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uni > Unit 8 muscles > Flashcards

Unit 8 muscles Flashcards

1
Q

Cardiac muscle

A

In heart- involuntary
Muscle fibres are

branched and striated

One nucleus per fibre

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2
Q

Skeletal muscle

A

It is what attaches to bone (by tendons)

movement (controlled by somatic nervous system)

Striated, fibres are long cylinders multi nucleotide

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3
Q

Smooth muscle

A

Involuntary
No striations, one nucleus per fibre, fibre is spindle shaped

In arteries, veins, digestive system, etc

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4
Q

Attachment points of a muscle: origin and insertion

A

Origin: attached to fixed part of bone

Insertion: attached to bone that will move

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5
Q

Flexer vs extensor

A

Decrease angle between 2 bones

Increase angle between 2 bones

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6
Q

Agonist vs antagonists in muscle movement

A

Agonist= main mover/muscle doing the work

Antagonist= does opposite action (help keep position)

Ex bicep and tricep are antagonist muscle group since they have opposite actions (extension and flexor)

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7
Q

Skeletal muscle made up of

A

Many muscle fibre, inside muscle fibre are multiple myofibrils (long cylinders), and each myofibril has sections that repeat called sarcomeres (this is what makes it have striated look)

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8
Q

Sarcolemma, sarcoplasm, sarcoplasmic reticulum

A
  1. Muscle cell membrane
  2. Cytoplasm of muscle cell
  3. Extensive network of smooth Er of muscle cell
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9
Q

Transverse tubules (t-tubules)

A

Help transmit atp deep into muscle cells ensuring all sarcomeres receive the contraction signal

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10
Q

Triad

A

T-tubule along with 2 terminal cisternae on either side

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11
Q

What do muscle cells contain to support high atp demand

A

Numerous mitochondria and glycogen granules

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12
Q

Actin vs myosin

A

Actin=thin filaments
Myosin= thick filaments (golf club shape)

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13
Q

Myosin function and its important binding sites

A

Myosin head to form crossbridges between thick and thin filaments

Has actin binding site and myosin atpase binding site (to hydrolysis)

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14
Q

G-actin

A

Thin- globular shape but assembled into long chains

Functions in contraction and is the primary structural protein of thin filaments

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15
Q

Trypomyosin and troponin

A

Threadlike- regulates contractions of sarcomere. Blocks binding site of myosin (so no contraction- unless ca++ binds)

Set of more regulatory proteins
3 polypeptide units
One binds with actin, ca++, and tropomyosin

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16
Q

Z-lines

A

Where sarcomere ends and where thin filaments attach

17
Q

What shortens during muscle contraction

A

Sarcomere
-not myosin or actin (they overlap)

Z-lines move closer together

A band same
Hzone and i band shorten

18
Q

M-line

A

Thick filaments held together by accessory proteins called m-line

Center of A band
Does not change length during contraction

19
Q

Powerstroke

A

Myosin head bound to atp, hydrolyses it and turns it to pi and adp- myosin head can now bind to actin (crossbridge), powerstroke occurs which releases ado and pi and new atp binds to stop. Process repeats

20
Q

Titin (function and why important)

A

Large elastic protein
Joins m-line and z-line at opposite ends of sarcomere

  • stabalize position of thick and thin filaments
  • improves muscle elasticity (return to resting length after contraction)
21
Q

Nebulin

A

An aligning protein
Aligns actin chain

22
Q

Sarcomere divided into bands/zones: A-band

A

Contains both actin and myosin
Areas where actin and myosin overlap

Dark band= myosin

23
Q

Sarcomere divided into bands/zones: H zone

A

Contain only myosin

Light band at centre of A-band

As myosin and actin progressively get overlapped, h-zone disappears

24
Q

Sarcomere divided into bands/zones: i-band

A

Contain only actin
-Light band that spans 2 adjacent sarcomeres

-shortens during contraction

-z disk in centre of the i band

25
Q

Skeletal muscle: physiology

A

Controlled by nervous system

26
Q

Upper motor neuron vs lower motor neuron synapse w/

A
  1. Synapse on lower motor neuron
  2. Synapse on skeletal muscle cells
27
Q

Resting/relaxed muscle

A

Tropomyosin covers myosin binding site. No ca++ because…

Ap stop arriving at neuromuscular junction, ach on end plate broken down therefore ryanodine receptor channels close

28
Q

End plate potential

A

Impulse on nerve terminal causes release of ach which opens na+ channels causing depolarization (threashold reached- AP generated) leads to contraction of muscle

29
Q

How is ca++ released in order to form crossbridge

A

AP spreads from motor end and plate to all directions (same as ripples on pond)

Reach t-tubles and reaches down stimulates change in dhp receptor

Dhp touches ryanodine receptor (mechanical gated c++ channels) on the sr and opens it

Ca flows from sr into cytosol (down conc) and bind to troponin

30
Q

Rigor mortis

A

Stiffness of death
Ca still leaks out of SR . Since dead- no atp to stop crossbridge no detaching

uni (33 decks)

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