PSIO 201 Exam 3

Question 1

Why are gap junctions important?

Answer 1

They allow the cells to contract in a coordinated fashion

Question 2

What is a neuromuscular junction?

Answer 2

A site where a nerve fiber communicates with a muscle fiber

Question 3

In the heart, what triggers the wave of electrical excitation that causes the heart to contract?

Answer 3

Pacemaker

Question 4

When acetylcholine binds to its receptors on the motor end plate, an ion channel opens & what ions diffuse quickly into the muscle cell?

Answer 4

Sodium

Question 5

What is the process by which action potentials of a nerve fiber lead to action potentials in the muscle fiber called?

Answer 5

Excitation

Question 6

What is acetylcholine?

Answer 6

The neurotransmitter released at a neuromuscular junction

Question 7

Temporal summation leads to a state of fluttering contraction known as what?

Answer 7

Incomplete tetanus

Question 8

All of the muscle fibers innervated by a single nerve fiber constitute what?

Answer 8

Muscle unit

Question 9

What is the indented region of the sarcolemma that participates in the neuromuscular junction called?

Answer 9

Motor end plate

Question 10

Muscles with what fascicle arrangement produce the strongest contractions?

Answer 10

Pennate

Question 11

What is the immediate trigger for the contraction of smooth muscle?

Answer 11

Calcium ions

Question 12

What fascicle arrangement produces the weakest muscle?

Answer 12

Circular

Question 13

What is excitation-contraction coupling?

Answer 13

The events that link the action potential of the sarcolemma to the activation of the myofilament contraction

Question 14

What are the alternating light and dark bands in skeletal muscle?

Answer 14

Striations

Question 15

What refers to the bundles of muscle fibers, wrapped in connective tissue, within a muscle?

Answer 15

Fascicles

Question 16

The synaptic knob does not touch the muscle fiber but is separated by what structure?

Answer 16

Synaptic cleft

Question 17

Within a synapse, a neuron ends in a swelling called what?

Answer 17

Axon terminal

Question 18

What fibers do skeletal muscles contain?

Answer 18

Slow oxidative & fast glycolytic

Question 19

A muscle shortens as it maintains tension in a what type of contraction?

Answer 19

Concentric

Question 20

The thickened notched ends of cardiac muscle cells which contain gap junctions are called what?

Answer 20

Intercalated discs

Question 21

What is calmodulin?

Answer 21

A protein that replaces troponin in smooth muscle cells

Question 22

In smooth muscle, which protein does calcium bind to?

Answer 22

Calmodulin

Question 23

On a myogram, the time between the stimulus & the twitch is known as what?

Answer 23

Latent period

Question 24

What is the type of muscle contraction in which there is a change in length, but no change in tension?

Answer 24

Isotonic

Question 25

What is a quick cycle of contraction in a whole muscle that occurs when a threshold level stimulus is reached?

Answer 25

Twitch

Question 26

The autonomic nervous system is important in the control of which 2 types of muscle tissue?

Answer 26

Smooth & cardiac

Question 27

Action potentials spread across the sarcolemma & continue down which structures into the sarcoplasm?

Answer 27

T tubules

Question 28

What occurs during the contraction phase of a muscle twitch?

Answer 28

It generates tension, pulling on its attachments

Question 29

During which phase of muscle contraction is calcium transported back into the cisternae & tropomyosin moves back to block the actin active sites?

Answer 29

Relaxation

Question 30

What is a starch-like carbohydrate that provides energy during intense exercise in muscle cells?

Answer 30

Glycogen

Question 31

What affects the strength of a muscle twitch?

Answer 31

How stretched the muscle was before stimulation

Question 32

What are the functions of smooth muscle?

Answer 32

Regulate pupil diameter, move material through the digestive tract, & constrict or dilate blood vessels to control blood pressure

Question 33

In an NMJ, after acetylcholine diffuses across the synaptic cleft, where does it bind to ligand-gated channels?

Answer 33

On the sarcolemma

Question 34

Regarding skeletal muscle contraction, what is excitation?

Answer 34

The process by which action potentials in a nerve fiber lead to action potentials in a muscle fiber

Question 35

What describes cardiac muscle tissue?

Answer 35

Striated, usually uninucleate, branching

Question 36

What fibers are adapted for a quick response?

Answer 36

Fast glycolytic

Question 37

At the synaptic knob of the motor neuron, calcium stimulates exocytosis of the synaptic vesicles to release what neurotransmitter into the synapse?

Answer 37

Acetylcholine

Question 38

What occurs during the relaxation phase of a myogram?

Answer 38

Muscle tension declines

Question 39

What is the muscle tissue that is typically slow to contract & slow to relax?

Answer 39

Smooth

Question 40

A synapse is the point where a nerve fiber meets a target cell. When the target cell is a muscle fiber, what is this type of synapse called?

Answer 40

Neuromuscular junction

Question 41

Which protein makes up the thick filaments of a myofibril?

Answer 41

Myosin

Question 42

Which tissue can propel content of a digestive organ?

Answer 42

Smooth muscle

Question 43

What are the characteristics of cardiac muscle cells?

Answer 43

Resistant to fatigue, contract with regular rhythm, contract nearly in unison

Question 44

What is the 5th step of muscle relaxation?

Answer 44

Tropomyosin covers the myosin binding sites

Question 45

During relaxation, where is calcium actively pumped back into?

Answer 45

Sarcoplasmic reticulum

Question 46

What type of contraction involves the development of tension but no change in length?

Answer 46

Isometric

Question 47

What is a sustained contraction in a whole muscle that occurs when a threshold level stimulus is reached?

Answer 47

Tetany

Question 48

What is true of endurance exercise?

Answer 48

It increases oxygen transport in the blood

Question 49

What is the perimysium?

Answer 49

A connective tissue sheath bundling many muscle fibers into a fascicle

Question 50

Cardiac muscle cells are considered what because they contract rhythmically & independently?

Answer 50

Autorhythmic

Question 51

What produces incomplete tetanus?

Answer 51

Temporal summation

Question 52

What are fibers that are well adapted to anaerobic respiration called?

Answer 52

Fast-twitch

Question 53

What are the characteristics of cardiac muscle?

Answer 53

Rich in myoglobin, large stores of glycogen, & uses aerobic respiration almost exclusively

Question 54

In smooth muscle cells, what binds the dense bodies to the membrane?

Answer 54

Intermediate filaments

Question 55

Within skeletal muscle cells, what extends from one Z disc to the next & constitutes one contractile unit?

Answer 55

Sarcomere

Question 56

What is the enzyme that breaks down acetylcholine?

Answer 56

Acetylcholinesterase (AChE)

Question 57

In flexing the elbow, what is the prime mover?

Answer 57

Brachialis

Question 58

What type of tension develops during the latent period of muscle contraction?

Answer 58

Internal

Question 59

The movement of an object or load results from the development of what kind of tension?

Answer 59

External

Question 60

In what condition are stimuli are so frequent that the muscle cannot relax, & the muscle twitches fuse into a smooth prolonged contraction?

Answer 60

Tetanus

Question 61

What fibers contain a fast-acting ATPase & phosphagen enzymes?

Answer 61

Fast-twitch

Question 62

When a nerve signal arrives at a synaptic knob, which voltage-gated channels open in the knob?

Answer 62

Calcium

Question 63

What is not naturally seen in the muscles of the body?

Answer 63

Complete tetanus

Question 64

When lifting something heavy, which type of contraction occurs first?

Answer 64

Isometric

Question 65

During relaxation, active-transport pumps in the sarcoplasmic reticulum move which ion from the sarcoplasm into the cisternae?

Answer 65

Calcium

Question 66

Which phase of contraction links the action potential in the sarcolemma to the activation of the myofilament?

Answer 66

Excitation-contraction coupling

Question 67

What occurs when calcium binds to troponin?

Answer 67

The troponin-tropomyosin complex changes shape & exposes the myosin binding sites (active sites)

Question 68

What describes the endomysium?

Answer 68

A loose connective tissue layer that surrounds each individual muscle cell

Question 69

What structures coordinate contraction in cardiac muscle cells?

Answer 69

Gap junctions

Question 70

Where is cardiac muscle found?

Answer 70

In the heart wall

Question 71

Which muscle tissue is rich in myoglobin, mitochondria, glycogen, & uses aerobic respiration almost exclusively for its energy needs?

Answer 71

Cardiac

Question 72

What must occur before tropomyosin can shift, revealing the active sites that allow myosin heads to bind to the actin filaments?

Answer 72

Calcium must bind to troponin

Question 73

Fatigue resistance is improved by what type of exercise that enhances the delivery & use of oxygen?

Answer 73

Endurance

Question 74

What is the 2nd step of muscle relaxation?

Answer 74

AChE breaks down ACh down

Question 75

Stimulus frequency affects the sarcoplasmic concentration of what?

Answer 75

Calcium

Question 76

What is the red pigment that stores oxygen needed for muscular activity in muscle cells called?

Answer 76

Myoglobin

Question 77

What are the functions of skeletal muscle?

Answer 77

Heat production, blood sugar regulation, control of body openings & passages, movement, joint stability

Question 78

What are connective tissue structures that attach bone to muscle called?

Answer 78

Tendons

Question 79

Cardiac muscle tissue is autorhythmic but what can increase or decrease the heart rate & contraction strength?

Answer 79

Autonomic nervous system

Question 80

What is the 1st step of muscle relaxation?

Answer 80

The nerve signal ceases

Question 81

What regulatory protein is associated with the thick filament of smooth muscle & activates myosin light-chain kinase?

Answer 81

Calmodulin

Question 82

What is the role of acetylcholinesterase?

Answer 82

It breaks down ACh, ending muscle stimulation

Question 83

What is the 3rd step of muscle relaxation?

Answer 83

Active transport pumps in the sarcoplasmic reticulum begin to pump calcium back into the cisternae

Question 84

What is another term for prime mover?

Answer 84

Agonist

Question 85

What are the pockets of sarcolemma smooth muscle cells that contain calcium channels?

Answer 85

Caveolae

Question 86

On a myogram, how does the relaxation phase compare to the contraction phase?

Answer 86

The relaxation phase is longer

Question 87

What is the 4th step of muscle relaxation?

Answer 87

Calcium releases from troponin

Question 88

What are slow-twitch fibers also known as?

Answer 88

Red fibers

Question 89

What are fibers that are well adapted to aerobic respiration called?

Answer 89

Slow-twitch

Question 90

What is the continuous forceful contraction in a muscle with no relaxation between stimuli?

Answer 90

Complete (fused) tetanus

Question 91

What does skeletal muscle contraction help produce?

Answer 91

Body heat

Question 92

What explains why cardiac muscle is resistant to fatigue?

Answer 92

Cardiac muscle uses little anaerobic fermentation