Chapter 9: Muscles

Question 1

Structure of skeletal muscle

Answer 1

• Attach to bone
• under conscious control
• every skeletal muscle is an organ.

Question 2

skeletal muscles are composed of…

Answer 2

• muscle tissue
• Nervous tissue(excite muscle; electricity)
• Blood-02/nutrients
• connective tissue- structural support

Question 3

muscle coverings

Answer 3

• Epimysium
• perimysium
• Endomysium

Question 4

Epimysium

Answer 4

surrounds the whole muscle

Question 5

fascicle

Answer 5

grouping of muscle fibers

Question 6

perimysium

Answer 6

surrounds fascicle within a muscle

Question 7

endomysium

Answer 7

surrounds muscle fibers

Question 8

Muscle fibers

Answer 8

muscle cell

Question 9

multinucleated

Answer 9

many cells

Question 10

sarcolemma

Answer 10

cell membrane

Question 11

sarcoplasm

Answer 11

cytoplasm

Question 12

myofibrils

Answer 12

thread like filament

• thin acting filament
• thick myosin filament

Question 13

sarcomeres

Answer 13

units of muscle

Question 14

Thick filaments

Answer 14

Myosin protein; heads from cross bridges

Question 15

thin filaments

Answer 15

Actin protein; associated with troponin and tropomyosin

Question 16

2 types of bands

Answer 16

I band

A band

Question 17

I band

Answer 17

light band; actin filaments

Question 18

A band

Answer 18

Dark band; thick myosin filaments overlapping with thin

acting filaments

Question 19

Z line

Answer 19

Anchor filaments; center I bands

Question 20

M line

Answer 20

anchors thick filaments

Question 21

H zone

Answer 21

center A band; thick myosin filaments

Question 22

striation pattern

Answer 22

arrangement of myofilaments in myofibrils

Question 23

contraction of a muscle fiber

Answer 23

*requires interactions from chemical and cellular components
*The actin and myosin filaments slide past one another, shortening the sarcomere
contraction=movement

Question 24

Neuromuscular junction

Answer 24

axon of a motor neuron, skeletal muscle fibers contract only when stimulated

Question 25

Parts of the NMJ( neuromuscular junction)

Answer 25

Motor neuron, motor and plate, synaptic cleft, synaptic vesicle, and neuro transmitter

Question 26

Synaptic cleft

Answer 26

space between nerve and muscle

Question 27

synaptic vesicle

Answer 27

storage container

Question 28

neuro transmitter

Answer 28

chemical message

Question 29

Acetylcholine (ACh)

Answer 29

neuro transmitter

Question 30

Acetylcholine (ACh) 4 steps to prepare a contraction

Answer 30

1-impulse causes release of ACh from synaptic vesicle
2-ACh binds to ACh receptors
3-causes changes in membrane permeability; Na+, K+(action potential)
4-causes release of Ca2+, leads to muscle contraction

Question 31

Myasthenia Gravis (MG)

Answer 31

• autoimmune disorder
• antibodies attack ACh receptors
• have only 1/3 normal number of ACh receptors
• Muscle weakness; muscle fatigue

Question 32

Treatment for MG

Answer 32

• Drugs that inhibit Acetylcholinesterase

* Immunosuppressant drugs

Question 33

Upon muscle stimulation steps

Answer 33

1-  impulses cause SR to release Ca+2
2- Ca+2 ion binds to troponin to change its shape
3- Position of tropomyosin is altered 
4- Binding sites on actin; exposed
5- Myosin head forming a cross-bridges

Question 34

Sliding filament model

Answer 34

• Sarcomeres shorten, thick and thin filaments slide past one another
• Thin and thick, not change length; just overlap

Question 35

relaxation process

Answer 35

1- acetylcholinesterase; decomposes ACh
2- muscle impulses stop when ACh is decomposed
3- Calcium pump moves Ca+2 back
4- Covers binding sites
5- Troponin-tropomyosin complex covers binding sites
6- Binding is now prevented
7- muscle fiber relaxes