Exam 2 Flashcards by Madison Felty

A- lions and K+ lions have _____ concentration inside the axon

Higher

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CI- ions and Na+ ions are more concentrated ______ the axon

Outside

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Inside the cell

Intracellular

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Extracellular

Outside the cell

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_______ can be produced by an influx of sodium ions and is produced by the opening of normally closed gates sodium channels

Depolarization

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Large, brief reversal in polarity of an axon and lasts one millisecond

Action Potential

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Voltage on a neural membrane at which an action potential is triggered via opening of the Na+ and K+ voltage sensitive channels

Threshold potential

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The state of an axon in the polarizing period when an action potential cannot typically occur

Absolute Refractory Period

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Increased electrical current is required to produce another action potential, potassium channels still open

Relative Refractory Period

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Propagation of an action potential on the membrane of an axon. Size and shape of the action potential remain constant along the axon

Nerve impulse

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Part of the axon that is not covered by myelin

Node of Ranvier

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Propagation of an action potential at successive nodes of ranvier

Saltatory Conduction

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how neurons integrate information

through dendritic spines, a neuron can establish more than 50,000 connections to other neurons.

Nerve impulses traveling from other neurons bombard the receiving neuron with all manner of inputs (excitatory and inhibitory)

The cell body, located between the dendritic tree and its axon, can receive inputs from many other neurons

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Brief depolarization of a neuron membrane in response to stimulation. Neuron is more likely to produce an action potential

Excitatory Postsynaptic Potential (EPSP)

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Brief hyperpolarization of a neuron membrane in response to stimulation–Neuron is less likely to produce an action potential

Inhibitory Postsynaptic Potential (IPSP)

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______ are associated with the opening of sodium channels: allows influx of Na+

Excitatory Postsynaptic Potential (EPSP)

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______ are associated with the opening of potassium channels (allows an influx of K+) or with the opening of chloride channels (allows an influx of Cl−)

Inhibitory Postsynaptic Potential (IPSP)

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Pulses that occur at approximately the same time on a membrane are summed

Temporal Summation

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Pulses that occur at approximately the same location on a membrane are summed

Spatial Summation

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Junction of cell body and axon. Rich in voltage-sensitive channels. Where EPSPs and IPSPs are integrated. Where action potentials are initiated

The Axon Hillock

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Reverse movement of an action potential from the axon hillock into the dendritic field

Back Propagation

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How Sensory Stimuli Produce Action Potentials

We receive information about the world through–bodily sensations (touch and balance)–auditory sensations (hearing)–visual sensations (sight)–chemical sensations (taste and olfaction)•Neurons related to these diverse receptors all have ion channels on their cell membranes.•These ion channels initiate the chain of events that produces a nerve impulse

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part of the muscle membrane that is contacted by the axon terminal

End Plate

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Chemical transmitter that the axon terminal releases at the muscle end plate

Acetylcholine

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NT that acts as a hormone to allow fight or flight during times of stress and as a neurotransmitter in the central nervous system

Epinephrine (EP, or adrenaline)

Chemical released by a neuron onto a target with an excitatory or inhibitory effect

Neurotransmitter

The junction where messenger molecules (neurotransmitters) are released from one neuron to excite or inhibit the next neuron

Chemical Synapse

Where the action potential terminates to release the chemical message

Presynaptic Membrane (axon terminal)

The receiving side of the chemical message; EPSPs or IPSPs are generated

Postsynaptic Membrane (dendritic spine)

Small gap where the chemical travels from presynaptic to postsynaptic membrane

Synaptic Cleft (space between)

Small membrane-bound spheres that contain the neurotransmitter(s)

Synaptic Vesicle (presynaptic)

Membranous compartment that holds several vesicles containing the neurotransmitter(s)

Storage granule (presynaptic)

Site to which a neurotransmitter molecule binds

Postsynaptic receptor (postsynaptic)

Study of the ways drugs affect the nervous system and behavior

Psychopharmacology

Chemical compounds administered to produce a desired change

Drugs

Substance that acts to alter mood, thought, or behavior, used to manage neuropsychological illness

Psychoactive Drug

How the Body Eliminates Drugs

Drugs are broken down (catabolized) in the kidneys, liver, and intestines. Drugs are excreted in urine, feces, sweat, breast milk, and exhaled air. Some substances that cannot be removed may build up in the body and become toxic

Drug Action at Synapses

Most psychoactive drugs exert their effects by influencing synaptic chemical signaling

Substance that enhances the function of a synapse

Agonist

Substance that blocks or decreases the function of a synapse

Antagonist

Drugs affect the synaptic function via:

Synthesis, Packaging and storage, release, receptor interaction, inactivation by reuptake, degradation

When a response to a drug weakens with repeated use.

Tolerance

Increase in number of enzymes in the liver, blood, or brain used to break down a substance

Metabolic tolerance

Activities of brain cells adjust to minimize effects of the substance

Cellular tolerance

People learn to cope with being intoxicated. Context can be powerful: tolerance levels higher for places where drug is typically taken.

Learned tolerance

Increased effects from the drug from successive doses.

Sensitization

Most drugs that have psychoactive effects influence chemical reactions at neuronal ____.

synapses

People have been using drugs for therapeutic and recreational reasons throughout history

Psychoactive Drugs

The most widely consumed psychoactive drug, caffeine

Adenosinergic

Nicotine is found in the leaves of the tobacco plant.

Cholinergic

At low doses, ______ agonists reduce anxiety; at medium doses, they sedate; at high doses, they anesthetize or induce coma

GABAergic

The _________ system has several receptors, such as NMDA, AMPA, and kainite

glutamatergic

Dopamine agonists that are used recreationally: Cocaine, amphetamine, methamphetamine. Dopamine agonists that are medically prescribed: Dextroamphetamine (Adderall), methylphenidate (Ritalin), L-dopa

Dopaminergic

Some _________ agonists are medically prescribed for the treatment of major depression.

Serotonergic

Any endogenous or exogenous compound that binds to opioid receptors to produce morphine-like effects. Includes codeine, morphine, heroin, oxycodone, fentanyl.

Opioidergic

Tetrahydrocannabinol (THC) is one of 84 ________ and the main psychoactive constituent in cannabis

Cannabinergic

Drugs prescribed for depression primarily exert their effect on the _____ system.

serotonergic

Alcohol has a selective depressant effect on the cortex (the region of the brain that controls judgment), while sparing subcortical structures (areas responsible for more primitive instincts, such as desire). “Too drunk to know better”

Disinhibition theory

Behavior under the influence of alcohol often differs with the context.

Limitation

Behavior under the effects of alcohol is _____

Learned

Under the influence of alcohol, people respond to a restricted set of immediate and prominent cues and ignore more remote cues and potential consequences

Behavioral Myopia

A pattern of drug use in which people rely on a drug chronically and excessively, allowing it to occupy a central place in their life

Substance Abuse

A complex brain disorder characterized by escalation, compulsive drug taking, and relapse; called substance use disorder per the DSM-5

Addiction

Physical and psychological behavior displayed by an addict when drug use ends

Withdrawl

Increased behavioral and cognitive activity so that at certain levels of consumption, the drug user feels energetic and in control

Psychomotor activation

______ are associated with an increased risk of drug initiation and drug addiction. Can include emotional, physical, and sexual abuse or neglect, among other experiences

Adverse childhood experiences (ACEs)

Females are ____ as sensitive to drugs as males, on average.

twice

Who is more likley to abuse nicotine, alcohol, cocaine, amphetamine, opioids, cannabinoids, caffeine, and PCP.

Women

habitual drug users initially experience pleasure but then endure psychological and physiological withdrawal symptoms as the drug wears off

Pleasure and Dependence

Wanting (craving) and liking (pleasure) may be produced by different parts of the brain

Wanting-and-liking Theory

Decision to take a drug is made in the _________

frontal cortex

Wanting drugs springs from activity in the ____ system

dopaminergic

The two most used drugs, ____ and ____, are legal.

Alcohol and Tobacco

Many substances, even natural ones such as glutamate, can be ______

neurotoxins

Does alcohol directly cause brain damage?

______ use is related to the blockage of cerebral blood flow and other changes in blood circulation

Cocaine

________ can be associated with damage to the thalamus and limbic system

Chronic alcohol use

Produces neurohormones to stimulate the pituitary gland

Hypothalamus

Secretes releasing hormones to influence target endocrine glands

Pituitary Gland

Release appropriate hormones into the blood to act on target organs and tissues

Target endocrine glands

Fat-soluble chemical messenger synthesized from cholesterol. Examples: gonadal (sex) hormones, thyroid

Steroid hormone

Chemical messenger synthesized by cellular DNA that acts to affect the target cell’s physiology. Examples: insulin, growth hormone

Peptide hormone

Maintain internal metabolic balance and regulation of physiological systems

Homeostatic hormones

Control reproductive functions, sexual development, and behavior

Gonadal (sex) hormones

Secreted in times of stress; important in protein and carbohydrate metabolism

Glucocorticoids

Caused by a failure of the pancreas to secrete enough (or any) insulin

Diabetes mellitus

High blood glucose levels; cells are not using glucose and therefore cannot function properly

Hyperglycemia

Low blood glucose levels

Hypoglycemia

A class of synthetic hormones related to the male sex hormone testosterone that have both muscle-building (anabolic) and masculinizing (androgenic) effects

Anabolic–Androgenic Steroids

A stimulus that challenges the body’s homeostasis and triggers arousal

Stressor

Physiological and behavioral arousal; any attempt to reduce the stress

Stress Response

A device that serves as a sensitive voltmeter. Used to record voltage changes on an axon

The Oscilloscope

A set of electrodes small enough to place on or into an axon

Microelectrodes

Movement of ions from an area of higher concentration to an area of lower concentration

Diffusion

Level of concentration of ions from one side of the membrane compared to the other.

Concentration Gradient

Difference in charge between two regions that allows a flow of current if the two regions are connected

Voltage Gradient

Crossing a Cell Membrane

1) Ions can cross a cell membrane through the appropriatly shaped channel 2) A gated channel changes shape to allow the passage of substances when gates are open and to prevent passage when one or both gates are closed. 3) a pump transported changes shape to carry substances across a cell membrane

Increase in electrical charge across a membrane (more negative). Usually due to the inward flow of chloride ions or outward flow of potassium ions

Hyperpolarization

****Steps of the Action Potential****

The voltage across the membrane suddenly reverses, making the intracellular side positive relative to the extracellular side (Na+ entry) then it abruptly reverses (K+exiting) to restore the resting potential (shown in (A))

a long-term neuromuscular disease that leads to varying degrees of skeletal muscle weakness.

Myasthenia gravi

Otto Loewi (1921)

Frog heart experiment. Role of the the vagus nerve and the neurotransmitter acetylcholine (ACh) in slowing heart rate

The neurotransmitter must be

1. Synthesized and stored in the axon terminal 2. Transported to the presynaptic membrane and released in response to an action potential 3. Able to activate receptors on the target-cell located on the postsynaptic membrane 4. Inactivated in synaptic gap or reuptake to presynaptic neuron

What effect does calcium influx have on NT release?

Calcium influx leads to NT vesicles to be brought down and then released into the synapse

Protein embedded in the membrane of a cell that has a binding site for a specific neurotransmitter

Transmitter-Activated Receptors

On postsynaptic side, neurotransmitter may

1. Depolarize the postsynaptic membrane causing excitatory action on the postsynaptic neuron (EPSP) 2. Hyperpolarize the postsynaptic membrane causing inhibitory action on the postsynaptic neuron (IPSP) 3. Initiate other chemical reactions that modulate either the excitatory or inhibitory effect, or influence other functions of the receiving neuron

Deactivation of the Neurotransmitter is Accomplished in at Least Four Ways

1.Diffusion away from synaptic cleft2.Degradation by enzymes in the synaptic cleft3.Reuptake into the presynaptic neuron for subsequent reuse4.Taken up by neighboring glial cells

the variety of NT's

over 50, some inhibitory AND excitatory, more than one active at synapse for some, no simple behavioral effects from NTs

How does an electrical synapse differ from a chemical synapse?

Electrical synapses are fast. Chemical synapses are more flexible (amplify or diminish signal).

Three Classes of Neurotransmitters

1. Small-molecule transmitters 2. Peptide transmitters 3. Transmitter gases

Act as hormones that respond to stress. Example: a mother bonding with her baby.

Peptide Transmitters

Active in maintaining waiking electroencephalographic pattern of the cortex. Alzheimers

Cholinergic System

Active in maintaining normal motor behavior. Parkinsons

Dopaminergic System

Active in maintaining emotional tone. Depression and Mania

Noradrenergic System

Active in maintaining waiking electroencephalographic pattern. Schizophrenia

Serotonergic System

Injecting into the brain

allows it to act quickly in low doses

orally taking drugs

safest option

drugs that are weak acids:

Pass from the stomach to the bloodstream

Drugs that are weak bases:

Pass from the intestines to the bloodstream

drugs Injected into muscle

encounter more barriers than inhaled drugs

Drugs inhaled:

Encounter few barriers to the brain

drugs injected into the bloodstream

encounter fewest barriers to the brain

Drugs contained into adhesive patches:

are absorbed through the skin into the bloodstream