Brainscape's Knowledge GenomeTM

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


See full index

An Sc 310 > Lec 13 - Muscles > Flashcards

Lec 13 - Muscles Flashcards

1
Q

what are the three types of muscle in the body

A

-skeletal, cardiac, smooth

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

what is a fascicle, what tissue is it surrounded by

A

-bundle of muscle fibres
-epimysium

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

what is a muscle fibre, what tissue is it surrounded by

A

-bundle of myofibrils
-epimysium

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

what is a myofibril, what tissue surrounds it

A

-bundle of filaments
-endomysium

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

what are the plasma membrane and cytoplasm called in muscle, are they single or multinucleated

A

-sarcolemma and sarcoplasm
-multi

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

what is the sarcoplasmic reticulum (SR)

A

-modified endoplasmic reticulum that surrounds each myofibril

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

what are the fxns of myofibrils, sarcoplasmic reticulum, mitochondria, T tubules in a muscle fiber

A

-myofibril: contractile structure
-sarcoplasmic reticulum: stores Ca2+
-mitochondria: energy
-transverse (T tubules): extensions of cell membrane, assoc w ends of sarcoplasmic reticulum

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

what are terminal cisternae

A

-enlarged end regions of the longitudinal tubules of the sarcoplasmic reticulum
-assoc w a network of transverse tubules (T tubules)

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

what helps the SR sequester Ca2+

A

Ca2+ ATPase

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

what do T tubules do

A

allow APs to move rapidly from cell surface to interior or fiber

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

what makes the striated appearance of skeletal and cardiac muscle

A

-myofibrils
-they are an arrangement of thick (myosin) and thin (actin) filaments that run parallel to long axis

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

what are sarcomeres, what are they formed by

A

-fundamental unit of myofibril
-formed by filaments

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

what are the proteins of myofibrils

A

-myosin (thick filaments)
-actin (thin filaments)
-tropomyosin and troponin (regulatory)
-titin and nebulin (accessory)

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

what is myosin

A

-motor protein that creates movement

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

what is actin

A

-protein that makes up thin filaments of muscle fiber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the 2 fxns of titin

A
  1. stabilize contractile filaments
  2. returns stretched muscle to resting length via its elasticity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is nebulin, what does it do

A

-inelastic giant protein that lies along thin filaments and attaches to Z disk
-helps align actin filaments of sarcomere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are the 5 components of a sarcomere

A
  1. Z disks
  2. I bands
  3. A band
  4. H zone
  5. M line
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are Z disks, what do they make up

A

-two Z disks and the filaments b/w them make up a sarcomere
-zigzag proteins
-attachment site for thin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are I bands, what filaments are found here

A

-lightest coloured bands of sarcomere
-only thin filaments found here

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is an A band, what filaments are found here

A

-darkest bands of sarcomere
-incl entire length of thick filament
-centre contains thick filaments only

22
Q

what is the H zone, what filaments are found here

A

-central region of A band, lighter than outer edges of A band
-thick filaments only

23
Q

what is the M line

A

-represents proteins that form the attachment site for thick filaments (like the Z disk for thin filaments)
-divides an A band in half

24
Q

each thin filament is surrounded by ___ thick filaments and ___ thin filaments encircle each thick filament

A

3,6

25
Q

what proteins ensure proper alignment in a sarcomere

A

-titin and nebulin

26
Q

how is the structure of actin formed

A

-G (globular) actin comes tgt to form a chain of F (filament) actin
-F actin strands forms dbl helix
-troponin and tropomyosin are attached

27
Q

is actin a contractile protein, what part of actin contains the binding site for myosin

A

-yes
-G actin

28
Q

what type of protein is tropomyosin, where is it found

A

-protein of muscle that forms a complex w troponin to regulate interaction of actin and myosin in muscle contraction
-overlaps myosin binding sites on actin

29
Q

what kind of protein is troponin, what three proteins is it made of, how does it ctrl skeletal muscle contraction

A

-regulatory
-TnI (attaches to actin, inhibitory)
-TnT (attaches to tropomyosin)
-TnC (binds Ca2+ reversibly)
-Ca2+ binding regulates muscle contraction

30
Q

why is myosin a dimer

A

-consists of two subunits

31
Q

what are myosin heads called, what do they do, what two binding sites do they have

A

-cross bridges
-bridge gap b/w thin and thick filaments
-actin binding site, ATPase site

32
Q

where are two myosin molecules joined tgt

A

at their tails, forming a bare zone

33
Q

where do the myosin heads and tail point to in a sarcomere

A

-tail toward M line
-head toward I band

34
Q

what is titin, what is it for

A

-elastic, long, accessory protein
-anchors thick filaments b/w M line and Z line
-structural support and elasticity

35
Q

what is nebulin, where is it attached, what does it do

A

-protein that lies along actin
-attaches to Z line disk but does not extend to M line
-regulates thin filament length during sarcomere assembly

36
Q

what is muscle contraction

A

-shortening of muscle

37
Q

what is the sliding filament theory of muscle contraction

A

-thick and thin filaments overlap
-neither filament shortens, but slide past each other
-only the muscle shortens

38
Q

what happens to the: A band, I band, H zone, sarcomere during the sliding of the filaments

A

-A band stays same length
-I band shortens
-H zone shortens
-sarcomere shortens

39
Q

what is the cross bridge cycle

A

-the sliding of filaments that is caused by cyclical formation and breaking of cross bridges

40
Q

describe the cross bridge cycle (5 steps)

A
  1. ATP binds to myosin head, myosin and actin dissociate from each other (released state, low energy)
  2. ATP hydrolyzed and myosin heads return to resting state (cocked state high energy)
    3.cross bridges form and myosin head binds to new position on actin (cross bridge state)
  3. P released, myosin heads change conformation and filaments slide past each other (power stroke stage)
  4. ATP released, filaments return to normal conformation but myosin is now attached to a diff part of actin than before (attached state)
    *cycle repeats
41
Q

how does the cross bridge cycle get its energy

A

-ATP hydrolysis

42
Q

what causes myosin heads to oscillate back and forth during the cross bridge cycle, what causes the high energy and low energy form of myosin

A

-conformational changes
-high: ADP and Pi bound to myosin so it has a high affinity for actin
-low: ATP bound to myosin so it has a low affinity for actin

43
Q

during the power stroke stage of the cross bridge cycle, what line does myosin push the thin filaments towards, what angles do the myosin heads bend at and what does it do

A

-M line in centre of muscle
-tilts from 90 to 45 degrees which causes thin and thick filaments to detach until myosin head returns to initial position

44
Q

why is asynchronous cycling important during muscle contraction

A

-to keep the cross bridge cycles of myosin out of sync w each other to never break complete contact b/w thin and thick filaments
-this is what continuously generates force in muscle contraction
-if contact was broken the muscle would not move

45
Q

what is excitation contraction coupling, what does it need

A

-sequence of events where an AP in sarcolemma causes contraction
-depends on neural input from motor neuron and requires Ca release from sarcoplasmic reticulum

46
Q

what happens when there is no Ca in the muscles for contraction

A

-troponin holds tropomyosin over myosin binding sites on actin
-no cross bridges b/w actin and myosin
-muscle relaxed

47
Q

what happens when Ca is present for muscle contraction

A

-Ca binds to troponin and causes movement of troponin which moves tropomyosin which exposes binding sites of myosin on actin
-cross bridges form b/w myosin and actin
-cycle occurs and muscle contracts

48
Q

what are the 6 steps of excitation contraction coupling

A
  1. AP in sarcolemma
  2. AP moves down T tubules
  3. DHP receptors of T tubules open Ca channels in lateral sacs of SR
  4. Ca increases in cytosol
  5. Ca binds to troponin which shifts tropomyosin
  6. cross bridge cycle occurs
49
Q

how is contraction terminated

A

-Ca must leave troponin to allow tropomyosin to cover myosin binding sites on actin

50
Q

how is Ca removed from the cytosol

A

-Ca2+ ATPase in SR pumps Ca from cytosol to SR

An Sc 310 (7 decks)

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