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Biology 20 AP > Ch. 10 - Muscles > Flashcards

Ch. 10 - Muscles Flashcards

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1
Q

What are the three types of muscle cells?

A
  • Skeletal Muscle Cells
  • Smooth Muscle Cells
  • Cardiac Muscle Cells
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2
Q

What is the appearance of skeletal muscle cells?

A
  • Tubular
  • Straited (bands of light and dark)
  • Very long
  • Thin and elongated structure, and these skeletal cells are referred to as fibers instead of cells
  • Have many nuclei
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3
Q

What is the function of skeletal muscle cells? Where is it found?

A
  • (Many) Supports the body (attached to bones and causes movement)
    -> Makes bones move
    -> Protects internal organs
    -> Stabilizes joints
    -> 600+ skeletal muscles in the body
  • Maintains a constant body temperature; shivering

Usually attached to the bones of skeletons.

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4
Q

What type of (ATP) energy does skeletal muscle rely on?

A

Both:
- Anaerobic respiration
- Aerobic respiration
(for ATP production)

…and creatine phosphate.

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5
Q

How does skeletcal muscle contract? What is its pattern?

A
  • Voluntary
  • Sliding Filament Model
  • (Unlike other two) Needs to be able to contract rapidly and remian contracted for long periods of time (different ATP)
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6
Q

What is the appearance of smooth muscle cells?

A
  • Non-straited (due to actin & myosin arrangement) AND non-tubular
  • Long
  • 1 nucleus
  • Tapered at ends
  • Arranged in parallel lines forming sheets
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7
Q

What is the function of smooth muscle cells? Where is it found?

A

To advancement the movement of substances OR control diameter of blood vessels.
- Eye iris
- Certain blood vessels; expand/contract diameter of them
- In hollow internal organ walls, especially digestive tract; ex: intestine, stomach, esophagus

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8
Q

What type of (ATP) energy does smooth muscle rely on?

A

Mitochondrial activity to provide ATP; aerobic.

Can use creatine phosphate.

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9
Q

How does smooth muscle contract? What is its pattern?

A
  • Involuntary
  • Fairly slow and controlled
  • Can sustain prolonged contractions without fatiguing, slowly
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10
Q

What is the appearance of cardiac muscle cells?

A
  • Straited
  • Net-like structure (because it’s branched)
  • Different with skeletal as it’s branched with cells connected by gap junctions
  • Tubular
  • 1 nucleus
  • Branched
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11
Q

What is the function of cardiac muscle cells?

A

Rhythmic contractions of heart

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12
Q

What type of (ATP) energy does cardiac muscle rely on?

A

Mitochondrial activity to provide ATP; aerobic.

Can use creatine phosphate.

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13
Q

How does cardiac muscle contract? What is its pattern?

A
  • Involuntary
    (different from others because…)
  • Generates own electrical impulses (contraction without external stimulation; spreads rapidly through muscle tissue
  • Each contraction is followed by a rest period; varies at the rate of contraction (lubb-dubb)
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14
Q

A muscle consists of:

A

Cells called muscle fibres. They are bundled (each surrounded by a layer of connective tissue), blood vessels, and nerves.

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15
Q

Each muscle fibre:
What is another name for this?

A

Muscle cell.
Made of many myofibrils, which are composed of two kinds of myofilament (actin and myosin).

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16
Q

What is a muscle fibre?

A

Consists of hundreds of thousnads of cylindrical subunits called myofibrils. Are the single muscle cell, and when bundled, creates a muscle.

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17
Q

What is the function of a muscle fibre?

A

Responsible for muscle contractions.

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18
Q

What is myoglobin?

A

Oxygen-binding pigment (similar to hemoglobin) in straited muscle fibres. Stored in sarcoplasm

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19
Q

What is the function of myoglobin?

A

Stores oxygen for use during muscle contractions.

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20
Q

What is the sarcolemma?

A

Cell membrane of a muscle fibre.

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21
Q

What is the function of the sarcolemma?

A

Surrounds the mucle fibre and regulates entry and exit of materials.

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22
Q

What is the sarcoplasm?

A

Cytoplasm of a muscle fibre.

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23
Q

What is the function of the sarcoplasm?

A

Site of metabolic processes for normal cell activities; contain myglobin and glycogen (which stores energy for muscle contractions).

24
Q

What is sarcoplasmic reticulum?

A

Smooth endoplasmic reticulum in a muscle fibre.

25
Q

What is the function of the sarcoplasmic reticulum?

A

Stores calcium ions needed for muscle contractions.

26
Q

What are myofibrils?

A

Made up of even smaller myofilaments, containing portein structures for muscle contraction.

Essentially organized bundles of myofilaments; cylindrical structures as long as the musle fibre itself.

27
Q

What is the function of myofibrils?

A

Contain myofilaments responsible for muscle contraction.

28
Q

What are thick filaments?

A

Fine myofilaments composed of bundles of protein called MYOSIN (~11 nm in diameter)

29
Q

What is the function of thick filaments?

A

Binds to actin and causes muscle contractions.

30
Q

What are thin filaments?

A

Fine myofilament composed of bundles of strands of protein called ACTIN (~5 nm in diameter)

31
Q

What is the function of thin filaments?

A

Binds to myosin and causes muscle contraction.

32
Q

Other than myofibrils, what does the muscle fibre consist of?

A

Numerous mitochondria (~300/fibre) and other common cell organelles.

33
Q

Describe the Sliding Filament Model to muscle contractions using these phrases to help:
1. Muscle contraction involves:
2. The “heads” of the myosin filaments:
3. When a myofilament contracts:
4. Since the actin myofilament is chemically bonded to the myosin head:
5. One after another the myosin heads:
6. Each step requires:
7. The myosin can only:
8. When a muscle is relaxed
9. When a nerve impulse from nerve cell stimulates a muscle:
10. Calcium binds to:
11. Myosin binds to the:
12. ATP is also required to:

A
  1. The movement of the thick myosin filaments past the thin actin filaments
  2. Attach to the actin and then bend and pull the actin filaments toward the middle, making the entire unit shorter (contracted). P from the previous contraction during attachment is released, and the flex releases the ADP.
  3. Myosin heads move first in a back and inward motion similar to that of flexing a wrist
    (It is detached from the actin when ATP attaches to the myosin, then ATP -> ADP + P when recocked.
  4. The actin is pulled along with the myosin heads as they flex.
  5. Flex and in affect “walk” step by step along the actin
  6. One molecule of ATP to provide the energy to reposition the myosin after each flex.
  7. Attach to the actin where the binding sites are exponsed
  8. The binding sites are blocked by a protein called tropomyosin.
  9. It causes calcium ions (Ca2+) to be released from the sarcoplasmic reticulum.
  10. Calcium binds to Troponin, causes the tropomyosin to change shape and be shifted away from the myosin binding sites.
  11. Actin filaments, and with the energy from ATP, the myosin heads bend and pull the actin filaments toward each other, shortening the filament. ADP and P is used.
  12. Detach myosin from the actin so as it can join to another site further along.

(For the purposes of Bio 20, it requires 2 ATP per cycle; the flex/pull and release)

34
Q

What is a Z-line?

A

The actin is anchored at one end of each myofilament at a position called the Z-line. Thus, it’s movement pulls the Z-line along with it.

35
Q

Why is the Z-line significant to muscle contraction?

A

With one actin myofilament being pulled in one direction and another being pulled inward in the opposite direction, the two pairs of molecules drag the Z lines together, causing the muscle to contract.

Extra information illustration:
A) The heads on the two ends of the myosin filament are oritented in opposite directions. When the heads attach to the actin, they bend toward the centre of the myosin.
B) As one end of the myosin filament and its attached Z line toward the centre, the other end of the myosin filament does the same.
C) Both Z lines move toward the centre, and contraction occurs.

36
Q

Why are energy sources for muscles significant?

A

ATP produced before sternuous exercise lasts only a few seconds.

37
Q

The muscles acquire ATP in 3 different ways depending on the avaliability of oxygen. What are they?

A
  1. Breakdown of creatine phosphate (~1 ATP)
  2. Aerobic cellular respiration (~ 36 ATP)
  3. Fermentation (anaerobic respiration) (~2 ATP)

2 and 3 breaks down glucose.
1 and 3 don’t require oxygen.

2/1/3

38
Q

What does muscle contraction require, but what is a limitation to skeletal muscle cells?

A

ATP, but skeletal muscle cells of mammals are incapable of storing ATP.

39
Q

What other high energy compound does skeletal muscle cells store?

A

Creatine phosphate (phosphocreatine) which is broken apart to provide the phosphate to transform ADP to ATP

40
Q

What is creatine phosphate and when does it get rebuilt.

A

Is rebuilt when the muscle is resting through a transfer of a phospohate group from ATP to creatine.

Creatine Phosphate + ADP -> Creatine + ATP
(Is an energy source)

41
Q

What is aerobic cellular respiration? What is the process?

A

Usually provides most a muscle with ATP.

Glycogen and fat are stored in muscle cells, and thus, muscle fibre can use glucose from glycogen and fatty acids from fats as fuel to produce ATp as long as oxygen is avaliable.

42
Q

Why, under sterneous exercise, the quantity of energy produced through mitochondrial activity is limited?

A

The amount of oxygen that the bloodstream can transport to the cells is limited. There is less O2 avaliable during exercise.

43
Q

What is anaerobic respiration (fermentation)?

A

Of glucose to lactic acid must provide the ATP when mitochondrial processes are too slow.

44
Q

What is the oxygen debt?

A
  • Oxygen refers to the oxygen required after anaerobic exercise that’s needed to convert lactic acid back to pyruvate
  • Fermentation does produce an O2 debt, which muscle cells can tolerate for a brief period.
45
Q

What are slow-twitch fibers and what type # are they? Example?

A

(Type 1 Fibers)
- Tend to be aerobic
- Contract slowly but resist fatigue (endurance)
- Tire only when fuel supply’s gone
- Many mitchondria produce ATP
- Surrounded by dense capillary beds and draw more blood than fast-twitch fibers; more O2 access
- Abundant supply of glycogen means prolonged production of ATP as oxygen is avaliable.
Ex: deep muscle of leg (soleus)

46
Q

What are fast-twitch fibers and what type # are they? Example?

A

(Type 2 Fibers)
- Depend on anaerobic respiration
- Vultnerable to lactic acid buildup and muscle fatigue
- Adapted for the rapid generation of power: sprints, weight lifting
- Rich in glycogen
- Fewer mitochondria
- Fewer blood vessels
Creatine phosphate is present in higher concentrations in fast-twitch muscle fibers
Ex: calf muscle (gastrocnemius)

47
Q

What are intermediate form muscles fibers? Example?

A
  • Human muscles have a 3rd intermediate form of muscle fibers.
  • There are fast-twtich but with a high oxidative capacity and are therefore more fatigue resistant.
  • Endurance training increase the proportion of these fibers
  • However, heredity also plays a large role in the proportion of fast-twitch and slow-twitch fibers in the body.
    Ex: eye muscle (laterla rectus)
48
Q

What is muscular dystrophy?

A

A collective term for several hereditary conditions in which the skeletal muscles degenereate, lose strength, and are gradually replaced by fatty and fibrous tissue that impedes blood circulation; this, in turn, accelerates muscle degeneration in a fatal apiral of positive feedback.

49
Q

What is botulism?

A

A potentially fatal muscular paralysis caused by a toxin produced by the bacteria Clostridium botulinum; this toxin prevents the release of a muscle-stimulating compound (acetylcholine) released by muscle-related cells of the nervous sytem, thus leading to paralysis.

50
Q

What are cramps?

A

Painful muscle spasms triggered by sternuous exercise, extreme cold, dehydration, salt (electrolyte) imbalance (potassium), low blood glucose, or reduced blood flow.

51
Q

What is a contracture?

A

Abnormal muscle shortening not caused by nerve stimulation; can result from inability to remove calcium ions from the sarcoplasm or from the contraction of scar tissue (as in people who’ve experiences severe burns).

52
Q

What is fibromyalgia?

A

Chronic muscular pain and tenderness often associated with fatigue and sleep distrubances; can be caused by infectious diseases, physical or emotional trauma, or medications.

53
Q

What is crush syndrome?

A

A shock-like state following massive crushing of the muscles (as in, for example, the aftermath of an earthquake, the collapse of a building following an explosion, or a traffic accident); associated with high fever, heart ireegularities caused by potassium ions released from the muscles, and kidney failure caused by blockage of the renal tubles with myoglobin released by the traumitized muscles.

54
Q

What is delayed onset muscle soreness?

A

Pain, stiffness, and tenderness felt from several hours to a day after strenuous exercise; associated with trauma to the muscles, disruptions in the myofibrils and sarcolemma, and increased levels of myoglovin and muscle-fibre enzymes in the blood.

55
Q

What is a sarcomere?

A

Any individual section of the myofilament; contractile unit of myofibril, the section located between the two Z-Lines..

The repeating units of myofibril.

56
Q

What is myositis?

A

Muscle inflammation and weakness resulting from infection or an autoimmune disease.

57
Q

What are ways the muscular system helps maintain homoestasis?

A
  • Shivering (temperature)
  • Movement
  • Circulation

Biology 20 AP (14 decks)

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