Test Muscle Physiology

What are the 7 functions of muscle

1. Body Movement
2. Maintain Posture
3. Respiration
4. Produce body heat
5. Communication
6. Construction of organs and vessels
7. Heart Beat

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==not that important to remember==

What are the 4 properties of muscles

Contractility, Excitability, Extensibility and Elasticity

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==Remember using CEEE==

What is ==contractility==?

ability to shorten when an adequate stimulus is received

What is ==excitability==?

ability to receive and respond to a stimulus

what is ==extensibility==?

ability to lengthen when an adequate stimulus is received

what is ==elasticity==?

ability to return to standard shape

What are the 3 muscle types?

Skeletal Muscles, Cardiac muscles and Smooth muscles

==Skeletal Muscles== location, function, nuclei type and appearance

1. Attached to bone
2. Body movement
3. Voluntary Control
4. Striated
5. Multinucleate

==Cardiac Muscle’s== location, function, nuclei type, and appearance

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1. Found in Heart
2. Involuntary Contraction
3. Single Nuclei
4. Intercalated disks
5. Circulate blood

==Smooth Muscle’s== location, function, nuclei type, and appearance

1. Found in blood vessels, glands, etc
2. Spindle Shaped
3. Single Nuclei
4. Involuntary contraction
5. No striations

Muscles can only ___(push/pull) and donot ___(push/pull)

pull; push. Just remember Muscles cannot push thats it

What are the 5 muscle components?

Muscle, Fascicle, Muscle Fiber, Myofibril and Myofilament

==Remember: (m, f, mf, m, mm)==

write the correct order from largest to smallest

muscle, fascicle, muscle fiber, myofibril, myofilament

(m, f , mf , m , m)

What is Action Potential?

rapid sequence of changes in the voltage across a membrane

What is resting state?

Cytosol (inside part of cell) has slightly negative charge.

Remember: Salty Banana (Na+ outside and K+ inside)

What is depolarization?

Influx of Na+ ions into neuron

What is repolarization?

attempt to restore. (K+ moves out, trying to balance contents inside cell)

What is Na+/ K+ pump?

Transports Na+ and K+ ions. Requires energy

Explain how Ach gets into synaptic cleft in Neuromuscular Junction

1. Action potential is sent along a neuron to axon terminal

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2. The AP causes Ca2+ channels to open and thus allowing calcium in

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3. Ca2+ causes vesicles containing the neurotransmitter Ach to fuse with the membrane of axon terminal and release Ach into synaptic cleft

Explain what happens after Ach reaches synaptic cleft in Neuromuscular Junction

4. Ach drifts through the synaptic cleft and binds with Na+ channels cuasing channels to open and allow Na+ to flow into cell and continue action potential

what does Achase does at Neuromuscular Junction

5. Once the Ap has continued the enzyme Achase will begin to breakdown excess Ach into components: acetic acid and choline

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6. Acetic acid is waste while choline is moved back into axon terminal where it combines with new acetic acid forming Ach. This new Ach will get stored in vescile

What is myofibrils composed of?

overlapping myofilaments called actin and myosin.

They slide over each other to contract the muscle fiber

What does sliding filament theory state?

Actin and myosin pull the z-line closer the M-line, shortening the length of the sarcomere

Explain Z-lines, I bands, Hzone and A bands?

Z-lines: ends of sarcomere

I bands: only contain thin filament (actin)

H zone: only thick filament (mysoin)

A band: center of sarcomere where think (myosin) and thin (actin) filaments overlap

Analogy to remember Sliding filament theory

Actin strands contain:

Troponin (Juliet’s dad, Lord capulet)

Tropomyosin (the door)

Active sites (Juliet)

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Myosin strands contain:

myosin heads (Romeo)

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Cacium Ca2+ (the donut)

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Romeo gives donut to the door and then door leaves, allowing Romeo to meet Juliet in Lord capulet’s castle

First 4 steps of Sliding Filament Theory (No need to memorize, just know Romeo’s Analogy)

1. Action potential along the sarcolemma travels through the T tubules causing the release of Ca2+ from sarcoplasmic reticulum

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2. Increase in calcium causes it to bind to troponin cuasing a conformational change (shape changes)

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3. This change is shape causes tropomyosin to move away from the active sites on actin exposing them

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4. The myosin head will bond with the active site on actin, forming a cross bridge and push the actin forward

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Last 8 steps of Sliding Filament Theory (No need to memorize, just know Romeo’s Analogy)

5. As ATP binds to myosin head, the head detaches from the actin

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6. The myosin head splits the ATP into ADP+P becomes re-energized and reorients

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7. Myosin head attaches to actin

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8. Myosin head rotates to the center of the sarcomere and pulls/pushes the actin to the center

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9. When the action potential ends, Ca2+ is reabsorbed via active transportation into the sarcoplasmic reticulum.

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10. As Ca2+ moves out of the sarcomere, it unbinds with troponin

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11. Without Ca2+, troponin moves the tropomyosin back into active sites

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12. Myosin moves back to starting position.

What is a muscle twitch?

a single contraction of a single muscle fiber in response to a single action potential. Can last 10 to 100ms

What are the three parts of muscle twitch?

1. Latent period (lag phase)
2. Contraction phase
3. Relaxation phase

What is latent period?

A short delay from the time AP reaches the muscle until the tension in the muscle.

What is the contraction phase?

cycling of cross-bridges (myosin and actin contractions)

What is relaxation phase?

Muscle return to normal length

What is Threshold stimulus?

Stimuli must meet a minimum threshold to produce a response

What is submaximal stimuli?

As stimulus continues (gets stronger) the more motor units that will be respond

What is motor unit?

Single motor neuron and all attached muscle fibers.

Remember:


1. Small = more coordinated but less power. Ex: hands
2. large = less coordinated but more power. Ex: legs

What is maximal threshold?

Maximum tension that can be achieved

What are supramaximal stimuli?

the continued stimulus at maximum tension will continue to have all motor units responding

Example: the sudden bursts of energy where you can push a car to protect something

What is the difference between incomplete tetanus and complete tetanus?

muscles take time to relax in between stimuli.


1. incomplete tetanus means muscles fibers may only partially relax
2. cmplete tetanus means signal reaching high frequency and making muscle fibers not relax at all

What are the 2 types of contractions?

Isometric and Isotonic.

Isotonic is further divided into Concentric and Eccentric

What is Isometric?

Same length but muscle tension changes.

Example: holding barbell, wall sits and planks

What is Isotonic?

Same muscle tone but muscle length changes.

What is concentric?

Muscle tension is generated as muscles shorten.

What is Eccentric?

Muscle tension is generated as muscle length

What are the 3 types of energy sources?

1. Creatine phosphate
2. Glycolysis (Anaerobic)
3. Cellular Respiration (Aerobic)

What is Creatine phosphate?

ADP reacting with creatine phosphate to produce ATP.

Occurs very quickly but can only provide energy about 10 seconds

What is Glycolysis (Anaerobic)?

Doesn’t require oxygen. Produces 2 ATP and 2 Lactic acid for every glucose.

Quick but only sustains for 1-3 minutes

What is Cellular Respiration (Aerobic)?

Requires oxygen. Most efficient with 38 ATP for 1 glucose.

Sustains longer (but slower) muscle contraction activity

What is Type I Fibers

Slow Twitch


1. Lots of Mitochondria
2. Depend of Cellular respiration for ATP
3. Resistant to Fatigue
4. Rich in myoglobin (red color, dark meat of turkey)
5. Activated by slow conduction, small diameter motor neurons
6. Dominant in muscles used for endurance and tonus. Ex: posture
7. Marathon / Cross Country runner’s

What is Type II Fibers

Fast twitch


1. Few Mitochondria
2. Rich in glycogen
3. Depend on creatine phosphate & glycongen for ATP
4. Fatigue easily with production of lactic acid
5. Low in myoglobin (white meat of turkey)
6. Activated by fast - conducting, large diameter motor neurons
7. Dominant in muscles used for rapid movement. Example: Eyes
8. Sprinters.

Congratulations, that’s the end of all terms.

make sure to practice using cfu’s and near pods.