A&P Chapter 9

Question 0

Contractibility

Answer 0

Ability of a muscle to shorten with force.

Question 1

Functions of the Muscular System

Answer 1

Body movement, posture, respiration, body heat production, communication, constriction of organs and vessels, heart beat.

Question 2

Excitability

Answer 2

respond to a stimulus.

Question 3

Extensibility

Answer 3

Stretch to a limited degree. Muscles can stretch when needed.

Question 4

Muscle types

Answer 4

Skeletal: Body movements; voluntary.
Smooth: walls of hollow organs; involuntary
Cardiac: Heart; involuntary.

Question 5

Fasciculi

Answer 5

bundles of fibers

Question 6

Perimyseum

Answer 6

connective tissue surrounding fasciculi.

Question 7

Epimysium

Answer 7

connective tissue surrounding entire muscle.

Question 8

Motor Neurons

Answer 8

nerve cells that stimulates muscle contraction.

Question 9

Neuromuscular Junctions

Answer 9

contact points between axons and muscle fibers.

Question 10

Muscle fiber development

Answer 10

Precursor cells –> myoblasts –> multinucleated cells

Question 11

Sarcolemma

Answer 11

Plasma membrane of muscle fiber

Question 12

Sarcoplasmic reticulum

Answer 12

Modified smooth endoplasmic reticulum

Question 13

Sarcoplasm

Answer 13

Muscle cytoplasm

Question 14

Myofibril

Answer 14

Threadlike connections between fibers

Question 15

Actin

Answer 15

Thin myofilaments

Question 16

Myosin

Answer 16

Thick myofilament

Question 17

Sarcomere

Answer 17

Basic structural unit and functional skeletal muscle.
Actin+ myosin
Powerhouse of the muscle

Question 18

Z-disk

Answer 18

Attachment point for actin

Z network

Question 20

ligand-gated ion channels

Answer 20

ligand binds to receptor channel

ion channel opens to allow ion to enter cell

Question 21

voltage-gated ion channels

Answer 21

open and close in response to voltage changes

Question 22

Resting membrane potential

Answer 22

resting= negative ions inside, positive ions outside

Question 23

depolarization phase

Answer 23

opening of channels and triggers contraction

Question 24

repolarization phase

Answer 24

closing of channels and relaxation

Question 25

calcium

Answer 25

release causes contraction

Question 26

muscle twitch

Answer 26

lag phase: time between stimulus and contraction. contraction phase: time of contraction relaxation phase: time of relaxation.

Question 27

Summation

Answer 27

``` repeated stimulation (stimulus strength and response) ```

Question 28

Recruitment

Answer 28

increased number of fibers (stimulus strength and response)

Question 29

Subthreshold stimulus

Answer 29

no contraction

Question 30

Threshold stimulus

Answer 30

contraction

Question 31

submaximal stimuli

Answer 31

additional motor units

Question 32

maximal stimuli

Answer 32

all motor units

Question 33

stimulus frequency

Answer 33

contraction increases as stimuli increases | repeated stimulation inhibits resting.

Question 34

incomplete tetanus

Answer 34

fibers partially relax between contractions.

Question 35

complete tetanus

Answer 35

no relaxation between contraction.

Question 36

isometric (muscle contraction)

Answer 36

no change in length but tension increases. | - postural muscles of the body.

Question 37

isotonic (muscle Contraction)

Answer 37

change in length but tension remains constant. - - Concentric: overcomes opposing resistance and muscle shortens. - - eccentric: tension maintained but muscle lengthens.

Question 38

muscle tone (muscle contraction)

Answer 38

constant tension by muscles for long periods of time

Question 39

fatigue

Answer 39

decreased capacity to work and reduced efficiency of performance.

Question 40

Fatigue Types

Answer 40

psychological: depends on mental state of individual. Muscular: results form ATP depletion. Synaptic: occurs in NMJ due to lack or acetylcholine.

Question 41

Physiological Contracture

Answer 41

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

Question 42

Rigor Mortis

Answer 42

development of rigid muscles several hours after death. Calcium leaks into sarcoplasm and attaches to myosin heads and crossbridges form. Ends when tissue start to deteriorate.

Question 43

Slow Twitch

Answer 43

Respond slow to stimulation | resistant to fatigue

Question 44

Fast twitch

Answer 44

respond slow to stimulation fewer mitochondria prone to fatigue ra

Question 45

Atrophy

Answer 45

decrease in size due to inactivity

Question 46

Heat production

Answer 46

exercise: metabolic rate and heat production Post-exercise: metabolic rate stays high due to oxygen debt. Shivering: uncoordinated contraction of muscle fibers resulting in shaking and heat production.

Question 47

Types of Smooth Muscle

Answer 47

Visceral or unitary : cells in sheets, function as a unit. --numerous gap junctions; wave of contraction -- digestive and reproductive tracts Multiunit: cells or groups of cells act as independent units. -- Sheets(blood vessels ); bundles(arrector pili and iris); single cells (capsule of spleen)