Chapter 11: Muscle Tissue

Question 1

Characteristics of Muscle

Answer 1

Excitability
Conductivity 
Contractility
Extensibility
Elasticity

Question 2

Skeletal Muscle

Answer 2

Voluntary striated muscle attached to bone. Has light or dark bands called striatons.

Question 2

Skeletal Muscle

Answer 2

Voluntary striated muscle attached to bone. Has light or dark bands called striatons.

Question 3

Muscle cells are usually called muscle fibers because of their length

Question 4

Sarcolemma

Answer 4

plasma membrane of a muscle fiber

Question 5

Sarcoplasm

Answer 5

Muscle cytoplasm. Contains long proteins called myofibrils, glycogen, and myoglobin

Question 6

Muscle Fibers are Multinuclear

Answer 6

Flattened nucleus pressed against inside of sarcolemma, as myoblasts fuse to produce each fiber in infants and each have a nucleus.
Some myelin remain as satellite cells between fiber and endomysium.

Question 7

Smooth sarcoplasmic reticulum

Answer 7

Surrounds myofibrils. Mitochondria sit in spaces of myofibrils.

Question 8

Myofilaments

Answer 8

Bundle of parallel proteins called myofilaments.
Thick Filaments: golf club. Made of hundreds of myosin.
Thin Filaments: 2 intertwined strands of fibrous actins. Each actin is like a beaded necklace, beads being globular (G) actin. Each G actin has an active site which binds to myosin. Tropomyosin blocks active site when muscle is relaxed. Tropomyosin has troponin attached to it.
Elastic Filaments: made of springing protein titin. Run through core thick filament and attach to M and Z ends.

Question 9

Contractile Proteins

Answer 9

Myosin and Actin are contractile proteins because they do the work to shorten muscles.

Question 10

Regulatory Proteins

Answer 10

Tropomyosin and Troponin because they determine which muscle should contract and which should not.

Question 11

Dystrophin

Answer 11

Links actin filaments to proteins of the sarcolemma. When thin filaments move, dystrophin transfers force to basal lamina.

Question 12

Striations

Answer 12

A (anisotropic) bands: dark, thick filaments lying side by side or overlapping.
H band: in middle of A band, thin filaments don’t reach.
M line: middle of H band

I band: Z bands anchor thin and elastic filaments, pulling in sarcolemma with shortening of cell.

Question 13

Muscle Structure Hierarchy

Answer 13

1. Muscle
2. Fasicle
3. Muscle Fiber
4. Myofibril
5. Sarcomere
6. Myofilaments

Question 14

Somatic Motor Neurons

Answer 14

Cell bodies are in the brain stem and spinal cord, with axons called somatic motor fibers which lead to muscle.

Question 15

Motor Unit

Answer 15

One nerve fiber and all muscle fibers innervated by it. All stimulated and react at same time.

Question 16

Small motor unit

Answer 16

More fine motor control, less strength. (hand, eye)

Question 17

Large Motor Unit

Answer 17

More strength than control (quadriceps)

Question 18

Synapse

Answer 18

When any nerve fiber meets target cells. When tagert cell is muscle fiber, synapse is called neuromuscular junction or motor end plate.
In synapse, nerve ends in swelling called axon terminal. Separated by target cell by synaptic cleft.

Question 19

ACh (acetylcholine )

Answer 19

ACh in axon terminal, moves out of terminal by exocytosis, and enter synaptic cleft. Chemical messenger.
Deficiecy leads to muscle weakness or myasthenia gravis

Question 20

Postsynaptic Membrane Folds

Answer 20

Folds with ACh receptors, increases surface area of ACh receptive membrane. Muscle nuclei underneath for synthesis of ACh