Chapter 46-Animal Sensory Systems And Movement

Front 1

locomotion

Back 1

the movement of an entire animal

Front 2

exoskeleton

Back 2

hard, hollow structures that envelop th body

Front 3

hydrostatic skeleton

Back 3

use the pressure of enclosed body fluids to support the body

Front 4

endoskeleton

Back 4

hard structures inside the body. composed of cartilage and bone

Front 5

cartilage

Back 5

cells scattered in a gelatinous matrix of polysaccharides and protein fibers. provides padding between bones

Front 6

bone

Back 6

made up of cells in a hard extrcellular matrix of calcium phosphate with small amounts of calcium carbonate and protein fibers. meet and interact with joints and allow limbs to swivel, hinge or pivot.

Front 7

skeletal muscles

Back 7

attached to bone, move the skeleton, multinucleated, unbranched, contains myofibrils, voluntary (signal from a motor neuron is needed)

Front 8

Cardiac muscle

Back 8

heart muscle, pumps blood, 1 or 2 nuclei, branched (intercalated discs), contains myofibrils involuntary movement

Front 9

smooth muscle

Back 9

intestines, arteries, other, it helps move food, help regulate blood pressure etc, single nucleus, no myofibrils, involunary movement.

Front 10

myofibrils

Back 10

long, slender structure composed of contractile proteins organized into repeating units (sarcomeres)

Front 11

sarcomeres

Back 11

the repeating contractile unit of a skeletal muscle cell; the portion of a myofibril located between adjacent Z discs.

Front 12

Sliding Filament Model

Back 12

the hypothesis that thin (actin) filaments and thck (myosin) filaments slide past eachother, thereby shortening the sarcomere. shortening of all sarcomeres in a myofibril results in contraction of the entire myofibril

Front 13

Actin

Back 13

thin filaments composed of two coiled chains of globular protein. One end of each is bound to the Z disk, which forms the wall of the sarcomere. the other end is free to interact with the thick filaments

Front 14

Myosin

Back 14

thick filaments. composed of multiple strands of long protein. anchored to the middle of the sarcomere. they are free at both ends to interact with the thin filaments.

Front 15

Z disk

Back 15

the structure that forms each end of a sarcomere. contains a protein that binds tightly to actin, thereby anchoring thin filaments.

Front 16

How do actin and myosin interact?

Back 16

1. the myosin head of the thick filament is attached to ATP but not to actin in a thin filament.
2. When ATP is hydrolyzed to ADP and inorganic phosphate, the neck of the myosin straightens and the head pivots. The myosin head then binds to a new actin subunit farther down the thin filament.
3. when inorganic phosphate is released, the neck bends bac to its original position. this bending called the power stroke, moves the entire thin filament.
4. after ADP is released, a new ATP molecule binds to the myosin to release from actin.

Front 17

tropomyosin

Back 17

A regulatory protein present in thin filaments that blocks the myosin binding sites on these filaments, thereby preventing muscle contraction.

Front 18

Troponin

Back 18

A regulatory protein, present in thin filaments, that can move tropomyosin off the myosin binding sites on these filaments, thereby triggering muscle contraction

Front 19

What happens when an action potential from a motor neuron arrives at a muscle cell and initiates contraction?

Back 19

1. The release of ACh from the motor neuron into the synaptic cleft between the motor neuron and the muscle cell is triggered
2. ACh diffuses across the synaptic cleft and binds to ACh receptors on the plasma membrane of the muscle cell.
3. action potentials are propagated along the length of the muscle fiber and spread into the interior of the fiber via invaginations of the muscle cell membrane called T tubules.
4. T tubules intersect with extensive sheets of smooth er called sarcoplasmic reticulum. when an action potential passes down a T tubule and reaches one of these intersections, a protein in the T tubule membrane changes conformation and opens calcium channels in the sarcoplasmic reticulum.