Ch 6: Muscle Tissue

Question 1

What are the properties of Muscular tissue?

Answer 1

Electrical excitability
Contractility
Extensibility
Elasticity

Question 2

What’s this:
Most fibers are attached by tendons to bones
Fibers are large, cigar-shaped, and multinucleate

Answer 2

Skeletal Muscle

Question 3

What are the other names for Skeletal muscle?

Answer 3

Striated and Voluntary

Question 4

Which muscle is the only voluntary one?

Answer 4

Skeletal

Question 5

What is this:
No Striations
Walls of hallow organs
Spindle shaped fibers that are uninucleate
Contractions are slow and sustained

Answer 5

Smooth Muscle

Question 6

What is this:

Striations
Involuntary
Found only in the walls of heart
Uninucleate

Answer 6

Cardiac Muscle

Question 7

What are the functions of the skeletal muscle?

Answer 7

Producing body movements
Stabilizing body positions
Generating heat

Question 8

In the sarcomere which is the name for the thin filaments?

Answer 8

Actin

Question 9

In the sarcomere which is the name for the thick filaments?

Answer 9

Myosin

Question 10

What does the Sarcoplasmic Reticulum (SR) do?

Answer 10

Stores and releases calcium
Surrounds the myofibril

Question 11

What do the sarcomere do?

Answer 11

Responsible for the shortening of muscle

Question 12

INFO FOR SLIDING FILAMENT MECHANISM

Answer 12

See picture on notes

Question 13

What are motor units?

Answer 13

I motor nerve and all fibers it innervates
Innervated by somatic motorneurons

Question 14

What are the 4 steps in the Skeletal muscle contraction?

Answer 14

1. Events at neuromuscular junction
2. Muscle fiber excitation
3. Excitation - contraction coupling
4. Cross bridge cycling

Question 15

What are the nerve stimulus and action potential parts we need to know?

Answer 15

Neuromuscular junction
Neurotransmitter (ACh)
Presynaptic membrane
Postsynaptic membrane
Synaptic Cleft
Ion Channels

LOOK AT PICTURE TO KNOW WHICH PART EACH IS

Question 16

The smaller the motor unit, the ________ there is

Answer 16

finer control

Question 17

What is motor unit recruitment?

Answer 17

Process in which the number of active motor units increases

Motor units contract alternatively to sustain contractions for longer periods of time

Question 18

In which muscle is it impossible to have fused tetanus?

Answer 18

Cardiac muscle

Question 19

What is the difference between unfused and fused tetanus?

Answer 19

Fused is a sustained contraction; whereas unfused has moments of relaxation

Question 20

How do muscles derive the ATP necessary to power the contraction cycle?

Answer 20

Creatine Phosphate - Anaerobic (10 sec of running)
Anaerobic glycolysis (30-40 secs - a sprint)
Cellular respiration - Aerobic (hours - a marathon)

Question 21

Force of Muscle Contraction:
Depends on number of cross bridges attached, which is affected by what 4 factors?

Answer 21

1. Number of muscle fibers stimulated: the more MUs recruited, the greater the force
2. Relative size of fibers: bulkier the muscle, greater the contraction
3. Frequency of Stimulation
4. Degree of Muscle Stretch

Question 22

Compared to the skeletal muscle, what’s different about the cardiac muscle?

Answer 22

More mitochondria (because it never gets to rest)
Contractions last 10-15 times longer
Don’s summate

Question 23

What are the 2 layers of sheets with fibers oriented at right angles to each other in the smooth muscle?

Answer 23

Longitudinal layer
Circular layer

Question 24

What is the longitudinal layer?

Answer 24

Fibers run parallel to long axis (outer) of organ
Contraction causes organ to shorten

Question 25

What is the circular layer?

Answer 25

Fibers run around circumference of organ (inner)
Contraction causes lumen of organ to constrict

Question 26

What is the difference between leaky ion channels and gated ion channels?

Answer 26

Leaky are always open
Gated (or ligand or voltage gated) open in response to stimulus