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Human Structure and Function I > Chapter 5: Muscular system > Flashcards

Chapter 5: Muscular system Flashcards

1
Q

What are the two types of myofilaments are muscle contractions dependent on?

A

Actin and myosin

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2
Q

What is the muscle plasma membrane called?

A

sarcolemma

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3
Q

What is the cytoplasm of a muscle cell called?

A

sarcoplasm

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4
Q

What are the three prefixes that refer to muscle?

A

myo, mys, and sarco

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5
Q

What are the three types of muscle?

A

Skeletal
Cardiac
Smooth

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6
Q

What are the function characteristics of muscle? 4

A

-Excitability or irritability – the ability to receive and respond to stimuli
-Contractility – the ability to shorten forcibly
-Extensibility – the ability to be stretched or extended
-Elasticity – the ability to recoil and resume the original resting length

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7
Q

Which muscle makes up 40% of the body’s weight

A

Skeletal muscle tissue

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8
Q

Which muscle tissue has striations?

A

Skeletal, Cardiac

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9
Q

Which muscle tissue is uninucleated?

A

cardiac and smooth

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10
Q

What is the origin of the skeletal muscle?

A

Where the short connective tissue fibers attach to the less movable attachment

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11
Q

What is the insertion of the skeletal muscle?

A

Where the connective tissue of the muscle forms a tendon in the more movable attachment

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12
Q

What is the function of the skeletal muscle?

A

 Force production for locomotion and breathing (diaphragm).
 Force production for postural support.
 Heat production during cold stress.

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13
Q

What is the endomysium? 3 points

A

fine sheath of connective tissue composed of reticular fibers surrounding each muscle fiber

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14
Q

What is the perimysium? 2 points

A

fibrous connective tissue that surrounds groups of muscle fibers called fascicles

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15
Q

What is the epimysium?

A

an overcoat of dense regular connective tissue that surrounds the entire muscle

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16
Q

How long and thick is one muscle fibril cell?

A

10-100 micrometer in diameter, and up to several cm long

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17
Q

Every muscle cell is a synctium. What does that mean?

A

produced by a fusion of ebryonic cells

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18
Q

What do sarcoplasm contain a lot of? 2

A

glycosomes and myoglobin

Glycosomes are membranes containing glycolytic enzymes.

They break down glucose into two halfs so that it could be converted to ATP

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19
Q

What does it mean to say that muscle fibers act in an all or nothing way?

A

They either all contract or all relax

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20
Q

What do fibers contain? 4

A

Organelles, myofibrils, sarcoplasmic reticulum and T-tubules

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21
Q

What are the dark and light parts of a myofibril called?

A

Dark A bands and light I bands

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22
Q

Which part of the muscles make up most of the muscle mass?

A

myofibrils

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23
Q

What is the smallest contractile unit of as muscle fiber?

A

Sarcomere

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24
Q

What are the two types of myofilaments?

A

Thick-myosin
Thin-actin

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25
Which zone dissapears when a sarcomere contracts?
The zone where only myosin is present (H-Zone)
26
What is the function of the z disc?
coin-shaped sheet of proteins (connectins) that anchors the thin filaments and connects myofibrils to one another
27
What protein is present in the M zone?
desmin
28
What is myosin composed of?
a rodlike tail and two globular heads
29
What is the head and the tail of myosin made up of? 4
Head - two smaller, light polypeptide chains called bridges Tail - two interwoven heavy polypeptide chains
30
What are singular spherical actin subunits called?
G actin
31
What are the regulatory subunits bound to actin called? 2
tropomyosin and troponin
32
Where do T-tubules penetrate the cells?
A-band and I-band junction
33
What is the function of terminal cisternae?
regulation of intracellular calcium levels
34
What are triads?
T tubules associations with the paired terminal cisternae
35
What is the function of T-Tubules?
conduct impulses to the deepest regions of the muscle
36
Which structures provide tightly linked signals for muscle contraction
T-Tubules and sarcoplasmic reticulum
37
What part of the muscles act as voltage sensors?
T-Tubules protiens
38
What is the function of sarcoplasmic reticulum foot protiens?
receptors that regulate Ca2+ release from the SR cisternae
39
Explain the sliding filament model. 4
- In the relaxed state, thin and thick filaments overlap only slightly. - Upon stimulation, myosin heads bind to actin and sliding begins. - Each myosin head binds and detaches several times during contraction, to generate tension and propel the thin filaments to the center of the sarcomere. - As this event occurs throughout the sarcomeres, the muscle shortens.
40
State and explain the four sequential events of contraction
* Cross bridge formation – myosin cross bridge attaches to actin filament * Working (power) stroke – myosin head pivots and pulls actin filament toward M line * Cross bridge detachment – ATP attaches to myosin head and the cross bridge detaches * “Cocking” of the myosin head - energy from hydrolysis of ATP cocks the myosin head into the high-energy state
41
What is the excitation contraction coupling?
It is the communication between the electrical events and the mechanical events that happen as a response
42
What happens when calcium ions binds troponin?
The blocking action of tropomyosin ceases and Actin active binding sites is exposed
43
What is the function of excitation contraction coupling?
to transform the electrical stimulation of the sarcolemma into muscle contraction
44
What is the one crucial event that starts muscle contraction?
The stimulus by nerve terminal
45
What is the neuromuscular junction?
junction between the motor nerve and skeletal muscle fiber
46
What is the axonal terminals
the terminal end of the axon
47
What happens when when a nerve impulse reaches the end of an axon at the neuromuscular junction?
- Voltage-regulated calcium channels open and allow Ca2+ to enter the axon. - Ca2+ inside the axon terminal causes axonal vesicles to fuse with the axonal membrane.
48
What happens after the fusion of axonal vesicles in the membrane?
-Releases ACh into the synaptic cleft via exocytosis. -ACh diffuses across the synaptic cleft to ACh receptors on the sarcolemma. -Binding of ACh to its receptors initiates an action potential in the muscle.
49
What is the role of acetylcholine at the nerve terminal? 3
-ACh binds its receptors at the motor end plate (on sarcolemma) -Binding opens chemically (ligand) gated channels -Na+ diffuses inwards and the interior of the sarcolemma becomes less negative
50
What causes depolarization in the skeletal muscle?
The opening of sodium channels, when the sodium enters the cell and potassium leaves it
51
How does depolarization spread? And what are the names given to each stage?
-Initially, this is a local electrical event called end plate potential -Later, it starts an action potential that spreads in all directions across the sarcolemma
52
Where does generation of active potential happen?
In muscle fiber
53
How can you describe a twitch movement?
A single contraction that goes into rest afterwards
54
How can you describe a summing of contractions?
A second nerve impulse that is sent before the first is recovered
55
How do you describe an unfused tetanus movement?
Severeal impulses sent before first comes to rest
56
How do you describe an fused tetanus movement?
when there is no relaxation of the muscle fibers between stimuli
57
When muscles cross a joint anteriorly what movement does it produce?
Felxion
58
When muscles cross a joint posteriorly what movement does it produce?
Extension
59
When muscles cross a joint medially what movement does it produce?
Adduction
60
When muscles cross a joint laterally what movement does it produce?
Abduction
61
Muscles located within the same group of muscles share the same what?
Action, innervation and blood supply
62
Muscles dorsal to upper limb bones produce which movement?
Extension
63
Muscles dorsal to lower limb bones produce which movement?
Flexion
64
What are skeletal muscle names based on? (6)
- Direction of fascicles and muscle fibers - Location of attachments - Number of origins - Action - Location - Shape - Relative size
65
What are the functional classification of muscles?
- Prime move - Antagonist - Synergist (adds extra force or reduces undesirable movements) - Fixator
66
What are the types of fascicle arrangements?
- Convergent - Parallel: Straplike Fusiform
67
What is in an example of parallel strap like muscle?
Sartorius
68
What is an example of fusiform parallel muscle?
Biceps brachii
69
What is an example of a convergent muscle?
Pectoralis major
70
What is a type of unipennate muscle?
Extensor digitorum longus
71
What is an example of bipennate muscle?
Rectus femoris
72
What is an example of multipennate muscle?
Deltoid
73
What is another name for circular muscles ?
Sphincter
74
What is an example of a circular muscle?
Orbicularis Oris/oculi
75
Describe first class lever
Effort. Load |. Fulcrum. |
76
Describe class 2 levers
|. Load Effort. |. Fulcrum
77
Describe third class lever
|. Load Fulcrum. Effort |
78
What is an example of first class lever?
Scissors
79
What is an example of second class lever?
Wheelbarrow
80
What is an example of third class lever?
Tweezers
81
What is the most used lever in body?
Third class
82
What is the law of levers?
When the effort is farther from the fulcrum than the load, the lever operates at a mechanical advantage

Human Structure and Function I (7 decks)

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