Chapter 3: Synapses Flashcards
Synapse
A specialized gap as a point of communication between two neurons
Reflexes
Automatic muscular responses to stimuli
Reflex Arc
A circuit from sensory neuron to muscle response
Charles Scott Sherrington
Introduced the term synapse
Temporal Summation
(summation over time)
Repeated stimuli within a frief time have a cummulative effect
Presynaptic Neuron
A neuron that delivers transmission
Postsynaptic Neuron
A neuron that receives a transmission
Excitatory Postsynaptic Potential (EPSP)
A graded depolarization
Spatial Summation
Combination of effects of activity from two or more synapses onto a single neuron
Inhibitory Postsynapic Potential (IPSP)
- A temporary hyperpolarization of a membrane
- Occurs whensynaptic input selectively opens the gates for potassium ions to lvave the cell for chloride ions to enter the ell
Spontaneous Firing Rate
A periodic production of action potentials even without synaptic input
Synaptic Cleft
The space between the presynaptic and postsynaptic cells
Neurotransmitters
Chemicals released by neurons that affect other neurons
Amino Acids
Acids containing an amine group (NH2)
Monoamines
Chemicals formed by change in certain amino acids
Acetylcholine
A chemical similar to an amino acid, except that it includes an N(CH3)3 group instead of an NH2, group
Neuropeptides
Chains of amino acids
Purines
A category of chemicals including adenosine and several of its derivatives
Gases
One of the categories of neurotransmitters, including nitric oxide and possibly others
Nitric Oxide
A gas released by many small local neurons
Vesicles
Tiny nearly spherical packets filled with neurotrasmitter molecules
MAO
(monoamine oxidase)
Enzyme that converts catecholamines and serotonin into synaptically inactive forms
Transmitter-gated
Ion channel that opens temporarily when a neurotransmitter binds to it
Ligand-gated channels
Channel that opens when a neurotransmitter attaches
Metabotropic
Sequence of metabolic reactions that produce slow and long-lasting effects at a synapse
G-Protein
Protein coupled to guanosine triphosphate (GTP), an energy-storing molecule
Second Messenger
Communicates to many areas within the cell
Neuromodulators
- Chains of amino acids
- Released mainly by dendrites
Neurogliaform Cell
A kind of neuron that releases huge amounts of GABA all at once, producing widespread inhibition
Hormone
A chemical secreted by cells in one part of the body and conveyed by the blood to *influence other cells *
Endocrine Gland
Hormone-producing glands
Protein and Peptide Hormones
Composed of chains of amino acids
Pituitary Gland
An endocrine gland attached to the base of the hypothalamus
Postirior Pituitary
Portion of the pituitary gland, which releases hormones synthesized by the hypothalamus
Anterior Pituitary
Portion of the pituitary gland, composed of glandular tissue
Oxytocin
Hormone released by posterior pituitary; important for sexual and parental behaviors
Vasopressin
- (antidiuretic hormone)
- hormone released by posterior pituitary
- raises blood pressure and enables kidneys to conserve water
Releasing Hormones
Hormone released by the hypothalamus that flows through the blood to the anterior pituitary
Acetylcholinesterase
An enzyme that breaks acetylcholine into two fragments: acetate and choline
Reuptake
Reabsorption of a neurotransmitter by the presynaptic terminal
Transporters
Special membrane protein where reuptake occurs in the neurotransmitter
COMT (catechol-o-methyltransferase)
Enzyme that breaks down excess dopamine into inactive chemicals that cannot stimulate the dopamine receptors
Autoreceptors
Receptors that respond to the released transmitter by inhibiting further synthesis and release
Gap Junction
A direct contact of one neuron with another, enabling electrical transmission
