Chapter #4 (p. 56-70)

Question 1

What are the two main types of cells that make up the nervous system?

Answer 1

neurons and glial cells

Question 2

Uninsulated sections of the axon are called what?

Answer 2

nodes of ranvier

Question 3

At the end of the axon are branches containing small bulbous structures called ____ ____.

Answer 3

terminal buttons or axon terminals

Question 4

What are the three passive processes?

Answer 4

1. Diffusion - tendency for a substance to move down its [gradient]
2. Electrostatic Charge - tendency for similar electrical charges to repel each other and for opposites to attract
3. Differential Permeability - use specialized protein channels (ion channels)

Question 5

Make sure we know diagram on page 60.

Answer 5

This SHOULD be review

Question 6

We say that action potentials are non-decremental, what does this mean?

Answer 6

they reach the axon terminal with the same strength as which they were initiated near the axon hillock

Question 7

When an AP jumps from node to node along the axon it is called?

Answer 7

saltatory conduction

Question 8

What are the two types of summation?

Answer 8

temporal and spatial

Question 9

Upon arrival of an action potential, the voltage-gated channels open and allow an influx of ___ which then triggers what?

Answer 9

Ca; the movement and fusion of synaptic vesicles with the presynaptic membrane and the exocytosis of neurotransmitter

Question 10

A ____ is a chemical that is synthesized and released by neurons and that modulates the effects of neurotransmitters

Answer 10

neuromodulator

Question 11

Do neuromodulators have short or long term effects?

Answer 11

both

Question 12

Fill in the blank with neurotransmitter or neuromodulator:

• _____ are typically released in greater amounts
• _____ generally travel further distances
• Substances that act as ____ in one synapse may also act as a ____ of transmission at a different synapse

Answer 12

neuromodulator
neuromodulator
neurotransmitter
neuromodulator

Question 13

In some synapses, postsynaptic receptor proteins contain binding sites directly connected to a gated ion channel; these are called?

Answer 13

ionotropic receptors

Question 14

The binding sites on ____ receptors are not directly connected to an ion channel.

Answer 14

metabotropic

Question 15

In a metabotropic receptor, where is the binding site?

Answer 15

The receptor sires are situated on the extracellular portion of a long protein on the cell membrane.

Question 16

(Metabotropic) When the neurotransmitter molecule binds to its receptor, what happens?

Answer 16

a subunit of the G protein breaks away - it is a secondary messenger now

Question 17

What are the two most known second messengers?

Answer 17

cAMP and GMP

Question 18

what two things can a second messenger do?

Answer 18

1. interact with a gated ion channel from inside the cell
2. alter the operation of nongated ion channels in a way that changes resting potential or the cell’s sensitivity to other stimuli

Question 19

Second messengers may also have even longer-term or permanent effects because they activate a type of protein called a ___

Answer 19

kinase

Question 20

Which kinase (A or G) is active for longer?

Answer 20

A kinase is much more persistent as a second messenger and can remain active for many minutes or even for hours

Question 21

Receptor sites for neurotransmitters are located not only on the postsynaptic neuron but also on the presynaptic neuron. What are these called?

Answer 21

autoreceptors

Question 22

what type of receptors are autoreceptors?

Answer 22

metabotropic

Question 23

What do autoreceptors provide feedback on?

Answer 23

the amount of neurotransmitter released in the synaptic cleft in order to regulate its levels through the activity of G proteins and second messengers

Question 24

The mechanism of autoreceptors causing a reduction in the synthesis and release of transmitter when the levels of neurotransmitter get to high is believed to be the cause of the delay in the effectiveness of some _______ drugs.

Answer 24

psychotherapeutic drugs such as antidepressant medication

Question 25

______ are metabotropic receptor sites that function very similarly to autoreceptors except that they respond not to the release of neurotransmitter by the cell upon which they reside, but to chemicals released by the postsynaptic cell or other nearby cells when they become depolarized.

Answer 25

heteroreceptors

Question 26

Transmission of chemical information from a postsynaptic to presynaptic cell is termed ____ ___

Answer 26

retrograde signaling

Question 27

What two ways does the synaptic cleft clear the transmitter?

Answer 27

1. the presynaptic cell reabsorbs the intact neurotransmitter molecule (reuptake) using a transporter protein
2. the synapse uses an enzyme (enzymatic degradation) to break down the neurotransmitter into its precursors which can also be taken back into the presynaptic membrane