Unit 5: Introduction to the Muscular System Flashcards
1
Q
What are the functions of the muscular system? (5)
A
- Produce movement of the skeleton
- Maintain posture and body position
- Support soft tissues
- Guard entrances and exits
- Regulate body temperature
2
Q
How many layers of connective tissue does the skeletal muscle have?
A
3
3
Q
What are the 3 connective tissue layers in a skeletal muscle?
A
- epimysium
- perimysium
- endomysium
4
Q
Epimysium (3)
A
- The outermost layer
- Separator from surrounding tissues
- Consist of collagen fibers
5
Q
Perimysium (2)
A
- Surrounds bundles of muscle fibers
- Inside of it are blood vessels, nerves, fibers, collagen, and elastic fibers
6
Q
What is another name for bundle of muscle fibers?
A
fascicles
7
Q
Endomysium (2)
A
- Surrounds the individual muscle fiber
- Has stem cells
8
Q
What does the collagen from the 3 connective tissue layers form?
A
- tendons
- aponeurosis
9
Q
Tendon
A
attach muscle to bone
10
Q
Aponeurosis (sheets)
A
connect muscles
11
Q
Sarcolemma
A
plasma membrane
12
Q
Sarcoplasm
A
cytoplasm
13
Q
Transverse Tubules
A
transmit nerve impulses thru entire fiber
14
Q
Sarcoplasmic Reticulum (2)
A
- surrounds each myofibril
- stores Ca2+
15
Q
Myofibrils
A
bundles of protein filaments called myofilaments
16
Q
How many myofilaments are there?
A
2
17
Q
What are the two types of myofilaments?
A
- actin (thin filaments)
- myosin (thick filaments)
18
Q
Sarcomere
A
Smallest functional unit
19
Q
Striations
A
alternating thick & thin filaments
20
Q
Z-line
A
boundary of a sarcomere
21
Q
I-Band
A
thin filaments and the proteins that bind them together
22
Q
A-Band
A
contains the entirety of the thick filaments as well as the intertwining of them with thin filaments
23
Q
H-Band
A
thick filaments only
24
Q
M-Line
A
attachment sites for thick filaments
25
What characteristics distinguish skeletal muscle cells from “typical cells?” (4)
- striated
- multinucleated
- tubular
- voluntary
26
What happens during muscle contraction? (4)
1) Sarcoplasmic reticulum releases Ca2+ in response to action potential from neuron
2) Ca2+ bind to troponin, causes shape change and allows tropomyosin to swing sway from actin proteins, exposing active sites
3) Myosin head attaches to active site of actin forming a cross bridge
4) Power Stroke: myosin heads pivot toward center of sarcomeres using energy from hydrolyzed ATP
27
What is the structure and function of the neuromuscular junction? (4)
1) Action potential (electrical signal) arrives
2) Neurotransmitter acetylcholine (Ach) is released into synaptic cleft
3) Ach binds to muscle cell at motor end plate → influx of Na+
4) Action potential travels across sarcolemma & down T tubules
28
Where does the striated appearance of skeletal muscles come from?
the alternating between thick and thin filaments
29
The all or none principle
a muscle fiber is either contracted or relaxed
30
How does muscle tension vary? (2)
- frequency of stimulation
- Number of muscle fibers stimulated
31
Muscle Tone
tension at rest 🡪 stabilizes bones & joints
32
Isotonic Contraction
tension rises & muscle changes length
33
Isometric contraction
develops tension but does NOT change length
34
How is glucose stored in muscles?
as glycogen
35
What is the role of creatine phosphate? (2)
- stores excess ATP in resting muscle
- can provide E for ~15 sec
36
Aerobic Metabolism (5)
- happens in mitochondria
- resting fibers use ATP to form glycogen & creatine phosphate
- Contracting fibers use glycogen 1st, then fat for ATP production
- provides 95% of ATP in resting cell
- yields ~34 ATP
37
Anaerobic Metabolism (3)
- breakdown of glucose in sarcoplasm primary energy source for peak activity
- results in lactic acid formation if no O2 is present
- yields 2 ATP
38
What causes muscle fatigue? (2)
- Depletion of energy reserves
- build up of lactic acid
39
Recovery Period
Liver converts lactic acid to pyruvic acid & releases glucose into blood to recharge muscle glycogen reserves
40
Oxygen Debt
additional O2 is needed
41
Fast Twitch Fibers (5)
- strong, quick contractions
- large diameter
- few mitochondria
- fatigue quickly
- large glycogen reserves
42
Slow Twitch Fibers (5)
- slow to contract
- small diameter
- more mitochondria
- high O2 supply
- contain myoglobin (red pigment that stores O2)
43
Why would there be oxygen debt after exercise?
additional O2 would be needed to bring levels back to normal
44
Which activity are fast fibers associated with?
anaerobic activity
45
Which activity are slow fibers associated with?
aerobic activity
46
Hypertrophy (2)
- muscle growth
- ↑’s mitochondria & glycogen reserves due to increase in muscle fiber diameter
47
Atrophy (2)
- fibers become small & weak due to lack of stimulation
- ↓’s muscle size & tone
48
Which type(s) of muscle is/are found in the walls of hollow organs and blood vessels?
Smooth Muscle
49
What is the primary function of smooth muscle tissue?
To line the insides of organs and tracts and regulate the movement of materials
50
What are some characteristics of cardiac muscle? (5)
- branched
- connected by intercalated discs
- contain gap junctions
- Automaticity
- Aerobic metabolism only
51
Gap Junctions (2)
- allow ion movement between cells
- pass action potentials from cell to cell
52
What are the 3 muscles and their striations and voluntariness?
- Skeletal Muscle: striated and voluntary
- Cardiac Muscle: striated and involuntary
- Smooth Muscle: nonstriated and involuntary
52
What effects do aging have on the muscular system? (4)
- smaller in diameter
- less ecstatic
- decreased tolerance for exercise
- decreased ability to recover from injury
53
What entails muscles becoming smaller diameter with aging? (5)
fewer...
- myofibrils
- myoglobin
- glycogen
- ATP
- Creatine Phosphate
54
What entails muscles becoming less elastic?
- increasing amounts of fibrous tissue, restricts movement & circulation
55
What entails muscles having decreased tolerance for exercise?
- Slower delivery of blood to muscles during exercise, faster fatigue
- Impaired ability to eliminate heat, causes overheating
