Chapt. 3 Flashcards
Tell me about a reflex arc.
these have a different speed of conduction compared to measure action potentials
Which is faster? The speed of conduction along an axon or the speed of conduction through a reflex arc?
The speed of conduction along an axon. It occurs at 40 m/s while a reflex’s speed is about 15 m/s.
What is temporal summation?
it explains that repeated stimuli can have a cumulative effect and can produce a nerve impulse when a single stimuli is too weak
What is a presynaptic neuron?
a neuron that delivers the synaptic transmission
What is postsynaptic neuron?
a neuron that receives the message
What is Excitatory Postsynaptic Potential (EPSP)?
graded potential that decays over time and space
What fact led to the idea of Spatial Summation?
the fact that several stimuli produce reflexes where a single stimuli cannot
What is Spatial Summation?
synaptic input from several locations can have a cumulative effect and trigger a nerve impulse (it is also critical to brain functioning)
What is Inhibitory Postsynaptic Potential (IPSP)?
it occurs when synpatic input selectively opens the gates for positively charged potassium ions to leave the cell or negatively charged chloride ions to enter the cells (serves as an active “brake” that suppresses excitation)
Explain Spontaneous Firing Rate.
it is the periodic production of action potentials despite synaptic input
What do EPSPs do to the number of action potentials occurring during the spontaneous firing rate?
increase it above the spontaneous firing rate
What do IPSPs do to the number of action potentials occurring during the spontaneous firing rate?
decrease it below the spontaneous firing rate
Communication across the synapse occurs via…?
chemical means
What are neurotransmitters?
chemicals that travel across the synapse and allow communication between neurons
What are the major categories of neurotransmitters?
- amino acids
- monoamines
- acetylcholine
- neuropeptides
- purines
- gases
What are reflexes?
autonomic muscular responses to stimuli
What are catecholimines?
these contain a catechol group and an amine group. (epinephrine, norepinephrine, dopamine)
What are the vesicles?
tiny spherical packets located in the presynaptic terminal where neurotransmitters are held for release
What is exocytosis?
the excretion of the neurotransmitter from the presynaptic terminal into the synaptic cleft (triggered by an arriving action potential)
How long does transmission across the synaptic cleft by a neurotransmitter take?
fewer than 0.01 microseconds
How many neurotransmitters do neurons release?
at least 2 different ones
What does the effect a neurotransmitter has depend on?
its receptor on the postsynaptic cell
Define the Ionotropic Effect.
This effect happens or takes place when a neurotransmitter attaches itself to receptors and immediately opens ion channels
What types of channels are controlled by a neurotransmitter?
transmitter-gated or ligand-gated channels
When do metabotropic effects occur?
when neurotransmitters attach to a receptor and initiate a sequence of slower and longer lasting metabolic reactions
What does the “General Rule” state about neurons?
a neuron delivers neuropeptides that diffuse to receptors throughout a wide area, but delivers other transmitters in small amounts directly adjacent to their receptors
What is the Exception to the “General Rule”?
the neurogliaform cell which is a neuron shaped like a glia cell that releases huge amounts of GABA all at once
Define a hormone.
a hormone is a chemical secreted by a gland or other cells that is transported to other organs by the blood where it alters activity
What are the endocrine glands responsible for?
the production of hormones
What do the transporters do?
they are special membrane proteins that facilitate reuptake
In what two ways is negative feedback in the brain accomplished?
through autoreceptors and post synaptic neurons
How do drugs work?
by mimicking our own neurochemistry
An antagonist is a drug that…
BLOCKS a neurotransmitter
An agonist is a drug that…
INCREASES a neurotransmitters EFFECTS
What parts of the nucleus respond to pleasure and motivation?
small parts respond to pleasure, large parts respond to motivation
Motivation is related to..
wanting
Pleasure is related to..
liking
In moderate amounts, alcohol is associated with what?
relaxation
What is alcoholism (alcohol dependence)?
the habitual use of alcohol despite medical or social harm
What can strongly influences alcoholism?
genetics
Contributed factors to substance abuse include:
- tolerance develops
- cravings in response to cues
- brain reorganization
What are some medications used to combat alcoholism?
- antabuse
- revia (naloxone)
- medications are mainly used to reduce cravings
How does Antabuse work?
it works by antagonizing (blocking) effects of acetaldehyde dehydrogenase and if a person drinks with it it turns into poisonous substance acetaldehyde and causes sickness (this medication is only moderately effective)
