Chapter 10 Tortora- Muscular tissue Flashcards
(130 cards)
1
Q
Motion results from the ______ and ______ of muscles
A
Alternating contraction and relaxation
2
Q
Muscular tissue makes up ______ Of total adult body weight
A
40 to 50%
3
Q
Primary functions of muscle
A
transform chemical energy into mechanical energy to generate force,perform work and produce movement
4
Q
Additional Functions of muscular tissue (4) (GPRS)
A
Stabilize body position
regulate organ volume
generate heat (thermogenesis)
propel fluids and food matter through various body systems
5
Q
Three types of muscular tissue
A
Skeletal
cardiac
smooth
6
Q
Skeletal muscle
A
Move the bones of the skeleton
7
Q
Cardiac muscle
A
Forms most of the heart wall
striated,but its action is involuntary
8
Q
Smooth muscle
A
walls of hollow internal structure such as blood vessels, airways and most organs in the abdominal pelvic cavity, skin
9
Q
Four main functions of muscular tissue (GPSS)
A
- producing body movement
- Stabilizing body positions
- storing and moving substances within the body
- generating heat
10
Q
Four properties of muscular tissue
A
Electrical excitability
contractility
extensibility
elasticity
11
Q
Electrical excitability
A
Ability to respond to certain stimuli by producing electrical signals called action potentials [Autorhythmic & chemical]
12
Q
Contractility
A
The ability of muscular tissue to contract forcefully when stimulated by an action potential
13
Q
Extensibility
A
The ability of muscular tissue to stretch, within limits, without being damaged
14
Q
Elasticity
A
The ability of muscular tissue to return to its original length and shape after contraction or extension
15
Q
Muscle fibers[myocyte]
A
Cells that make up the organ of skeletal muscles because of their elongated shape
16
Q
Components of connective tissue
A
- Surrounds and protects muscular tissue
- subcutaneous layer which separates muscle from skin
- stores most of the bodies triglycerides which serves as an insulating layer that reduces heat loss
- protect muscle from physical trauma
17
Q
Fascia
A
-Dense sheet of irregular connective tissue that lines the body wall and limbs and supports and surrounds muscles and other organs of the body
-allows free movement of muscles
– fill space between muscles
18
Q
Three layers of connective tissue
A
Epimysium
Perimysium
Endomysium
18
Q
Epimysium
A
Outer layer dense irregular
19
Q
Perimysium
A
Surrounds groups of 10 to 100 or more muscle fibre separating into fascicles or bundles
Dense irregular
20
Q
Endomysium
A
Penetrates the interior of each fascicle and separate individual muscle fibres
-mostly reticular fibres
21
Q
Fascicles
A
Bundle of 10 to 100 muscle fibers
– large [seen by naked eye]
21
Q
Tendon
A
Rope-like structure that attaches a muscle to the periosteum of a bone
22
Q
Aponeurosis
A
When connective tissue elements extend as a broad, flat sheet
23
Fibromyalgia
Clinical connection
- Chronic, painful, nonarticular rheumatic Disorder that affects the fibrous connective tissue components of muscles, tendons, and ligaments
- A striking sign is pain that results from gentle pressure at specific “tender points”
[Severe fatigue, poor sleep, headaches, depression, IBS, and irritability to carry out daily activities]
24
Nerve and blood supply
The blood capillaries bring an oxygen and nutrients and remove heat, waste products of muscle metabolism
25
Sarcolemma
Plasma membrane of a muscle cell
26
Transverse [T1] tubules
- tunnel in from the surface towards the center of each muscle fiber
- filled with interstitial fluid
27
Muscle action potential travel along the ____ and through the ________
Sarcolemma
| T tubules
28
Sarcoplasm
Cytoplasm of a muscle fibre [includes glycogen]
29
Myoglobin
Muscle protein that releases oxygen when needed by the mitochondria for ATP production
-Protein found only in muscle, that binds oxygen molecules that if using the muscle fibres from interstitial fluid
30
Myofibrils
Small threadlike structures in sarcoplasm
- contractile organelles of skeletal muscle
- Extend entire length of muscle fiber
- prominent striations make the entire skeletal muscle fiber appear striped [striated]
31
Sacroplasmic reticulum [SR]
Fluid filled system of membranous sacs that encircle each myofibril
32
Terminal cisterns
Dilated end sacs of the SR
33
Triad
T tubule and 2 terminal cisterns on each side
34
Muscular hypertrophy
Clinical connection
- Muscle growth.
| - Enlargement of existing muscle fibers by very forceful, repetitive muscular activity
35
Muscular fibrosis
Clinical connection
Replacement of muscle fibers by fibrous scar tissue
36
Muscular atrophy
Clinical connection
A decrease in size of individual muscle fibres as a result of progressive loss of myofibrils
37
In a relaxed muscle fiber, the sarcoplasmic reticulum stores_______
Calcium ions
38
There are ______ thin filaments for every thick filament in the region of filament overlap
Two
39
Filaments
Small protein structures within myofibrils
40
Sarcomere
Compartments of filaments that do not extend the entire length of a muscle fibre
41
Components of a sarcomere
```
Z disks
A band
I-band
H zone
M line
```
42
Thin filaments
Composed mainly of the protein actin
8 nm in diameter and 1 to 2 µm long
- Contain smaller amounts of tropomyosin & troponin (regulatory protein)
43
Thick filaments
16 nm in diameter and 1 to 2 µm long lines composed of the protein myosin
44
Z disc
Plate-shaped region of dense material that separate ones sarcomere from the next
45
A band
Middle part of sarcomere that extends entire length of thick filaments and include those parts of thin filaments that overlap thick filaments
46
I band
Lighter, less dense area of sarcomere that contains remainder of thin filaments but no thick filaments
47
H zone
Narrow region centre of each A band that contains thick filaments but no thin filaments
48
M line
Region in centre of H zone that contains proteins that hold thick filaments together at center of sarcomere
48
Two contractile proteins in muscle
Myosin [thick]
| Actin [thin]
50
Three kinds of proteins myofibrils are built from
Contractile [Generate force]
Regulatory [Switch on and off]
Structural [Alignment]
51
2 myosin binding sites
Actin binding
| ATP binding
52
Two regulatory proteins
Tropomyosin
| Troponin
53
Myosin
- Main component of thick filaments
- functions as a motor protein in all three types of muscle tissue
- pull various cellular structures to achieve movement by converting the chemical energy in ATP to the mechanical energy of motion [production of force]
- Shaped like to golf clubs twisted together
- each head has two binding sites, tail points towards the M line of sarcomere center
- 300 molecules to form a single thick filament
54
Actin
Main component of the thin filament
- twisted into helix
- Myosin binding sites, where myosin head can attach
55
Five structural proteins
```
Titin
A-actinin
Myomesin
Nebulin
Dystropin
```
56
Tropomyosin
- Component of a thin filament
- when skeletal muscle fiber is relaxed tropomyosin covers myosin binding sites on actin molecules preventing myosin for binding to actin
57
Troponin
- Component of a thin filament
- when Calcium ions binds to troponin, it changes shape moving tropomyosin away from the myosin binding sites on actin
- Begins muscle contraction of myosin bind to actin
58
Skeletal muscle
Organ made up of fascicles that contain muscle fibers [cells], blood vessels and nerves wrapped in epimysium
59
Fascicle
Bundle of muscle fibres wrapped in perimysium
60
Muscle fiber [cell]
- Long cylindrical cell
- Covered by endomysium & Sarcolemma which contains sarcoplasm, myofibrils , peripherally located nuclei, mitochondria, transverse tubules, SR & terminal cisterns
- striated appearance
61
Myofibril
Threadlike contractile elements within sarcoplasm of muscle fiber that extend entire length of fiber, composed of filaments
62
Filaments [myofilaments]
Contractile proteins within myofibrils
63
Four steps of the contraction cycle
ATP hydrolysis
Myosin attaches to Actin
Power stroke
Detachment of myosin from Actin
64
Sliding of thin filaments past thick filaments produces ________
Muscle shortening
65
Rigor Mortis
Clinical connection
- Having 3 to 4 hours after death in the last 24 hours
- ATP synthesis ceases shortly after breathing stops therefore cross bridges cannot detach
- Muscles are in a state of rigidity [cannot contract or stretch]
66
Contraction & relaxation of Skeletal muscle fibers
-Lengths of the thick and thin filaments were the same in both relaxed and contracted muscle [like an accordion]
– thick & thin filaments slide past one another
68
Length tension relationship
For skeletal muscle, indicates how the forcefulness of muscle contraction depends on length of the sarcomeres within a muscle before contraction begins
69
Sliding filament mechanism
-Muscle contraction occurs because myosin heads attach to and walk along the thin filaments at both ends of sarcomere pulling the thin filaments towards the M line
69
Somatic motor neurons
Neurons that stimulate skeletal muscle fibers to contract
71
Synapse
Region where communication occurs between two neurons, or between a neuron and a target cell
72
Synaptic cleft
Small gap at most synapses that separate two cells
73
Neuromuscular junction [NMJ]
synapse between a somatic motor neuron and a skeletal muscle fibre where muscle action potentials arise
73
Neurotransmitter
Chemical messenger that allows cells to communicate
75
Four ways a nerve impulse [nerve action potential] elicits a muscle action potential
– Release of acetylcholine
- activation of ACH receptors
- production of muscle action potential
- termination of ACH activity
75
Muscle metabolism
Production of ATP in muscle fibers
76
Three ways muscle fibres produce ATP [Muscle metabolism]
Creatine phosphate
Anaerobic glycolysis
Aerobic respiration
77
A Skeletal muscle fibre has only one___________ ________ it is usually located near the midpoint of the fiber
neuromuscular junction
78
Anaerobic glycolysis
Does not require oxygen
Glucose is catabolized to generate ATP
Produces fewer ATP, faster, can occur when oxygen levels are low
Provide enough energy for approximately two minutes of max muscle activity
79
Creatine phosphate
- Energy rich molecules in muscle fibers
- synthesized by excess ATP produced while muscle fibres are relaxed
- 3 to 6 times more plentiful than ATP in the sarcoplasm
- First source of energy when muscle contraction begins because formation of ATP from CP occurs rapidly [Other two mechanisms take longer]
81
Aerobic respiration
Series of oxygen requiring reactions [kreb cycle]
Slower than anaerobic glycolysis, yield much more ATP
Produces nearly all the needed ATP for activities at last several minutes to an hour or more
82
Together stores of _______ and _______ provide enough energy for muscles to contract maximally for about 15 seconds
Creatine phosphate
| ATP
83
Two sources of oxygen for muscle tissue
-Diffuses into muscle fibres from blood
| – released from myoglobin within muscle fibers
84
Muscle fatigue
- inability of a muscle to maintain force of contraction after prolonged activity
- feeling of tiredness and desire to cease activity
- protective mechanism to stop a person from exercising before muscle becomes damaged
- In adequate release of calcium ions from the SR
- Depletion of creatine phosphate
- ATP levels are not much lower and fatigue muscle versus resting muscle
85
Other Factors that contribute to muscle fatigue
- Insufficient oxygen
- depletion of glycogen and other nutrients
- buildup of lactic acid & ADP
- failure of action potentials
87
Three ways metabolic conditions are restored to resting level [After exercise]
- Convert lactic acid back into glycogen stores in liver
- Resynthesize creatine phosphate and ATP in muscle fibers
- replace the oxygen removed from myoglobin
88
Oxygen use after exercise is also boosted by These three ongoing changes
- elevated body temperature [after exercise] increases the rate of chemical reactions
- heart & the muscles used in breathing are still working harder than at rest, thus consuming more ATP
- tissue repair processes are occurring at an increased pace
89
Recovery oxygen uptake
Elevated use of oxygen after exercise [oxygen debt]
90
Each skeletal muscle fibre has only a single _____________.
Neuromuscular junction
91
A single somatic motor neuron makes contact with an average of ___________ Skeletal muscle fibres and all of the muscle fibres in one motor unit contract in unison.
150
92
Twitch contraction
Brief contraction of all muscle fibres in a motor unit in response to a single action potential
93
Motor unit
Somatic motor neuron plus all of the skeletal muscle fibers it stimulates
94
Latent period
Delay between application of stimulus and contraction
95
Contraction period
Peak tension develops a muscle fibre
96
Relaxation period
Myosin heads detach from Actin
97
Refractory period
Period of lost excitability
98
Frequency of stimulation
Second contraction will actually be stronger than the first [wave summation]
99
Unfused tetanus [incomplete]
- Sustained but wavering contraction
| - when SMF is stimulated at a rate of 20 to 30 times per second
100
Fused tetanus [complete]
- Sustained contraction were individual twitches cannot be detected
- stimulated at a rate higher than 80 to 100 times per second
- Happens when more Ca2+ is released from the SR while levels of Ca2+ in the sarcoplasm are still elevated
101
Motor unit recruitment
Process in which the number of active motor units increases
102
Anaerobic training
Stimulate synthesis of muscle proteins and increase muscle size overtime [muscle hypertrophy]
weightlifting activitiesg
103
Aerobic training
Build endurance for prolonged activities
Repeated activity such as jogging, or aerobic dancing increase the supply of oxygen rich blood available
104
Muscle tone
Small amount of tightness or tension in the muscle due to weak, involuntary contraction
105
Isotonic contraction
Force of contraction
| Tension developed in the muscle remains almost constant while the muscle changes in length
106
Concentric isotonic contraction
Great enough to overcome the resistance of the object to be moved, the muscle shortens and poles on another structure, such as tendon, to produce movement, and reduce angle at a joint
107
Eccentric isotonic contraction
When the length of a muscle increases during a contraction
108
Isometric contraction
Tension generated is not enough to exceed the resistance of the object to be moved, and the muscle does not change in length
109
Skeletal muscle fibres
Not all like in composition and function
Vary in content of myoglobin
110
Three types of skeletal muscle fibres
Slow oxidative fibers
Fast oxidative-glycolytic fibers
Fast glycolytic fibers
111
Slow oxidative fibers
Dark red, large amounts of myoglobin and many blood capillaries
- generate ATP mainly by aerobic respiration [why oxidative fibers]
- slow speed of contraction
- longer to reach peak tension
- very resistant to fatigue
- Capable of prolonged, sustained contractions for many hours
- maintain posture and aerobic endurance type activities
112
Fast oxidative-glycolytic fibers
Largest fibers
-large amount of myoglobin and many blood capillaries. [Dark red parents]
– generate considerable ATP by aerobic respiration
-high resistance to fatigue
-also generate ATP by anaerobic glycolysis
-fast [hydrolyze 3 to 5 times faster]
-Reach peak tension more quickly but our brief and duration [less than 100 msec]
-Activities such as walking and sprinting
113
Fast glycolytic fibers
Low myoglobin content
- Few blood capillaries
- white in colour
- generate ATP mainly by glycolysis
- Hydrolyze ATP rapidly
- contract strongly in quickly
- Intense anaerobic movement of short duration [weightlifting or throwing ball]
- pretty quickly
- FG fibres of a weightlifter maybe 50% larger than a sedentary person
114
Most skeletal muscles are a mixture of all three types of skeletal muscle fibres
Slow oxidative
Fast oxidative-glycolytic
Fast glycolytic
115
Approximately half of the fibres in a typical skeletal muscle are _______
Slow oxidative
116
Distribution and recruitment of different Types of muscle fibres depends on These three factors
Action of muscle
Personal training regiment
Genetic factors
117
Effective stretching
Stretching called muscles does not increase flexibility and may cause injury
- Tissue stretch best when slow, general force is applied at elevated tissue temperatures
- Exercise his muscle more deeply and thoroughly than external measures [a.k.a. warm up[
118
Strength training
Process of exercising with progressively heavier resistance for the purpose of strengthening the musculoskeletal system
-increases bone strength by increasing deposition of bone materials
119
Anabolic steroids
Clinical connection
Taken to increase muscle size by increasing the synthesis of proteins in muscle
120
Cardiac muscle tissue [principal tissue in heart wall]
- Intercalated discs are unique to cardiac muscle fibers [contain desmosomes, gap junctions]
- has an endomysium and perimysium but lacks and epimysium
- Remains contracted 10 to 15 times longer than Skeletal muscle [from single action potential]
- Has an auto rhythmic system
- Contracts and relaxes Approximately 75 times a minute
- the continuous, rhythmic activity is a major difference between cardiac in skeletal muscle tissue
121
Smooth muscle tissue
Activated involuntarily
122
Two types of smooth muscle tissue
Visceral and multi unit
123
Visceral [SMT]
Found in skin, tubular arrangements that form part of walls of small arteries and veins, hollow organs [stomach, intestines, uterus, urinary bladder]
124
Multiunit [SMT]
Found in walls of large arteries, airways to lungs, arrector pili muscle [Attached a hair follicles], muscles of the iris that adjust pupil diameter
-Individual fibres with own motor neuron terminals
125
Characteristics of Skeletal Muscle
Appearance-Long cylinder fibers with many peripherally located nuclei, Striated
Location –Most commonly attached by tendons to bones
Fiber diameter-very large
Connective tissue components-endomysium, perimysium, epimysium
Fiber length-very large
Contractile proteins organized into sarcomeres- no
SR-abundant
Transverse tubules present-yes, align with each A-I band junction
Junction between fibers-none
Autorhythmicity- no
Source of Ca2+ for contraction-SR
Regulator proteins for contraction-troponin & tropomyosin
Speed of contraction-fast
Nervous control-voluntary [somatic nervous system]
Contraction regulation-acetylcholine
Capacity for regeneration-limited, via satellite cells
126
Characteristics of cardiac muscle
-branch cylinder fibre with one centrally located nucleus; intercalated discs join neighbouring fibers; striated
Location – heart
Fiber diameter-large
Connective tissue components-endomysium & perimysium
Fibre length – large
Contractile proteins organized into sarcomeres- yes
SR-some
Transverse tubules present- Yes, aligned with each Z disc
Junctions between fibers-intercalated discs contain gap junctions and desmosomes
Autorhythmicity- yes
Source of Ca2+ for contraction-SR & Interstitial fluid
Regulator proteins for contraction-troponin & tropomyosin
Speed of contraction-moderate
Nervous control-involuntary [autonomic nervous system]
Contraction regulation-acetylcholine & Norepinephrine
Capacity for regeneration-limited, Under certain conditions
127
Characteristics of smooth muscle
-fiber thickest in middle, tapered at each end, and with one centrally positioned nuclei; not striated
Location – Walls of hollow viscera, airways, blood vessels, Iris & ciliary body of eye, Arrector pili muscles of hair follicles
Fiber diameter-small
Connective tissue components-endomysium
Fibre length – intermediate
Contractile proteins organized into sarcomeres- no
SR-very little
Transverse tubules present- No
Junctions between fibers-gap junctions In visceral smooth muscle; none in multi unit smooth muscle
Autorhythmicity- yes, in viseral smooth muscle
Source of Ca2+ for contraction-SR & Interstitial fluid
Regulator proteins for contraction-calmodulin & myosin light chain kinase
Speed of contraction-slow
Nervous control-involuntary [autonomic nervous system]
Contraction regulation-acetylcholine & Norepinephrine
Capacity for regeneration-Considerable [compared with other muscle tissues, but limited compared with epithelium],
128
Ligament
tough,flexible fibrous connective tissue that connects two bones, or cartilages or hold together a joint
129
Hypertrophy
enlargement of existing cells
130
Hyperplasia
An increase in the number fibers
