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Physiology > Module 3 > Flashcards

Module 3 Flashcards

1
Q

What are the three basic types of muscle?

A

skeletal, cardiac, and smooth

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2
Q

What is the function of all muscles?

A

Provide some type of force

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3
Q

two primary contractile proteins in a sarcomere during muscle contraction

A

actin & myosin

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4
Q

Actin and Myosin slide past each other to 1. _________ the sarcomere which shortens the 2. ________ which will eventually shorten the entire 3. ________

A
  1. Shorten
  2. Muscle cell
  3. Muscle
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5
Q

1._______ and 2._______ themselves never shorten, they just slide 3. ________ into a more compact arrangement.

A
  1. Actin
  2. Myosin
  3. together
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6
Q

This process generates force so that muscles can pull on things (bones) and move them

A

Sliding Filament Model of Muscle Contraction

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7
Q

What triggers the opening of voltage-gated calcium ion channels in the axon terminal of the somatic motor neuron?

A

The change in voltage due to the action potential reaching the axon terminal

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8
Q

What is the role of calcium ions in the axon terminal of the somatic motor neuron?

A

triggers vesicles to undergo exocytosis.

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9
Q

What happens when ACh is released into the neuromuscular junction?

A

diffuses across the synapse and binds to ACh receptors on the motor end plate of the skeletal muscle cell.

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10
Q

Skeletal muscles
Function:
Attachment:

A

Function: the movement of bones (generate force along single axis)
Attachment: Connected to two bones by tendons (exceptions include some facial muscles, larynx, and sphincters)

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11
Q

How many vesicles of neurotransmitter (ACh) get exocytosed for every action potential

A

125 vesicles of neurotransmitter get exocytosed (three times as much as needed).

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12
Q

How are skeletal muscle fibers (cells) formed?

A

fusion of multiple myoblasts during development (they are long multinucleate cells)

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13
Q

Skeletal muscle is primarily controlled by which nervous system?

A

the somatic nervous system (under voluntary control)

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14
Q

Why does smooth muscle lack the striations found in cardiac and skeletal muscles?

A

because it lacks sacromeres

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15
Q

How are the thick and thin filaments in smooth muscle similar to those in skeletal muscle?

A

the thick and thin filaments are more or less parallel to each other.

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16
Q

Are smooth muscle contractions typically slower or faster than skeletal and cardiac muscle contractions?

A

Smooth muscle contractions are typically slower than skeletal and cardiac muscle contractions

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17
Q

What are the 3 roles of acetylcholinesterase?

A
  1. degrades the excess ACh,
  2. prevent continuous stimulation
  3. precise control of muscle contraction
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18
Q

What is the initial depolarization called when ACh binds to receptors on the motor end plate, and ligand-gated sodium ion channels open in the sarcolemma?

A

End Plate Potential (EPP).

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19
Q

What happens at threshold?

A

voltage-gated sodium ion channels open, allowing more sodium ions to enter the muscle cell, triggering an action potential.

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20
Q

Where is smooth muscle often found in the body & including what 6 organs?

A

often found in sheets surrounding hollow organs and tubes.
1. the stomach
2. intestines
3. urinary bladder
4. uterus
5. blood vessels
6. lungs

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21
Q

Where does the action potential travel after sweeping across the surface of the muscle cell?

A

T-tubules

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22
Q

What are the 2 roles of the T-tubules in muscle cell contraction?

A
  1. Transmit the action potential
  2. Coordination of muscle contraction.
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23
Q

Which nervous system primarily controls smooth muscle?

A

Involuntarily controlled by the autonomic nervous system

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24
Q

What triggers the opening of voltage-gated calcium ion channels in the sarcoplasmic reticulum (SR)?

A

The action potential

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25
Q

What is the result of the opening of voltage-gated calcium ion channels in the SR?

A

Calcium ions move down their electrochemical gradient from inside the SR to the cytoplasm, increasing the concentration of calcium ions in the cytoplasm and initiating muscle contraction.

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26
Q

In multi-unit smooth muscle, why must individual muscle cells be innervated independently?

A

They do not contain gap junctions

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27
Q

Why doesn’t single-unit smooth muscle need extensive ennervation to contract synchronously?

A

They are linked to other smooth muscle cells by gap junctions

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28
Q

What is the initial state of troponin and tropomyosin at rest?

A

troponin is in its normal configuration, allowing tropomyosin to physically block the myosin binding sites on the actin molecule.

29
Q

Where is cardiac muscle exclusively located in the body?

A

the heart

30
Q

What happens to troponin when calcium is released from the sarcoplasmic reticulum (SR)?

A

Calcium ions bind, causing it to change shape.

31
Q

What is the role of troponin ( not in normal configuration) in relation to tropomyosin and the myosin binding sites on actin?

A

drags tropomyosin off the myosin binding sites on the actin when it changes shape. (attached to tropomyosin)

32
Q

Is cardiac muscle striated?

A

Yes

33
Q

What triggers the release of ADP and Pi from the myosin head during muscle contraction?

A

The binding of myosin to actin

34
Q

What happens to the myosin head after the release of ADP and Pi?

A

moves into its low-energy form and pivots toward the middle of the sarcomere.

35
Q

Why are cardiac muscle cells branched?

A

to generate force in multiple directions.

36
Q

What is pacemaker activity in the context of cardiac muscle?

A

the ability of cardiac muscle to generate its own electrical signals, initiating contractions.

37
Q

What action of ADP and Pi opens up a binding site for a new ATP on the myosin head?

A

The detachment of ADP and Pi from the myosin head

38
Q

What happens when the new ATP binds to the myosin head?

A

It triggers a conformational change in the myosin, causing it to detach from the actin.

39
Q

What is the fate of ATP after it binds to the myosin head and the myosin detaches from actin?

A

ATP is hydrolyzed into ADP and Pi, which stay bound to the myosin head.

40
Q

How is the energy released from ATP hydrolysis utilized by the myosin head?

A

The energy is captured by the myosin head, triggering it to move back into its high-energy (recocked) form.

41
Q

Cardiac muscle is considered to be myogenic, describe myogenic?

A

signals that initiate contraction originate within the heart itself

42
Q

What is the overall process of myosin binding and unbinding to actin called?

A

cross-bridge cycle.

43
Q

Cardiac muscle is regulated primarily by what system?

A

the autonomic nervous system (under involuntary control)

44
Q

What condition determines how long muscle contraction will continue?

A

The ceasing of action potentials from the somatic motor neuron.

45
Q

Define muscle

A

collection of muscle cells

46
Q

Define fassicle

A

bundles of muscle cells together with their associated connective tissue, blood vessels, and nerve cells within a muscle

47
Q

Single muscle cell, fusion of multiple myoblasts during development; these are excitable cells

A

Muscle fiber (myofiber)

48
Q

Define Sarcolemma

A

muscle fiber’s plasma membrane

49
Q

What 2 things happens when a somatic motor neuron stops sending action potentials?

A

Action potentials cease and calcium voltage-gated channels in the sarcoplasmic reticulum (SR) close.

50
Q

Define Sarcoplasm

A

Semifluid cytoplasm of a muscle cell

51
Q

How do calcium ions return to the SR after the cessation of action potentials?

A

Calcium pumps transport calcium ions back into the SR, decreasing the cytoplasmic calcium concentration.

52
Q

What is the result of the decreasing concentration of calcium ions in the cytoplasm?

A

they detach from troponin

53
Q

What does troponin do after calcium ions detach from it?

A

moves back into its original configuration.

54
Q

Rod-like bundle that contains the contractile machinery (actin and myosin), runs along length of muscle fiber

A

Myofibril

55
Q

What is the role of tropomyosin in muscle relaxation?

A

Tropomyosin blocks the binding of myosin sites

56
Q

saclike membranous network that surrounds myofibrils and releases calcium ions to trigger muscle contractions

A

Sarcoplasmic reticulum

57
Q

Fundamental functional unit of contraction found in myofibrils that repeats over and over; bordered on each side by Z-lines (protein that runs perpendicular to the muscle axis) which anchor actin during contraction

A

Sacromere

58
Q

Thin filaments= ____+ _____+ _____

A

actin (contractile protein) + troponin + tropomyosin

59
Q

1._________ is formed from a double chain of globular proteins that is wound with 2.____________(a fibrous molecule) to form a strand; 3. __________ (a globular complex of three proteins) holds tropomyosin to actin

A
  1. Actin
  2. tropomyosin
  3. troponin
60
Q
  1. ______ _______: formed from hundreds of myosin molecules
  2. __________is formed from 3. ______ filamentous protein tails and two 4. ___________ heads
A
  1. Thick Filaments
  2. myosin
  3. two
  4. globular
61
Q

Proteins for actin attachment

A

Z Line

62
Q

S= Skeletal S1= Smooth (single-unit) S2= Smooth (multi-unit) C= Cardiac
Determine which types of muscles have the following porperties?
1. Striations?
2. Actin and myosin
3. gap junctions?
4. peacemaker activity?
5. Recruitment?

A

S= Skeletal S1= Smooth (single-unit) S2= Smooth (multi-unit) C= Cardiac
Determine which types of muscles have the following porperties?
1. Striations?
- S, C
2. Actin and myosin?
- All muscle types
3. gap junctions?
- S1, C
4. peacemaker activity?
- S1, C
5. Recruitment?
-S, S2

63
Q

Determine whether the level of control is voluntary (V) or involuntary(I) for each muscle type
1. _____ Skeletal
2. _____ Smooth (single-unit)
3. ______Smooth (multi-unit)
4. ______Cardiac

A

Determine whether the level of control is voluntary (V) or involuntary(I) for each muscle type
1. __V___ Skeletal
2. ___I__ Smooth (single-unit)
3. ___I___Smooth (multi-unit)
4. ___I___Cardiac

64
Q

Varicosities-diffuse is the neuroeffector junction for all of the muscle types except?

A

Skeletal (neuromuscular junction-specific)

65
Q

All of the basic muscle types have hormonal control except?

A

Skeletal

66
Q

T/F sarcoplasmic reticulum and extracellular fluid is the source of calcium for all muscle types?

A

False, SR is the only source of calcium for skeletal muscle

67
Q

What regulatory protein binds calcium in skelatal and cardiac muscle? Smooth muscle?

A

Troponin in skeletal and cardiac muscle, calmodulin in smooth muscle

68
Q

Myosin ATPase activity is the fastest in what type of muscle and slowest in what type of muscle?

A

It is fastest in skeletal, intermediate in cardiac, slowest in smooth muscle.

Physiology (10 decks)

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