Brainscape's Knowledge GenomeTM

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


See full index

PHY 503 MODULE 4.1 > Module 6.1-6.6 > Flashcards

Module 6.1-6.6 Flashcards

1
Q

what are the steps (1-7) of acetylcholine release at the neuromuscular junction.

A
  1. Action potential arrives at an axon terminal
  2. Voltage-gated calcium channels open
  3. Calcium initiates vesicular fusion
  4. ACh is released
  5. AChR is bound by its agonist
  6. Ligand-gated sodium channels open in bottom of sub neural cleft
  7. An end-plate potential is generated and reaches threshold
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

END-PLATE POTENTIAL (EPP)

A
  • EPP would become smaller and slower with distance from the endplate and would spread in both directions if the stimulus were applied to the middle of the fiber
  • The muscle is treated with curare to limit Ach receptor activation to subthreshold responses.
  • The delay in response is a function of acetylcholine release, diffusion, and activation of postsynaptic receptors.
  • The delay in response time increases as a function of the distance from the end plate.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

True/False: Ach Release-details:Ca2+ channels are localized around linear structures on the presynaptic membrane called dense bars.

A

True

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

TRUE/FALSE :Extracellular magnesium interferes with the ability to generate an end-plate potential by preventing calcium from entering into the muscle fiber to stimulate contraction.

A

False:The magnesium does interfere with the generation of an end-plate potential, resulting in a lower EPP voltage. But, this EPP effect on the muscle is because there is less calcium entering the neuron, not the muscle itself. With less calcium entering the presynaptic motor neuron, there is less transmitter being released into the neuromuscular junction, which means less engagement with transmitter receptors on the postjunctional muscle fiber and thus a lower EPP voltage.

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

prevent the release by blocking voltage gated sodium channels, prohibiting the generation of action potentials.

A

Tetrodotoxin and Saxitoxin (anatognist)

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

produce by mamba snakes)- block presynaptic potassium channels, and inhibits membrane repolarization, which prolongs the duration of the action potential and facilitates transmitter release due to the extra calcium influx at the nerve terminal.

A

Dendrotoxin (anatognist)

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

produced by mollusks and block specific isoforms of voltage gated calcium channels at the frog neuromuscular junction. Virtually irreversible and inhibits transmitter release, abolishing muscle end plate potentials when stimulated through the nerve.

A

Omega Conotoxins:

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

Curare and aplpha-bungarotoxin:

A

both block the nicotinic acetylcholine receptor, but differ in mechanism. Curare blockage is reversible, whereas alpha-bungarotoxin is not.

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

Is Tetanus acetylcholine?

A

No

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

True/False: Omega-conotoxin will prevent an end-plate potential by binding and inactivating AChR channels.

A

False:Omega-conotoxins block isoforms of neuronal voltage-gated calcium channels

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

TRUE/FALSE: Botox causes flaccid paralysis by preventing ACh release.

A

TRUE: Botox is a purified form of C. botulinum, which functions to inhibit the release of acetylcholine from motor neuron

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

TRUE/FALSE: Tetrodotoxin can bind to Na+ channels on both sides of the motor end-plate.

A

TRUE

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

Curariform drugs (D-tubocurarine)

A
  • Block nicotinic Ach channels by competing for Ach binding site
  • Reduces EPP amplitude therefore, no AP
    Curare is a natural muscle relaxant and chemical compound
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Botulinum toxin

A
  • Decreases the release of Ach from the nerve terminals.
  • Insufficient stimulus to initiate an AP
    medication used to manage and treat therapeutic and cosmetic purposes.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

True/False: Calcium levels in the myoplasm remain at their peak for the duration of the muscle contraction

A

False: Myoplasmic calcium levels are already tapering off as muscle tension is reaching its peak, and they return to resting levels before tension has returned to rest.

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

Isometric contractions:

A

Contraction that occur at a constant length.

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

Isotonic contraction:

A

muscle shortening occurs at the constant load.

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

A powerlifter is at the finals of a competition. In order to maximize his power, he first sets up behind the bar and activates his lats and hamstrings without pulling it off the ground. Then, in one explosive lift, the bar is pulled up, and the lift is completed. Which types of contraction are used in his power clean lift?

A

Both Isometric and Isotonic
Reasoning: Isometric contraction occurs as he actively contracts the muscles in preparation for the lift but before the load has been moved (e.g., contraction at a constant muscle length). Isotonic contraction occurs as he is lifting the load (e.g., contraction and muscle length shortening at a constant load).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

tension measured before muscle contraction. Find this tension in response to stretching or extending muscle.

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

generated when cross-bridge cycling is engaged but active tension cannot be measured directly. It is determined indirectly.

A

Active tension

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

True/False: The total tension in skeletal muscle is indirectly calculated from measuring and adding both the passive tension and active tension.

A

False: The active tension cannot be directly measured. The active tension is determined by subtracting the measured passive tension from the measured total tension.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

True/False: The resting length is when total tension is the highest value without the contribution of passive tension.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

the load opposing muscle shortening velocity, in reference skeletal muscle-the weight and friction of an object to be moved.

A

Afterload

24
Q

Skeletal Muscle: Type 1 (slow twitch fibers) are _________ are resistant to fatigue and can maintain the force of contraction upon repeated stimulation.

A

OXIDATIVE: (characteristic of antigravity and posture muscles like the soleus muscles of the lower leg. (major reason is that type 1 fibers rely on oxidative methods to generate sufficient ATP to maintain contraction. Typically smaller in diameter, have low levels of glycolytic enzymes but many mitochondria and have a particularly high capillary density to maintain oxygen levels for oxidative metabolism.)

25
Q

Skeletal Muscle: - Type 2 (fast twitch fibers) ______________- have varying abilities to resist fatigue but are generally considered to be much less resistant to fatigue than slow twitch fibers.

A

GLYCOLYTIC :( type 2 fibers are larger in diameter and rely heavily on glycolysis for ATP production. Low myoglobin levels, few mitochondria and being less vascularized than slow fibers, fast twitch skeletal muscles can generate greater force profiles but cannot sustain that force for long periods of time.)

26
Q

Marathon runners rely on close on _________because their primary source of metabolism is __________.

A

slow fibers, oxidative

27
Q

Which type of fiber fatigues most easily?

A

Motor neurons with larger cell bodies innervates fast twitch fibers so the motor units that are recruited are larger and more fatigued.

28
Q

grading of force through changes in the number of active motor units and the firing rate of recruited units.

A

Rate Coding

29
Q

What are the 3 types of fibers that differ in contractile and regulatory proteins?

A

myoglobin content (muscle color), number of mitochondria , and amount of glycogen, and the metabolic pathways, either oxidative or glycolytic that used to generate ATP.

-(these biochemical properties determine contraction and relaxation speeds, the maximal force that can be generated, and the fiber susceptibility to fatigue.

30
Q

produce rapid, powerful contractions using glycolysis as the main metabolic pathway for energy production. These fibers tire rapidly and classified fast fatigable motor units.

A
  • Type llB: fast twitch
31
Q

have more mitochondria, a greater oxygen supply and higher endurance capacity then type IIb. Known as fast fatigue-resistant units.

A
  • Type IIA: fast twitch
32
Q

A champion sprinter’s leg muscle would likely have a high abundance of_________skeletal muscle fibers. These_________ close fibers would utilize energy sources for the rapid generation of ATP to sustain strong contractions during this short burst of exercise.

A

fast twitch, type IIB

33
Q

__________ for skeletal muscle depends in part on diet, with glycogen serving as a major substrate for ATP production.

A

Endurance

34
Q

__________ is a storage molecule for ATP and fastest way to synthesize ATP

A

-Creatine

35
Q

Cori Cycle

A
  • Our bodies gave a system to stave off fatigue that is due to the depletion of metabolic reserves and low pH resulting from anaerobic respiration
36
Q

True/False: The Cori cycle recycles anaerobic fermentation metabolites through gluconeogenesis in the liver.

A

True: Lactate is transported in the blood to the liver where it is converted to pyruvate and then to glucose. The glucose can then be transported back to the muscle to be used again for anaerobic glycolysis.

37
Q

What is the key feature for temperature maintenance during exertion.

A

PRODUCTION OF SWEAT

38
Q

ducts empty into hair cells follicles and produce a turbid, viscous fluid that is rich in lipids and carbohydrates. THEY HAVE NO ROLE IN TEMPERATURE REGULATION. They are under the influence of sex hormones and begin to exhibit functionality at puberty.

A

Apocrine Sweat Gland:

39
Q

numerous and are found all over the body with greater density and size on the palms of the right hand and the soles of the feet. All of the eccrine glands are present at birth and are functional within a few months. The density of these glands decrease as the skin enlarges during normal growth. KEY ROLE IN TEMPERATURE REGULATION. But secretory activity of these can be evoked by food, emotion, and pain

A

Eccrine Sweat Gland

40
Q

What are likely consequences of a mutated, non-functioning CFTR channel in the lumen of an eccrine sweat gland?

A

Impaired absorption of chloride
- Impaired absorption of sodium
- Saltier sweat than normal

41
Q
  • autoimmune disease in which the immune system produces antibodies directed against nicotinic acetylcholine receptors, which leads to destruction of these receptors. the result is a progressive loss of nicotinic receptors and degeneration of the postjunctional folds at the neuromuscular function.
A

Myasthenia Gravis

42
Q
  • The autoimmune response attacks presynaptic neuronal voltage-gated calcium channels. Less transmitter means lower resulting potentials.
  • This condition can be treated with acetylcholinesterase inhibitors so that the little acetylcholine that does get released is able to remain within the junction long enough to improve its chances of activating its receptors in the muscle
A

LEMS: LAMBERT-EATON MYASTHENIC SYNDROME

43
Q

True/False: In myasthenia gravis, normal amounts of ACh are released at the neuromuscular junction.

A

True :
Explanation: Autoantibodies attack the nicotinic ACh receptors and cause weak end-plate potentials, which do not affect the pre-synaptic neuron.

44
Q

True/False: In Lambert-Eaton myasthenic syndrome, normal amounts of ACh are released at the neuromuscular junction.

A

False:
Explanation: Autoantibodies attack the presynaptic neuronal voltage-gated calcium channels, which impairs vesicular fusion to release ACh into the neuromuscular junction, resulting in weak end-plate potentials.

45
Q

MG/LEMS: Repetitive nerve stimulation measures the electrical activity of the muscle upon stimulation. Based on what you know about myasthenia gravis (MG) and Lambert Eaton myasthenic syndrome (LEMS), high frequency repetitive stimulation could show an increase in muscle contraction activity in a patient with which condition?

A

LEMS

Remember that the problem with LEMS is that there is not enough release of ACh due to fewer functional voltage-gated calcium channels on the presynaptic neuron. Repetitive stimulation could increase the number of functional channels (limited though they may be) that are open and elevate the presynaptic intracellular calcium levels enough to improve ACh vesicular fusion and release into the neuromuscular junction. For MG, the problem is not the release of transmitter, it’s the reception of that signal on the muscle side because the autoantibodies block the nAChR on the muscle fiber. Despite a possible initial increase in activity at the outset, repetitive stimulation in this case is not likely to result in sustained increases in muscle activity as fatigue sets in and EPPs no longer reach threshold.

46
Q
  • Affect neurotransmitter release
  • Have their greatest effect on the inhibition of synaptic transmission by inhibitory neurons in the spinal cord.
  • The result of blocking the inhibitory transmitter release is that muscle contraction will proceed unencumbered
A

Clostridial Toxins

47
Q

________ prevents glycine release from inhibitory interneurons. _______prevents acetylcholine release from other motor neurons.

A

Tetanus toxin, Botulinum toxins

48
Q

Calmodulin

A

Smooth muscle synapse: small highly conserved protein. Has two roughly symmetrical globular domains separated by a flexible linker region. Contains 4 EF-hand motifs(helix loop), which binds a calcium ion. Which means a single calmodulin can bind up to 4 calcium ions.

49
Q

Varicosities

A

Smooth muscle synapse: at each contact the axon diameter expands to form varicosities. A series of swellings that contain the presynaptic components for vesicular transmitter release. Each varicosity is close to the postsynaptic membrane of the smooth muscle cell.

50
Q

What smooth muscle that contracts as a single unit.

A
  • Unitary smooth muscle
51
Q

predominant type of smooth muscle within the walls of visceral organs: found in small intestine, uterus, and many blood vessels

A
  • Visceral
52
Q

found in regions where finer control and gradual responses are desired. Contracts as multiple independent units. Found in some blood vessels, the iris and ciliary of the eye, and piloerector muscles of the skin (responsible for goosebumps).

A
  • Multiunit smooth muscle:
53
Q

(cluster if membrane receptors and proteins) in Sarcolemma
Include a variety of surface proteins: adrenergic and muscarinic receptors, calcium and potassium channels. 2nd messenger generations like phospholipase C and adenylyl cyclase.
- receptors
- g proteins
- ion channels
- 2degree messengers

A

Caveolae

54
Q

what removes calcium into the extracellular environment from the smooth muscle cytosol post-contraction?

A

PMCA (plasma membrane calcium ATPase)
-NCX (sodium-calcium exchanger)

55
Q

TRUE/FALSE: Calcium directly causes MLCK to phosphorylate myosin

A

False:Explanation: Calcium does cause MLCK to phosphorylate myosin, however it does this indirectly. Calcium binds to calmodulin, which in turn will activate MLCK.

56
Q

What are ways calcium can enter the smooth muscle cell cytosol?

A
  • Activation of a GPCR that will cleave PIP2
  • Voltage-gated calcium channels in the caveolus
  • Store-operated calcium channels on the plasma membrane
  • Through ligand-gated calcium channels on the SR membrane.
57
Q

Initiates contraction
- Activates MLCK
- Binds calponin
- Activates Ca2+ -CaM dependent protein kinases

A

Ca2+-CALMODULIN

PHY 503 MODULE 4.1 (3 decks)

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