- thick filaments consist of a number of parallel strands of the protein myosin

Sliding Filament Model

•proposed by A.F. Huxley•sarcomere contracts (shortens) as

thin filaments slide across thick filaments

•filaments don’t shorten•a myosin head on thick filament

binds to an actin monomer on the thin filament

Sect 30.9

p. 615

• hydrolysis of an ATP molecule causes the myosin head to bend

•filaments will then slide past each other (similar to boat/oar)

•myosin head is released from the first actin monomer & attaches to a new one

* each head can move at about 5 movements per second

Characteristics for Cardiac Muscle

•found in heart•striated•generates its own action

potentials w/out the help of the nervous system

Characteristics of Smooth Muscle

•found in the digestive tract•lacks striations•involuntary•contractions are slow but

can be sustained over long periods of time