L8: What are Muscle Made of?

Question 1

What are the anterior and posterior parts of the body?

Answer 1

Anterior: front
Posterior: back

Question 2

What is the difference between a tendon and a ligament?

Answer 2

Tendon: connects bone to muscle
Ligament: connects bone to bone

Question 3

What are the 2 main characteristics of muscle cells?

Answer 3

1. Long
2. Cylindrical

Question 4

What are fascicles wrapped by?

Answer 4

Perimysium

Question 5

What is the structure of muscle fibres?

Answer 5

Muscle fibres are packed proteins that form striated patterns (think body builders on stage)

Question 6

What is the difference between a motor neuron and a motor unit?

Answer 6

Motor neuron: A singular neuron that generates electrical impulses

Motor unit: A singular neuron and all the muscle fibres it innervates

Question 7

What connects a neuron to muscle? What is its purpose?

Answer 7

A synapse which is responsible for carrying neurotransmitters between cells. Allows electrical impulses to travel between cells

Question 8

How are a motor unit’s associated muscle fibres distributed throughout the muscle?

Answer 8

Adjacent muscle fibres tend to not be connected to the same motor neuron (keeps everything moving smoothly)

Question 9

What neurotransmitter is responsible for the stimulus of skeletal muscles?

Answer 9

Acetylcholine

Question 10

Why is it important tendons to be strong?

Answer 10

Any tension developed in each muscle cell is transferred to the tendon. It keeps the muscle from snapping off the bone with each contraction

Question 11

What are the 2 main types of muscle contractions?

Answer 11

1. Isotonic (changes)
2. Isometric (constant)

Question 12

What are the 2 subtypes of isotonic contractions?

Answer 12

1. Concentric (shortens)
2. Eccentric (stretches)

Question 13

What are the 2 ways to increase muscle force?

Answer 13

1. Increasing the rate of muscle activation
2. Increasing motor unit recruitment

Question 14

What is Henneman’s size principle and its explanation for low and high forces?

Answer 14

1. Low forces: require small and slow motor units which have low threshold motor neurons
2. High forces: require large and fast motor units which have high threshold motor neurons

Question 15

How does Henneman’s size principle apply to small and large muscles like the hand and the quads?

Answer 15

The hand would value rate over recruitment as it requires small and precise movements

Contrarily, the quads would value recruitment over rate as they require large and powerful movements

Question 16

What are the 3 types of muscle fibres?

Answer 16

1. Type 1
2. Type 2A
3. Type 2B

Question 17

How do the 3 types of muscle fibres differ from one another in terms of contraction speed and fatigue resistance?

Answer 17

1. Type 1: Slow contraction, fatigue resistant
2. Type 2A: Fast, fatigue resistant
3. Type 2B: Fast, fatigable

Question 18

What type of respiration does each type of muscle fibre use?

Answer 18

1. Type 1: Aerobic
2. Type 2A: Anaerobic
   Type 2B: Anaerobic

Question 19

Why don’t all muscles have the same proportion of muscle fibres?

Answer 19

Each muscle has a different purpose. The hands will have more Type 1 muscle fibres as they don’t need to perform high-intensity movements.

Contrarily, the quads would have more Type 2 fibres as they need to perform high-intensity movements like sprinting, jumping, and squatting

Question 20

What are some sex-based differences in muscle fibre proportions?

Answer 20

Women tend to to have a greater proportion of Type 1 muscle fibres whilst men tend to have a greater proportion of Type 2 muscle fibres

Question 21

Can you change muscle fibre types?

Answer 21

The science is inconclusive. It would be extremely difficult to convert Type 1 muscle fibres to Type 2 (vice versa).

If possible, it would take decades of intense and prolonged training

Question 22

What 3 variables influence muscle fibre proportion?

Answer 22

1. Genetics
2. Environment
3. Sampling and technical variance (imprecise science)