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Mam phys > Slide set 5 - Chapter 12: Skeletal muscles > Flashcards

Slide set 5 - Chapter 12: Skeletal muscles Flashcards

1
Q

What are the 3 different types of muscles?

A
  • Skeletal
  • Smooth
  • Cardiac
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2
Q

What are 3 types of skeletal muscle groups (based on their contraction), and what action does it do on the bone?

A
  • Flexors : brings bone together
  • Extensor: moves bones away
  • Antagonistic muscle groups: flexor-enxtensor pairs
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3
Q

What are the connective tissue component of the skeletal muscle structure? Where are they situated?

A
  • Epimysium: coarse sheath covering the muscle as a whole
  • Perimysium: Though connective tissue binding together fascicles
  • Endomysium: connective tissue membrane that covers skeletal muscle fibers
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4
Q

What are the parts of muscle (from small to big…) (ce qui s’emboîte genre)

A
  • Myofibrils
  • Muscle fibers in…
  • Fascicles in…
  • Muscle
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5
Q

In the muscle, the thick filaments are ______ and the thin filaments are ______

A

myasin (thick)

actin (thin )

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6
Q

How do you call muscle cells? what are some characteristics?

A 
Muscles cells are called FIBERS
- Fiber threadlike shape
- Cell fusion during development 
- Contain a lot of mitochondria
- Contain several nuclei 
-
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7
Q

Skeletal muscle fibers have the same structural parts as other cells BUT they have different name for these structures. What are the names, and what cell structure do they replace

A

Sarcolemma–> Plasma membrane of muscle fibers

Sarcoplastic reticulum (SR) -> type of smooth endoplastic reticulum

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8
Q

What are characteristics of sarcoplastic reticulum?

A
  • Network of sacs and tubules found within muscle fibers

- Plays a role in Ca+ regulation during contraction (unique to muscle, calcium is essential in contraction)

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9
Q

What are structures unique to skeletal muslce?

A
  • T tubule

- Triade

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10
Q

What is T tubule in skeletal muscle ? What is its function?

A
  • It extends across the cell
  • They are formed from inward extension of the sarcolemma

FUNCTION:

  • Chief function is to allow electrical signals traveling along the sarcolemma to move deeper into the cell
  • Requirement for contraction
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11
Q

What is the triad (part of muscle cells), what is its function?

A
  • Formed from a triplet of tubules made of the sarcoplasmic reticulum which surrounds the T-tubule
  • Arrangement allows a signal traveling along the T-tubule to stimulate adjacent membranes on sarcoplasmic reticulum
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12
Q

What is a sarcomere?

A

Segment of myofibril between two successive Z lines

Contractile unit of muscle fibers

Each myofibril consist of many sarcomere

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13
Q

When does the A band occur?

A

When thick and thin microfilament overlap!

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14
Q

What kind of neurons signals skeletal muscle? Can a muscle be stimulated by hormone?

A

motor neuron

Skeletal muscle cannot be stimulated by hormone

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15
Q

What type of muscle can be stimulated through endocrine or paracrine factor?

A

Smooth muscle

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16
Q

What compose the thin filaments?

A
  • Actin
  • Troponin
  • Tropomyosin
17
Q

What compose the thick filaments?

A
  • Myosin
18
Q

What are the 4 types of prots that make up myofilaments?

A

Myosin, actin, troponin, tropomyosin

19
Q

What is the role/characteristics of myosin?

A
  • Makes up almost all the thick filament
  • Thick filaments do not attach to Z lines (thick= in the middle of sarcomere)
  • Has myosin head
20
Q

What is the role/characteristics of actin ?

A

Actin is a globular protein that forms 2 fibrous strands that twists around each other to form bulk of thin filaments

21
Q

What is the role/characteristics of tropomyosin

A

protein that blocks the active sites on actin molecules, so that myosin can’t bind- Myosin can only bind when there is calcium, so when no calcium, tropomyosin binds

22
Q

What is the role/characteristic of troponin ?

A

Protein that holds tropomyosin molecules in place

23
Q

_(thin or thick)_____ filaments attach to both Z lines of a sarcomere

A

Thin filaments

24
Q

What is a neuromuscular junction?

A
  • It is a synapse where neurotransmitter molecules transmit signals
25
Q

Where do the muscle and motor neuron connect?

A

Connect to sarcolemma at the motor endplate (where the motor neuron makes contact)

26
Q

What type of receptor is there on the motor endplate?

A

Ach receptors, because calcium needed for Ach to be released

27
Q

What are the steps of the mechanism of contraction?

A
  • Initiation: Action potential traveling down motor neuron to reach neuromuscular junction
  • Motor neuro releases ACETYLCHOLINE (ACh)
  • ACh binds with receptors on the muscle fiber and depolarizes the cytoplasmic membrane of the muscle fiber (sarcolemma)
  • Action potential travels down the inward projecting T-tubules thant reach deep into the muscle fiber
  • Voltage change triggers opening of the voltage gated Ca 2+ channels
  • This allows passive diffusion of the Ca 2+ out of the SR where it triggers the contraction process
28
Q

What is the effect of calcium release in skeletal muscle contraction (on actin/myosin more specifically…)?

A
  • Calcium will bind to troponin, allowing actin-myosin binding
  • Myosin heads execute power stroke
  • Actin filament slides toward center of sarcomere
29
Q

How does calcium allow myosin and actin to bind?

A

Calcium ions will bind to the troponin of the thin filament, allowing tropomyosin to shift and expose the active actin sites on the thin filament

Myosin of thick filament will then bind to active site of actin

30
Q

What does binding of myosin do by binding to actin?

A

Binding of myosin triggers ATP hydrolysis to ADP and P.

Energy of broken bond transferred to myosin

RElease of stored energy provides the force needed for the head to move back to its original position

31
Q

What happens after contraction? What is done with calcium?

A

Relaxation

Immediately after Calcium ions are released, sarcoplasmic reticulum begins actively pumping them back into sacs

Calcium ions are removed from troponin molecules on thin filaments, shutting down contraction

Mam phys (11 decks)

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