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Cell Physiology > Lectures 10-11 > Flashcards

Lectures 10-11 Flashcards

1
Q

What is flexion?

A

moves bones closer together

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2
Q

What is extension?

A

moves bones away from each other

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3
Q

How do skeletal muscle groups work in coordination?

A

one flexes limb or contracts | other = relaxes and extends

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4
Q

What is muscle fascicle?

A

bundle of muscle fibers

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5
Q

What is sarcolemma?

A

the covering of the muscle cell (cell membrane)

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6
Q

What is “sarco”?

A

prefix relating to muscle | flesh or muscular substance

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7
Q

What is “sarcoplasm”?

A

cytoplasm

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8
Q

What is sarcoplasmic reticulum?

A

modified endoplasmic reticulum in muscle fibers

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9
Q

What is the function of the sarcoplasmic reticulum?

A

store calcium (AKA: calcium stores)

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10
Q

What is the purpose of calcium in muscle cells?

A

signals for muscles to start contracting

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11
Q

What are the T-tubules?

A

continuation of the sarcolemma

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12
Q

What are the 4 functions of T-tubules?

A

brings APs into interior of muscle fiber | makes contact with individual units within muscle fiber | site of depolarization | responsible for Ca2+ release

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13
Q

Why is it important to increase the surface area within a muscle cell?

A

in order for all of the muscle fibers to exceed depolarization and be stimulated equally

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14
Q

What is a myofibril?

A

individual unit within muscle fiber

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15
Q

What is the functional unit of the muscle?

A

myofibril

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16
Q

What is the function of the myofibril?

A

contract/relax muscle when neuron sends a signal to the muscle fiber

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17
Q

What is the functional unit of the myofibril?

A

sarcomere

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18
Q

What components make up the sarcomere?

A

myosin | actin | M-line | Z-disk

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19
Q

How long is the sarcomere in length?

A

3 um

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20
Q

What is the M-line of the sarcomere?

A

mid-line

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21
Q

What is the Z-disk of the sarcomere?

A

ends of the sarcomere

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22
Q

What is the myosin of the sarcomere?

A

thick filaments

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23
Q

What are myosin heads of the thick filament?

A

hydrolyzes ATP and moves on actin to pull it closer (contraction) or further (relaxation)

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24
Q

What is actin?

A

thin filament

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25
When will the myofibril slide back and forth?
when the calcium is released from the sarcoplasmic reticulum
26
Why is it important for the sarcomere to have a lot of surface area?
need calcium release to be efficiently and generously throughout the cell as each one of the myosin heads depends on the calcium in order to function
27
What is titin?
elastic protein provides elasticity | joins Z-disk to thick filaments
28
What is nebulin?
inelastic protein | keeps actin aligned
29
What is G-actin?
individual globular actin protein
30
What is F-actin?
chain of actin molecules | filamentous actin
31
Why do skeletal muscle cells have a lot of mitochondria?
use and need a lot of energy
32
What molecule binds to the myosin heads?
ATP
33
What does "myo" mean?
fiber in the muscle
34
What are the parts of myosin?
2 tails intertwine | 2 protein chains per head (light chain and heavy chain)
35
What is the function of the myosin head heavy chain?
motor domain | binds ATP to actin | hydrolyzes ATP
36
What is the function of the myosin light chains?
regulatory and structural role
37
What is tropomyosin?
wraps around F-actin | blocks binding site on actin = doesn't allow myosin head to bind to actin
38
What is troponin?
within the F-actin, where calcium binds to
39
What are actin-myosin cross-bridges?
bridge between myosin binding to actin (basically myosin heads on actin)
40
What is muscle tension?
force created by muscles --> can provide support on your body
41
What does load mean?
weight or force that opposes contraction
42
What does relaxation mean?
release of tension created by contraction = stops contraction
43
What is the contraction-relaxation cycle?
switch between contraction and relaxation stages
44
What is excitation-contraction coupling?
coupling of the excitation of the muscle cell from the action potential which will contract the muscle
45
What is the relaxed state of actin-myosin?
myosin head cocked | tropomyosin partially blocks actin binding site
46
What are the motor neurons triggered by in order to send info to muscles?
CNS
47
What or where does the motor neuron innervate the muscle cell?
neuromuscular junction (NMJ)
48
What are DHP channels?
calcium channel
49
What is the DHP channel activated by?
depolarization wave on sarcolemma
50
What is the DHP channel tethered to and what is its role?
RyR channel | open up RyR channels
51
What is RyR channel?
ryanodine receptor channel located on sarcoplasmic reticulum
52
What is ligand binding to a receptor dependant on?
concentration of the ligand
53
What is the relationship between APs of the motor neuron and muscle fiber?
muscle cell depolarizes when the motor neuron repolarizes
54
What is the delay due to in the timing of the excitation-contraction coupling of skeletal muscle contraction
diffusion of Ca2+ from sarcoplasmic reticulum to the actin-myosin complex | cross-bridges have to form = all take time
55
What phase is the delay called?
latent phase
56
When does the relaxation phase begin?
when calcium is being taken back up
57
What is a phasic contraction? What is an example of one?
muscle = usually at rest | contracts only when it receives a stimulus | esophagus, peristalsis movement
58
What is a tonic contraction? What is an example of one?
muscle = always contracting | relaxes only when it receives a stimulus | sphincters to pee and poo // vascular smooth muscles constantly in contraction or relaxation phases
59
What are the 2 types of smooth muscles?
single-unit and multi-unit
60
What is single-unit smooth muscle? What is an example of one?
connected via gap junctions channels inserted into membrane = electrical continuity | excited together |. ie: small intestine
61
What is a multi-unit smooth muscle? What is an example of one?
individual connections, individual varicosities | excited individually | ie: eye
62
Order the three kinds of muscles from fastest to slowest in contraction speed.
skeletal >>> cardiac >>> smooth
63
What are the 2 differences in sarcomeres in smooth muscle cells from skeletal muscle cells?
no Z-disks, no lined-up sarcomeres | actin/myosin = aligned based on the shape of cell
64
What are dense bodies?
connects actin and myosin in smooth muscle cells
65
Why are there more myosin heads in smooth muscle cells than in skeletal muscle cells?
so that they can move more actin during cross-bridges
66
What does a phosphatase enzyme do?
dephosphorylate
67
What does autorhythmic mean?
does not need a signal to contract and function | can generate its own electrical activity
68
How many twitches would a normal supply of ATP sustain?
8
69
Which ATP-producing pathway is too slow to replenish ATP supply?
glycolysis
70
What molecule can be a substitute for ATP to provide energy?
phosphocreatine
71
What does phosphocreatine have that allows it to provide energy if broken?
high-energy phosphate bonds
72
What enzyme transfers a phosphate from phosphocreatine to ADP?
creatine kinase
73
What is twitch?
1 contraction/relaxation cycle
74
What characteristic of phosphocreatine allows it to be used as a diagnostic tool?
different isoforms of creatin between the three muscle types
75
What can high levels of creatine in circulation indicate? What molecule also escapes with creatin that can aid with the diagnosis if it is present at high levels in circulation?
indicates damage at that muscle type (such as cardiac) | troponin (also has different isoforms)
76
What is a Neuromuscular Junction?
specialized synapse between muscle cells and neurons
77
What is atrophy?
muscle cells start to die
78
In which muscles are nicotinic ACh receptors (NAChR) found?
skeletal muscles
79
In which muscles are muscarinic ACh receptors found?
smooth and cardiac muscles
80
What causes Myasthenia gravis?
loss of acetylcholine receptors
81
What is Myasthenia gravis?
autoimmune diseases attacking ACh receptors
82
What is a power stroke?
movement of myosin head pulling F-actin closer

Cell Physiology (13 decks)

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