Muscular System (Lecture)

Question 1

What are the characteristics of a motor unit?

Answer 1

• all or nothing contractions
• uses recruitment to stimulate more or fewer muscle fibers depending on the strength needed

Question 2

What are types of muscle contractions and their definition?

Answer 2

1. Isotonic/concentric: muscle gets shorter
2. Isometric: Muscle contracts, but maintains the same length
3. Eccentric: Lengthened muscle contraction. (damaging to muscle, but builds more muscle)

Question 3

Define hypertrophy

Answer 3

Muscle fibers growing in size (not numbers) to adapt to heavy resistance

Question 4

Define Atrophy

Answer 4

Muscle fibers decreasing in size due to lack of activity

Question 5

Define Type I muscle fibers

Answer 5

• Slow-twitch
• lots of mitochondria and myoglobin
• less prone to fatigue
  smallest diameter

Question 6

Define Type II muscle fibers

Answer 6

• fast-twitch
• fewer mitochondria and myoglobin
• more prone to fatigue
• large diameter

Question 7

Define Type IIa muscle fibers

Answer 7

• medium speed twitch
• medium amount of mitochondria and myoglobin
• intermediate endurance
• medium diameter

Question 8

In descending order, name the organizational level of a skeletal muscle

Answer 8

Muscle (organ)
Fascicle
Muscle Fiber (cell)
Myofibril (organelle)
Sarcomere
Myofilament/filament

Question 9

Name the tissue that wraps the muscle and what kind of tissue it’s made of

Answer 9

Epimysium; made of dense irregular CT

Question 10

Name the tissue that wraps fascicles and what kind of tissue it’s made of

Answer 10

Perimysium; dense irregular CT

Question 11

Define fascicle

Answer 11

a bundle of muscle fiber

Question 12

What tissue wraps an individual muscle fiber and what kind of tissue is it made of?

Answer 12

Endomysium; areolar CT

Question 13

Define myofibril

Answer 13

rodlike contractile organelles composed of sarcomeres

Question 14

Define sarcomere

Answer 14

a contractile unit that makes up myofibrils and is made of contractile myofilaments

Question 15

What holds sarcomeres in place

Answer 15

Titin proteins

Question 16

Which is the thick myofilament and which one is thin?

Answer 16

Myosin-Thick
Actin-Thin

Question 17

Name three components of a muscle fiber with differentiating names than a generic cell and their equivalent

Answer 17

Sarcolemma-plasma membrane
Sarcoplasm-cytoplasm
Sarcoplasmic Reticulum-Endoplasmic Reticulum

Question 18

Define Class I levers and give an example

Answer 18

• Effort, Fulcrum, Resistance
• Extension at the elbow

Question 19

Define class II levers and give an example

Answer 19

• Effort, Resistance, Fulcrum
• plantar flexion at the ankle

Question 20

Define class III levers and give an example

Answer 20

• Resistance, effort, fulcrum
• Flexion at the elbow

Question 21

What is a muscle agonist?

Answer 21

The primary muscle that will be doing the moving

Question 22

What is a synergist muscle?

Answer 22

Secondary muscles that help the agonist muscle perform movements. Can be direct or indirect

Question 23

What is an antagonist muscle?

Answer 23

A muscle that performs opposite contraction movement of an identified muscle agonist

Question 24

What part of the sarcomere is identified and what is its composition?

Answer 24

A-Band

Consists only of the length of the myosin

Question 25

What part of the sarcomere is identified and what makes it up?

Answer 25

I-Band

Only actin

Question 26

What would be present here if the muscle were not contracted and what would it consist of?

Answer 26

H-Band

only myosin

Question 27

What is used to describe how muscles and sarcomeres contract using different bands and zones?

Answer 27

Sliding filament theory

Question 28

What is pictured?

Answer 28

Cardiac muscle cell

• multiple nuclei
• striated
• intercalated discs

Question 29

What is pictured?

Answer 29

Smooth muscle cell

• single nucleus
• involuntary, nonstriated