BIOM*3200- Unit 9 (Synaptic Transmission & Muscle Physiology)

Beeopboop

The site where a neuron communicates with another cell is called a:
A) Node of Ranvier
B) Synapse
C) Axon hillock
D) Soma

B

Which type of synapse uses neurotransmitters to transmit signals?
A) Electrical synapse
B) Chemical synapse
C) Gap junction
D) Myelin junction

B

Electrical synapses are connected by:
A) Synaptic vesicles
B) Gap junctions
C) Voltage-gated sodium channels
D) Receptor proteins

B

Which ion triggers neurotransmitter release at the axon terminal?
A) Na⁺
B) K⁺
C) Ca²⁺
D) Cl⁻

C

Voltage-gated calcium channels open in response to:
A) Neurotransmitter binding
B) Action potential depolarization at the terminal
C) Hyperpolarization of the membrane
D) ATP hydrolysis

B

Neurotransmitters are stored in:
A) Synaptic cleft
B) Synaptic vesicles
C) Postsynaptic density
D) Axon hillock

B

Which process moves neurotransmitters into vesicles?
A) Simple diffusion
B) Vesicular transport proteins
C) Osmosis
D) Passive leak channels

B

The space between the presynaptic and postsynaptic membranes is the:
A) Axon hillock
B) Synaptic cleft
C) Synaptic vesicle
D) Receptor zone

B

At the neuromuscular junction, the neurotransmitter released is:
A) Dopamine
B) Glutamate
C) Acetylcholine
D) GABA

C

Acetylcholine at the neuromuscular junction binds to:
A) Voltage-gated Na⁺ channels
B) Nicotinic receptors
C) Muscarinic receptors
D) GABA receptors

B

Which enzyme breaks down acetylcholine in the synaptic cleft?
A) Acetylcholinesterase
B) Monoamine oxidase
C) Catechol-O-methyltransferase
D) Tyrosine hydroxylase

A

Excitatory postsynaptic potentials (EPSPs) bring the membrane potential:
A) Closer to threshold
B) Further from threshold
C) To +30 mV
D) To 0 mV instantly

A

Inhibitory postsynaptic potentials (IPSPs) typically involve:
A) Na⁺ influx
B) K⁺ efflux or Cl⁻ influx
C) Na⁺ efflux
D) Ca²⁺ influx

B

Temporal summation occurs when:
A) Multiple inputs arrive simultaneously from different locations
B) One synapse is activated repeatedly in rapid succession
C) EPSPs and IPSPs cancel each other
D) Action potentials are generated in dendrites

B

Spatial summation occurs when:
A) Inputs from multiple synapses combine
B) A single synapse fires repeatedly
C) EPSPs and IPSPs occur at the same site
D) Only inhibitory inputs are active

A

The “all-or-none” principle applies to:
A) Action potentials
B) Graded potentials
C) EPSPs
D) IPSPs

A

Which neurotransmitter is the main excitatory transmitter in the CNS?
A) GABA
B) Glycine
C) Glutamate
D) Acetylcholine

C

Which neurotransmitter is the main inhibitory transmitter in the CNS?
A) Acetylcholine
B) Glycine
C) Glutamate
D) GABA

D

At an excitatory cholinergic synapse, Na⁺ enters the postsynaptic cell via:
A) Voltage-gated Na⁺ channels
B) Ligand-gated ion channels
C) Leak channels
D) Secondary active transporters

B

GABA binding to its receptor usually results in:
A) Na⁺ influx
B) Cl⁻ influx
C) K⁺ influx
D) Ca²⁺ influx

B

Which ion movement causes depolarization?
A) Na⁺ influx
B) K⁺ efflux
C) Cl⁻ influx
D) Cl⁻ efflux

A

Which ion movement causes hyperpolarization?
A) Na⁺ influx
B) K⁺ efflux
C) Cl⁻ efflux
D) Na⁺ efflux

B

The term “synaptic delay” refers to:
A) The time for an action potential to travel along the axon
B) The time between arrival of an AP and postsynaptic potential
C) The time required for neurotransmitter degradation
D) The refractory period of the neuron

B

Electrical synapses have almost no delay because:
A) They lack vesicles
B) They transmit signals via direct ion flow through gap junctions
C) They use more neurotransmitter
D) They have more receptors

B

Which property is unique to chemical synapses?
A) Bidirectional signal transmission
B) Neurotransmitter release into a cleft
C) Gap junctions
D) Direct ion coupling

B

Which event directly triggers vesicle fusion during exocytosis?
A) Na⁺ influx
B) Ca²⁺ binding to synaptotagmin
C) K⁺ efflux
D) Cl⁻ influx

B

Which protein complex is critical for vesicle docking?
A) Myosin
B) SNARE complex
C) Tubulin
D) Actin

B

Which type of receptor produces faster postsynaptic effects?
A) Metabotropic
B) Ionotropic
C) G-protein coupled
D) Enzyme-linked

B

Metabotropic receptors signal via:
A) Direct ion channel opening
B) G-protein activation and second messengers
C) Electrical coupling
D) Passive diffusion

B

Which neurotransmitter is used at the neuromuscular junction of skeletal muscles?
A) Acetylcholine
B) Glutamate
C) Norepinephrine
D) Dopamine

A

Which neurotransmitter is derived from tryptophan?
A) Serotonin
B) Dopamine
C) Norepinephrine
D) Epinephrine

A

Which neurotransmitter is derived from tyrosine?
A) Acetylcholine
B) Dopamine
C) GABA
D) Glutamate

B

Monoamine neurotransmitters are inactivated mainly by:
A) Acetylcholinesterase
B) Monoamine oxidase (MAO) and reuptake
C) Passive diffusion
D) SNARE proteins

B

Which amino acid is the precursor for GABA?
A) Glutamate
B) Glycine
C) Aspartate
D) Serine

A

Glycine acts primarily as an inhibitory neurotransmitter in the:
A) Brain
B) Spinal cord
C) Neuromuscular junction
D) Adrenal medulla

B

Which synaptic plasticity process strengthens synapses after high-frequency stimulation?
A) Long-term potentiation (LTP)
B) Long-term depression (LTD)
C) Synaptic delay
D) Habituation

A

Which receptor is important in LTP in the hippocampus?
A) AMPA receptor
B) NMDA receptor
C) GABA_A receptor
D) Nicotinic receptor

B

NMDA receptors are unique because they require:
A) Only glutamate binding
B) Glutamate binding and depolarization to remove Mg²⁺ block
C) Only depolarization
D) GABA binding

B

AMPA receptors allow passage of:
A) Na⁺ and K⁺
B) Only Cl⁻
C) Only K⁺
D) Na⁺ and Cl⁻

A

Synaptic vesicle recycling is important because:
A) Vesicles degrade quickly
B) The presynaptic terminal has limited vesicle supply
C) Neurotransmitters cannot be reused
D) Postsynaptic receptors are destroyed after use

B

Which enzyme synthesizes acetylcholine?
A) Choline acetyltransferase
B) Acetylcholinesterase
C) Tyrosine hydroxylase
D) Dopamine beta-hydroxylase

A

Which neurotransmitter acts at both ionotropic and metabotropic receptors?
A) Acetylcholine
B) GABA
C) Glutamate
D) All of the above

D

Which condition is associated with loss of cholinergic neurons in the brain?
A) Parkinson’s disease
B) Alzheimer’s disease
C) Huntington’s disease
D) ALS

B

Which disease is linked to dopamine deficiency in the basal ganglia?
A) Huntington’s disease
B) Parkinson’s disease
C) Alzheimer’s disease
D) Epilepsy

B

Which neurotransmitter is involved in mood regulation and is targeted by SSRIs?
A) Dopamine
B) GABA
C) Serotonin
D) Glutamate

C

Which neurotransmitter is released from adrenergic neurons?
A) Acetylcholine
B) Norepinephrine
C) Dopamine
D) Glutamate

B

Which neurotransmitter is released from cholinergic neurons?
A) Acetylcholine
B) Norepinephrine
C) Glutamate
D) Dopamine

A

Which of the following is a catecholamine?
A) Serotonin
B) Dopamine
C) GABA
D) Glutamate

B

Which neurotransmitter is synthesized from glutamate via glutamic acid decarboxylase?
A) GABA
B) Glycine
C) Serotonin
D) Dopamine

A

Which process decreases synaptic strength after prolonged low-frequency stimulation?
A) Long-term depression (LTD)
B) Long-term potentiation (LTP)
C) Synaptic delay
D) Facilitation

A

1. What is the voltage across the membrane of all cells in the body, which is maintained as a potential difference? a. Action potential b. Equilibrium potential c. Resting membrane potential d. Synaptic potential

(c)

2. In neurons, what is the typical resting membrane potential (rmp)? a. +30 mV b. 0 mV c. +70 mV d. -70 mV

(d)

3. What primarily accounts for the negative charge inside the cell compared to the outside at resting membrane potential? a. Active transport of Ca2+ b. Diffusion of Cl- c. Permeability properties of the plasma membrane d. Sodium-potassium pumps

(c)

4. How do the Na+/K+ pumps contribute to maintaining the potential difference across the membrane? a. They pump 3 K+ ions out for every 2 Na+ ions in. b. They pump equal numbers of Na+ and K+ ions in opposite directions. c. They pump 3 Na+ ions out for every 2 K+ ions in. d. They prevent the diffusion of large organic molecules.

(c)

5. What happens to the membrane potential when it is reduced (becomes less negative)? a. Hyperpolarization b. Repolarization c. Overshoot d. Depolarization

(d)

6. What happens to the membrane potential when it is increased (becomes more negative)? a. Depolarization b. Repolarization c. Overshoot d. Hyperpolarization

(d)

7. What term describes the ability of neurons and muscle cells to produce and conduct changes in membrane potential? a. Adaptability b. Conductivity c. Excitability d. Refractoriness

(c)

8. What is the specific event that occurs when depolarization of an axon reaches a threshold level? a. A gradual return to resting potential. b. Hyperpolarization. c. Inactivation of Na+ channels. d. A sudden and very rapid change in membrane potential.

(d)

9. What is the immediate effect of depolarization to a threshold level on Na+ channels in an axon? a. They close. b. They become inactivated. c. They open. d. They become less permeable to Na+.

(c)

10. What type of gates do the Na+ channels of the axon membrane have? a. Chemically regulated b. Ligand-gated c. Mechanically regulated d. Voltage regulated

(d)

11. What kind of feedback loop is created when Na+ entry into an axon accelerates depolarization, opening more voltage-regulated Na+ gates? a. Negative feedback loop b. Homeostatic loop c. Positive feedback loop d. Inhibitory loop

(c)

12. What are the changes in Na+ and K+ diffusion and the resulting changes in membrane potential collectively called? a. Graded potential b. Synaptic potential c. Action potential d. Equilibrium potential

(c)

13. During an action potential, what is the primary cause of the rapid depolarization and overshoot of the membrane potential to a positive charge (e.g., +30 mV)? a. Outward diffusion of K+ b. Inactivation of Na+ channels c. Explosive increase in Na+ diffusion d. Opening of K+ channels

(c)

14. What causes the repolarization phase of an action potential, where the membrane potential returns to negative values? a. Inward diffusion of Na+ b. Outward diffusion of K+ c. Activation of the Na+/K+ pump d. Opening of Cl- channels

(b)

15. What limits the peak depolarization of an action potential, preventing it from reaching the full Na+ equilibrium potential? a. Delayed opening of K+ channels b. Increased K+ permeability c. Inactivation of the Na+ channels d. Activation of the Na+/K+ pump

(c)

16. What term describes the event where the inside of the membrane briefly becomes more negative than the resting membrane potential during an action potential? a. Depolarization b. Overshoot c. Repolarization d. After-hyperpolarization

(d)

17. How long does a typical action potential in an axon last from depolarization to repolarization and back to resting potential? a. Approximately 1 msec b. Approximately 5 msec c. Approximately 3 msec d. Approximately 10 msec

(c)

18. What is the amplitude (size) of action potentials, once a threshold value is reached? a. Graded b. Variable c. Dependent on stimulus strength d. All-or-none

(d)

19. How does the nervous system code for stimulus strength in a neuron? a. By increasing the amplitude of action potentials. b. By decreasing the duration of action potentials. c. By increasing the frequency of action potentials. d. By varying the speed of action potential conduction.

(c)

20. What process refers to the activation of more and more axons as the intensity of stimulation increases? a. Summation b. Potentiation c. Adaptation d. Recruitment

(d)

21. During which period can a second stimulus, no matter how strong, not produce an action potential? a. Relative refractory period b. Latent period c. Absolute refractory period d. After-hyperpolarization

(c)

22. What causes the absolute refractory period? a. Opening of K+ channels b. Outward diffusion of K+ c. Inactivated Na+ channels d. Na+/K+ pump activity

(c)

23. During which period can an action potential be produced only if the stimulus strength is greater than the usual threshold? a. Absolute refractory period b. Latent period c. Relative refractory period d. Hyperpolarization

(c)

24. What primarily causes the relative refractory period? a. Inactivated Na+ channels b. Continued outward diffusion of K+ c. Active transport of Na+ d. Closing of K+ channels

(b)

25. In an unmyelinated axon, how are action potentials produced along its length? a. They skip from one node to the next. b. Only at specific, widely spaced channels. c. Along the entire length of the axon. d. By direct electrical current flow only.

(c)

26. Why is the area that has previously produced an action potential in an unmyelinated axon unable to produce another immediately? a. It is experiencing hyperpolarization. b. The Na+/K+ pumps are too slow. c. It is still in its refractory period. d. It has run out of neurotransmitters.

(c)

27. What is the process called when action potentials appear to "leap" from node to node in a myelinated axon? a. Continuous conduction b. Decremental conduction c. Saltatory conduction d. Segmented conduction

(c)

28. Where are voltage-gated Na+ channels highly concentrated in myelinated axons? a. In the cell body b. Along the entire myelin sheath c. At the nodes of Ranvier d. In the terminal boutons

(c)

29. Why do myelinated axons conduct action potentials faster than unmyelinated axons? a. They have more voltage-gated channels. b. They require more action potentials along their length. c. They have more cable-like spread of depolarization and fewer sites for action potential production. d. Their myelin sheath directly conducts the electrical current.

(c)

30. What two factors increase the speed of action potential conduction in axons? a. Increased resistance and decreased diameter. b. Decreased myelination and increased resistance. c. Increased diameter and myelination. d. Decreased temperature and increased length.

(c)

31. What is the functional connection between a neuron and a second cell called? a. Ganglion b. Nucleus c. Synapse d. Tract

(c)

32. What are synapses between a neuron and a muscle cell often called? a. Axosomatic synapses b. Electrical synapses c. Neuromuscular junctions d. Axoaxonic synapses

(c)

33. In almost all synapses, what is the direction of transmission? a. Bidirectional b. From postsynaptic to presynaptic neuron c. From the axon of the presynaptic neuron to the postsynaptic neuron d. Random

(c)

34. What is required for two cells to be electrically coupled? a. Synaptic cleft b. Neurotransmitter release c. Voltage-gated channels d. Gap junctions

(d)

35. What proteins form the transmembrane structures with an aqueous core in gap junctions? a. SNARE proteins b. Synaptotagmin c. Connexins d. Cell adhesion molecules

(c)

36. In which tissues are gap junctions known to be present, allowing action potentials to spread from cell to cell? a. Skeletal muscle and glands b. Cardiac muscle and most smooth muscles c. Adipose tissue and bone d. Connective tissue and epithelial tissue

(b)

37. What are the swollen presynaptic axon endings in chemical synapses called? a. Dendritic spines b. Axon hillocks c. Nissl bodies d. Terminal boutons

(d)

38. What is the narrow space between the presynaptic terminal bouton and the postsynaptic cell in a chemical synapse? a. Gap junction b. Intercalated disc c. Synaptic cleft d. Axonal transport space

(c)

39. Neurotransmitter molecules within presynaptic neuron endings are contained within which structures? a. Mitochondria b. Endoplasmic reticulum c. Synaptic vesicles d. Lysosomes

(c)

40. What process is triggered by action potentials, leading to the release of neurotransmitters into the synaptic cleft? a. Pinocytosis b. Endocytosis c. Exocytosis d. Phagocytosis

(c)

41. What ion's entry into the terminal bouton, through voltage-gated channels, triggers the exocytosis of synaptic vesicles? a. Na+ b. K+ c. Cl- d. Ca2+

(d)

42. What complex of proteins bridges the vesicle membrane and the plasma membrane, facilitating docking of synaptic vesicles? a. G-protein complex b. Connexin complex c. SNARE complex d. CAMs complex

(c)

43. Which protein, anchored to the synaptic vesicle membrane, binds to Ca2+ and interacts with the SNARE complex to cause neurotransmitter release? a. Syntaxin b. SNAP-25 c. Synaptobrevin-2 d. Synaptotagmin

(d)

44. What are proteins in the pre- and postsynaptic membranes that project into the synaptic cleft and bond to each other, ensuring close proximity for rapid chemical transmission? a. G-proteins b. SNARE proteins c. Cell adhesion molecules (CAMs) d. Receptor proteins

(c)

45. What happens to the membrane potential of the postsynaptic membrane during an excitatory postsynaptic potential (EPSP)? a. It becomes more negative (hyperpolarizes). b. It remains unchanged. c. It becomes less negative (depolarizes). d. It reaches an all-or-none amplitude.

(c)

46. What happens to the membrane potential of the postsynaptic membrane during an inhibitory postsynaptic potential (IPSP)? a. It becomes less negative (depolarizes). b. It remains unchanged. c. It reaches an all-or-none amplitude. d. It becomes more negative (hyperpolarizes).

(d)

47. Where are voltage-regulated ion channels primarily found in a neuron? a. Dendrites b. Cell body c. Axons d. Synaptic cleft

(c)

48. Where are chemically regulated ion channels found in a neuron? a. Axon hillock b. Nodes of Ranvier c. Axon terminals d. Postsynaptic membrane

(d)

49. How do chemically regulated channels typically open? a. In response to depolarization. b. In response to hyperpolarization. c. In response to the binding of postsynaptic receptor proteins to their neurotransmitter ligands. d. In response to the Na+/K+ pump activity.

(c)

50. What type of change in membrane potential do chemically regulated ion channels produce? a. All-or-none action potential b. Refractory period c. Graded potential d. Equilibrium potential

(c)