Levels of Organization (muscle organ/muscle cells)

Question 1

Fascia

Answer 1

layers of tough, connective tissue

Question 2

Belly

Answer 2

enlarged fleshy body of muscle located between the slender points of attachments

Question 3

epimysium

Answer 3

outer layer of fascia that can extend to bone and form tendons

Question 4

Perimysium

Answer 4

connective tissue layer that surrounds fascicles

Question 5

endomysium

Answer 5

connective tissue layer around individual muscle fibers

Question 6

muscle

Answer 6

organ of muscular system, composed of muscle and connective tissue

Question 7

fascicles

Answer 7

muscle bundle fiber or a collection of muscle fibers

Question 8

myofibrils

Answer 8

long bundled protein filaments that extend the entire length of the muscle fibers

Question 9

Muscle fiber

Answer 9

cells of the muscular system

Question 10

Myofilaments

Answer 10

protein strands, actin (thin) and myosin (thick)

Question 11

Sarcolemma

Answer 11

plasma membrane of muscle fiber

Question 12

Transverse (T) Tubules

Answer 12

tubelike inward folds of the sarcolemma that extends into the cell at regular intervals.

Question 13

Transverse (T) Tubules function

Answer 13

Carry electrical impulses into the center of muscle fiber, allowing muscle fiber to contract

Question 14

Sarcoplasm

Answer 14

cytoplasm of muscle fiber (liquid inside of the cell)

Question 15

Sarcoplasm Reticulum

Answer 15

specialized Endoplasmic reticulum of muscle fiber

Question 16

Sarcoplasmic Reticulum function

Answer 16

Stores high amounts of Calcium ions. Release calcium ions from S.R. is a “switch: for muscle contraction

Question 17

Terminal Cisternae

Answer 17

enlarged portions of S.R.

Question 18

Triad

Answer 18

2 terminal cisternae and their associated T tubules

Question 19

Sarcomere

Answer 19

contractile units that make up myofibrils, smallest portion of muscle that can contract, contains myofilaments

Question 20

Actin (thin)

Answer 20

composed of 3 parts: actin, tropomyosin, and troponin

Question 21

tropomyosin

Answer 21

long fibrous protein that lies in the groove along actin strand. Covers the “attachment/active site” in relaxed muscles

Question 22

troponin

Answer 22

anchors troponin to actin, prevents tropomyosin from uncovering actin attachment site in a relaxed muscle, and binds calcium ion

Question 23

Myosin (thick)

Answer 23

composed of elongated myosin molecules shaped like golf clubs

Question 24

Rod portion of myoson

Answer 24

lying parallel to myosin molecule

Question 25

myosin heads

Answer 25

two structures that extend laterally

Question 26

myosin heads functions

Answer 26

binds to active site on actin to form cross bridge, are attached to the rod with a hinge region that bends and straightens during contraction, heads break down ATP releasing energy

Question 27

Z disks

Answer 27

stationary acchors for actin mypfilaments. Created boundary for the sarcomere

Question 28

I Bnds

Answer 28

two light staining regions. Contains only actin. Includes Z Disks and extends to myosin

Question 29

A Band

Answer 29

darker staining band in the center of each sarcomere. Contains both actin and myosin

Question 30

H Zone

Answer 30

center of A Band, contains only myosin

Question 31

M-Line

Answer 31

middle of H Zone. Consists of protein filaments that hold myosin in place

Question 32

neuromuscular junction

Answer 32

point of contact between a motor neuron and a muscle fiber

Question 33

Presynaptic terminal/synaptic knob

Answer 33

part of the neuromuscular junction, contains enlarged axon terminals

Question 34

Synaptic vesicles

Answer 34

small spherical sacs that contain acetylcholine (neurotransmitter)

Question 35

Synaptic cleft

Answer 35

space between presynaptic terminal and muscle fiber (muscle and nerve are NOT in physical contact with each other)

Question 36

postsynaptic menbrane

Answer 36

portion of the sarcolemma of muscle fiber (area directly underneath a nerve fiber

Question 37

muscle contraction phases

Answer 37

Excitation, Excitation-Contraction Coupling, Contraction, and Relaxation

Question 38

Electrical potential

Answer 38

difference in electrical charges from one point to another

Question 39

charge inside of a cell

Answer 39

negative

Question 40

charge outside of a cell

Answer 40

positive

Question 41

Polarized

Answer 41

separation of charges between the inside of the call and the outside

Question 42

Depolarization

Answer 42

change in membrane potential, interior of cell becomes slightly positive and there is an influx of Na+ into cells

Question 43

Repolarization

Answer 43

Interior membrane returns to negative charge, influx of K+ out of cells

Question 44

Action Potential

Answer 44

quick up and down shift in voltage that spreads along sarcolemma