Neurons, synaptic transmission and neurotransmitters(3) Flashcards
What are the 3 types of neurone?
Sensory neurones
Motor neurones
Relay neurones
What is a neurone
A neurone is the basic building block of the nervous system. Neurons are nerve cells that process and transmit messages through electrical and chemical signals
What is a neurotransmitter
A neurotransmitter is a brain chemical released from synaptic vesicles. Neurotransmitters relay signals from one neurone to another across a synapse. They can have excitatory and inhibitory functions
What is synaptic transmission
Synaptic trnasmission is the process by which neighbouring neurones communicate with each other by sending chemical messages across the gap called a synpase
What is a sensory neurone
Carries messages from the sensory receptors such as touch and moves along nerves to the CNS.
What is a motor neurone
The motor neurone carries the messages from the CNS along nerves in the PNS to move around the body
What is a relay neurone
Relay neurones connect sensory and motor neurone and have short dendrites and short axons
What is the function of a neutone?
Neurones carry messages around the body at a vast speed. They may be responsible for muscle movements or chemical reactions
What is excitation
Excitation occurs when receptor stimulation results in an increase in the positive charge of the postsynaptic neuron which increases the likelihood of the neuron firing
What is inhibiton
Inhibition, in psychology, conscious or unconscious constraint or curtailment of a process or behaviour, especially of impulses or desires.
What is summation
Summation, in physiology, the additive effect of several electrical impulses on a neuromuscular junction, the junction between a nerve cell and a muscle cell. Individually the stimuli cannot evoke a response, but collectively they can generate a response.
What is the Role of the Neurone?
The purpose of the neurone is to transmit messages around the body.
There are networks of millions of neurons in the brain and body that are all connected and communicate with each other.
How does Communication along Neurones happen?
- The dendrite receives a message, often from another neurone
- This triggers an action potential (electonic message within the cell body)
- This action potential travels down the axon. The myelin sheath & nodes of Ranvier help speed up the process
- The action potential reaches the axon terminals and terminal buttons
- The terminal buttons pass this message to the next part of the body. This could be another Neurone, a muscle or a gland.
How are messages sent through the synapse?
- And electrical message (action potential) is sent along the axon of the presynaptic neurone
- Eventually it reaches the axon terminals
- Neurotransmitters are released into the synaptic cleft, and diffuse across the space between the two neurones
- The neurotransmitters attach to the receptor of the dendrite of the postsynaptic neurone
- When enough receptors are activated (the threshold is reached), a new action potential is created on the next neurone
- Any neurotransmitter that remains in the synapse is taken back into the presynaptic neuron in a process called reuptake
What is the Function of Neurotransmitters?
Different neurotransmitters are responsible for regulating different feelings and behaviours
What is the Role of Dopamine?
Dopamine is associated with pleasure reward and reinforcement.
It is involved in addictive behaviours.
It is also involved in posture and the control of movement
What is the Role of Serotonin?
Serotonin is involved with mood control and feelings such as happiness.
It is also involved in pain, sleep, temperature and hunger.
What is the Role of Norepinephrine/Noradrenaline?
Norepinephrine is associated with the fight and flight response, with attention, and being ready for action.
What is the Role of Acetylcholine?
Stimulate muscle contraction, and is involved in motor control the movement.
It is linked to memory, thinking and learning.
It is also involved in expressions of some emotions e.g. anger and sexuality.
What is the Effect of Alcohol on Behaviour?
Short-Term: Varies depending on the individual, the mood and their environment. It can reduce anxiety and inhibition, or make an individual more aggressive.
Long Term: It can be addictive, lead to liver failure and damage to the brain & nervous system
What is Alcohol’s ‘mode of action’?
Has a depressant effect on the CNS, by inhibiting messages in the neurones and synapses.
It does this by increasing GABA (an inhibitory neurotransmitter).
What is the role of the Hippocampus?
The hippocampus in involved in synaptic functioning; and is in the medial temporal lobe
