The Muscular System

Question 1

Muscular System

Answer 1

the driving force, the power behind movement, is muscle tissue

Question 2

Three kinds of muscle tissue:

Answer 2

Skeletal, Cardiac, Smooth

They differ from one another in their microscopic anatomy, location, and control by the nervous and endocrine system

Question 3

contractility

Answer 3

the basic physiological property of muscle tissue: the ability to contract or shorten

Question 4

excitability (or irritability)

Answer 4

the capacity to receive and respond to a stimulus

Question 5

extensibility

Answer 5

the ability to be stretched

Question 6

elasticity

Answer 6

the ability to return to original shape after being stretched or contracted

Question 7

Skeletal tissue

Answer 7

attached primarily to bones, and it moves parts of the skeleton

striated because altering light and dark bands are visible when the tissue is examined under a microscope

voluntary muscle because it can be made to contract and relax by conscious control

Question 8

striations

Answer 8

produced by a characteristic arrangement of contractile proteins, myosin and actin

Question 9

epimsium

Answer 9

sheath of connective tissue surrounding the muscle

Question 10

fascicle

Answer 10

a small bundle or cluster of muscle fibers

Question 11

perimysium

Answer 11

sheath of connective tissue surrounding each fascicle

Question 12

muscle fiber

Answer 12

muscle cell

Question 13

sarcolemma

Answer 13

plasma membrane of a muscle cell (fiber)

Question 14

myofibril

Answer 14

threadlike structure, running longitudinally through a muscle fiber consisting of thick filaments (myosin) and thin filaments (actin, troponin and tropomyosin) (myofilaments) which are arranged in sacromeres

Question 15

sacromere

Answer 15

basic contractile unit of striated muscle fibers

Question 16

satellite cells

Answer 16

scattered, lie between the endomysium and the musce fibers. they function in repair of damaged muscle tissue

Question 17

exceptions to skeletal muscle pattern

Answer 17

external sphincter of the bladder and diaphragm (they do not cause movements of the skeleton)

Question 18

Cardiac muscle

Answer 18

striated, but differs markedly from skeletal muscle in appearance

found only in the heart where the myocardial cells are short branched, and intimately interconnected to form a continuous fabric

intercalated discs are characteristic of heart muscle

Question 19

intercalated discs

Answer 19

special areas of contact between adjacent cells

Question 20

gap junctions of intercalated discs

Answer 20

couple myocardial cells together mechanically and electrically

because all cells in the myocardium are electrically joined, the myocardium behaves as a single unit. stimulation of one myocardial cell results in the stimulation of all other cells in the mass and the whole heart contracts

Question 21

Unlike skeletal muscle, the heart:

Answer 21

cannot produce a graded contraction by varying the number of cells stimulated to contract

Question 22

Unlike skeletal muscle that produces contraction that are graded depending on the number of cells stimulated, the heart:

Answer 22

contracts to its full extent each time because all of its cells contribute to contraction

Question 23

The ability of myocardial cells to contract however, can be increased by the:

Answer 23

sympathetic system and by stretching of the heart chambers

the heart contains two distinct myocardial chambers: atria and ventricles

Question 24

Cardiac muscle is able to produce ____ ____ automatically.

Answer 24

action potentials

Question 25

The pacemaker

Answer 25

where cardiac action potentials normally originate a specialized group of cells

Question 26

autonomic innervation

Answer 26

regulates the rate of spontaneous depolarization, and thus the rate of the heart beat

Question 27

In skeletal muscle there is a direct excitation-contraction coupling between:

Answer 27

the transverse tubules (plasma membrane) and the sarcoplasmic reticulum

Question 28

Stimulation of heart muscle leads to:

Answer 28

Ca2+ entry into the cytoplasm though voltage-gated channels. This Ca2+ stimulates the opening of Ca2+ release channels of the sarcoplasmic reticulum. Known as Ca2+ induced Ca2+ release

Question 29

Transverse Tubules

Answer 29

small cylindrical invaginations of sarcolemma of striated muscle fiber that conduct muscle action potentials towards the center of the muscle fiber

Question 30

Smooth muscle

Answer 30

each fiber is short, spindle shaped and slender which contain only one nucleus near the center of the fiber, at its widest point actin, myosin, and tropomyosin are present but troponin is absent in each fiber the actin and myosin myofilaments are very thin and are arranged more randomly than in skeletal muscle fibers lack striations