Chapter 2.4 The Synapse Flashcards
neural communication reaches the axon
terminal and the message must cross the synaptic gap, then to the adjacent postsynaptic neuron. This is called ___
synaptic transmission
In 1921, ______ who stimulated the heart of a frog with electrical impulses and had it pump a small amount of nutrient solution. When the fluid was transferred to another heart, it operated in a
similar way. This provided proof that chemical substances also convey nerve signals to the organ and led the discovery of chemical transmission of nerve impulses.
Otto Loewi
The concept of synapse was first introduced in 1897 by ________, an English
neurophysiologist. He discovered the synaptic connections between neurons through a knee-jerk reflex dog experiment.
Charles Scott Sherrington
Synapse comes from the Greek terms
“syn-” (together) and “haptein” (to clasp)
What are the 4 properties of synapse?
speed of conduction, temporal summation, . spatial summation, inhibitory synapses
it is a____ property of synapse that the speed of conduction through the reflex arc varied but was never more than about 15 meters per second (m/s), whereas the velocities along
sensory or motor nerves were at about 40 m/s. That is
after he pinched a dog’s foot, the dog flexed that leg after a short delay
Speed of Conduction
repeated stimuli within a brief time have a cumulative
effect, called _____. A light pinch of the dog’s foot did not evoke a reflex, but a few rapidly repeated pinches did.
Temporal Summation
It is a property of a synapse that a two-point pinch on the dog’s leg produces a reflex than a single pinch, that a combination of excitations produced an action potential.
Spatial Summation
It is a ____ property of a synapse that vigorously pinched a dog’s foot, the flexor muscles of that leg contracted, and so did the extensor muscles of the other three legs. This process
is called__________, a small hyperpolarization is produced in the
postsynaptic cell as a result of input from the presynaptic cell.
Inhibitory Synapses; Inhibitory postsynaptic potential (IPSP
What are the 2 types of synapse?
electrical synapse, chemical synapse
This types of synapse takes place at the gap junction wherein the membrane of one
neuron comes into direct contact with the membrane of another to allow electrical signals travel straight over the synapse such as sodium and potassium ions. This process is involved
in learning, memory, and escape behaviors, those require fast transmission.
Electrical synapse
This is a type of synapse that a gap between two neurons where information passes chemically, in the form of neurotransmitter molecules.
Chemical synapse
What are the sequence of synapse according to chemical events?
- Neurotransmitters
- Synthesis of Transmitters
- Storage of Transmitters
- Release and Diffusion of Transmitters
- Activating Receptors of the Postsynaptic Cell
- Inactivation and Reuptake of Neurotransmitters
- Negative Feedback from the Postsynaptic Cell
____ at a synapse, a neuron releases chemical that affect another neuron.
These chemicals are known as neurotransmitters such as Acetylcholine, and among others.
Neurotransmitters
_____ neurons synthesize nearly all neurotransmitters from amino
acids, which the body obtains from proteins in the diet. For example, Acetylcholine
is synthesized from choline, which is abundant in milk, eggs, and peanuts.
Synthesis of Transmitters
______ most neurotransmitters are synthesized in the presynaptic
terminal, near the point of release. The presynaptic terminal stores high concentrations of
neurotransmitter molecules in vesicles.
Storage of Transmitters
________ At the end of an axon, depolarization opens
calcium gates in the presynaptic terminal that causes exocytosis or the bursts of release of
neurotransmitter from the presynaptic neuron.
Release and Diffusion of Transmitters
_____ Released neurotransmitters activated the
the postsynaptic cell with two activating effects
Activating Receptors of the Postsynaptic Cell
What are the 2 activating effects in postsynaptic cell?
Ionotropic Effects and Metabotropic Effects
_________ the enzyme acetylcholinesterase breaks it into two
fragments: acetate and choline. The choline diffuses back to the presynaptic neuron, which
takes it up and reconnects it with acetate already in the cell to form acetylcholine again. This process is called _______
Inactivation and Reuptake of Neurotransmitters; process called reuptake
_______ The postsynaptic cell evokes the release
of retrograde messenger that suppresses the release of neurotransmitter from the presynaptic
cell.
Negative Feedback from the Postsynaptic Cell
______ It is an activating effect when ions (sodium, potassium, calcium) pass in response
to a neurotransmitter. For example, when acetylcholine attaches the receptor, it folds
outward, widening the sodium channel, allowing sodium influx
Ionotropic Effects
______ It is an activating effect when a neurotransmitter attaches to this another group of
receptor, it requires G proteins and second messengers in order to conduct ionic
activity in neurons.
Metabotropic Effects
