Lecture 13: Muscle

Question 1

What are the three types of muscle in the body?

Answer 1

Smooth, skeletal, cardiac

Question 2

What do skeletal muscle cells look like? What regulates them?

Answer 2

Very large cells, 3-5k nuclei, long and tubular, striated. Regulated by somatic nervous system.

Question 3

What are gap junctions?

Answer 3

How smooth and cardiac cells communicate with each other.

Question 4

What is skeletal muscle made of?

Answer 4

Muscle fibers (myocytes, muscle cells), peripheral nerves, vasculature.

Question 5

_______ accounts for all voluntary body movement.

Answer 5

Contraction

Question 6

What does endomysium do? Perimysuim? What types of tissue are they?

Answer 6

Endomysium surrounds each individual fiber. Perimysium surrounds a bundle of muscle fibers. Connective tissue.

Question 7

What does fascicle do? Epimysium?

Answer 7

Fascicles are a bundle of fibers wrapped in perimysium. Epimysium surrounds the entire muscle.

Question 8

Tendons are continuous with the _________ of bone. What does that term mean?

Answer 8

Periosteum. Means outside of bone.

Question 9

Muscle fibers are made of _____________. These are made of ______________.

Answer 9

Myofibrils. Sarcomeres (basic contractile unit).

Question 10

What is the difference between actin and myosin?

Answer 10

Actin = thin filament
Myosin = thick filament

Question 11

What is viewed in the H zone?

Answer 11

Only myosin, nothing else.

Question 12

Muscles enlarge with ________. More ______ and _________ are packed into the muscle cells.

Answer 12

Hypertrophy, actin, myosin.

Question 13

Describe the sliding filament theory.

Answer 13

Actin and myosin filaments slide past each other during muscle contraction.

Question 14

Which areas of a sarcomere shortens during contraction? What stays the same?

Answer 14

Sarcomere, H zone, I zone stays the same. A zone stays the same.

Question 15

Describe myosin.

Answer 15

Thick filament = long tail region, power molecule. Many myosin in one thick filament.

Question 16

Describe actin.

Answer 16

Acts as a regulator and decides when myosin can attach. Actin globules form 2 coiled chains.

Question 17

What does tropomyosin do? Troponin?

Answer 17

Tropomyosin runs along actin and blocks binding sites. Troponin holds tropomyosin in place and regulates with calcium ions.

Question 18

Why does rigor mortis happen?

Answer 18

The absence of ATP to release cross-bridge, causes semi-permanent tensing of muscles.

Question 19

What is contraction coupling?

Answer 19

Electrical signal (excitation) from brain along motor neuron tells a muscle to move (contraction).

Question 20

_______ ________ moves like a __ along muscle membrane. It is propagated down __-________.

Answer 20

Action potential, wave, T-tubules

Question 21

Name the six steps of excitation contraction coupling.

Answer 21

Neurotrans, action potential, t-tubules, sarcoplasmic reticulum, release of calcium ions, contraction.

Question 22

Relaxation occurs when _____ is ______________.

Answer 22

Calcium, re-sequestered.

Question 23

What are the three factors that regulate muscle force production?

Answer 23

Muscle length, action potential frequency, number of fibers

Question 24

If muscle length is too ________ or ________, force production is ___________.

Answer 24

Stretched, compression, decreased

Question 25

What is a motor unit?

Answer 25

One motor neuron and all the muscle fibers it innervates

Question 26

What are the three types of skeletal muscle fibers?

Answer 26

Slow oxidative, fast oxidative-glycolytic, fast-glycolytic