AnP Chapter 10 (LO8) Flashcards
(106 cards)
1
Q
Body contains over ——muscles which comprise about –% of adults weight
A
Body contains over 600 muscles which comprise about 40% of adults weight
2
Q
3 TYPES OF MUSCLES
A
Cardiac muscle
Smooth muscle
Skeletal muscle
3
Q
Cardiac muscle
A
Found only in heart
Consists of short, branching fibers that fit together at intercalated discs
Striated
Is a type of involuntary muscle because it contracts automatically
4
Q
Smooth muscle
A
Found in digestive tract, blood vessels, bladder, airways and uterus
Nonstriated
Involuntary muscle
5
Q
Skeletal muscle
A
Attached to bone and causes movement of the body
Voluntary: contracted at will
6
Q
SKELETAL MUSCLE STRUCTURE
A
Consists of bundles of tiny fibers that run the length of muscle
Most fibers are about 3cm long and 0.05mm wide
7
Q
Endomysium
A
delicate connective tissue that covers each muscle
8
Q
Fascicles
A
muscle fibers grouped in bundles
9
Q
Perimysium
A
a sheath of tougher connective tissue that encases fascicles
10
Q
Epimysium
A
layer of connective tissue that surrounds and binds all the muscle fiber together
11
Q
Fascia
A
connective tissue that surrounds the muscle outside the epimysium
12
Q
Deep fascia
A
lies between muscles
13
Q
Superficial fascia
A
resides just underneath the skin
14
Q
Skeletal may attach to bone in 1 of 2 ways
A
Direct attachment
Indirect attachment
15
Q
Direct attachment
Indirect attachment
A
Direct attachment: muscle fibers merge with the periosteum of the bone forming a strong attachment
Indirect attachment: the epimysium extends past the muscle as a tendon
16
Q
STRUCTURE OF MUSCLE FIBERS
A
Muscle cells are called muscle fibers because they’re long, thread like
Have multiple nuclei pressed against the side of the plasma membrane
Complex interior
17
Q
Sarcolemma
A
the plasma membrane surrounding each fiber
18
Q
Sarcoplasm
A
cytoplasm of the cell
19
Q
Myofibrils
A
long protein bundles that fill the sarcoplasm
Store glycogen (used for energy) and 02
20
Q
Sarcoplasmic reticulum (SR)
A
smooth endoplasmic reticulum of a muscle fiber
Surrounds each myofibril
Where calcium ions are stored
21
Q
Myofilaments:
A
2 types thick and thin
22
Q
Myosin
actin
A
Myosin: protein that makes up thick myofilaments
Actin: protein that makes up thin myofilaments
23
Q
Transverse tubules
A
extend across the sarcoplasm
Formed from inward projections of the sarcolemma
Allow electrical impulses to travel deep into the cell
24
Q
THICK FILAMENTS
A
Consists of hundreds of myosin molecules stacked together
Myosin head faces outward
Myosin molecule is shaped like a golf club
25
THIN FILAMENTS
Consist of 2 chains of actin
Look like string of beads
actin
tropomyosin and troponin
26
Actin
tropomyosin and troponin
Actin: contractile protein
Tropomyosin and troponin: proteins entwined with actin
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STRUCTURE OF MYOFIBRIL
Thick and thin myofilaments stack together to form myofibrils
28
Sarcomere
units of contraction of the myofilaments of a muscle
29
Z-disc/z-line
a plate/disc that serves as an anchor point for thin myofilaments
30
cross-bridge
when myosin attaches to actin
31
*contraction occurs when...
*contraction occurs when the myosin head latches onto actin
32
Motor neuron
a nerve that can stimulate skeletal muscle to contract
Found in brainstem and spinal cord
33
Axons
carry impulses to skeletal muscles
Each branch stimulated a different muscle fiber
34
Neuromuscular junction
connection between motor neuron and a muscle fibre
35
Synaptic cleft
between end of the motor nerve and the muscle fiber
36
HOW MUSCLE FIBERS CONTRACT
1. When an impulse reaches end of motor neuron and neurotransmitter is released acetylcholine (Ach) the neurotransmitter released into the synaptic cleft
2. Ach stimulates receptors in the sarcolemma: membrane surrounding muscle fiber
3. Electrical impulses sent over the sarcolemma along T tubules
- --T tubules cause the sacs in the sarcoplasmic reticulum to release calcium
4. The calcium binds with the troponin to expose attachment points on actin
- --The myosin heads of thick grab the thin and muscle contraction occurs
37
HOW MUSCLE FIBERS RELAX
1. Ach is no longer released when nerve impulses stop arriving at the neuromuscular junction
2. Acetylcholine esterase: breaks down remaining Ach
3. Calcium ions are pumped back into the sarcoplasmic reticulum
4. Troponin and tropomyosin prevent the myosin head from grasping the thin filament
5. Muscle relaxes
38
Myasthenia
body produces antibodies against receptors for Ach nerve transmission is poor and profound muscular weakness
39
Tetanus
“lock jaw” bacteria which causes motor neurons to fire excessively leads to overstimulation of muscles resulting in severe muscle spasms
40
how MUSCLE TONE works
1. Sarcomeres are shortened in overly contracted fibers
- -Fibers can’t contract very for before thick filaments bump into z-discs
- -Contractions are weak
2. An overly stretched fibers thin filaments have little overlap
- -Only small part of thin filament accessible for myosin heads to grab
- -Contractions are weak
3. When thin and thick filaments partially overlap contractions are strong
- -Z-discs are far enough apart to allow for movement during contraction
- -Thin/thick filaments overlap enough to allow the myosin head to grip the thin actin filaments
41
Muscle tone
continuous state of partial contraction
Allows you to stand, hold head up and maintain posture
Allows you to react quickly to a dangerous situation
42
Motor unit
one motor neuron and all the fibers (group) it stimulates
A single motor can consist of a few fibers or hundreds
These fibers are scattered throughout the muscle rather than bunched this allows contraction to be spread over wide area
43
Threshold
minimum voltage needed to cause a muscle fiber to contract
44
Twitch
brief contraction when a fiber receives a stimulus at or above threshold
45
Force of contraction is affected by a number of things including
size of muscle, the degree of stretch and number of muscle fibers contracting
46
Nervous system responds to demands placed on muscles in 2 ways
Altering the frequency of the stimulus
Altering the intensity of the stimulus
47
how Stimulus frequency works
1. Frequency of stimuli can alter contraction strength
2. The last contraction will be stronger than the first when a muscle contracts several times in a row
3. Sarcoplasmic reticulum doesn’t have time to completely reabsorb calcium ions
4. Increased calcium = more forceful contraction
48
Treppe
phenomenon that each successive twitch contracts more forcefully than previous
49
Incomplete tetanus
condition of rapid contraction with only partial relaxation
50
Complete tetanus
impulses arrive so fast that the muscles can’t relax at all between stimuli
51
Strong stimulus
May stimulate all the fibers in a motor nerve
Nerve fibers call on muscle fibers to contract (more fibers contracting= stronger)
Recruitment: the process by which an increasing number of motor units are called into action
52
Weak stimulus
Just a few nerve fibers
May stimulate just one nerve fiber and the muscle fibers connected
Fewer fibers= weaker
53
Isotonic contractions
muscle contraction that shortens the muscle
Ex)lift barbell
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Isometric contractions
muscles contract by increasing tension while the length stays the same
Ex) pulling on cable fastened to a stationary object
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At rest energy is obtained by...
metabolizing fatty acids
56
Aerobic respiration
used to break down fatty acids for energy
57
Creatine phosphate (CP):
compound stored in muscle and broken down when muscles restock their supply of ATP
Can furnish the muscle with fuel for 20 secs high activity or 1 minute of moderate activity
58
Anerobic respiration
use of glucose when CP runs out before oxygen has reached an acceptable level
Can generate energy quickly and is useful for intense bursts of activity
59
Lactic acid:
produced by-product from anerobic respiration which accumulates in muscle and leads to muscle fatigue
60
After about 10mins of moderate activity heart and lungs increase oxygen to muscles...
Muscles shift back to aerobic respiration which produces c02 and water rather than lactic acid
61
Origin
refers to the end of the muscle that attaches to the more stationary bone
Ex) origin of biceps is the scapula which is relatively immobile
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Belly
the thick midsection of the muscle
63
Insertion
the end of the muscle that attaches to the movable bone
Ex) insertion of biceps is the radius muscle pulls the radius towards the scapula
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Prime mover
main muscle triggering the movement
65
Synergists
the muscles that assist the prime mover
66
Antagonist
muscles balancing the movements by opposing the action of prime mover
When prime mover contacts antagonist relax and give prime mover control
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Hypertrophy
strength training causing muscles to enlarge
Intense exercise slightly injure fibers as the body repairs the fibers enlarge
68
Atrophy
lack of use causes the muscle fibers and entire muscle to shrink
Endurance exercise stimulates the growth of blood vessels in muscles allowing increase supply of 02 and glucose necessary for ATP
69
Frontalis
raises eyebrows when glancing upwards or showing surprise
70
Orbicularis oculi
a sphincter muscle that closes the ye when blinking or squinting
71
Zygomaticus
draws the mouth upward when laughing
72
Orbicularis oris
closes the mouth and purses the lips ex kissing
73
Buccinator
assists in smiling, blowing and chewing
74
Temporalis
aids in closing jaw
75
Masseter
closes jaw
76
Sternocleidomastoid
flexes the head, rotates head opposite side only one muscle contracts
77
Trapezius
extends head also elevates shoulder
78
External intercostals
lie superficially between ribs; elevate ribs during inspiration
79
Diaphragm
enlarges the thorax to trigger inspiration
80
External oblique
compresses the abdominal organs which aids in forcefull expiration, vomiting, and defecation also allows flexion of vertebral column and rotation and lateral bending of trunk
run in a Downward and anterior direction
81
Rectus abdominis
flexes the lumbar region of the spinal column to cause bending forward at the waist; extends from sternum to pubic bone
82
Transverse abdominis
compresses the contents of the abdomen
runs in a Horizontal direction
83
Internal oblique
stabilizes the spine and maintains posture, also permits rotation of waist
runs in a Upward and anterio direction
84
Deltoid
abducts, flexes, rotates the arm; involved in swinging the arm; raises arms
85
Pectoralis major
flexes and adducts the upper arm, such as when climbing or hugging
86
Trapezius
raises and lowers shoulders; stabilizes scapula during arm movements
87
Latissimus dorsi
adducts the humerus; extends upper arm backwards; pull the body upward when grasping an object overhead
88
Rotator cuff
```
tendons of 4 muscles form rotator cuff
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
```
89
Brachialis
the prime mover when flexing the forearm
90
Biceps brachii
assists the brachialis when flexing the forearm; also flexes elbow and supinates the forearm
91
Triceps brachii
the prime mover when extending the forearm
92
Brachioradialis
helps the brachialis and the biceps brachii flex the forearm
93
Pronator muscle
Supinator muscle
Pronator muscle: allow the arm to pronate
Supinator muscle: lies deep in forearm near elbow allows supination
94
Flexor
Extensor
Flexor: muscles that flex wrist; located on anterior of forearm
Extensors: muscles that extend the wrist; located on posterior of forearm
95
Iliopsoas
flexes the thigh
Illiacus
Psoas major
96
Sartorius
longest muscle in body; aids in flexion of hip and knee; abducts and laterally rotates the thigh
97
Adductor muscles
rotate and draw the thigh in toward the body consists of
Adductor magnus
Adductor brevis
Adductor longus
Gracilis
98
Quadriceps femoris
the most powerful muscle in the body; prime mover for knee extensions consists of
```
4 muscles:
Vastus intermedius
Rectus femoris
Vastus lateralis
Vastus medialis
```
99
Gluteus Medius
abducts and rotates the thigh outward
100
Gluteus maximus
the bulkiest muscle in the body; produces backswing of leg when walking and provides power for climbing stairs
101
Gluteus minimus
this muscle lies beneath the other two; it assists the gluteus Medius in abducting when leg is extended; aids in internally/externally rotating thigh
102
Hamstrings
group of muscles consisting of following 3:
Biceps femoris
Semitendinosus
Semimembranosus
All work to extend thigh at hip, flex knee, and rotate leg
103
Calf is 2 muscles:
Gastrocnemius (more superficial)
Soleus (deeper)
104
Calcaneal (Achilles) tendon
tendon of the gastrocnemius
105
Extensor digitorum longus
extends toes and turns foot outward
106
Tibialis anterior
keep toes from dragging on floor
