Chapter 5 - Muscular System

Question 1

What is the muscular system?

Answer 1

This system links the nervous and nervous system and is responsible for generating the forces that MOVE the human body.

Note: Bones help us stand up straight, where as the muscles help us move and attach to the bones via tendons.

Question 2

What are the 3 types of muscles in the body?

Answer 2

skeletal, cardiac (heart), and smooth (tissues and internal organs)

Question 3

What is skeletal muscle? What are the primary functions?

Answer 3

The type of muscle tissue that connects to bones and generates the forces that create movement.

Primary functions: Produce movement, support the skeletal system (bones), help with homeostasis by producing heat.

Question 4

What is the fascia?

Answer 4

The first layer of connective tissue. It surrounds the skeletal muscles and bones.

Question 5

What is epimysium?

Answer 5

The inner layer of the fascia that directly surrounds the muscle. Also known as “deep fascia”.

Question 6

What are fascicles?

Answer 6

The largest bundle of fibers that within a muscle. Fascicles are surrounded by perimysium.

Question 7

What is perimysium?

Answer 7

Connective tissue surrounding a muscle fascicle.

Question 8

What is endomysium?

Answer 8

Connective tissue that wraps around individual muscle fibers within a fascicle.

Question 9

What is glycogen?

Answer 9

Glucose (sugar), that is deposited and stored in bodily tissues (like liver and muscle cells). The storage form of carbohydrates.

Question 10

What is myoglobin?

Answer 10

Protein-based molecule, that carries oxygen into the muscles.

Question 11

What is myofibrils?

Answer 11

Where contraction of a muscle occurs. They are the contractile components of a muscle cell.

*These are the circles within the muscle fiber.

The myofilaments (actin and myosin) are contained within a myofibril.

Question 12

What is myofilaments?

Answer 12

The filaments of a myofibril; include actin and myosin.

Question 13

What is Actin?

Answer 13

A thin myofilament that helps produce muscular contraction.

Question 14

What is Myosin?

Answer 14

A thick myofilament that helps product muscular contraction.

Question 15

What is Sarcomere?

Answer 15

The structural unit of a myofibril composed of actin and myosin filaments between two Z-lines. This is the functional unit of the muscular system, this is where muscular contraction occurs.

Question 16

What is the Z-line?

Answer 16

The meeting point of each sarcomere.

Question 17

What is neural activation?

Answer 17

The nervous system’s signal that tells a muscle to contract.

The communication link between the nervous system and the muscular system.

Question 18

What is the neuromuscular junction?

Answer 18

The specialized site where the nervous system communicates directly with muscle fibers.

Question 19

What is synapse?

Answer 19

A junction or small gap between the motor neuron and muscle cells.

Question 20

What is a motor unit?

Answer 20

A motor neuron and all of the muscle fibers that it innervates.

Question 21

What is action potential?

Answer 21

Nerve impulse that is relayed from the central nervous system, through the peripheral nervous system, and into the muscle across the neuromuscular junction.

Question 22

What are neurotransmitters?

Answer 22

Chemical messengers that cross the synapse between neuron and muscle and assist with nerve transmission.

Essentially, neurotransmitters represent the translation of the nervous system’s electrical message into a form the muscle cells can understand and act on.

Question 23

What is Acetylcholine (ACh)?

Answer 23

A neurotransmitter used by the neuromuscular system

It helps the action potential cross the synapse into the muscle, which initiates the steps in a muscle contraction.

Question 24

What is Sliding Filament Theory?

Answer 24

The series of steps in muscle contraction involving how myosin (thick) and actin (thin) filaments slide past one another to produce a muscle contraction, shortening the entire length of the sarcomere.

Question 25

What is excitation-contraction coupling?

Answer 25

The physiological process of converting an electrical stimulus to a muscle contraction.

Question 26

What is a power stroke?

Answer 26

The myosin heads bind to actin and pull them toward the sarcomere center, which slides the filaments past each other, shortening the muscle.

Question 27

What is ATP (Adenosine Triphosphate)?

Answer 27

A high-energy molecule that serves as the main form of energy in the human body; known as the energy currency of the body.

Question 28

What is resting length?

Answer 28

The length of a muscle when it is not actively contracting or being stretched.

Question 29

What are Type I muscle fibers?

Answer 29

Muscle fibers that are small in size, generate lower amounts of force, and are more resistant to fatigue.

(Standing up, maintaining posture)

Question 30

What are Type II muscle fibers?

Answer 30

Muscle fibers that are larger in size, generate higher amounts of force, and are faster to fatigue.

(Physical activities - Running or Jumping)

Question 31

What is the All-or-nothing principle?

Answer 31

Motor units cannot vary the amount of force they generate; they either contract maximally or not at all.

Question 32

What are Capillaries?

Answer 32

The smallest blood vessels and the site of exchange of elements between the blood and the tissues.

Question 33

What is the main difference between Type I and Type II muscle fibers?

Answer 33

Type I - smaller in size, less force produced, slow to fatigue, “slow twitch”, more capillaries, increased oxygen delivery

Type II - larger in size, more force produced, “fast twitch”, fewer capillaries, short-term contractions