Chapter 3- Synapses Flashcards
Sherrington deduced that transmission at a synapse must be slower than conduction along an axon. This was based on what kind of evidence?
The speed of reflexive responses
What is the correct sequence of chemical events at a synapse?
Synthesis, Transport, Release, Reuptake
What is a synapse?
A specialized gap between neurons
What is a reflex?
Automatic muscular responses to stimuli
What is a reflex arc?
Circuit from sensory neurons to muscle response
What is Temporal summation?
Repeating stimuli within a brief time have a cumulative effect
What is a postsynaptic neuron?
The cell that receives the message
What is a pre-synaptic neuron?
The cell that delivers the transmission
What is an Excitatory postsynaptic potential ( EPSP)?
Graded depolarization that occurs when sodium ions enter the cell. If it does not reach it’s threshold, depolarization decays quickly
What is an Inhibitory Postsynaptic potential? ( IPSP)
Hyperpolarization that occurs when synaptic input selectively opens the gates for potassium ions to leave the cell ( carrying a positive charge) of for chlorine ions ( negative charge) to enter the cell
What is the speed of conduction along an axon?
40 m/s
What is the speed of conduction through a reflex arc?
15 m/s
What is spatial summation?
Synaptic inputs from various locations combine their effects on a neuron. critical to brain functioning
What happens at an inhibitory synapse?
Input from an axon hyperpolarizes the postsynaptic cell
What is the Spontaneous Firing Rate?
Periodic reproduction of action potentials even without synaptic input
What is a neurotransmitter?
Chemicals released by one neuron that affect a second neuron
Name the six types of neurotransmitters
Amino Acids, Neuropeptides, Acetylcholine, Monoamines, Purines, Gases
What is exocytosis?
Excretion of the neurotransmitters from the presynaptic terminal into the synaptic cleft. Triggered by an action potential reaching the end of an axon.
Name 3 neurotransmitters that are Catecholamines.
Epinephrine, Norepinephrine, and dopamine
Where are neurotransmitters stored?
Most neurotransmitters are synthesized in the presynaptic terminal
What are vesicles?
tiny packets that store high concentrations of neurotranmitters
Does a single neuron release all of the neurotransmitters?
No, many release a combination of two or more neurotransmitters
Why does a neuron release a combination of neurotransmitters instead of just one?
Because that specific combination makes the message more complex
What are Ionotropic effects?
They occur at one type of receptor, are quick and only last for a brief time, convey messages and are good for vision and hearing
What are Metabotropic effects?
They initiate a series of metabolic reactions, are slower and longer lasting , use a large variety of neurotransmitters and are good for taste, smell ad pain