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A&P 1 - Test 4 > Chapter 9 > Flashcards

Chapter 9 Flashcards

1
Q

What are the characteristics of slow-twitch muscle fibers?

A
  • Red fibers
  • Contain many mitochondria
  • Abundant blood supply
  • Aerobic
  • Sustained contractions with little fatigue
  • Example: muscles involved with posture.
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2
Q

List the events that occur during contraction with the sliding of actin filaments.

A

When calcium ions are present, the myosin binding sites on actin are exposed: Cross-bridges attaches to actin. When this is formed, the myosin head is in a “cocked” position. The head contains an ADP and P and when this bond forms, the P molecule is released. Shortening occurs when the myosin head springs from the cocked position and pulls the actin filament over it. After the actin has been moved, the ADP is released from the myosin head. ATP binds to cross-bridge. Cross-bridges break. Myosin heads are released from actin. The ATP molecule is then broken down into the ADP and P. The energy released allows the cocking of the head of the myosin molecule.

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3
Q

What are the characteristics of cardiac muscle?

A
  • Located only at the heart
  • Unique arrangement of thin and thick filaments into groups
  • Large, developed transverse tubules
  • Less developed sarcoplasmic reticulum
  • Self-exciting tissue – “Pacemaker” S.A. Node
  • Responsible for pumping blood
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4
Q

What are the similarities in all muscle types?

A
  • All are composed of muscle fibers - elongated fibers.
  • All muscle tissue is contractile Cell membrane is called the sarcolemma Cytoplasm is called sarcoplasm
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5
Q

Define neuromuscular junction, motor unit, motor end-plate, and neurotransmitter.

A

Neuromuscular Junction - the site where a motor neuron axon and a skeletal muscle fiber meet. (also called synapse or synaptic cleft) Motor Unit- is one motor neuron and the skeletal muscle fibers that it innervates (controls) Motor End-Plate - the specific part of a skeletal muscle fiber’s sarcolemma directly beneath the NMJ Neurotransmitter - chemical substance released from a motor end fiver, causing stimulation of sarcolemma of muscle fiber

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6
Q

What is muscle tone?

A

A continuous state of partial contraction

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7
Q

Define recruitment of motor neurons

A

The progressive activation of a muscle by successive recruitment of motor units to accomplish increasing gradations of contractile strength.

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8
Q

Discuss thick and thin filaments.

A
  • Thick filament (Myosin) - protein that terminates into a double globular head or cross bridge.
  • Thin (Actin) - coiled helical structures; the string is the fibrous strands and the beads are subunits of globular actin 2 protein:- Troponin & Tropomyosin
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9
Q

What are the muscles for the Quadriceps Femoris Group?

A
  • Rectus femoris
  • Vastus medialis
  • Vastus lateralis
  • Vastus intermedius
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10
Q

What is tetany?

A

Sustained contraction of muscle with no relaxation period (a cramp).

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11
Q

What are the three pathways in which ATP is regenerated?

A
  1. Coupled Reaction with Creatine Phosphate (CP)
  2. Anaerobic Cellular Respiration
  3. Aerobic Cellular Respiration
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12
Q

Define Tropomyosin and Troponin.

A
  • Tropomyosin - rod-shaped protein spiraling around actin backbone to stabilize it.
  • Troponin - complex of polypeptides Binds to actin, tropomyosin, calcium.
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13
Q

What is a myogram?

A

A recording of a muscle contraction

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14
Q

What is a latent period?

A

A small time delay between stimulation and contraction

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15
Q

List the types of filaments found in myofibrils.

A
  • Thick - composed of protein myosin.
  • Thin - composed predominantly of protein, actin.
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16
Q

List and define cardiac muscle, including control, number of nuclei, presence of striation, location and any unique characteristics

A

Control: Involuntary

Nucleation: Mono-nucleated

Stration: straited

Location: Heart

Characteristics: Contract rhythmically.

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17
Q

What is isometric contraction?

A

Muscle contraction in which muscle attachments do not move; “equal length.”

18
Q

What isoxygen debt?

A

The oxygen debt is the amount of oxygen necessary to:

  • Support the conversion of lactic acid to glucose (glycogen).
  • Restore ATP concentrations
  • Restore creatine phosphate concentrations
19
Q

What is summation?

A

Is a sustained contraction, due the combination of force from individual twitches

20
Q

What are the Muscles of Mastication?

A
  • Temporalis
  • Internal Pterygoid
  • Masseter
  • External Pterygoid
21
Q

What is isotonic contraction?

A

The muscle shortens and its attachments move; “equal force.”

22
Q

What is muscle fatigue?

A

A state of physiological inability to contract

23
Q

Define threshold stimulus for skeletal muscle

A

The minimal strength of stimulation required to cause a contraction, +30mV

24
Q

What are the characteristics of fast-twitch muscle fibers?

A
25
Q

What are the muscles of the Hamstring Group?

A
  • Semitendinosus
  • Semimembranosus
  • Biceps femoris
26
Q

List and define skeletal muscle including control, number of nuclei, presence of striation, location and any unique characteristics

A

Control: Voluntary

Nucleation: Multi-nucleated

Striation: Striated

Location: in muscles that attach to and over bones of the skeleton

Characteristics: Contract rapidly and vigorously; fatigue quickly; exert a large force.

27
Q

Define the structures of a sarcomere.

A
  • A-band - composed of overlapping thick and thin filaments.
  • I-band - composed of only thin filaments.
  • H- zone composed of only thick filaments.
  • Z- line - divides individual sarcomeres ^ site of thin filaments attachments
  • M- line - site of attachment for thick filaments.
28
Q

Discuss the role of calcium in muscle contraction.

A

In the absence of calcium, calcium ions are stored in the sarcoplasmic reticulum. Tropomyosin blocks the binding sites on actin from myosin cross-bridges. When calcium ions are present, calcium binds to troponin causing a conformational change in the troponin-complex - causes tropomyosin to rotate, opening binding sites on actin allow the myosin cross bridge to attach.

29
Q

What is a motor unit?

A

Motor unit is a single α-motor neuron and all of the corresponding muscle fibers it innervates

30
Q

What is the all-or-nothing response?

A

The process by which a muscle will contract. If a muscle fiber is brought to threshold potential or above, then the muscle fiber will contract, if the threshold potential is not met the muscle will not contract.

31
Q

Define threshold potential for skeletal muscle

A

A skeletal muscle fiber’s resting membrane potential must be depolarized from –100mV to –70mv before an impulse begins

32
Q

List and define smooth muscle, including control, number of nuclei, presence of striation, location and any unique characteristics

A

Control: Involuntary

Nucleation: Mono-Nucleated

Striation: lacks striation

Location: Found at the walls of hollow organs and blood vessels

Characteristics: Contractions are slow and sustained; does not fatigue easily.

33
Q

What are the muscle of the rotator cuff?

A
  • Supraspinatus
  • Infraspinatus
  • Subscapularis
  • Teres minor
34
Q

What is a twitch?

A

A single contraction followed by relaxation

35
Q

Discuss change during contraction.

A
  • Z lines move together.
  • I band become smaller
  • H zone become smaller (can disappear)
  • A bands move closer together but do not change size.
36
Q

What is a refractory period?

A

The needed to return the muscle fiber back to resting membrane potential

37
Q

Define “Sliding Filament Theory.”

A

Muscle contractions involved the sliding movement of the thin filaments past the thick filaments. Sliding continues until the overlapping between the thin and thick filaments is complete. (Filament size not changed)

38
Q

Define Contractile Proteins and Regulatory Protein.

A
  • Contractile Protein are involved in the shortening of the muscle fiber. Actin and Myosin.
  • Regulatory Protein regulate the contraction of a muscle fiber Troponin and Tropomyosin.
39
Q

How do both types of smooth muscle contract?

A

Multi-unit Smooth Muscle - Contraction is rapid and vigorous.

Visceral Smooth Muscle - Slow, sustained, rhythmic contractions.

40
Q

What is acetylcholinesterase and its function?

A

Acetylcholinesterase is an enzyme present in the neuromuscular junction and It immediately destroys acetylcholine, so the motor end-plate is no longer stimulated

41
Q

Define sarcolemma, transverse tubules, sarcoplasm, sarcoplasmic reticulum, and myofibrils.

A
  • Sarcolemma - cell membrane
  • Transverse tubules - are membranous tunnels running through the muscle fiber.
  • Sarcoplasm - cytoplasm Sarcoplasmic reticulum - smooth ER of the fiber; forms a membranous network around the myofibrils Myofibrils - form muscle fibers.
42
Q

What are the two types of smooth muscle and where are they found?

A
  • Multi-unit S.M. - irises of the eyes and walls of blood vessels.
  • Visceral S.M. - hollow organs (stomach, SI, LI)

A&P 1 - Test 4 (4 decks)

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