Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL 155 MIDTERM > Muscles > Flashcards

Muscles Flashcards

1
Q

What subtype of muscle is the skeletal muscle?

A

Striated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How are skeletal muscles organized?

A
  • Epimysium (dense irregular connective) surrounds the perimysium, blood vessels and nerves
  • perimysium surrounds each fascicle (dense elastic connective tissue)
  • each fascicle has 20-60 muscle fibres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How are myofibers organized?

A

Endomysium surrounds myofibrils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are myosatellite cells?

A

Cells that help repair damaged myofibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do myofibres produce multiple nuclei?

A

Many myoblasts fuse together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the descending order of muscle organization?

A

Epimysium>perimysium>endomysium>

Muscle>fascicle>myofibre>myofibril

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the names for the muscles’ plasma membrane, endoplasmic reticulum, and cytoplasm

A

Sarcolemma, sarcoplasmic reticulum, sarcoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What two structures do the T-tubules connect?

A

Sarcolemma and sarcoplasmic reticulum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where do motor neurons contact myofibres?

A

NMJ (motor end plate + synaptic cleft + axon terminal)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the transmembrane potential of a myofibre at rest?

A

Slightly more negative on the inside of the sarcolemma than outside (-85mV)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the concentrations of sodium, potassium and calcium, large anions and chloride inside and outside the cell?

A

Na: ICF=12 ECF= 145 (more + outside the cell)
K: ICF= 139 ECF= 4 (more + inside the cell)
Cl-: ICF=4 ECF=120 (more - outside the cell)
A-: ICF=140 ECF= 0 (more negative inside the cell)
Ca2+: ICF=0.0002 ECF= 1.8 (more positive outside the cell)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

At rest, which ion can move through ion channels?

A

Potassium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What do motor neurons release?

A

Neurotransmitter (ACh) that allows the sodium ions into the myofibre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What kind of receptors are ACh receptors?

A

ligand-gated ion channels—only lets in ions if ach is bound to outer surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the steps of muscle cell excitation?

A
  1. Electrical activity in the motor neuron triggers release of vescicles containing NT into synaptic cleft
  2. NT binds to the receptor proteins, which open and allow Na+ into the cell
  3. Enzymes in the extracellular space (AChE) get rid of the neurotransmitter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the effect of Curare (interferes with ACh binding to the ACh receptors)?
What its the effect of novichok (blocks enzyme that breaks down ACh in the synaptic cleft)?

A

Curare: flaccid paralysis because muscle cannot depolarize
Novichok: rigid paralysis: causes spasms/seizures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does depolarization spread through the NMJ?

A

By electro tonic current

18
Q

What does the spread of depolarization of the motor neuron trigger? What does this do?

A

Voltage gated sodium channels, enhances depolarization

19
Q

What structure brings the plasma membrane action potential into the vicinity of the sarcoplasmic reticulum? What does this do?

A

T-tubule; triggers release of calcium ions in the sarcoplasmic reticulum

20
Q

What proteins are involved in transducing the electrical signal into the release of stored Ca2+ from the sarcoplasmic reticulum?

A

DHPR: dihydropyridine receptor changes its shape
RyR: ryanodine receptor: reacts to the movement of the DHPR by opening an ion channel to let calcium flow

21
Q

How can targeted electrical stimulation make your muscles contract? Why does this increase muscle mass?

A
  • the electrical signal is hitting the nerve
  • work causes microtears and doing more work creates signals for muscle fibrils to grow width wise and get more myosatellite cells
22
Q

What are thin filaments connected by and what is it made out of?

A

The Z line; actinin

23
Q

What is the thin filament made out of?

A

F-actin: twisted strand of G-actin
Nebulin: a protein that extends along the F-actin strand in the cleft— holds together
Tropomyosin: double-stranded molecule that is bound to troponin
Troponin: three globular subunits

24
Q

What is the function of tropomyosin?

A

Covers the active sites of G-actin

25
Q

What are the functions of the three troponin subunits?

A
  1. One subunit binds to tropomyosin
  2. One subunit binds to actin
  3. One subunit binds to 2 calcium ions
26
Q

What is the structure of the thick filaments?

A

Myosin molecules, each made of myosin subunits twisted around each other

27
Q

What is the sliding filament theory?

A

1) H bands and I bands get smaller
2) the zones of overlap and get larger
3) Z-lines move closer together
4) width of A bands remain constant

28
Q

Where are the H, I and A bands?

A

H: the middle section of the thick filaments
A: entire thick filament, including zone of overlap
I: thin filament region

29
Q

Where does a sarcomere begin and end?

A

From one Z line to the next Z line

30
Q

During contraction, what gets shorter?

A

The sarcomere

31
Q

The thin filament is made out of ________ and the thick filament is made out of ___________

A

Actin, myosin

32
Q

What structure attaches the thick filament to the Z-line?

A

Titin, a large elastic protein

33
Q

What does calcium bind to that allows the myosin to bind to actin?

A

Calcium binds to troponin and reveals the binding site on the G-actin

34
Q

What are the steps of the power stroke?

A
  1. Myosin binds to binding site on actin, neck changes conformation
  2. ATP breaks the bond by binding to myosin neck
  3. After myosin detaches, ATP is hydrolyzed and the neck position is reset
35
Q

What would happen if a muscle fibre ran out of ATP?

A
  • calcium would build up in the sarcoplasm because ATP is needed to operate Ion pumps that remove Ca2+
  • myosin heads would not be able to reset
36
Q

What determines the amount of tension produced by a muscle?

A
  • The number of myosin heads that are able to bind to actin in a contraction cycle
  • the number of fascicles in the muscle
37
Q

What are the three phases of a single muscle “twitch” contraction

A

1) latent period: time it takes for excitation of MN to release ACh, trigger AP and spread to T tubules
2) contraction phase: increasing tension during contraction is due to Ca build up
3) relaxation: decrease in tension during the relaxation phase is due to Ca being removed from the sarcoplasm

38
Q

What is a motor unit?

A

The motor neuron and ALL the muscle fibres it contacts

39
Q

How many NMJ’s does each muscle fibre have?

A

One

40
Q

What is asynchronous recruitment?

A

Skeletal muscle contraction must be maintained for an extended period of time, motor units rotate so that each unit is only active part of the time

BIOL 155 MIDTERM (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions