Lecture 11: Muscle - Structure & Function

Question 1

What’re the three different types of muscle?

Answer 1

• Skeletal, Smooth, and Cardiac

Question 2

What are the functions of skeletal muscle?

Answer 2

• Movement
• Heat production
• Posture (maintaining posture for long periods of time)
• Communication (diaphragm needs to contract in a certain way to make sounds)

Question 3

What happens when we want to conserve heat?

Answer 3

• We shiver

Question 4

What does myo / sarco mean?

Answer 4

• Muscle (in Latin & Greek)

Question 5

Transverse leg picture includes:

Answer 5

• Fascia, Fat, Skin, Blood Vessels, Nerves, Muscles

Question 6

How is connective tissue arranged?

Answer 6

• Epimysium → Fascicle → Covered in perimysium → Muscle Fibre → Wrapped by endomysium

Question 7

How is muscle tissue arranged?

Answer 7

• Muscle Fibre → Sarcoplasmic Reticulum → T Tubule → Myofibrils → Myofilaments (in sarcomere)

Question 8

How big is a skeletal muscle fibre?

Answer 8

• Up to 40cm, parallel, cylindrical, multi-nuclear

Question 9

What does a skeletal muscle fibre look like?

Answer 9

• Striated, protein arrangement

Question 10

Myofilaments are made of…

Answer 10

• Thick and thin proteins

Question 11

The thin filaments attached to the sarcomere are made up of…

Answer 11

• Mostly Actin (Some Troponin, and Tropomyosin)

Question 12

The thick filaments are made up of…

Answer 12

• Myosin heads

Question 13

What is the sarcolemma?

Answer 13

• Phospholipid bilayer (membrane)

Question 14

What triggers muscle contraction?

Answer 14

• Calcium

Question 15

What is a sarcomere?

Answer 15

• A contractile unit

- End-on-end along myofibril length

Question 16

How big is a sarcomere?

Answer 16

• 2 micrometers

Question 17

How does a muscle actually contract?

Answer 17

• Thin draws towards each other over thick
• Z lines move closer together
• Individual lengths stay the same
• Energy is consumed
• Calcium is essential

Question 18

If you want a large ROM do you want long or short muscle cells?

Answer 18

• Long

- Means it can shorten more

Question 19

What determines thickness of muscle?

Answer 19

• Number of muscle fibres
• Greater number of fibres = greater CSA
• And tension

Question 20

Why is the angled arrangement of muscle fibres important?

Answer 20

• More tension is developed
• Because there are more fibres in a smaller space
• Not so great ROM

Question 21

Are relaxed muscles active?

Answer 21

• Slightly

Question 22

How’re we maintaining posture?

Answer 22

• Nerve impulses go down from spinal chord and activate muscle fibres
• No movement produced but keeps muscles firm and healthy
• Helps stabilize joints and maintain posture