Exam 2 Flashcards
A- lions and K+ lions have _____ concentration inside the axon
Higher
CI- ions and Na+ ions are more concentrated ______ the axon
Outside
Inside the cell
Intracellular
Extracellular
Outside the cell
_______ can be produced by an influx of sodium ions and is produced by the opening of normally closed gates sodium channels
Depolarization
Large, brief reversal in polarity of an axon and lasts one millisecond
Action Potential
Voltage on a neural membrane at which an action potential is triggered via opening of the Na+ and K+ voltage sensitive channels
Threshold potential
The state of an axon in the polarizing period when an action potential cannot typically occur
Absolute Refractory Period
Increased electrical current is required to produce another action potential, potassium channels still open
Relative Refractory Period
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
Part of the axon that is not covered by myelin
Node of Ranvier
Propagation of an action potential at successive nodes of ranvier
Saltatory Conduction
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
Brief depolarization of a neuron membrane in response to stimulation. Neuron is more likely to produce an action potential
Excitatory Postsynaptic Potential (EPSP)
Brief hyperpolarization of a neuron membrane in response to stimulation–Neuron is less likely to produce an action potential
Inhibitory Postsynaptic Potential (IPSP)
______ are associated with the opening of sodium channels: allows influx of Na+
Excitatory Postsynaptic Potential (EPSP)
______ 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)
Pulses that occur at approximately the same time on a membrane are summed
Temporal Summation
Pulses that occur at approximately the same location on a membrane are summed
Spatial Summation
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
Reverse movement of an action potential from the axon hillock into the dendritic field
Back Propagation
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
part of the muscle membrane that is contacted by the axon terminal
End Plate
Chemical transmitter that the axon terminal releases at the muscle end plate
Acetylcholine
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?
No
______ 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
- Synthesized and stored in the axon terminal
- Transported to the presynaptic membrane and released in response to an action potential
- Able to activate receptors on the target-cell located on the postsynaptic membrane
- 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
- Depolarize the postsynaptic membrane causing excitatory action on the postsynaptic neuron (EPSP)
- Hyperpolarize the postsynaptic membrane causing inhibitory action on the postsynaptic neuron (IPSP)
- 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
- Small-molecule transmitters
- Peptide transmitters
- 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
