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A&P After Midterm Saint > Muscle Tissue > Flashcards

Muscle Tissue Flashcards

1
Q

What are the 4 Main functions of muscle tissue

A

Produce the Body movements, Maintain posture, Move Substances within the body, and Generate heat

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2
Q

What are muscle tissues composed of

A

Composed of elongated cells called myocytes or muscle fibers

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3
Q

What are the three types of muscle tissue

A
  1. Skeletal muscle
  2. Cardiac muscle
  3. Smooth muscle
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4
Q

What does a Skeletal muscle tissue require to contract

A

Requires innervation from a somatic motor neuron to contract

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5
Q

What is it called when a a muscle tissue doesn’t have a innervation

A

Atrophic

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6
Q

The muscles are separated from the skin by the subcutaneous layer or hypodermis composed by________ and _____________

A

Adipose tissue

Areolar tissue

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7
Q

What is Epimysium

A

Outer layer encircling the whole muscle

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8
Q

What is Perimysium

A

Surrounds bundles of 10-100 cells forming fascicles

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9
Q

What is Endomysium

A

Separates each individual muscle fiber from each other

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10
Q

What is a tendon

A

Tendons are rope-like extensions of the three connective tissue layers(1. Epimysium, 2. Perimysium
3. Endomysium) beyond the muscle fibers attaching the muscle to the periosteum of a bone

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11
Q

What does Fascia do

A
  • Supports and surround the muscles and other organs of the body
  • Holds together muscles with similar functions
  • Allows free movement of muscles
  • Carries the nerves, blood vessels, and lymphatics
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12
Q

Where do you see cardiac muscle tissue

A

Occurs only in the heart

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13
Q

Is Cardiac muscle tissue faster then Skeletal Tissue

A

Moderate speed of contraction, not as fast as skeletal muscle

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14
Q

How are the cardiac muscles attached to each other

A

The cells are strongly attached end-to-end by the intercalated discs

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15
Q

The Intercalated Discs are kept by_______ and ________

A
  1. Desmosomes
    • Weld-like junctions preventing separation
    of the cells during strong contractions
2. Gap junctions
• Allow for very fast communication
between many connected cells, which
contract all at once with the same nerve
impulse
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16
Q

What happens if the heart is cut off from innervation

A

Capable of contraction by auto-stimulation

If innervation was cut off, still the heart can contract

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17
Q

build-in rhythm of the heart is called

_______

A

autorhythmicity

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18
Q

What 2 things can adjust the heart beat by acting on the pacemaker

A

Hormones and neurotransmitters

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19
Q

What do Smooth Muscle Tissue look like

A

Non striated, spindle-like cells, thicker at the center with a single, centrally- located nucleus

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20
Q

Are smooth muscles voluntary or involuntary

A

Involuntary muscle innervated by the ANS (autonomic nervous system)

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21
Q

The Smooth Muscle: two types?

A
  1. Visceral (single unit) smooth tissue
    • Skin, hollow organs like stomach, intestines, uterus, bladder
    • Fibers connect by gap junctions and contract in unison as a single unit
  2. Multi-unit smooth tissue
    • Large arteries, airways, arrector pili, iris, ciliary body
    • Individual fibers with own nerve
    • Few gap junctions between neighboring cells
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22
Q

The Smooth Muscle Tissue are Located in:

A
  • The walls of hollow internal organs
  • The skin
  • Blood vessels
  • Airways
  • Organs of abdominopelvic cavity
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23
Q

Are Smooth Muscle Tissue fast or slow

A

Slow speed of contraction

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24
Q

What are myocytes

A

The muscle cell, also known as the myocyte is the smallest subunit of all muscular tissues and organs throughout the body

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25
Q

The mature skeletal muscle cell measures about __ mm

in length, some can reach __ mm

A

The mature skeletal muscle cell measures about 10 mm

in length, some can reach 30 mm

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26
Q

What is the Sarcolemma of the Muscle Cell

A

Sarcolemma: is the plasma membrane

of the muscle cell

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27
Q

What are the Transverse (T) tubules of the Sarcolemma

A

Thousands of invaginations of the sarcolemma

toward the center of muscle cell

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28
Q

What are Transverse (T) tubules filled with

A

T tubules are filled with extracellular fluid allowing for the instant stimulation of all parts of the cell simultaneously with the same stimulus

29
Q

What is the Sarcoplasm of the Muscle Cell

A

Sarcoplasm: is the cytoplasm of the muscle cell

30
Q

What does Sarcoplasm contain

A

It contains:
• Large amounts of glycogen

  • Myoglobin (protein only found in muscle)
  • Abundant mitochondria close to the contractile proteins

• Myofibrils: the contractile organelles
that contain the myofilaments (thin
and thick)

• Sarcoplasmic reticulum (SR)
membranous sacs encircling each
myofibril. The dilated ends of the SR
are called terminal cisterns. A T
tubule and two terminal cisterns form
a triad

• The SR stores calcium ions for the
muscle contraction

31
Q

What is Myoglobin

A

protein only found in muscle

32
Q

What are Myofibrils

A

the contractile organelles that contain the myofilaments (thin and thick)

33
Q

What is the Sarcoplasmic reticulum (SR)

A

membranous sacs encircling each myofibril. The dilated ends of the SR are called terminal cisterns. A T tubule and two terminal cisterns form a triad
• The SR stores calcium ions for the muscle contraction

34
Q

The myofibrils contain smaller protein structures called the filaments or___________

A

myofilaments

35
Q

What are the two myofilaments

A
  • Thin filaments are composed of protein actin

* Thick filaments are composed of protein myosin

36
Q

What is a sarcomere

A

The filaments inside one myofibril are arranged in compartments called The Sarcomeres

The Sarcomeres are the basic functional units of a myofibril

37
Q

How are the Sarcomere separated

A

The Sarcomeres are separated from each other within the muscle cell by a dense protein material called the Z discs
One sarcomere extends from one Z disc to the next Z disc

38
Q

The myofibrils are built from three kinds of proteins:

A
  1. Contractile:
    • Generate the forces for contraction
  2. Regulatory:
    • Help switching the contraction process on and off
  3. Structural:
    • Keep the thin and thick filament aligned
    • Provide elasticity and extensibility
    • Link the myofibrils to the sarcolemma
39
Q

What is a Motor Unit

A

A motor neuron innervating a group of muscle fibers is called a Motor Unit

40
Q

What does the motor unit need to contract

A

The motor unit requires the stimulation of the motor neuron to contract

41
Q

The site where the communication between the motor neuron and the muscle cell occurs is called the _______

A

neuromuscular junction (NMJ)

42
Q

How does the Sliding Filament Mechanism result in

muscle contraction?

A

The skeletal muscle cell shortens because the thick and thin filaments slide pass each other

43
Q

How does the Sliding Filaments Mechanism work?

A
  1. Myosin pulls on actin, causing the thin filament to slide inward
  2. Consequently, Z discs move toward each other and the sarcomere shortens
  3. Thanks to the structural proteins, there is a transmission of force throughout the entire muscle, resulting in whole muscle contraction
44
Q

What is the Role of the Intracellular Calcium

A

AN INCREASE of calcium within the muscle cell
(in the sarcoplasm) starts the filament sliding
The muscle contracts

45
Q

What happens After the excitatory electrical impulse has expired

A

An active transport system pumps the calcium back

to its “prison” within the Sarcoplasm Reticulum (SR)

46
Q

What happens when a decrease of calcium within the muscle cell happens

A

Turns off the sliding process
The muscle turns back to its original length
The muscle relaxes

47
Q

what is adenosine triphosphate molecule (ATP)

A

The adenosine triphosphate molecule (ATP) provides the energy for muscle contraction

48
Q

How much ATP is stored inside the muscle

A

Only little ATP is stored inside the muscle

49
Q

How long can the ATP in the muscles power them

A

There is just enough ATP in the muscle to power muscle contraction for a few seconds

50
Q

Production of ATP in Skeletal Muscle: three sources

A
  1. ATP from Creatine phosphate (15 sec)
  2. ATP from anaerobic glycolysis (2 Min
  3. ATP from aerobic respiration (several Min-HR)
51
Q

When does muscle fatigue occur? 5 reasons

A 
The muscle cannot produce enough ATP
Insufficient oxygen
Depletion of glucose
Build up of lactic acid
Some unexplained mechanisms
52
Q

What are Isotonic Contractions

A

Occur when a constant load moves
through the ROM at a joint

The tension (muscle tone) remains
almost constant during such
contraction
53
Q

There are two types of Isotonic Contractions:

A
  1. Concentric Contraction
    The muscle shortens and pulls on another structure (For example, the flexion of the
    forearm by the biceps brachii.)
  2. Eccentric Contraction
    The overall length of the muscle increases during contraction (For example, during the extension
    of the previous movement)
54
Q

What is a Isometric Contraction

A

The muscle does not or cannot shorten but the tension of the muscle increases greatly

55
Q

What are Twitch Contractions?

A

Brief contraction of the entire motor unit from a single stimulation.
The eyeball muscles are fast-twitch

56
Q

What are the proprioceptors?

A

Receptors imbedded in the muscles, they allow the recognition of our own body. We can locate our head and limbs even when we are not looking at them

The brain is constantly receiving information related to body parts positions. So, continuous adjustments are made to ensure coordination

57
Q

The Proprioceptors Include:

A
  1. Muscle Spindles
    • Within skeletal muscles
  2. Tendon Organs or Golgi Tendon Organ (GTO)
    • Within tendons
58
Q

High myoglobin content are the___________

A

red muscle fibers
• Contain more mitochondria
• Better blood supplied

59
Q

Low myoglobin content are the

A

white muscle fibers

60
Q

The three Types of Skeletal Muscle Fibers:

A
  1. Slow Oxidative (SO) Fibers
  2. Fast Oxidative-Glycolytic (FOG) Fibers
  3. Fast Glycolytic (FG) Fibers
61
Q

What are Slow Oxidative (SO) Fibers

A
  • Dark-red colored, high myoglobin content. Highly blood supplied
  • Generate ATP by aerobic respiration (oxidative)
  • Contraction cycle proceeds at a slow pace
  • Twitch contractions last from 100-200 msec
  • Longer to reach peak tension
  • Very resistant to fatigue
  • Capable of prolonged sustained contraction
  • Adapted to maintain posture, aerobic, endurance-type of activities (marathon running)
62
Q

What are Fast Oxidative-Glycolytic (FOG) Fibers

A
  • The largest fibers
  • Dark-red appearance

• Contain large amounts of myoglobin. Highly blood
supplied

  • Can generate large amount of ATP by aerobic respiration
  • Moderate resistance to fatigue
  • Generate ATP by anaerobic glycolysis too
  • Twitch contractions last less than 100 msec
  • FOG fiber muscles contribute in walking and sprinting
63
Q

What are Fast Glycolytic (FG) Fibers

A
  • Low myoglobin content. Few blood capillaries
  • Appear white color
  • Contain large amount of glycogen
  • Generate ATP mainly by glycolysis
  • Contract strongly and quickly
  • Adapted for intense anaerobic movements of short duration
  • Strength training requiring great strength for short times increase these fibers
  • Fatigue very quickly
  • FG fibers are used for weight lifting and throwing balls
64
Q

What is Motor Unit Recruitment

A

Motor units recruitment is the process in which the number of active motor units increases

Weakest motor units are recruited first followed by stronger motor units

Motor units contract alternately to sustain contractions for longer periods of time

65
Q

What is the distribution of Types of Fibers

A

Most skeletal muscles are a mixture of all three types of fibers
About 50% of a typical skeletal muscle are SO fibers
The ratio FG to SO fibers is genetically determined

66
Q

Neck, back and leg postural muscles have higher proportion of __ fibers

A

SO

67
Q

Proximal muscles of the upper limb have higher proportion of __ fibers

A

FG

68
Q

Lower limb muscles have large number of __ and ___ fibers

A

SO and FOG

A&P After Midterm Saint (8 decks)

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