Across the Membrane

Question 1

In the case of a neurotransmitter, what are the three different processes can occur after the NT is released into the synaptic cleft and binds to a receptor (either pre- or post-synaptic receptor)?

Answer 1

Diffusion, Enzyme degradation, Reuptake

Question 2

the neurotransmitter detaches from receptor, drifting out of the synaptic cleft, here it becomes absorbed by glial cells.

Answer 2

diffusion

Question 3

enzymes break it down. Usually, astrocytes absorb the excess neurotransmitters and pass them on to enzymes or pump them directly into the presynaptic neuron.

Answer 3

Enzyme degradation

Question 4

re-absorption of a neurotransmitter into the neuron. Transporters, or membrane transport proteins, pump neurotransmitters from the synaptic cleft back into axon terminals (the presynaptic neuron) where they are stored and reused.

Answer 4

reuptake

Question 5

If a drug can initiate a cellular response like that caused by the normal endogenous neurotransmitter it is

Answer 5

agonist action

Question 6

If a drug can initiate a cellular response that is like the normal endogenous NT, but lower amplitude it is

Answer 6

partial agonist

Question 7

If a drug can block access to the binding site

Answer 7

antagonist action

Question 8

If a drug can initiate a cellular response opposite to that caused by the normal endogenous neurotransmitter it is

Answer 8

inverse agonist action

Question 9

If the receptor is near the normal endogenous neurotransmitter binding site, and the drug can facilitate the binding of the normal endogenous neurotransmitter to its normal receptor

Answer 9

allosteric action

Question 10

Sometimes, the binding of a substance has a helper function. This is called

Answer 10

allosteric action

Question 11

If administration of a drug reduces the effect of the agonist

Answer 11

antagonist

Question 12

blocks binding, but does not produce an effect on its own

Answer 12

antagonist

Question 13

Some antagonists are competitive

Answer 13

more agonist can overcome it

Question 14

Some antagonists are non-competitive

Answer 14

more agonist cannot overcome it and it binds irreversibly to the receptor

Question 15

Name the four sites for drug action

Answer 15

Ion Channel Receptors
G-Protein Coupled Receptors
Enzymes
Transporter Proteins

Question 16

Describe how drug effects occur at a neuron level.

Answer 16

Effects are caused by an interaction with receptor sites on proteins (on the neuron). Drug binding causes a change in the function of these proteins in a characteristic response.

Question 17

Fast neurotransmitters (milliseconds) that transmit things like vision or hearing

Answer 17

ionotropic receptors

Question 18

bind to a receptor to facilitate the action of the neurotransmitter

Answer 18

Allosteric agonists

Question 19

G-protein coupled receptors are also called

Answer 19

metabotropic receptors

Question 20

The neurotransmitter binds directly to ligand-gated ion channel in the postsynaptic membrane, which closes or opens a channel gate and alters the flow of specific ions into a gated cell.

Answer 20

The direct pathway

Question 21

G-protein opens or closes ion channels in one of two ways

Answer 21

Directly

Indirectly through secondary messengers (e.g., cAMP)

Question 22

The extracellular signal molecule binds with the G-protein receptor on the cell surface and activates phospholipase C, which is located on the plasma membrane. The lipase hydrolyzes phosphatidylinositol 4,5-bisphosphate into two second messengers: inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). IP3 binds with the IP3 receptor in the membrane of the smooth endoplasmic reticulum and mitochondria to open Ca++ channels. DAG helps activate protein kinase C, which phosphorylates many other proteins, changing their catalytic activities, leading to cellular responses and changes in the ion channel.

Answer 22

INDIRECT PHOSPHATIDYLINOSITOL PATHWAY:

Question 23

Adenylyl cyclase is a 12-transmembrane glycoprotein that catalyzes ATP to form cAMP. The cAMP produced is a second messenger in cellular metabolism and is an allosteric activator of protein kinase A. Protein kinase A is an important enzyme in cell metabolism due to its ability to regulate cell metabolism by phosphorylating specific committed enzymes in the metabolic pathway

Answer 23

INDIRECT cAMP PATHWAY

Question 24

What breaks down breaks down monoamines?

Answer 24

monoamine oxidase

Question 25

What breaks down breaks down acetylcholine?

Answer 25

acetylcholinesterase

Question 26

The characteristic of a receptor that describes its exclusivity for a particular substance is called its

Answer 26

receptor binding specificity

Question 27

a substance are molecularly identical, but geometrically different

Answer 27

isomer

Question 28

substances that are mirror images of each other

Answer 28

optical isomer

Question 29

A mix of optical isomers is called

Answer 29

enantiomers

Question 30

levo

Answer 30

left

Question 31

dextro

Answer 31

right

Question 32

sinister

Answer 32

left

Question 33

rectus

Answer 33

right

Question 34

the immediate response from the binding

Answer 34

The acute effect of a drug at its receptor

Question 35

changes in the number of receptors or the change in the sensitivity of existing receptors to binding with the exposed substance

Answer 35

chronic effects due to a drug

Question 36

An increase in the number of receptors is called xxxxx and occurs most often in response to a xxxxx

Answer 36

upregulation, non-competitive antagonist

Question 37

xxxxxx or a decrease in receptors occurs most often in response to long-term exposure to a

Answer 37

Downregulation, agonist

Question 38

, long-term exposure to an agonist can cause the existing receptors to

Answer 38

lose sensitivity for the endogenous NT

Question 39

and long-term exposition to an antagonist can cause receptors to

Answer 39

become more sensitive to the endogenous NT