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Biology 20 (Alberta) > Muscular System > Flashcards

Muscular System Flashcards

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1
Q

What are the attributes of smooth muscle tissue?

A
  • Non-striated (no lines)
  • Each have a single nucleus
  • Contract involuntarily
  • Can sustain prolonged contraction without fatigue
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2
Q

Where is smooth muscle tissue located?

A

Found in walls of internal organs (ex. esophagus → peristalsis)

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3
Q

What are the attributes of cardiac muscle tissue?

A
  • Striated, tubular, and branched
  • Each have single nucleus
  • Contract involuntarily
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4
Q

Where is cardiac muscle tissue located?

A

Found in walls of heart

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5
Q

What are the attributes of skeletal muscle tissue?

A
  • Striated and tubular
  • Each have many nuclei
  • Contract voluntarily
  • Found in pairs (one action always has an opposing action)
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6
Q

When muscles contract they _________

A

SHORTEN

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7
Q

Contraction = ________; Relaxation = _________

A

WORK; NO WORK

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8
Q

What are the functions of the muscular system?

A

Support → contraction of muscles opposes force of gravity

Movement → allows for movement of bones as well as eyes and face

Maintain Temperature → ATP breakdown releases heat and spreads it throughout body!

Protection → acts as padding for bones and cushions organs

Stabilize Joints → tendons help hold bones to joints

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9
Q

What are tendons?

A
  • Fibrous connective tissue
  • Connect muscles to bones
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10
Q

What are ligaments?

A
  • Fibrous connective tissue
  • Connect bones to bones
  • Located within joints
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11
Q

What are muscles?

A
  • Organ surrounded by connective tissue & composed of several tissues
  • Largest unit
  • Attached to bone by tendons
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12
Q

What are muscle fibers?

A
  • Highly specialized cells that convert chemical energy (ATP) into kinetic energy
  • Organized into larger bundles (up to 20 cm long)
  • Connective tissue wraps fibres
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13
Q

What are myofibrils?

A
  • Rod-like structures found in muscle cells
  • Made up of repeating units: sarcomeres
  • Organized in parallel within a muscle cell, allowing for coordinated contraction of the entire muscle
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14
Q

What are sarcomere?

A
  • Functional unit of a muscle
  • Composed of myofilaments (actin & myosin)
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15
Q

What are A bands?

A

Dark area because actin and myosin overlap (how we see the striations in skeletal muscle)

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16
Q

What are I bands?

A

Lighter areas of muscle are the just actin

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17
Q

How are sarcomere divided?

A

Z lines divide sarcomere

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18
Q

What is the H zone of a sarcomere?

A

H zone is the area where myosin can be seen

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19
Q

What are myofilaments?

A
  • Protein fibres that make up the contractile elements of muscle cells
  • Responsible for muscle contraction
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20
Q

What is the basis of the sliding filament theory?

A

During muscle contraction, the myosin filaments bind to and pull on actin filaments, shortening the sarcomeres and causing the muscle to contract

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21
Q

What are the two types of myofilaments?

A
  • Actin (thin filament)
  • Myosin (thick filament)
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22
Q

What is tropomyosin

A

Protein that blocks the sites myosin bind to on actin

23
Q

What is myoglobin?

A

oxygen-binding pigment; stores oxygen for muscle contractions.

24
Q

What is the sarcolemma

A

membrane of muscle fibre; regulates entry and exit of materials.

25
Q

What is troponin?

A

Protein that binds to calcium ions, causing tropomyosin to shift position, exposing the binding sites

26
Q

What is the structure of myosin?

A
  • Two polypeptide chains wrapped around each other
  • Many of these myosin molecules stick together to form a thick filament
  • Shaped like a golf club, but with 2 heads
  • Ends have globular heads that stick out to form a cross bridge
27
Q

What are the major steps of the sliding filament model?

A
  1. Presence of calcium ions allow myosin head to attach to actin
  2. Myosin head flexes, pulling on the actin filament
  3. Myosin head releases and unflexes via ATP
  4. Myosin reattaches to actin further down fibre
28
Q

How is calcium released for muscle contraction?

A

Sarcoplasmic reticulum releases calcium ion, which binds to troponin

29
Q

What happens to muscle fiber during muscle contraction?

A

Muscle fibre shortens

30
Q

Which process provides the majority of energy for muscle contraction?

A

Aerobic Respiration

31
Q

What are the three processes for converting energy for muscle contraction?

A
  1. Aerobic cellular respiration
  2. Breakdown of creatine phosphate
  3. Fermentation (anaerobic respiration)
32
Q

What is creatine phosphate?

A

Creatine phosphate is a high energy molecule that is built-up/replenished during rest

33
Q

How does creatine phosphate convert energy for muscle contraction?

A

Regenerates ATP by contributing a phosphate in the midst of sliding filaments

34
Q

How does aerobic respiration convert energy for muscle contraction?

A

When oxygen is present, glucose (from glycogen) or fatty acids (from fat) can be converted to ATP

35
Q

How is oxygen transported to the mitochondria for cellular respiration to take place?

A

Myoglobin pigment has higher affinity for oxygen than hemoglobin so it steals oxygen away from hemoglobin, and provides to mitochondria

36
Q

When would fermentation occur in muscle contraction?

A

When ATP is used faster than the body is able to replenish it, which is usually due to lack of oxygen

37
Q

What is the downside to fermentation?

A

Causes lactic acid/lactate build-up

38
Q

What is the formula for aerobic respiration?

A

O2 + C6H12O6 = CO2 + H2O + ATP

39
Q

What does the accumulation of lactate in the muscle fiber cause?

A

Makes sarcoplasm more acidic, causing enzymes to stop functioning

40
Q

Why does respiration rate stay high after strenuous exercise?

A

Respiration rate stays high in order to repay the oxygen debt from cellular respiration when lactic acid is converted back to pyruvate

41
Q

What happens if fermentation lasts longer than 2-3 minutes?

A

muscle cramping and fatigue will occur (lack of ATP = muscles can’t relax)

42
Q

What is rigor mortis?

A
  • When animals die, there is no more ATP and therefore no release of myosin from actin myofilaments
  • Usually lasts around 36 hours
43
Q

What is atrophy?

A

Reduction of size, tone and power of muscle that is often caused by disuse of muscle

44
Q

Hypertrophy

A

Exercise induced increase in muscle mass

45
Q

What is a muscle twitch?

A
  • A single contraction that lasts a mere fraction of a second
  • Twitches added together in a process called summation.
  • Once tetanus occurs, you can no longer see the individual twitches
    Muscles fatigue due to a depletion in energy reserves will cause no contraction despite stimulation
46
Q

What is a myogram?

A
  • Measures force of a muscle contraction in a skeletal muscle with time
47
Q

What is tetanus?

A

When a muscle is not allowed to relax completely between stimuli, the contraction gradually increases in intensity until it reaches a maximum (tetanus), which is sustained until the muscle fatigues.

48
Q

What are the three types of muscle twitches?

A
  1. Slow-twitch (Type I)
  2. Fast Twitch (Type II)
  3. Intermediate Twitch (Type III)
49
Q

Describe slow-twitch (Type I)

A
  • Dark colour
  • Contains myoglobin
  • Have many surrounding capillaries
  • Contract slowly, but resist fatigue
  • Produce most ATP aerobically
  • Glycogen and fat allow the abundant mitochondria to maintain steady, prolonged ATP production
  • Best suited for endurance type activities (ex. biking, swimming, long distance running)
50
Q

Fast-twitch (Type II)

A
  • Light colour
  • Little or no myoglobin
  • Fewer blood vessels
  • Adapted for rapid generation of power, but fatigue quickly.
  • Rich in glycogen; large number of sarcomeres.
  • Depends on anaerobic energy production, putting the individual at risk of lactate accumulation
  • Best suited for short term, power activities (ex. sprinting, tennis, weight lifting)
51
Q

What is the latent period?

A

The time between stimulation and initiation of contraction

52
Q

What is the contraction period?

A

When the muscle shortens

53
Q

What is the relaxation period?

A

muscle returns to its former length

Biology 20 (Alberta) (12 decks)

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