Biological Psychology- Test 2

Neurochemistry

Neurochemistry

basic chemical composition and processes of the nervous system

Neuropharmacology

study of compounds that selectively affect the nervous system

Exogenous substances

molecules from OUTSIDE our own bodies, used throughout human history to affect our physiology and behavior

Endogenous

occurs naturally WITHIN the body

Endogenous ligands

substances that the brain produces

receptors

protein molecules in the postsynaptic membrane

When activated by a neurotransmitter, the receptors

Change shape- ionotropic receptors

Alter chemical reactions in the target cell- metabotropic receptors

Ligands may be

Agonists, Antagonists, Inverse agonists

Agonists

mimic effects of another transmitter

Antagonists

bind receptor without activating it

Inverse agonists

bind to receptor and initiates opposite effect of usual transmitter

competitive ligands

Drugs that act as either agonists, antagonists or inverse agonists

bind to the same part of receptor molecule as endogenous ligand

noncompetitive ligands (neuromodulators)

bind to modulatory sites that are not part of the receptor complex that normally binds the transmitter

Co-localization (co-release)

occurs when nerve cells contain more than one type of neurotransmitter

The most prevalent excitatory neurotransmitters in the brain are

glutamate, aspartate

Glutamate is associated with

excitotoxicity

gamma-aminobutyric acid (GABA) is associated with

inhibitory

GABAa

ionotropic, producing fast, inhibitory effects

GABAb

metabotropic, slow inhibitory effects

GABAc

ionotropic with a chloride channel

GABA agonists, like Valium, are

potent tranquilizers

_____ was mapped by the enzymes involved in its synthesis

Acetylcholine (ACh)

Cholinergic nerve cell bodies and projections contain _____

ACh

Acetylcholine (ACh) is lost in

Alzheimer's disease

Acetylcholine (ACh) is involved with

learning and memory

Two types of ACh receptors

Nicotinic, Muscarinic

Nicotinic

ionotropic and excitatory

(Example: Muscles use nicotinic ACh receptors (nAch)—paralysis can be induced with an antagonist, such as curare)

Serotonin (5-hydroxytryptamine, 5-HT) is implicated in _____ , mood, _____ behavior, and anxiety.

sleep, sexual

Two main classes of monoamine neurotransmitters

Catecholamines, Indoleamines

Catecholamines (from tyrosine)

dopamine, epinephrine, norepinephrine

Indoleamines (from tryptophan)

melatonin, serotonin

Dopamine (DA) is important in _____ and neuronal loss in a dopamine pathway is a cause of ___________ disease.

motor control Parkinson's

DA is involved in

reward, reinforcement, and learning

abnormalities are associated with schizophrenia

Norepinephrine (NE) is also known as

noradrenaline

Cells producing noradrenaline are

noradrenergic

The NE systems modulate processes including

mood, arousal, and sexual behavior.

Muscarinic

G protein-coupled (metabotropic), slower, and excitatory or inhibitory

(Muscarinic ACh receptors can be blocked by atropine or scopolamine to produces changes in cognition)

____, such as Prozac, increase 5-HT activity—effects depend on which receptor subtypes are affected.

Antidepressants

Peptides act as neurotransmitters at some synapses, or as _____

hormones

Opioid peptides mimic

opiate drugs such as morphine

Pituitary hormones are

oxytocin, vasopressin

_____ are in gut, spinal cord, or brain

Peptides

Nitric oxide (NO)

• Produced in cellular locations • Does not interact with membrane-bound receptors (diffuses out of and into cells) • Can act as a retrograde transmitter

Many drugs are _____ that act upon specific receptor molecules.

ligands

_____ is a gas neurotransmitter

Nitric oxide (NO)

Drugs may target ___________ receptor subtypes.

one or a few

binding affinity

the degree of chemical attraction between a ligand and a receptor

A drug with a ___________ affinity for its receptor will be effective at very ___________ doses.

high, low

Neurotransmitters are ___________ ligands, allowing them to rapidly ___________ from receptors.

low affinity, dissociate

efficacy

intrinsic activity, ability of a bound ligand to activate the receptor

Agonists have ___________ efficacy

high

Antagonists have ___________ efficacy

low

Partial agonists produce a _____ response regardless of dose.

medium

dose-response curve (DRC)

graph of the relationship between drug doses and the effects

pharmacodynamics

functional relationship between drugs and their response

DRC is a tool to understand

pharmacodynamics

_____ of two drugs can be compared by their ED50 values.

Relative potency

A drug that has comparable effects at ___________ doses is more potent.

lower

The therapeutic index is the separation between the ___________ dose and a ___________ one.

effective, toxic

Drug tolerance

successive exposures have decreasing effects

Metabolic tolerance

Organ systems become more effective at eliminating the drug

Functional tolerance

Target tissue may show altered sensitivity to the drug

Changes in numbers of receptors can alter _____ in the direction opposite to the drug's effects

sensitivity

Neurons _____ in response to an agonist drug (fewer receptors available)

down-regulate

Neurons _____ in response to an antagonist

up-regulate

Cross-tolerance

tolerance to a whole class of chemically similar drugs

(ex- building a resistance to anesthesia because of alcohol abuse because both drugs affect the body similarly)

Withdrawal symptoms may be caused by

drug tolerance

Sensitization

drug effects become stronger with repeated treatment

(ex- cravings)

bioavailable

free to act on the target (The ability of a nutrient to be readily absorbed and used by the body)

The amount of drug that is bioavailable varies with

route of ingestion

Duration of a drug's effect is determined by

how it is metabolized

Routes of Drug Administration

• Ingestion (liquids, pills, suppositories)

• Inhalation (snorting/smoking)

• Peripheral injection (into the veins, arm, etc)

• central injection (into the central nervous system, ex-epidural)

Pharmacokinetics

factors that affect the movement of a drug through the body

blood-brain barrier

a filtering mechanism, tight junctions within the CNS that prevent the movement of large molecules

What can limit drug availability?

blood-brain barrier

Local anesthetics block

sodium channels (and therefore action potential)

Most drugs affect _____ transmission

synaptic

exogenous neuromodulator that blocks the effect of adenosine

Caffeine

adenosine

endogenous neuromodulator that inhibits catecholamine release

Caffeine stimulates

catecholamine release, causing arousal

Adenosine is normally released along with the catecholamines and acts on

autoreceptor

autoreceptors

receptors on the same terminal that released it

Presynaptic events can be modified by drugs that

Affect how long transmitters remain in the synapse (transmitter reuptake)

They interfere with transporters

Block transmitter degradation causing neurotransmitters to have lasting effects

transporters

specialized proteins that return the transmitter to the presynaptic membrane (e.g., cocaine)

degredation

breakdown of neurotransmitters

Cholinesterase inhibitors

inhibit the breakdown of ACh at the synapse by the enzyme acetylcholinesterase (AChE), causing prolonged muscle contraction

Postsynaptic receptors can be directly _____ or _____ by drugs

blocked, activated

Antipsychotics

neuroleptics, class of drugs used to treat schizophrenia

Typical antipsychotics

selective dopamine D2 antagonists (reduce the positive symptoms of schizophrenia, such as delusions and hallucinations)

Atypical antipsychotics

block some serotonin receptors and seem to reduce negative symptoms of schizophrenia (such as social withdrawal and blunted emotional responses)

Antidepressants

treat depression

Monoamine oxidase (MAO) inhibitors prevent

breakdown of monoamines at the synapses

Accumulating monoamines and prolonging their activity is a major feature of _____

antidepressants

Tricyclic antidepressants increase

norepinephrine and serotonin at the synapses by blocking their reuptake into presynaptic axon terminals

Selective serotonin reuptake inhibitors (SSRIs)

like Prozac or Zoloft allow serotonin to accumulate in the synapses, with fewer side effects than tricyclics

Anxiolytics

tranquilizers, depressants

depressants are

drugs that reduce nervous system activity

Benzodiazepine agonists

act on GABAa receptors and enhance the inhibitory effects of GABA (ex- Barbiturates)

Benzodiazepines bind at an

orphan receptor (no known endogenous ligand)

Opium is extracted from

poppy seeds