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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
- 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