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BPK 142 Lecture Flashcards > (DONE) Lecture 4 - Skeletal Muscle > Flashcards

(DONE) Lecture 4 - Skeletal Muscle Flashcards

1
Q

what differentiates muscle cell fibers from other cells in the body?

A
  • able to shorten and dvelop tension
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2
Q

what are the 3 types of muscle tissue

A
  • skeletal muscle
  • smooth muscle
  • cardiac muscle
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3
Q

describe skeletal muscle (where, pattern, and control)

A
  • attaches and moves skeleton
  • striated pattern
  • under voluntary control
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4
Q

describe smooth muscle (location, pattern, control)

A
  • found in the walls of hollow organs and blood vessels
  • no set pattern unlike skeletal; making it smooth
  • involuntary control
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5
Q

describe cardiac muscle

- location and control

A
  • contractile tissue of heart wall

- involuntary control

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6
Q

list a few functions of the skeletal muscle (9)

A
  • locomotion
  • breathing
  • posture and body position maintenance
  • stabilize joints
  • support soft tissue
  • generate heat to maintain body temperature
  • guard entrances and exits to body
  • chewing food and talking
  • nutrient reserves (muscle can be broken down to make energy)
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7
Q

what is fasciculi

A
  • bundles of muscle fibers
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8
Q

if fasciculi run parallel to the long axis of muscle, what is the advantage and disadvantage?

A
  • greater range of motion but less strength
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9
Q

if fasciculi insert diagonal/ pennate into a tendon running the length of the muscle, what is the advantage/ disadvantage?

A
  • smaller ROM, greater strength
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10
Q

differentiate between unipennate, bipennate, and multipennate

A
  • all fasciculi insert on one side of tendon (semimembranous)
  • fasciculi insert on both sides of tendon (rectus femoris)
  • several tendons converge (deltoid)
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11
Q

if a fasciculi is described as one of the following, what does it mean?

  • longitudinal (strap)
  • radiate (convergent)
A
  • fasciculi run parallel to long axis of muscle

- fibers fan out from a single attachment (ex: pectoralis major)

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12
Q

what does it mean when muscles are antagonistic to eachother

A
  • they oppose eachother upon contraction (one shortens, one lengthens)
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13
Q

what are fixator/ stabilizezr muscles

A
  • muscles that immobilize a bone or joint near the origin of a prime mover muscle so they may act more efficiently
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14
Q

differentiate between the origin and insertion and belly portion of muscles

A
  • the less movable end of a muscle
  • the more movable end of a muscle
  • the widest portion of a muscle
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15
Q

give an example of a group of muscles that do not insert on bone?

A
  • the facial expression muscles insert into the skin!
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16
Q

list the 3 layers of connective tissue and answer:

  • what do they surround
  • what is their function?
A
  • endomysium
  • periysium
  • epimysium
  • surround muscle fibers/ the whole muscle
  • maintain intramuscular pressure
17
Q

why do muscles have a striated pattern of light and dark areas? What is each section of the repeated pattern called?

A
  • each muscle cell contains many myofibrils that consist of a large array of contractile proteins arranged in a series
  • sarcomere: the section of repeated array of contractile proteins
18
Q

what are the 2 main contractile proteins of sarcomere?

A
  • actin (thin) and myosin (thick)
19
Q

explain the sliding filament theory

A
  • when muscles are activated, the cross bridges on myosin attach to actin and rotates with the aid of ATP causing the actin filament to slide over the myosin. This behaviour causes the sarcomere to shorten
20
Q

why are muscle tissues heavily surrounded by capillaries?

A
  • muscle tissues can have high metabolic rates, requiring abundant blood supply
21
Q

angiogenesis

A
  • formation of new blood vessels (can be induced by physical training)
22
Q

motor unit

  • what is it?
  • what does it consist of
  • what do they do?
A
  • Functional unit of muscle
  • Consists of motor neuron and all the muscle fibers that motor neuron innervates
  • Motor neuron will innervate (supply with nerves) about 200 muscle fibers
  • Can range from 2-2000 muscle fibers (depending on fine movement or gross movements)
23
Q

describe the all or none law

A
  • when and only if the cell body of the motor neuron receives a strong enough stimuli, an action potential is generated and travels along the axon, stimulating each and every muscle fiber in the motor unit
24
Q

what are the 2 ways to classify motor units?

A
  • fast twitch and slow twitch
25
Q

what are the 2 ways a muscle can control force production?

A
  • activate more motor units
  • frequency/ wave summation: many action potentials are generated and the mechanical force response adds up; 5x the force of a single twitch
26
Q

when is the muscle maximally activated?

A
  • all motor units are activated

- activated at a high firing rate

27
Q

explain motor unit recruitment order and how it depends on the exercise intesnity

A
  • if muscle force requirement is large: motor units with larger axons are recruited
  • slow twitch muscle units are activated if light/ moderate effort is needed
  • rapid and powerful movement activates FOG and FG units
28
Q

isometric contraction vs eccentric conctration

A
  • no change in muscle length

- muscle lengthens while activated (lowering barbell after curl)

29
Q

what are 3 factors that impact the expression of muscle strength

A
  • initial length of muscle fibers
  • speed of shortening
  • angle of pull of muscle
30
Q

describe sarcopenia

A
  • age related loss of skeletal muscle mass, strength and function
31
Q

list 3 characteristics of old age related to health

A
  • decline in muscle mass strength and power
  • decreased physical activity
  • decreased food intake
32
Q

How much does muscle mass decrease every decade after 30? What if you’re physically active?

A
  • 3-8%

- 1-2% every year past 50yrs

33
Q

what causes sarcopenia (5)

A
  • neural apoptosis (death of motor control brain cells)
  • decline in mitochondrial function
  • physical inactivity
  • hormonal imbalance
  • inadequate protein and vitamin d intake
34
Q

If you have sarcopenia, what are you at risk for? (4)

A
  • loss of physical functioning
  • disability risk
  • dependency towards others
  • more medical care costs

BPK 142 Lecture Flashcards (13 decks)

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