Muscular System Ch 8 vocab

Question 1

a bands

Answer 1

Large, dark bands in a skeletal muscle fiber that alternate with lighter I bands to give a striped appearance to skeletal muscle fibers under a microscope. Composed of thick filaments of the contractile protein myosin.

Question 2

abduction

Answer 2

the joint movement where an extremity is moved away from the median plane

Question 3

actin filament

Answer 3

formed of one of the two contractile proteins of muscle (the other is myosin), these slide over each other to produce the shortening of the muscle cell that we refer to as muscle contraction

Question 4

adduction

Answer 4

the joint movement where an extremity is moved toward the median plane

Question 5

adenosine diphosphate (ADP)

Answer 5

the discharged form of ATP. A nucleotide that contains two phosphoric acid groups. When a phosphate group is split off of an ATP molecule to produce ADP, energy is released that powers the sliding of the actin and myosin filaments in muscle over each other. When the phosphate group is reattached, which requires another energy source, ADP is converted back to ATP and the molecule is ready to provide energy again.

Question 6

adenosine triphosphate (ATP)

Answer 6

A high-energy molecule produced int he mitochondria of cells. It is a nucleotide that contains three phosphoric acid groups. When a phosphate group is split from an ATP molecule to produce ADP, energy is released that powers the sliding of the actin and myosin filaments in muscle over eachother. When the phosphate group is reattached, which requires another energy source, ADP is converted back to ATP and the molecule is ready to provide energy again. The more active a cell or body part is, the more ATP it will have produced and stored. For instance, muscles have a great deal of stored ATP, whereas fat has relatively little.

Question 7

aerobic metabolism

Answer 7

Oxygen- consuming metabolism. The type of metabolism in muscle in which the supply of available oxygen is sufficient to keep up with the energy needs of the muscle fibers. Aerobic metabolism extracts the maximum amount of energy from glucose molecules.

Question 8

antagonist

Answer 8

Something that opposes the action of something else. An antagonist muscle or muscle group directly opposes the action of a prime mover muscle or muscle group that is directly producing a desired movement

Question 9

aponeuroses

Answer 9

a broad sheet of fibrous connective tissue that attaches certain muscles to bones or to other muscles

Question 10

brachium

Answer 10

the upper arm. The area of the thoracic limb between the elbow and the shoulder

Question 11

cardiac muscle

Answer 11

striated, involuntary muscle that is found exclusively in the heart. Influenced by the autonomic nervous system. Has one centrally located nucleus and intercalated discs that form special connections between the muscle branches.

Question 12

creatine phosphate (CP)

Answer 12

the molecule in muscle cells that splits to release the energy necessary to reattach the detached phosphate group to an ADP molecule to convert it back to the high-energy molecule ATP.

Question 13

cross-bridge

Answer 13

tiny levers on the myosin filaments of muscle. A muscle cell contracts by ratcheting the cross-bridges back and forth to pull the thinner actin filaments toward the center of the myosin filaments.

Question 14

cutaneous muscle

Answer 14

“skin muscles.” thin muscles in the connective tissue beneath the skin. When a cutaneous muscle contracts, it causes the skin to twitch

Question 15

dense body

Answer 15

structures in smooth muscle cells to which the small contractile units of actin and myosin attach. These structures correspond to the Z lines of skeletal muscle to which the actin filaments attach.

Question 16

diaphragm

Answer 16

the thin, dome-shaped sheet of muscle that forms the boundary between the thoracic and abdominal cavities. A muscle that helps produce inspiration when it contracts. Dome-shaped at rest with convex surface directed cranially. When it contracts, the dome of the diaphragm flattens out, which increases the volume of the thoracic cavity and causes air to be drawn into the lungs

Question 17

endomysium

Answer 17

the thin, delicate layer of connective tissue that surrounds each individual skeletal muscle fiber

Question 18

epimysium

Answer 18

the tough, connective tissue layer that covers and delineates individual muscles. Surrounds groups of skeletal muscle fascicles

Question 19

expiratory muscle

Answer 19

a muscle whose action is to decrease the size of the thoracic cavity; this squeezes air out of the lungs, producing exhalation

Question 20

fascicle

Answer 20

a group of skeletal muscle fibers bound together by a layer of fibrous connective tissue called the perimysium

Question 21

fixator

Answer 21

a muscle that stabilizes a joint so that other muscles can produce effective movements of other joints

Question 22

H band

Answer 22

the light colored area in the middle of the A band

Question 23

I band

Answer 23

large, light bands in a skeletal muscle fiber that alternate with the darker A bands to give a striped appearance to skeletal muscle fibers under a microscope. Composed of thin filaments of the contractile protein actin.

Question 24

inspiratory muscle

Answer 24

a muscle whose action is to increase the size of the thoracic cavity; this causes air to be drawn into the lungs, thereby producing inhalation

Question 25

intercalated disc

Answer 25

end to end attachment sites between adjacent cardiac muscle cells. They securely fasten the cells together and transmit impulses from cell to cell. Allows large groups of cardiac muscle cells to function as a single unit.

Question 26

involuntary muscle

Answer 26

an old name for smooth muscle (also defined as muscle that you don’t have conscious control over)

Question 27

involuntary striated muscle

Answer 27

an old name for cardiac muscle (also defined as striped muscle that you don’t have conscious control over)

Question 28

lactic acid

Answer 28

a waste product of anaerobic metabolism in skeletal muscle; an end product of the metabolism of carbohydrates. It is created by the conversion of pyruvate into lactic acid after the fermentation of cellulose. The buildup of lactic acid in a muscle that has been forced into anaerobic mode by overstrenuous activity can cause discomfort

Question 29

linea alba

Answer 29

the sheet of fibrous connective tissue (aponeurosis) that connects the abdominal muscles from each side on the ventral midline

Question 30

motor unit

Answer 30

one nerve fiber and all the skeletal muscle fibers it innervates. Those with small numbers of muscle fibers per nerve fiber are capable of fine, delicate movements. Those with large numbers of muscle fibers per nerve fiber are capable of large, powerful movements

Question 31

multi-unit smooth muscle

Answer 31

the type of smooth muscle composed of individual smooth muscle cells or small groups of cells. Found where small, delicate involuntary contractions are needed. Requires nerve impulses to stimulate its contractions.

Question 32

myofibril

Answer 32

microscopic fiberlike structures that occupy most of the cytoplasm (sarcoplasm) in skeletal muscle cells. They are composed of filaments of the contractile proteins actin and myosin and are packed together longitudinally in the muscle cells

Question 33

myoglobin

Answer 33

a protein in muscle cells that has properties similar to hemoglobin. Can store and release large quantities of oxygen to fuel aerobic metabolic processes in the muscle cells

Question 34

myosin filament

Answer 34

one of the two contractile proteins of muscle (actin is the other one) that slide over eachother to produce the shortening of the muscle cell that we refer to as muscle contraction

Question 35

neuromuscular junction

Answer 35

the connection between the end bulb of a motor nerve fiber and a skeletal muscle cell. There is a tiny space (the synaptic space) between the end of the nerve fiber and the sarcolemma of the muscle fiber

Question 36

nonstriated involuntary muscle

Answer 36

an old name for smooth muscle (also defined as not striped muscle that you have no conscious control over)

Question 37

perimysium

Answer 37

the fibrous connective tissue layer in skeletal muscle that surrounds groups of muscle fibers and binds them into groups called fascicles.

Question 38

sarcolemma

Answer 38

the cell membrane of a muscle cell

Question 39

sarcomere

Answer 39

the basic contracting unit of skeletal muscle. Consists of the actin and myosin filaments between Z lines in a muscle cells. Myofribrils are composed of many of these stacked end to end.

Question 40

sarcoplasm

Answer 40

the cytoplasm of a muscle cell

Question 41

sarcoplasmic reticulum

Answer 41

the organelle in a muscle cell that is equivalent to the endoplasmic reticulum of other cells. It stores calcium ions necessary to initiate the muscle contraction process. Release of CA2+ from the sarcoplasmic reticulum is stimulated by a nerve impulse

Question 42

sinoatrial node

Answer 42

(SA) a group of specialized cardiac muscle cells int he wall of the right atrium of the heart that act as the heart’s pacemaker. The impulse that starts each heartbeat is initiated here.

Question 43

skeletal muscle

Answer 43

multinucleated, striated, voluntary muscle that enables conscious movement of an animal; the type of muscle that moves the bones of the skeleton and is under conscious control

Question 44

skeletal muscle fiber

Answer 44

a skeletal muscle cell. Because of their thin, long fiberlike appearance, their cells are often called skeletal muscle fibers

Question 45

smooth muscle

Answer 45

nonstriated, involuntary muscle having only one nucleus per cell; the type of muscle found in soft internal organs and structures. No striped appearance. Not under conscious control. Found in digestive tract, assists with movement of food through the gut (peristalsis)

Question 46

synergist

Answer 46

something that aids the action of something else. This type of muscle contracts at the same time as a prime mover and assists it in carrying out its action

Question 47

tendon

Answer 47

fibrous connective tissue bands that connect skeletal muscles to bones

Question 48

transverse tubule

Answer 48

transverse tubules formed by inward extensions of the sarcolemma. -Function is to allow electrical impulses traveling along the sarcomere to move deeper into the cell.

Question 49

twitch contraction

Answer 49

a single skeletal muscle fiber contraction. It can be divided into three phases: a brief, latent phase, a longer, contracting phase, and an even longer relaxation phase.

Question 50

viscera

Answer 50

refers to the soft, internal organs enclosed within a body cavity such as the lungs, kidneys, and intestines. The term is used to describe the organs of the abdominal and thoracic cavities

Question 51

visceral smooth muscle

Answer 51

the type of smooth muscle found in the walls of many soft internal organs, such as the intestine, urinary bladder, and uterus. Cells are linked to form large sheets that show rhythmic waves of contraction without external nerve stimulation

Question 52

voluntary striated muscle

Answer 52

an old name for skeletal muscle (also defined as striped muscle that is under conscious control)

Question 53

Z line

Answer 53

They are discs to which the actin filaments are attached. They look like lines because of the angle at which they are usually viewed.