Chapter 2.2

Question 1

Steps that take place during chemical synaptic transmission

Answer 1

The action potential arrives at the presynaptic axon terminal. The depolarization causes an influx of Ca2+, promoting exocytosis which causes vesicles to fuse to the membrane and release neurotransmitter. The molecules bind to receptor molecules which open channels and allow ions to flow and initiate an excitatory or inhibitory postsynaptic potential. The EPSP or IPSP spread passively over the dendrite and cell body to the axon hillock. Synaptic transmission is stopped, and transmitter may also activate presynaptic receptors to decrease transmitter release.

Question 2

Synaptic delay

Answer 2

The brief delay between the arrival of an action potential at the axon terminal and the creation of a postsynaptic potential

Question 3

How are receptor molecules activated to transfer information?

Answer 3

Ligands fit into the ligand-binding sites of the receptor and activate or block it

Question 4

Ligand

Answer 4

A substance that binds to receptor molecules, such as a neurotransmitter or drug that binds to postsynaptic receptors

Question 5

Acetylcholine (ACh)

Answer 5

A neurotransmitter that is produced and released by parasympathetic postganglionic neurons, by motor neurons, and by many neurons in the brain

Question 6

Curare

Answer 6

A neurotoxin that causes paralysis by blocking acetylcholine receptors in muscle

Question 7

Bungarotoxin

Answer 7

A neurotoxin, isolated from the venom of the many-banded krait, that selectively blocks acetylcholine receptors

Question 8

Agonist

Answer 8

A substance that mimics or boosts the actions of a transmitter or other signaling molecule

Question 9

Antagonist

Answer 9

A substance that blocks or reduces the actions of a transmitter or other signaling molecule

Question 10

Cholinergic

Answer 10

Referring to cells that use acetylcholine as their synaptic transmitter

Question 11

Degradation

Answer 11

The chemical breakdown of a neurotransmitter into inactive metabolites

Question 12

How are the actions of synaptic transmissions stopped?

Answer 12

Degradation
Reuptake

Question 13

Acetylcholinesterase (AChE)

Answer 13

An enzyme that inactivates the transmitter acetylcholine

Question 14

Reuptake

Answer 14

The process by which released synaptic transmitter molecules are taken up and reused by the presynaptic neuron, thus stopping synaptic activity

Question 15

Transporter

Answer 15

A specialized membrane component that returns transmitter molecules to the presynaptic neuron for reuse

Question 16

Axo-dendritic synapse

Answer 16

A synapse at which a presynaptic axon terminal synapses onto a dendrite of the postsynaptic neuron, either via a dendritic spine or directly onto the dendrite itself

Question 17

Axo-somatic synapse

Answer 17

A synapse at which a presynaptic axon terminal synapses onto the cell body (soma) of the postsynaptic neuron

Question 18

Axo-axonic synapse

Answer 18

A synapse at which a presynaptic axon terminal synapses onto the axon terminal of another neuron

Question 19

Dendro-dendritic synapse

Answer 19

A synapse at which a synaptic connection forms between the dendrites of two neurons

Question 20

Knee-jerk reflex

Answer 20

A variant of the stretch reflex in which stretching of the tendon beneath the knee leads to an upward kick of the leg

Question 21

How do electrical synapses transfer across neurons?

Answer 21

Two connexons between the two cells are connected and form a gap junction. Electric current passes through this junction in the form of ions from one cell to the next