Chapter 10 - Muscles Flashcards
1
Q
Three Types of Muscles
A
- Skeletal
- Cardio
- Smooth
2
Q
Muscular System
A
only skeletal muscles
3
Q
Myology
A
study of the skeletal muscles
4
Q
Skeletal Muscle
A
- Voluntary
- Striated
- Attached to bone
- Muscle cell = “muscle fiber” or “myofiber”
- Mutinucleated
5
Q
Cardiac Muscle
A
- Involuntary
- Striated
- Cell = “cardiocyte” or “myocyte”
- Short, branched cells
- Intercalated discs w/ gap junctions
- Typically mononucleated
6
Q
Smooth Muscle
A
- Involuntary
- Non-striated
- Fusiform cell shape
- Mononucleated
7
Q
Functions of Muscle
A
- Movement (body parts, communication)
- Stability
- Heat production
- Control of body openings & passages
- Store nutrients (amino acids, glycogen)
8
Q
Properties of Skeletal Muscle
A
- Excitability (responsiveness)
- Conductivity (electrical impulse)
- Contractility (shorten)
- Extensibility (stretch)
- Elasticity (recoil)
9
Q
Fascia
A
wraps muscle group
10
Q
Epimysium
A
wraps muscle
11
Q
Perimysium
A
wraps fascicle
12
Q
Endomysium
A
wraps muscle cell
13
Q
Skeletal Muscle Shapes
A
- Fusiform - tapered ends
- Parallel - uniform width
- Triangular (convergent) - tapered at one end
- Pennate - feather-shaped
- Circular - forms rings around body openings
14
Q
Muscle Attachments
A
- Indirect - tendon, connects into periosteum and matrix
- Aponeurosis - broad sheet of tendon (e.g. scalp, wrist, abdomen)
- Direct - muscle to bone, w/ collagen fiber
- Other tissues, i.e. dermis
15
Q
Origin
A
muscle attachment at relatively stationary end
16
Q
Insertion
A
muscle attachment at more mobile end
17
Q
Belly
A
muscle area between origin and insertion
18
Q
Functional Groups of Muscles
A
- Prime Mover - produce main force of action
- Synergist - aids prime mover, may stabilize joint
- Antagonist - opposes prime mover (antagonistic pair act on opposite sides of joint)
- Fixator - prevents bone movement
19
Q
Lever Model for Muscles
A
Lever = bone
Fulcrum = joint
Effort of Force = muscle
Resistance = object moved
20
Q
First Class Lever
A
- “Seesaw”
- E.g. extension of neck
- Fulcrum in middle (atlanto-occipital joint)
- Resistance is weight of head
- Effort by neck muscle to hold head erect
21
Q
Second Class Lever
A
- “Wheelbarrow”
- E.g. bouncing child on thight
- Fulcrum = hip
- Resistance is weight of child in middle
- Effort from quads
22
Q
Third Class Lever
A
- “Paddling Canoe”
- Most common
- E.g. Paddling
- Fulcrum = elbow
- Resistance is weight in hand
- Effort from biceps & brachialis
23
Q
Sarcolemma
A
muscle fiber plasma membrane
24
Q
Transverse (T) Tubules
A
conduct impulses from the sarcolemma down into the cell
25
Sarcoplasm
cytoplasm of skeletal muscle cell (fiber)
* Myofibrils (contain myofilaments)
* Glycogen (carbohydrate)
* Myoglobin (red pigment)
26
Sarcoplasmic Reticulum
endoplasmic reticulum of skeletal muscle cell (fiber)
* terminal cisternae (enlarged areas of sarcoplasmic reticulum surrounding the T tubules)
* Ca++ reservoir
27
Types of Myofilaments
1. Myosin
| 2. Actin
28
Myosin
- Myofilament
- Thick, contractile
- Heads project from bundled tails of hundreds of molecules
29
Actin
- Myofilament
- Thin, contractile
- Fibrous (F) Actin = resembles necklace
- Globular (G) Actin = resemble one head of necklace
- Active site = myosin binding site area on G actin
30
Skeletal Muscle Regulatory Proteins
1. Tropomyosin ("gate") - blocks active sites when muscle is relaxed
2. Troponin ("lock") - attaches to tropomyosin, binds calcium ("key") when excited
31
Muscle Striations
narrow stripes (light and dark) that run perpendicular to the length of the cell
32
A Band
area of myosin and actin overlap
33
H Band
central region of A band that is lighter due to lack of actin
34
M Line
midline of A band (and H band) that anchors myosin filaments together
35
I Band
area of actin filaments
36
Z Disc
midline of I Band, protein that anchors actin filaments together, define boundaries of a sarcomere
37
Sarcomere
basic unit of striated muscle tissue
38
Motor neuron's synaptic knob contains vesicles with _____________.
Acetylcholine (ACh)
39
Junctional folds of muscle cell's membrane contain _________ _________.
Acetylcholine (ACh) Receptors
40
Motor Unit
- Consists of one motor neuron and multiple muscle fibers
- Behaves as a single, functional unit
- Fibers from one unit are dispersed in muscle
41
Phases of Contraction and Relaxation
1. Excitation
2. Excitation-Contraction Coupling
3. Relaxation
42
Excitation of a Muscle
1. nerve signal arrives at knob
2. knob releases ACh, which binds to muscle's receptors, opening ion gates and exciting muscle
3. excitation spreads down and through muscle cell
43
Excitation-Contraction Coupling
1. electrical impulse triggers calcium release from SR
2. calcium binds troponin, which moves tropomyosin to expose actin
3. myosin breaks down ATP and extends head
4. myosin form cross-bridge with actin
5. myosin pulls actin in power stroke, then detaches, reattaches, pulls again, etc.
44
Relaxation of a Muscle
1. nerve signal stops
| 2. SR reabsorbs calcium, tropomyosin blockade resumes, and tension subsides
45
At rest, muscle receives about ___________ of heart's output.
one-quarter
46
During heavy exercise, muscular system receives more than _______________ of heart's output.
three-quarters
47
Muscle Growth and Atrophy
- resistance exercise stimulates production of more myofilaments, thus more myofibrils
- growth by hypertrophy
- exercise also stimulates production of mitochondria, myoglobin, glycogen, and blood vessels
- unused muscles atrophy
48
Two Classes of Muscle Fibers
Type I = Slow Oxidative (SO)
| Type II = Fast Glycolytic (FG)
49
Slow Oxidative Muscle Fibers
- slow-twitch, red, Type I
- small diameter
- aerobic ATP production
- abundant: mitochondria, myoglobin, capillaries
- resistant to fatigue
- predominate in postural muscles (e.g. soleus, back muscles)
50
Fast Glycolytic Muscle Fibers
- fast-twitch, white, Type II
- large diameter
- anaerobic ATP production
- abundant glycogen
- fatigue quickly
- predominate in quick response muscles (e.g. gastrocnemius, bicep)
51
Myopathies
diseases of the muscle
52
Muscular Dystrophy
- several types of skeletal muscle degeneration
- most common
* Duchenne
* Hereditary (sex-linked)
53
Myasthenia gravis (MG)
- autoimmune disease
- affects women age 20-40
- destruction of ACh receptors
54
How Muscles are Named
1. Size (e.g. brevis = short)
2. Shape (e.g. teres = round)
3. Location (e.g. brachii = of the arm)
4. Number of heads (e.g. biceps = two heads)
5. Orientation of the fibers (e.g. rectus = straight)
6. Action (e.g. flexor = muscle that flexes joint)
