12.14.3 Human Regulation: Synaptic Events: Cell-Cell Communication

Question 1

Human Regulation: Synaptic Events: Cell-Cell Communication

Answer 1

• A synapse is the gap between neurons that facilitates cell signaling.
• As a depolarization wave reaches the presynaptic terminal, vesicles containing neurotransmitters will fuse with the presynaptic membrane and release neurotransmitters into the synapse. These neurotransmitters will bind to protein receptors
in the postsynaptic terminal.
• Neurotransmitters bound to protein receptors can trigger either inhibitory or excitatory signals.
• Some drugs function by binding to neurotransmitter receptors.

Question 2

synapse

Answer 2

• A nerve impulse travels down an axon of a nerve until it reaches the terminal branches of the axon. The signal then passes from one neuron to the next across a synapse to the dendrite of the next neuron.

Question 3

presynaptic terminal

Answer 3

• As the nerve impulse reaches the presynaptic terminal, the action potential triggers an influx of Ca+2. This Ca+2 influx causes synaptic vesicles to fuse with the
  presynaptic terminal and release their contents
  (neurotransmitters) into the synapse.

Question 4

neurotransmitter

Answer 4

• Neurotransmitters bind to protein receptors on the
  postsynaptic membrane. The bound receptors open ion channels, allowing ions to pass through. The influx of ions into the neuron changes its membrane potential, either depolarizing (excitatory signal) or hyperpolarizing (inhibitory signal) the cell. When the membrane potential reaches the threshold potential, an action potential will be triggered. Neurotransmitters are then quickly degraded causing ion channels to close.

Question 5

Drugs that mimic a natural stimulatory neurotransmitter have the effect of

Answer 5

• stimulating the neurons that respond to the neurotransmitter being mimicked by binding to receptor sites.

Question 6

Neurotransmitters enter the synaptic cleft by

Answer 6

• exocytosis triggered by a rise in cytoplasmic Ca2+ concentrations.

Question 7

The action potential in the postsynaptic cell is initiated by

Answer 7

• binding of the neurotransmitter to specific receptor proteins causing ion channels to open and allow the influx of specific ions into the cell.

Question 8

The communication of action potentials from the presynaptic cell to the postsynaptic cell involves the following progression of signals in vertebrates:

Answer 8

• electrical → chemical → electrical

Question 9

A neuron may release a neurotransmitter that can stimulate or ________ an impulse in the ______________.

Answer 9

• inhibit, post-synaptic neuron

Question 10

True or false?
Neurotransmitters bind to postsynaptic receptors permanently holding them open allowing ions to flow into the postsynaptic neuron.

Answer 10

• false