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A&P > The Muscular System > Flashcards

The Muscular System Flashcards

1
Q

What does the muscular system consist of

A

muscles
associated c.t. such as tendons

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2
Q

Functions of the muscular system

A

movement (body, blood, air, food,)
support
heat production
protection

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3
Q

Characteristics of muscle tissue that make it unique compared to epithelial, connective, or nervous tissues

A

Contractility - ability to actively shorten

Extensibility - ability to stretch or lengthen

Elasticity - ability to return to original shape after shortening or stretching

Excitability - ability to respond to stimuli by producing and conducting action potentials (electric signals). Nervous tissue also has this capability

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4
Q

Subtypes of muscle tissue are categorized based on _________ and include ________

A

location, appearance, and whether muscle is able to contract on command or not

  1. SKELETAL (location); Striated (appearance); VOLUNTARY (control)
  2. VISCERAL (location, in hallow organs); SMOOTH (appearance); involuntary (control)
  3. CARDIAC (location); striated (appearance); involuntary (control)

***CAPS WORDS = UNIQUE WORDS

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5
Q

Fascia definition

A

may be considered c.t. that surrounds and anchors nearly all body structures

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6
Q

Superficial fascia

A

under the deeper layer of the skin (the dermis) and is also referred to as the subcutaneous layer or hypodermic.

connects skin to deeper structures, such as muscle or bone as well as the location for storage of a good deal of our body fat

p. 14 of coloring book

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7
Q

deep fascia

A

surrounds, protects, and anchors organs and does not store fat

p. 14 of coloring book

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8
Q

three layers of deep fascia that are associated with skeletal muscles are:

A

epimysium
perimysium
endomysium

these layers consist of the same material but surround different parts of the muscle

p. 14 of coloring book

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9
Q

Epimysium

A

this extension of deep fascia surround the ENTIRE MUSCLE

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10
Q

Perimysium

A

is deep to the epimysium and surrounds BUNDLES OF MUSCLE FIBERS known as fascicles

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11
Q

Endomysium

A

deepest layer of fascia surrounds INDIVIDUAL muscles cells known as MUSCLE FIBERS

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12
Q

“-mysiums” extend beyond the end of muscle fibers to form ____

A

tendons

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13
Q

Tendon

A

extensions of fascia beyond the muscle fibers

many are cord-like structures

all tendons attach muscle to something

p.42 in coloring book

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14
Q

Aponeurosis

A

a broad, flat sheet of tendon

p.42 in coloring book

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15
Q

Muscle fiber, AKA _____

A

muscle cell

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16
Q

Muscle fibers/cells are:

A

the result of the fusion of many small embryonic cells (myoblasts), to form mature skeletal muscle cells with multiple (100+) nuclei

once fused, these cells DO NOT UNDERGO CELL DIVISION. They can HYPERTROPHY or ATROPHY but they don’t grow new cells

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17
Q

if muscle fibers are lost…

A

they will not be renewed but are generally replaced by fibrous c.t. (fibrosis(

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18
Q

Muscle fiber organization

A

muscles fibers are group into bundles called fascicles

FASCICLES are bundles of muscle fibers/cells

muscle fibers contain organelles called MYOFIBRILS

myofibrils are made up of thin and thick MYOFILAMENTS (filaments)

p. 12 and 42 in coloring book

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19
Q

components of a muscle fiber structure

A

myofibrils
sarcolemma
sarcoplasm
myoglobin
sarcoplasmic reticulum
transverse (T) tubules

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20
Q

Myofibrils

A

contractile organelles that make up muscle fibers

made of thin and thick myofilaments that overlap one another in a repeating pattern

sections of this overlapping pattern are known as SARCOMERES

p. 12 of coloring book

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21
Q

Sarcolemma

A

the plasma membrane of the muscle cell

p., 12 of the coloring book

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22
Q

Sarcoplasm

A

they cytoplasm of the muscle cell, within the sarcolemma

contains glycogen (the storage form of glucose) and myoglobin

p. 12 of the coloring book

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23
Q

myoglobin

A

a reddish protein in the sarcoplasm that binds to oxygen

similar to hemoglobin in the blood

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24
Q

Sarcoplasmic reticulum

A

a system of flattened sacs surrounding myofibrils

similar to the smooth endoplasmic reticulum of other cells and stores calcium, which will have a role in contraction

p. 12 of coloring book

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25
Q

Transverse (T) tubules

A

tiny invaginations of the sarcolemma towards the center of each muscle fiber

they help convey impulses quickly through the muscle

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26
Q

Sarcomeres and the various regions

A

sarcomeres arr sections of the repeating overlapping myofilaments

Regions:
Z line/disc
A Band
I Band
H Zone
M line
titin

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27
Q

Myofilaments

A

tiny proteins that make up muscle fibers

these do NOT run the entire length of the muscle fibers but overlap one another in a repeating pattern in skeletal muscle

some are thinner, some are thicker

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28
Q

Thin myofilaments

A

consist primarily of a protein called ACTIN

actin molecules twist around one another to form a twisting helix

other proteins - troponin and tropomyosin - “block” attachment sites on the thin filaments

p 12 of coloring book

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29
Q

thick myofilaments

A

consist primarily of protein molecules known as MYOSIN

myosin molecules resemble golf clubs with heads that extend towards the thin filaments

p. 12 in coloring book

30
Q

Neurons

A

NERVE CELLS that conduct impulses

31
Q

neuromuscular junction

A

a gap between a nerve cell (neuron) and a muscle cell/fiber

these may be looked at as a type of synapse, though some prefer to reserve that term for a similar gap between neurons

p. 71 of coloring book

32
Q

neurotransmitters

A

CHEMICALS released by neurons into gaps such as neuromuscular junctions

neurotransmitter used at skeletal muscles is a chemical known as acetylecholine (ACh)

p 71 in coloring book

33
Q

motor unit

A

consists of a NERVE CELL AND THE MUSCLE FIBERS that it controls (innervates)

motor units may consist of several muscle fibers or several hundred

p. 71 in coloring book

34
Q

two types of muscle attachments

A

ORIGIN - tends to be the attachment that is more fixed when the muscle produces its typical movement

INSERTION - usually the attachment that moves during the most common movement produced by the muscle

*this does not mean that origins never move. Some muscles can produce movement at either attachment

p. 43 in coloring book

35
Q

Basics steps in getting a muscle fiber to contract:

A
  1. Nerve impulse travels over a neuron that leads to a muscle fiber
  2. release NEUROTRANSMITTER by the neuron
  3. propagation of an ACTION POTENTIAL through muscle fiber
  4. release of CALCIUM from storage in the muscle, which “unblocks” the thin myofilaments
  5. formation of CROSS BRIDGES between thin and thick myofilaments
  6. SLIDING of thin myofilaments over thick myofilaments and shortening of sarcomeres
36
Q

Nerve impulse

A

NEURONS (nerve cells) and MUSCLE FIBERS “meet”, though do not touch at gaps known as NEUROMUSCULAR JUNCTIONS. These may be looked at as a type of synapse

Neurons terminate and turn into axon terminals, which in turn divide into synaptic end bulbs. These contain hundreds of synaptic vesicles where acetylcholine (ACh) is stored

p 71 in coloring book

37
Q

ACh Release

A

When a nerve impulse arrives at the end of they synaptic end bulb, protein channels in the cell membrane of the neuron open and allow calcium to flow into the cell

Ca+ triggers synaptic vesicles of ACh to undergo exocytosis and RELEASE ACH into the synaptic cleft (1)

ACh BINDS TO RECEPTORS ON the motor end plate of THE MUSCLE FIBER, opening ion channels that allow Na+ to flow into the muscle fiber (2)

this triggers the SPREAD OF A MUSCLE ACTION POTENTIAL (impulse) along the sarcolemma of the muscle fibers and into the T tubules (3). This in turn TRIGGERS RELEASE OF CALCIUM from storage in the sarcoplasmic reticulum

ACh is rapidly broken down by the enzyme acetylcholinesterages (AChE) (4)

38
Q

Cross bridge formation

A

at rest, actin filaments are covered by tropomyosin, which are connected to the protein troponin

Ca+ bind with troponin, moving tropomyosin away, unblocking the binding sites on actin

myosin heads bind onto the exposed actin filaments, forming cross bridges

39
Q

Contraction cycle

A

Once attached to actin, myosin heads rotate, releasing the ADP. This slides the attached thin myofilament towards the center of the sarcomere. This movement is referred to as the POWER STROKE

*see more details on slide 6 of the Muscular System 2 powerpoint

40
Q

Energy for muscle contraction and relaxation

A

Energy is needed to contract and relax muscles

ATP is the DIRECT source of energy for these processes

When ATP is broken down into ADP and phosphate, energy is released. This energy may be used to contract or relax muscles

41
Q

In muscle contraction/relaxation, the ENERGY FROM ATP is needed to:

A

slide the thin actin filaments over the thick

to pump Ca+ back into storage in the sarcoplasmic reticulum and for other metabolic reactions occurring within the skeletal muscle

42
Q

ATP in muscle fibers in enough to fuel muscle for a few seconds. To continue contraction….

A

ENERGY FROM OTHER SOURCES must be used to REFORM ATP

43
Q

Three notable sources of energy to reload ATP

A
  1. creatine phosphate
  2. anaerobic glycolysis
  3. aerobic respiration
  • the use of creatine phosphate for energy is unique to muscles, whereas all body cells may utilize the other two forms
44
Q

Creatine phospate

A

a high energy compound found in muscle fibers

45
Q

energy from creatine phospate

A

formation of ATP from CP is VERY QUICK AND is an immediate SOURCE OF ENERGY TO RELOAD ATP

Together with ATP and CP stores, muscles can contract for about 15 seconds

more info on CP on slide 10 of the muscular system 2 power point

46
Q

Anaerobic glycolysis

A

refers to the BREAKDOWN OF GLUCOSE to provide energy for ATP production WITHOUT USING OXYGEN

GLYCOGEN = storage form of glucose (found in the liver and limited amounts in the muscles)

Provides enough energy for approx. 2 minutes of maximal muscle activity

47
Q

most of the lactic acid created from glycolysis…

A

diffuses into the blood and may be sued as an indicator of ANAEROBIC ACTIVITY

48
Q

Aerobic respiration

A

muscles may use oxygen to provide energy for ATP production via AEROBIC RESPIRATION

Aerobic respiration can use GLUCOSE, FATTY ACIDS, AND AMINO ACIDS as sources of fuel source whereas anaerobic glycolysis can only use glucose

aerobic respiration provides MUCH MORE ENERGY than anaerobic glycolysis - 30-32 ATP molecules instead of 2

49
Q

Compare and contrast Anaerobic glycolysis and Aerobic respiration.

Oxygen needed?
Fuel type
waste products
efficiency
activities

A

ANAEROBIC GLYCOLYSIS
Oxygen- not needed
Fuel - glucose
Waste Product - lactic acid
Efficiency -less
Activities - high intensity short duration

AEROBIC RESPIRATION
Oxygen- needed
Fuel - glucose, amino acids, fatty acids
Waste Product - CO2, water, heat
Efficiency - more
Activities - low intensity, long duration

50
Q

Muscle FIBERS contract on a _________ basis

A

all or nothing

either fully contract or not at all

stimulus is strong enough to contract fiber or not

51
Q

ENTIRE MUSCLES contract on a _______ scale

A

graded scale;

muscles may contract with varying levels of force

52
Q

more forceful contractions occur by ____

A

recruiting more motor units

the individual fibers/cells in the motor unit, however, are contracting on an all-or-nothing basis

53
Q

Key types of contraction

A

isotonic (subtype - concentric and eccentric)
isometric
static (tonic)
tetanic

54
Q

Isotonic contraction

A

tension remains the same while the length of the muscle changes

  1. CONCENTRIC - muscle shorten (towards center)
  2. ECCENTRIC - muscles lengthen (away from center)
55
Q

Isometric contraction

A

length stays the same, while tension chagnes

56
Q

static (tonic) contraction

A

continual partial contraction

57
Q

Tetanic contraction

A

complete sustained contraction

*typically associated with cramp or spasm

58
Q

Different roles of muscles during contraction

A

Movers (agonists)
PRIME MOVERS
ANTAGONISTS
fixators
stabilizers

59
Q

PRIME MOVERS

A

the muscles best at producing a movement, often due to their angle of pull

60
Q

ANTAGONISTS

A

these muscles relax to allow movement

they tend to be opposite the movers in function and location

61
Q

Define fatigue

A

the inability of a muscle to maintain force of contraction after prolonged activity

62
Q

Factors that may play a role in muscle fatigue:

A

BUILD UP OF WASTE PRODUCTS (ADP and hydrogen ions)
DEPLETION OF RESOURCES (such as glucose)
LACK OF OXYGEN (limit aerobic respiration)

63
Q

DOMS - Delayed-onset muscle soreness

A

soreness in muscles after exercise

64
Q

DOMS is most likely due to

A

microscopic damage to the muscle fiber

NOT lactic acid

65
Q

When muscles get bigger

A

hypertrophy

66
Q

when muscles shrink

A

atrophy

67
Q

3 subtypes of skeletal muscle fibers

A
  1. SLOW OXIDATIVE (SO, type I)
  2. FAST OXIDATIVE GLYCOLYTIC (FOG, type IIA)
  3. FAST GLYCOLYTIC (FG, IIB)
68
Q

Slow oxidative (SO, Type I) muscle fibers

A

smallest and least powerful

contain large amounts of MYOGLOBIN and appear red in color

generate ATP via aerobic pathways, so are referred to as OXIDATIVE

SLOW-TWITCH - contract slowly

FATIGUE RESISTANT - well suited for endurance

69
Q

fast oxidative glycolytic (FOG, type IIA) muscle fibers

A

INTERMEDIATE in diameter

well supplied with capillaries and contain a good amount of MYOGLOBIN, so appear red in color

mostly aerobic (OXIDATIVE), but also store good levels of glycogen (GLYCOLYTIC)

FAST-TWITCH - contract quickly

show resistance to fatigue

70
Q

fast glycolytic (FG, type IIB) muscle fibers

A

LARGEST in diameter; most powerful

contain little myoglobin and appear WHITE in color

ATP generated by anaerobic glycolysis (GLYCOLYTIC)

FAST-TWITCH - contract quickly

TIRE QUICKLY- but generate a great deal of force

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