Chapter 10 Flashcards
1
Q
approximately how many muscles are in the body that forms the muscular system
A
around 700 muscles
2
Q
what are the three types of muscle in the body
A
- skeletal
- cardiac
- smooth
3
Q
skeletal muscle
A
striated muscle under voluntary control
4
Q
cardiac muscle
A
striated muscle under involuntary control
5
Q
smooth muscle
A
non striated muscle under involuntary control
6
Q
what does striated muscle mean
A
it has dark and light bands
7
Q
what are the properties of muscle tissue
A
- exciatability
- contractility
- elasticity
- extensibility
8
Q
excitability as a property of muscle tissue
A
muscle cells are responsive to input from stimuli
9
Q
contractility as a property of muscle tissue
A
- stimulation of muscle fiber can lead to contraction and shortening of muscle fiber
- concentric movements
10
Q
elasticity as a property of the muscle tissue
A
contracted muscle cells can treturn to resting length when applied tension is removed
11
Q
extensibility as a property of muscle tissue
A
ability of muscle fiber to be stretched beyond its resting length
- eccentric movement
12
Q
what are the characteristics of skeletal muscles
A
- each muscle is considered an organ
- striated: marked with long thin parallel streaks
- usually attached to bones
13
Q
what are the functions of skeletal muscle
A
- support
- temperature regulation
- maintenance of posture
- body movement
- storage + movement of materials
14
Q
gross anatomy of skeletal muscle tissue
A
- muscle fibers are organized into bundles called fascicles
- muscle fibers contain myofibrils
- myofibrils are composed of myofilaments
15
Q
what are the components of the connective tissue of skeletal muscle
A
3 layers of concentric connective tissue composed of collagen and elastic fibers
16
Q
what is the function of the connective tissue within skeletal muscles
A
- provide protection
- the sites for blood vessels and nerve distribution
17
Q
endomysium
A
- areolar CT
- the innermost layer of connective tissue that surrounds and electrically insulates each muscle fiber
18
Q
perimysium
A
- dense irregular CT
- surrounds the fasicles
19
Q
epimysium
A
- dense irregular CT
- surrounds the entire muscle
- has deep fascia and superficial fascia
20
Q
deep fascia
A
surrounds each muscle and separates muscel from each other
21
Q
superficial fascia
A
separates muscle from skin
22
Q
muscle attachments
A
at the ends of each muscle all CT merge to form a tendon
23
Q
tendons
A
attaches muscles to bone, skin, or another muscle
24
Q
what percentage of tendons are muscle to bone
A
90%
25
what percent of tendons are muscle to skin or another muscle
10%
26
what appearance to tendons have
- a cordlike appearance
- sometimes aponeurosis appearance
27
what is an aponeurosis appearance
appears as a flat sheet
28
upon contraction of the muscle what happens to the articulating bones
one articulating bone is moved the other does not move
29
origin
less moveable point of attachment
30
insertion
more moveable point of attachment
31
what is the microscopic anatomy of skeletal tissue
- sarcolemma
- sarcoplasmic reticulum
- myofibrils
- myofilaments (actin and myosin)
- sarcomere
32
sarcolemma
plasma membrane of the muscle fibers
33
sarcoplasm
cytoplasm of the muscle fibers
34
sarcoplasmic reticulum
smooth ER of the muscle fibers
35
myofibrils
cylindrical structures that extend the entire length of cell
36
myofilaments
- short bundles of proteins that comprise a myofibril
- organized of repetitive groupings
- two types (thick and thin filaments)
37
thick filaments
- composed of bundled molecules of myosin
- 11 nm in diameter
38
myosin
single molecule has a head and elongated tail
- heads are what forms the crossbridges with thing filaments during contraction
39
thin filaments
- composed of 2 strands of spherical molecules twisted around each other
- 5-6 nm in diameter
- has 2 regulatory proteins
40
what are the two types of actin molecules
F actin and G actin
41
sarcomere
functional contractile unit in skeletal muscle fibers
42
parts of a sarcomere
- A band
- I band
- H zone
- M line
- Z disc
43
A band
- region of the sarcomere that contains the myosin (thick filament) and overlapping part of actin
- dark
- has no change in length during contraction
44
I band
- region of the sarcomere that contains the actin filaments and actin filaments of adjacent sarcomeres
- light
- changes in length during contraction
45
H zone
- light central region of the A band that only consists of the myosin
- changes in length during contraction
46
M line
protein meshwork in the H zone that keeps the thick filaments aligned
47
Z disc
protein structure in the middle of the I band that serves as an attachment site for one end of thin filaments
48
how does a contraction occur
- muscle fibers shorten by interactions between thick and thin filaments
- generates tension
49
motor unit
a single motor neuron and the muscle fibers it controls
50
how many muscle fibers does a single motor unit control
typically controls only some
51
how are the size of motor units related to the degree of control
inversly
52
all or none principle
- muscle fibers contract completely or not at all
- if a motor unit is stimulated all fibers under its control will contract not just some
53
muscle tone
constant tension ina resting muscle
54
how do muscles avoid fatigue
- motor units are stimulated randomly
- a few at first then rotates with other motor units
55
what are the two types of muscle contractions
isometric and isotonic
56
isometric contraction
- length is constant, tension is changing
- muscle tension < resistance
57
isotonic contraction
- tension is constant and length is changing
- muscle tension >= resistance
- concentric and eccentric contraction
58
concentric contraction
muscle is shortening
59
eccentric contraction
- muscle is lengthening
- helps to slow down movements
60
types of skeletal muscle fibers
- slow oxidative (Type I)
- fast oxidative (Type IIa)
- fast glycolytic (Type IIb)
61
characteristics of Type 1 muscles fibers
- ATP use: slow
- capacity to make ATP: high, aerobic
- colors of fibers: dark red
- contractile velocity: slow
- fiber distribution: found in greatest abundance in muscles of the trunk especially postural muscle
- primary fiber function: endurance
62
characteristics of Type IIa
- ATP use: fast
- capacity to make ATP: moderate, aerobic
- colors of fibers: lighter red
- contractile velocity: fast
- fiber distribution: found in greatest abundance in muscles of the lower limbs
- primary fiber function: medium duration
63
characteristics of Type IIb
- ATP use: fast
- capacity to make ATP: limited, anaerobic
- colors of fibers: white
- contractile velocity: fast
- fiber distribution: found in greatest abundance in muscles of the upper limbs
- primary fiber function: short duration, intense movements
64
how many types of skeletal muscle fibers do muscles normally contain
usually contain all 3 muscle fiber types
65
how does a single motor unit control other muscle fibers
a single motor unit will control only muscle fibers of the same type
66
why do slow muscle fibers dominate postural areas
meant for longer duration periods
- postural muscles contract continuously to support body
67
how are muslce fibers organized
organized into fasicles
68
what are the different types of fascicle arrangement
- circular
- parallel
- convergent
- pennate
69
what is a circular fascicle arrangement
fibers arranged concentrically around an opening
70
what is the function of a circular arrangement
acts as a sphincter to open and close
71
what is an example of a circular fascicle arrangement
the orbicularis oris muscle
72
what is a parallel fascicle arrangement
- fascicles are paralllel to the long axis of the muscle
- upon contraction the body of the muscle will increase in diameter
- high endurance position not very strong
73
what is an example of a parallel fascicle arrangement
rectus abdominus
74
what is a convergent fascicle arrangement
triangular muslce with a common attachment site
- The direction of the pull can be changed
- does not pull as hard as equal-sized parallel muscle
75
example of a convergent fascicle arrangement
pectoralis major
76
what is a pennate fascicle arrangement
- muscle body has I or more tendon
- unipennate, bipennate, and multipennate
77
how are the fasicles arranged in a pennate arrangement and why
are attached in an oblique angle to a tendon that allows for a harder pull on muscle to occur compared to parallel muscle
- due to the relationship of pull vs stabilize axes
78
unipennate arrangement
all muscle fibers are on the same side of the tendon
79
example of a unipennate arrangement
extensor digitorum
80
bipennate arrangement
muscle fibers on both sides of the tendon
81
example of bipennate arrangement
rectus femoris
82
multipennate
tendon branches within muscle
83
example of a multipennate arrangement
deltoid
84
muscle atrophy
- wasting of muscle tissue that results in reduction of muscle size, tone, power
- cause by lack of stimulation
85
sarcopenia
excessive muscle atrophy
86
muscle hypertrophy
- increase in muscle fiber size, not # of muscle cells
- result of repetitive stimulation of muscle fibers
87
what occurs as a result of muscle hypertropy
- mitochondria increase in # = increase in ATP
- myofibrils and myofilaments increase in # = increase in muscle size
88
what are the 3 types of levers
- first class
- second class
- third class
89
what does the fulcrum represent in a lever
the joint
90
what does resistance represent in a lever
weight applied
91
what does effort represent in a lever
the muscle contracting
92
what is a first class lever
fulcrum is in the middle with weight and effort on the ends
93
example of first class lever
neck joint performing flexion and extension with the effort being trapezius muscle
94
95
what is a second class lever
fulcrum at one end, resistance in middle and effort upwards at the other end
96
what is an example of a second class lever
the foot
fulcrum: metatarsalphalangeal joint
effort: calf muscle and achilles tendom
resistance the mid foot
97
what is a third class lever
resistance in further from the fulcrum, effort upwards in the middle and fulcrum at the opposite end
98
what is the most common type of lever within the body
90% of levers are the third class
99
which type of lever is the most inefficient
third class
100
what are the actions of skeletal muscles
agonist
antagonise
synergist
stabilizers
101
agonist
produces specific movement when it contracts
- the prime mover
102
antagonist
muscle whose action opposes that of agonist
103
synergist
muscle that asists agonist in perfomring action
104
stabilizers
muscle that maintain area position to isolate needed muscles
