The Neuromuscular Junction (Nmj)

20 Questions | By Mgartz | Updated: Mar 21, 2022 | Attempts: 757

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1.

The Neuromuscular Junction (NMJ) A synapse between a motor neuron axon and the motor end plate (consists of excitable muscle fibers) Uses ___ as a transmitter
- A.
  
  AChE
- B.
  
  5-HT
- C.
  
  NE
- D.
  
  ACh
2.

Mediate NMJ and autonomic ganglia function Are found on muscle endplates and peripheral ganglia Distinct subtypes exist at NMJ and autonomic ganglia pentameric ionotropic receptors (Similar to GABA_A) Gate Na+ and K+ ions, and in some forms, Ca++ ions Net effect of activation is depolarization OF POSTSYNAPTIC CELL
- A.
  
  Muscarinic receptors
- B.
  
  Nicotinic receptors
- C.
  
  Dopamine receptors
- D.
  
  Serotonin receptors
3.

____________was the first widely used Neuromuscular Blocking Agents
4.

Two types of neuroblockin agents which one work by over-stimulating nicotinic receptors, causing muscle fiber membrane depolarization
- A.
  
  Polarizing agents
- B.
  
  Depolarizing agents
- C.
  
  Competitive agents
- D.
  
  Noncompetitive agents
5.

Two types of neuroblockin agents which one work by antagonizing ACh receptors
- A.
  
  Polarizing agents
- B.
  
  Depolarizing agents
- C.
  
  Competitive agents
- D.
  
  Noncompetitive agents
6.

Neuromuscular blocking agents currently in use typically have a slow onset, and long duration of action
- A.
  
  True
- B.
  
  False
7.

Currently only ____________ is used as a depolarizing neuromuscular blocking agent
- A.
  
  Pancuronium
- B.
  
  Succinylcholine
- C.
  
  Vecuronium
- D.
  
  Rocuronium
8.

Chemical makeup of neuromuscular blocking agents include:
- A.
  
  Natural alkaloids and congeners
- B.
  
  Ammonio steroids
- C.
  
  Benzylisquinolones
9.

Competitive agents tend to be ____, ____ molecules, ______ bottom
10.

Natural or synthetic alkaloids are not often used because lots of ‘side effects’, including causing _________release_______ also have a relatively ______duration of action
- A.
  
  Histamine, long
- B.
  
  5-HT, long
- C.
  
  Histamine, short
- D.
  
  5-HT, short
11.

Pancuronium
- A.
  
  Prototype ammonio steroid
- B.
  
  No histamine release
- C.
  
  Block muscarinic receptors, and causes tachycardia
- D.
  
  Don’t have ganglionic blocking actions, don’t alter vagus nerve function
- E.
  
  Prototype benzylisquinolone
12.

Atracurium
- A.
  
  Prototype ammonio steroid
- B.
  
  No histamine release
- C.
  
  Block muscarinic receptors, and causes tachycardia
- D.
  
  Don’t have ganglionic blocking actions, don’t alter vagus nerve function
- E.
  
  Prototype benzylisquinolone
13.

Benzylisquinolones
- A.
  
  Prototype ammonio steroid
- B.
  
  No histamine release
- C.
  
  Block muscarinic receptors, and causes tachycardia
- D.
  
  Don’t have ganglionic blocking actions, don’t alter vagus nerve function
- E.
  
  Prototype benzylisquinolone
14.

Neuromuscular Blocking Competitive Antagonists When applied directly to skeletal muscle, nicotinic agonists cause a localized _________
15.

Neuromuscular Blocking Agent MOA: Depolarizing Agents
- A.
  
  Depolarization effect on the postsynaptic muscle is long lasting
- B.
  
  A short period of repetitive excitation and muscle twitching followed by…Blockade of neurotransmission and paralysis
- C.
  
  Initial action of depolarizing agents is to cause opening of ion channels
- D.
  
  All are true
16.

Depolarization is achieved when muscle fibers are no longer responsive to ACh at With prolonged depolarization, muscle ____________, and Na+, Cl- and Ca++ are gained Depolarizing blockers are hydrolyzed by _____________
- A.
  
  Postsynaptic cell
- B.
  
  K+ is depleted
- C.
  
  Butyrylcholinesterases
- D.
  
  Presynaptic cell
- E.
  
  K+ is increased
17.

What is true about NMJ Blocker Toxicity
- A.
  
  Results in bronchospasm, hypotension, increased secretory activity
- B.
  
  Can cause histamine release
- C.
  
  Dangerous in patients with CHF who are taking diuretics, digoxin
- D.
  
  Life threatening in individuals with ion regulation dysfunction
- E.
  
  Dangerous in patients withsignificant burns, soft tissue damage, and in children
- F.
  
  Cause a significant release of K+ from intracellular sites
18.

Overdoses can be treated by AChE inhibitors like
- A.
  
  Edrophonium
- B.
  
  Neostigmine
- C.
  
  Pyridostigmine
- D.
  
  Atropine
- E.
  
  Trimethaphan
19.

Step 1: activation of nAChRs, rapid depolarization of postsynaptic sites Due to inward Na+ current (Ca++ current when neuronal nAChRs involved) Step 2: an action potential is caused in postganglionic neuron when threshold reached (mediated by nAChRs) Step 3: the action potential is followed by a slow IPSP, then a slow EPSP (mediated by mAChRs; does not occur in all ganglia) Step 4: a second late, slow EPSP follows (mediated by peptidergic release)
- A.
  
  Nicotinic Neurotransmission
- B.
  
  Muscarinic Neurotransmission
- C.
  
  Ganglionic Neurotransmission
- D.
  
  Cholinergic Neurotransmission
20.

Nicotine
- A.
  
  Has actions on both effector and chemosensory sites
- B.
  
  Can rapidly cause receptor desensitization
- C.
  
  Causes a transient stimulation of all autonomic ganglia
- D.
  
  Ultimate response is due to summation of all nicotine’s effects on an organ/system
- E.
  
  Pharmacological actions are complex, unpredictable