Lec 4: Muscle Anatomy and Physiology

Question 1

Types of muscles

Answer 1

• Skeletal
• Smooth
• Cardiac

Question 2

Skeletal muscle function

Answer 2

• Force production
• Temperature regulation
• Sensation

Question 3

Stretch receptors within the body of a muscle that primarily detects changes in the length of the muscle

Answer 3

Muscle spindles

Question 4

The muscle that creates movement at the joint, contracts effectively to produce a concentric, isometric, or eccentric contraction

Answer 4

Agonist

Question 5

The main muscle that does the opposite action of the agonist

Answer 5

Antagonist

Question 6

The helper muscle that helps the agonist do the same movement and eliminate undesired movement

Answer 6

Synergist

Question 7

A muscle that fixes and stabilizes one segment to allow another segment to move smoothly and efficiently

Answer 7

Stabilizer

Question 8

Smallest structural and functional muscle fiber unit

Answer 8

Sarcomere

Question 9

Main force generators in the muscle

Answer 9

Cross bridges

Question 10

How does a skeletal muscle contract?

Answer 10

Brain sends signal to muscle –> signal spreads across the muscle resulting in releasing calcium from its storage sacs –> exposure of attachment sites on actins –> Myosin attaches with the specific sites on the actin and produces a power stroke –> Cross-bridges slides actin towards the center of the sarcomere causing shortening:
https://www.youtube.com/watch?v=BVcgO4p88AA&t=2s

Question 11

a protein that stabilizes the myosin filament and maintains it in the center between actin filaments, prevents overstretching of the sarcomere, produces passive force, recoils the sarcomere after it’s stretched

Answer 11

Titin

Question 12

A type of force that is not associated with metabolic energy consumption, and is not a part of the cross-bridge forces

Answer 12

Passive force

Question 13

A type of force that needs great bodily control

Answer 13

Passive force

Question 14

A type of muscle activation where the muscle lengthens under tension, negative mechanical work is done, tension is highest

Answer 14

Eccentric contraction (called contraction even though the muscle lengthens)

Question 15

A type of muscle activation where muscle length doesn’t change, no mechanical work is done, only metabolic work is done

Answer 15

Isometric contraction

Question 16

Concentric and eccentric contractions are a type of

Answer 16

Isotonic contraction

Question 17

A type of muscle activation where muscle length shortens causing joint movement, positive mechanical work is done, tension is lowest

Answer 17

Concentric contraction

Question 18

The angle at which the fibers insert into the tendon

Answer 18

Pennation angle

Question 19

Muscle shape that allows for greater cross-sectional area on account of force production (decreased tensile component of muscle contraction)

Answer 19

Pennate muscle

Question 20

How can we use ultrasound in assessing muscle production

Answer 20

by calculating cross-sectional area, pennation angle of muscle

Question 21

Mechanical factors affecting muscle force production

Answer 21

• Muscle length
• Velocity of contraction

Question 22

The muscle that has more shortening ability

Answer 22

Muscle with parallel fibers (the length of fibers within a muscle is a function of the architecture of that muscle rather than of the muscle’s total length)

Question 23

Type of muscle force that’s maximum at resting length and zero at maximum and shortened length

Answer 23

Active force

Question 24

Type of muscle force that increases as muscle length increases

Answer 24

• Passive force
• Overall force

Question 25

Effect of contraction velocity on force production

Answer 25

Contractile force is maximum when contraction velocity is zero, and decreases as contraction velocity increases