Biopsychology- Neurons And Synaptic Transmission Flashcards
Neuron -
The basic building blocks of the nervous system, neurons are nerve cells that process and transmit messages through electrical and chemical signals.
Sensory neurons -
These carry messages from the PNS (peripheral nervous system) to the CNS (central nervous system). They have long dendrites and short axons.
Relay neurons -
These connect the sensory neurons to the motor or other relay neurons. They have short dendrites and short axons.
Motor neurons -
These connect the CNS (central nervous system) to effectors such as muscles and glands.
They have short dendrites and long axons.
Synaptic transmission -
The process by which neighbouring neurons communicate with each other by sending chemical messages across the gap (the synaptic cleft) that separates them.
Neurotransmitter -
Brain chemicals released from synaptic vesicles that relay signals across the synapse from one neuron to another. Neurotransmitters can be broadly divided into those that perform an excitatory function and those that perform an inhibitory function.
Excitation -
When a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neuron. This increases the likelihood that the neuron will fire and pass on the electrical impulse.
Inhibition -
When a neurotransmitter, such as serotonin, makes the charge of the postsynaptic neuron more negative. This decreases the likelihood that the neuron will fire and pass on the electrical impulse.
What are the three types of neurons?
The three types of neurons are motor neurons, sensory neurons, and relay neurons.
What is the function of sensory neurons?
Sensory neurons carry messages from the peripheral nervous system (PNS) to the central nervous system (CNS). They have long dendrites and short axons.
What is the function of relay neurons?
Relay neurons connect sensory neurons to motor neurons or other relay neurons. They have short dendrites and short axons.
What is the function of motor neurons?
Motor neurons connect the central nervous system (CNS) to effectors such as muscles and glands. They have short dendrites and long axons.
What do neurons do in general?
Neurons transmit signals electrically and chemically, providing the nervous system with its primary means of communication.
How many neurons are in the human nervous system, and where are most of them located?
There are 100 billion neurons in the human nervous system, 80% of which are located in the brain.
What is the primary means of communication in the nervous system?
Neurons transmit signals electrically and chemically, providing the nervous system with its primary means of communication.
What are the three types of neurons?
The three types of neurons are:
• Motor neurons
• Sensory neurons
• Relay neurons
What is the size range of neurons?
Neurons vary in size from less than a millimetre to up to a metre long.
What does the cell body (soma) of a neuron contain?
The cell body contains a nucleus, which holds the genetic material of the cell.
What are dendrites, and what is their function?
Dendrites are branch-like structures that protrude from the cell body. They carry nerve impulses from neighbouring neurons towards the cell body.
What is the function of the axon in a neuron?
The axon carries impulses away from the cell body down the length of the neuron.
What is the myelin sheath, and what does it do?
The myelin sheath is a fatty layer that covers the axon. It protects the axon and speeds up electrical transmission of impulses.
What are nodes of Ranvier, and what is their role?
Nodes of Ranvier are gaps in the myelin sheath. They speed up impulse transmission by forcing the impulse to ‘jump’ across the gaps along the axon.
What are terminal buttons, and what is their function?
Terminal buttons are found at the end of the axon. They communicate with the next neuron in the chain across a gap known as the synapse.
What happens during the firing of a neuron?
When a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split second, causing an action potential. This creates an electrical impulse that travels down the axon.
What is synaptic transmission?
Synaptic transmission is the process by which neurons communicate chemically across a synapse.
What is the synapse?
The synapse is the space between neurons (the synaptic cleft), including the presynaptic terminal and postsynaptic receptor site.
How are signals transmitted within and between neurons?
Signals within neurons are transmitted electrically, while signals between neurons are transmitted chemically via synaptic transmission.
What happens at the presynaptic terminal during synaptic transmission?
When the electrical impulse reaches the presynaptic terminal, it triggers the release of neurotransmitters from synaptic vesicles.
What are neurotransmitters?
Neurotransmitters are chemicals that diffuse across the synapse to the next neuron in the chain.
What happens once the neurotransmitter crosses the synapse?
It is taken up by the postsynaptic receptor sites, where the chemical message is converted back into an electrical impulse.
How do neurotransmitters fit into postsynaptic receptor sites?
Each neurotransmitter has a specific molecular structure that fits perfectly into a receptor site, like a lock and key.
What is an example of a neurotransmitter and its function?
Acetylcholine (ACh) is found at motor neuron-muscle junctions and causes muscles to contract.
What is the difference between excitation and inhibition in neurotransmitters?
- Excitation: Makes a neuron more positively charged and likely to fire (e.g., adrenaline).
- Inhibition: Makes a neuron more negatively charged and less likely to fire (e.g., serotonin).
What is summation in the context of synaptic transmission?
Summation is the process of adding excitatory and inhibitory influences on a neuron. If the net effect is excitatory, the neuron is more likely to fire; if inhibitory, it is less likely to fire.
When is the action potential of a postsynaptic neuron triggered?
The action potential is triggered only if the sum of excitatory and inhibitory signals reaches the threshold
