neurons + synaptic transmission Flashcards
(25 cards)
What is a neuron?
A nerve cell that processes and transmits messages through electrical and chemical signals.
What do sensory neurons do?
They carry messages from the peripheral nervous system (PNS) to the central nervous system (CNS).
What is the function of relay neurons?
They connect sensory neurons to motor or other relay neurons. They have short dendrites and short axons.
What do motor neurons do?
They connect the CNS to effectors such as muscles and glands, causing a response.
What are dendrites?
Branchlike structures that protrude from the cell body and carry nerve impulses from neighboring neurons toward the cell body.
What is the axon?
A long fiber that carries impulses away from the cell body down the length of the neuron.
What is the myelin sheath?
A fatty layer that covers the axon and speeds up electrical transmission of the impulse.
What are nodes of Ranvier?
Gaps in the myelin sheath that speed up transmission by forcing the impulse to jump across the gaps.
What are terminal buttons?
Structures at the end of the axon that communicate with the next neuron across a synapse.
What is a synapse?
A tiny gap between neurons where chemical messages are transmitted.
What is synaptic transmission?
The process by which neighboring neurons communicate with each other by sending chemical messages across the synapse.
What are neurotransmitters?
Brain chemicals released from synaptic vesicles that relay signals across the synapse from one neuron to another.
What is the role of a postsynaptic receptor site?
It receives neurotransmitters from the synapse, converting the chemical message back into an electrical impulse.
What is excitation in synaptic transmission?
When a neurotransmitter increases the positive charge of the postsynaptic neuron, increasing the likelihood it will fire.
What is inhibition in synaptic transmission?
When a neurotransmitter increases the negative charge of the postsynaptic neuron, decreasing the likelihood it will fire.
What is an action potential?
A brief change in electrical charge that occurs when a neuron is activated, causing an electrical impulse to travel down the axon.
Where are the cell bodies of motor neurons located?
They may be in the CNS, but their long axons form part of the PNS.
Where are sensory neurons located?
Outside the CNS, in the PNS in clusters known as ganglia.
What is the direction of information flow in a neuron?
From dendrites to cell body to axon to terminal buttons.
What is summation in synaptic transmission?
The process by which excitatory and inhibitory influences on a postsynaptic neuron are summed; if net effect is excitatory, the neuron fires.
What is the reflex arc?
A neural pathway that controls a reflex action, such as the knee-jerk reflex.
What is the sequence of neurons in a reflex arc?
Sensory neuron → relay neuron → motor neuron.
What is the function of acetylcholine (ACh)?
A neurotransmitter found at each point where a motor neuron meets a muscle; it causes muscles to contract.
What is the function of serotonin?
A neurotransmitter that causes inhibition in the receiving neuron, making it less likely to fire.
