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EVERYTHING ELMHURST > Anatomy: Muscle Physiology > Flashcards

Anatomy: Muscle Physiology Flashcards

1
Q

What is Contractility?

A

Ability to contract; Proteins in the cell come closer together

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2
Q

What is Excitability?

A

The ability to respond to stimulus

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3
Q

What is Extensibility?

A

Ability to be stretched without breaking apart

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3
Q

What is Conductivity?

A

Ability to conduct electrical changes across entire plasma membrane

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4
Q

What is a Sarcomere?

A

basic structural and functional unit of muscle tissue. the repeating unit within a myofibril (thread-like structure in muscle fibers responsible for contraction).

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4
Q

What is Elasticity?

A

Ability to return to original shape & length after being stretched

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5
Q

What is a Myofibril?

A

Long (thread like), cylindrical structures found within muscle fibers (muscle cells) that plays a key role in muscle contraction.

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5
Q

What is Voltage in the context of Muscle Physiology?

A

Difference in charge ( potential ) between two points.
The electrical potential difference across the cell membrane of muscle fibers.

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6
Q

Muscle Contraction Phase: Excitation phase

A
  1. Nerve Signal: A nerve sends a signal to the muscle.
  2. Muscle Activation: This signal releases a chemical called acetylcholine (ACh), which activates the muscle fiber.
  3. Action Potential: The activation creates an electrical impulse (action potential) that spreads along the muscle’s surface.
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7
Q

Muscle Contraction Phase: Excitation-contraction phase

A
  1. Calcium Release: The action potential signals the muscle to release calcium from storage areas (sarcoplasmic reticulum).
  2. Preparing for Contraction: Calcium binds to proteins that move aside, exposing sites on the actin (thin filament) for myosin (thick filament) to attach.
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8
Q

Muscle Contraction Phase: Contraction phase

A
  1. Muscle Shortening: Myosin heads attach to actin and pull, causing the muscle to contract and shorten.
  2. Energy Use: The process needs energy from ATP to keep going and to release myosin from actin afterward.
  3. Relaxation: When the nerve signal stops, calcium is reabsorbed, and the muscle relaxes.
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9
Q

Describe the major functions of muscle tissue

A
  • Movement: Muscles enable body movement, including voluntary (skeletal) and involuntary (smooth and cardiac) actions.
  • Posture: Muscles help maintain posture and body position.
  • Joint Stability: Muscles stabilize joints during movement.
  • Heat Production: Muscle contractions generate heat, helping to maintain body temperature.
  • Circulation: Cardiac muscle pumps blood, while smooth muscle helps move blood through vessels.
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10
Q

Define the sliding filament theory of skeletal muscle contraction.

A

The sliding filament theory explains how muscle contraction occurs. It states that during contraction, thick (myosin) and thin (actin) filaments slide past each other, causing the sarcomere to shorten. Myosin heads attach to actin, pull it inward, and then detach, repeating this cycle.

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10
Q

Describe the sequence of events involved in the contraction of a skeletal muscle fiber.

A
  1. At the Neuromuscular Junction:
    A nerve signal reaches the end of a motor neuron.
    The neuron releases a chemical called acetylcholine (ACh) into the gap (synaptic cleft).
    ACh binds to receptors on the muscle fiber, creating an electrical signal (action potential) in the muscle.
  2. Excitation-Contraction Coupling:
    The action potential spreads along the muscle fiber’s surface and into the T-tubules.
    This signal causes the release of calcium from storage in the muscle (sarcoplasmic reticulum).
    Calcium binds to a protein (troponin), which moves another protein (tropomyosin) out of the way, exposing sites on actin for myosin to attach.
  3. Cross-Bridge Cycling:
    Myosin heads grab onto actin and pull it, causing contraction (power stroke).
    ATP attaches to myosin, helping it release from actin.
    The energy from ATP re-cocks the myosin head for another pull.
    This cycle continues as long as calcium and ATP are present.
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10
Q

Describe the arrangement & composition of the following components of a sarcomere: A-band, I-band, H-zone, Z-disc (line), and M-line.

A
  • A-band: The dark band that contains both thick myosin filaments and overlapping thin actin filaments. It’s where the muscle generates force.
  • I-band: The light band that contains only thin actin filaments. It appears lighter under a microscope.
  • H-zone: A lighter area within the A-band that contains only thick myosin filaments. It disappears during contraction.
  • Z-disc (line): The boundary of a sarcomere; it anchors the thin filaments and connects adjacent sarcomeres.
  • M-line: The middle of the H-zone; it anchors the thick myosin filaments.
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10
Q

What are the 3 parts of the Neuromuscular Junction?

A
  • Axon Terminal: The end of the motor neuron that releases acetylcholine (ACh).
  • Synaptic Cleft: The small gap between the axon terminal and the muscle fiber.
  • Motor End Plate: The specialized region of the muscle fiber membrane that contains ACh receptors.
11
Q

Describe the sources of ATP that muscle fibers use for skeletal muscle contraction.

A
  1. Creatine Phosphate: Provides a quick source of ATP through a simple reaction but lasts only for a few seconds.
  2. Glycolysis: Breaks down glucose anaerobically (without oxygen) to produce ATP; faster but less efficient and produces lactic acid.
  3. Oxidative Phosphorylation: Uses oxygen to produce ATP through the aerobic breakdown of glucose and fatty acids; it’s more efficient and provides energy for longer durations.
12
Q

What is a Fibrous (IMMOVABLE) Joint and what are some examples?

A

Structure: Connected by dense connective tissue.
Movement: Generally immovable
Function: Provide stability and protect internal structures, especially in the skull.

Ex: sutures in the skull

13
Q

What is a Cartilaginous Joint and what are some examples?

A

Structure: Connected by cartilage.
Movement: Slightly movable
Function: Absorb shock and allow for limited flexibility, aiding in stability and support.

Ex: intervertebral discs, growth plates

14
Q

What is a Synovial Joint and what are some examples?

A

Structure: Separated by a fluid-filled joint cavity.
Movement: Freely movable, allows for wide range of motion.
Function: Facilitate a wide range of motion and activities, allowing for dynamic movements in the body. (MOST COMMON JOINT)

Ex: Knee joint, elbow joint, shoulder joint, wrist joint, etc.

15
Q

What are the 3 types of Functional joints/class?

A

Synarthroses (Immovable Joints), Amphiarthroses (Slightly Movable Joints), Diarthroses (Freely Movable Joints)

16
Q

What are the 3 Types of Muscle & their functions?

A

Skeletal, Cardiac, Smooth

Skeletal: Long, CYLINDRICAL, and striated (striped) fibers. (MULTI-NUCLEATED)– MOVEMENT & STABILIZES JOINTS

Cardiac: Short, branched, STRIATED fibers; Wall around the heart. (UNI-NUCLEATED) – PUMPS BLOOD THROUGHOUT BODY

Smooth: Spindle-shaped, non-striated fibers; Wall around organs not including the heart. (UNI-NUCLEATED) – DIGESTION, AIR FLOW

17
Q

What is the function of the sarcoplasmic reticulum?

A

Stores calcium ions, Releases calcium into the cytoplasm, which triggers muscle contraction, then AFTER contraction, the SR Reabsorbs calcium ions, allowing the muscle to relax.

18
Q

What is the Endomysium?

A

Connective tissue surrounding individual muscle fibers.

19
Q

What is the Perimysium?

A

Connective tissue surrounding bundles (fascicles) of muscle fibers.

20
Q

What is the Epimysium?

A

Connective tissue surrounding the entire muscle.

21
Q

What are Motor Units?

A

Basic functional units of skeletal muscle. Unit that leads to movement.

22
Q

What is the Neuromuscular Junction?

A

A specialized synapse where a motor neuron communicates with a muscle fiber to initiate muscle contraction.

23
Q

What is an Action Potential?

A

An electrical impulse that stimulates muscle contraction

24
Q

What are T-Tubules (Transverse Tubules)?

A

Extensions of the muscle cell membrane that help transmit the action potential into the cell.

25
Q

Explain the process of Calcium Release

A

The action potential travels along the T-tubules, causing the sarcoplasmic reticulum to release Ca²⁺.

26
Q

Muscle Fibers: Type I

A
  • Aerobic, endurance-oriented.
  • Fatigue-resistant.
27
Q

Muscle Fibers: Type II

A
  • Type IIa: Intermediate, both aerobic and anaerobic.
  • Type IIb: Anaerobic, high power but fatigue quickly.
28
Q

What is Muscle Fatigue?

A

Decrease in ability to produce force due to accumulation of lactic acid, depletion of energy stores, or ion imbalances.

29
Q

What are the 3 kinds of Joints?

A

Fibrous, Synovial, and Cartilaginous joints

EVERYTHING ELMHURST (17 decks)

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