ch. 9

Question 1

Active tension

Answer 1

force applied to an object to be lifted when a muscle contracts

Question 2

Stretched muscle

Answer 2

not enough cross-bridging

Question 3

Crumpled muscle

Answer 3

myofilaments crumpled, cross–bridges can’t contract

Question 4

Total tension

Answer 4

active plus passive

Question 5

Passive tension

Answer 5

tension applied to load when a muscle is stretched but not stimulated

Question 6

isometric contractions

Answer 6

(same length) no change in length but tension increases during contraction

Question 7

isotonic contractions

Answer 7

change in length but tension constant

Question 8

Concentric

Answer 8

overcomes opposing resistance and muscle shortens

Question 9

Eccentric

Answer 9

tension maintained but muscle lengthens

Question 10

Muscle tone

Answer 10

constant tension by muscles for long periods of time

Question 11

Frequency

Answer 11

number of action potential produced per unit of time

Question 12

Propagate

Answer 12

Spread from one location to another. Action potential does not move along the membrane: new action potential at each successive location.

Question 13

Ligand-gated

Answer 13

Ligands are molecules that bind to receptors.

Question 14

what happens when ACh attaches to __

Answer 14

muscle cell, Na+ gate opens. Na+ moves into cell due to concentration gradient

Question 15

Repolarization:

Answer 15

return of resting membrane potential. with pump

Question 16

Synapse

Answer 16

axon terminal resting in an invagination of the sarcolemma

Question 17

what happens in muscle relaxation

Answer 17

Ca2+ moves back into sarcoplasmic reticulum by active transport; Requires energy

Ca2+ moves away from troponin-tropomyosin complex

Complex re-establishes its position and blocks binding sites.

Question 18

Creatine phosphate

Answer 18

During resting conditions stores energy to synthesize ATP

Question 19

Oxygen debt

Answer 19

oxygen taken in by the body, above that required for resting metabolism after exercise. ATP produced from anaerobic sources contributes

Question 20

msucle fatigue

Answer 20

Decreased capacity to work and reduced efficiency of performance

Question 21

Physiological contracture:

Answer 21

state of fatigue where due to lack of ATP neither contraction nor relaxation can occur

Question 22

Rigor mortis

Answer 22

development of rigid muscles several hours after death. Ca2+ leaks into sarcoplasm and attaches to myosin heads and crossbridges form.
No ATP available to release.
Rigor ends as tissues start to deteriorate.

Question 23

Psychological muscle fatugue

Answer 23

depends on emotional state of individual

Muscular

Question 24

Caveolae

Answer 24

: indentations in sarcolemma; may act like T tubules

NO Transverse Tubules

Question 25

Dense bodies

Answer 25

instead of Z disks as in skeletal muscle; have noncontractile intermediate filaments. NO Z disks.

Question 26

calmodulin

Answer 26

Ca2+ required to initiate contractions; binds to calmodulin which regulates myosin activity

Question 27

relaxation of a smooth muscle

Answer 27

caused by enzyme myosin phosphatase removes phosphate group while cross-bridges are not attached
relaxation occurs more slowly

Question 28

latch state

Answer 28

in smooth muscle, the tension it sustains

sustained contractions in sm

Question 29

types of smooth muscle, which is more common

Answer 29

visceral and multiunit

visceral is more common

Question 30

visceral smooth muscle

Answer 30

organs such as stomach and urinary tract
sheets reproductive
lack direct contact with NS
Numerous gap junctions; waves of contraction
Often autorhythmic; peristalsis
Most hollow organs (gut), uterus, bladder

Question 31

multiunit

Answer 31

in sheets, bundels, and single cells
cell or groups of cells can operate as independent units; fine innervation or 1 cell
Sheets (blood vessels); 
bundles (arrector pili and iris); 
Muscles of the iris dilate or constrict
Within almost every organ

Question 32

how long do action potentials last in cardiac muscle

Answer 32

Action potentials of longer duration and longer refractory period
Ca2+ regulates contraction