Brainscape's Knowledge GenomeTM

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


See full index

physiology IV > Excitation Contraction Coupling > Flashcards

Excitation Contraction Coupling Flashcards

1
Q

How does the NEURONAL AP travel down the motor neuron?

A

In a saltatory fashion

-skips over nodes of ranvier

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

What occurs once the neuronal AP reaches the bouton?

A

It depolarizes the bouton

  • Voltage gated ca2+ channels in the plasma membrane open
  • ca2+ rushes into the bouton
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is caused by an elevated level of ca2+ in the bouton?

A

Vesicles of ACh fuse with the membrane

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

After ACh is dumped into the synaptic terminal, what channels are able to open?

A

ACh binds to receptors on MUSCLE –motor end plate

-allows Na+ to rush in and depolarize

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

The rushing in of Na+ ions at the motor endplate creates what?

A
  • an Endplate action potential

- propagates along the muscle fiber

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

What is the result of the endplate potential?

A

-nearby voltage gated Na+ in MUSCLE membrane open leading to a MUSCLE AP

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

What inactivates ACh in the synaptic cleft?

A

Acetylcholinesterase on the motor end plate

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

What is myasthenia gravis?

A

Antibodies created to nicotinic ACh receptors at the neuromuscular junction

  • muscle fatigability
  • reduced excitation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are some possible sites for blocking neuromuscular transmission in skeletal muscle?

A 
Nerves
1. Motor neuron disease 
2. Demyelinating disease 
Muscle
1. Neuromuscular junction disease 
2. Muscle disease 
3. Sarcomere disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is ALS?

A
  • Motor neuron death in the spinal cord
  • loss of neuronal action potential
  • reduced excitation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is guillan barre syndrome?

A

autoimmune response against myelin

  • impaired neuronal AP
  • reduced excitation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is muscular dystrophy?

A
  • reduced attachment of muscle to ensheathing membrane

- reduced contraction

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

What is malignant hyperthermia?

A
  • Mutation in Ryr1 - excessive ca2+ release in muscle
  • triggered by inhaled anesthetics
  • excessive contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What occurs as the muscle action potential travels down the T-tubules?

A
  • opens ca2+ channels -ryanodine receptors in SR

- Ca2+ floods sarcoplasm

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

Can skeletal muscle contract in the absence of calcium extracellularly?

A

YES - calcium comes from the SR in muscle contraction (cycling is intracellular)

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

What is calcium’s role in the sarcoplasm?

A

It allows actin to interact with myosin cross-bridges – development of tension

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

What is the skeletal muscle triad?

A

1-Tubule surrounded by 2 sarcoplasmic reticulum cisternae

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

How are the tubules and cisternae attached?

A
  • Direct coupling
  • L type ca2+ channels in T tubule
  • Ryanodine receptors in cisternae of SR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the three steps of ca2+ release at the skeletal muscle triad?

A
  1. Membrane depolarization opens L-type ca2+ channel or DHP receptors (t-tub)
  2. Coupling causes ca2+ release channel in SR to open (ryanodine receptors)
  3. Ca2+ exits SR and activates troponin C → muscle contraction
20
Q

What is calcium induced calcium release?

A

In addition to being stimulated by DHP receptors, ryanodine receptors are also triggered by the presence of ca2+ in the cytoplasm (released by other ryanodine receptors)

21
Q

What is the major mechanism of skeletal muscle relaxation?

A

SERCA pumps

-hydrolyze ATP to pump ca2+ into SR

22
Q

What are the two minor methods of skeletal muscle relaxation?

A
  • PMCA - pumps 1 ca2+ out of cell in exchange for 1 ATP

- NCX - Lets 3 Na2+ into cell to pump 1 ca2+ out of the cell

23
Q

What is the temporal relationship between AP, ca2+ release and tension in skeletal muscle?

A
  • NA+ dependent AP is <5 msec - rapid
  • triggers transient inc in ca2+
  • leads to slower development of tension
24
Q

What is the result of a single action potential?

A

-twitch

25
Q

What is the result of high frequency APs with oscillation?

A

-Unfused tetanus

26
Q

What is the result of high frequency APs without oscillation?

A

-Fused tetanus

27
Q

What is the term for an increase in muscle tension from successive action potentials?

A

Summation

28
Q

What is the term for mantained contraction in response to repetitive stimulation?

A

Tetanus

29
Q

What two things control the strength of contraction in skeletal muscle?

A

1) rate coding - frequency of stimulation

2) recruitment of additional motor units

30
Q

What is treppe?

A

The steady increase in tension in successive twitches

31
Q

Is treppe the same thing as summation?

A

NO - each twitch relaxes to zero tension before the next twitch initiates

32
Q

How does treppe occur?

A
  • repeated stimulation of the muscle at low frequency
  • ca2+ release from previous twitches exceeds ca2+ uptake
  • Increases the number of crossbridges formed
  • May warm up the muscle - inc enzymatic rate
33
Q

What is a motor unit?

A

A somatic motor neuron and all the myofibers it innervates

34
Q

Why is tetanus able to occur?

A

the functional refractory period of the AP in a twitch is much shorter than contraction time

35
Q

How does recruitment occur?

A

Large motor units are recruited after small

-as more force is required

36
Q

What is involved in fine motor control?

A

Small motor units

37
Q

What is the energy source of slow twitch fibers?

A

Oxidative

38
Q

What is the energy source of Fast twitch type IIa fibers?

A

Oxidative

39
Q

What is the energy source of fast twitch type IIb fibers?

A

Glycolytic (anaerobic metabolism of glucose)

40
Q

List in order the energy sources for contraction (5)

A
  1. ATP
  2. Phosphocreatine
  3. Anaerobic metabolism of glucose
  4. Oxidative metabolism of glucose
  5. Oxidative metabolism of fats, carbs, proteins
41
Q

What is muscle pain or burn?

A

Lactic acid build up

-anaerobic glycolysis (Fast twitch IIb)

42
Q

What is Delayed onset muscle soreness?

A
  • not correlated with lactic acid

- muscle damage, inflammatory response

43
Q

What is Muscle Fatigue

A

-decline in muscle tension as result of previous contractile activity

  • dec shortening velocity
  • slower rate or relaxation
44
Q

What causes muscle fatigue? Is there a correlation with ATP?

A

build up of lactic acid and inorganic phosphates

-NOT due to low ATP (has high levels)

45
Q

What is high frequency fatigue?

A
  • high intensity, short duration exercises
  • failure of AP to conduct down T-tubule
  • fast recovery
46
Q

What is low frequency fatigue?

A
  • Low intensity, long duration exercises
  • build up of lactic acid and phosphates
  • changes the conformation of muscle proteins
  • slow recovery

physiology IV (40 decks)

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