Unit 3.4 - The Cells Of The Nervous System And Neuro Transmitters Flashcards
What do sensory neurons do?
Take impulses from sensory receptors to the central nervous system
What do interneurons do?
Transport impulses between sensory and motor neurons within the central nervous system
What do motor neurons do?
Take impulses from central nervous system to and affecter e.g. a muscle or gland
Why does myelination increase the speed of impulse transmission
Axon fibres are covered in myelin sheath which insulates the axon and speeds up impulse conduction
When does myelination increase from?
From birth to adolescence
What can certain diseases do to the myelin sheath?
Destroy it causing a loss of coordination
What do glial cells do?
Support neurons and produce myelin sheath
What is a synapse?
An area of communication between an axon of one neuron and a dendrite of another
What is a neurotransmitter?
A chemical that relays the message from the presynaptic neuron to the postsynaptic neuron
Describe the chemical transmission at synapse
- nervous impulse travels down the pre synaptic axon
- vesicles with neurotransmitters triggered to move to and fuse with presynaptic membrane
- neurotransmitter secreted into synaptic cleft
- receptors in post synaptic membrane recognise transmitter molecules and bind with them
- nervous impulse continuous along dendrite of post synaptic neuron
Why is it important to remove neurotransmitters from the synapse?
To prevent continuous stimulation of postsynaptic neuron is
What are the two types of signals?
Inhibitory or excitatory
What determines whether a signal is inhibitory or excitatory?
Type of receptor
What can synapses filter out?
Weak stimuli arising from insufficient secretion of neurotransmitters
What must happen in order to reach the threshold on the postsynaptic membrane to transport the impulse
A minimum number of neurotransmitter molecules must attach to receptors in order to reach the threshold on the postsynaptic membrane to transmit the impulse
What can I summation of a series of weak stimuli trigger?
Enough neurotransmitters to fire and impulse
What can convergent pathways do?
Release a Knouff neurotransmitter molecules to reach threshold and trigger and impulse
What are endorphins?
Neurotransmitters that stimulate neurons involved and reducing the intensity of pain
What does endorphin production increase in response to?
Severe injury, prolonged exercise, stress and certain foods
What are endorphins also connected to?
Feelings of euphoria obtain from activities such as eating, sex and prolonged exercise
What is dopamine?
A neurotransmitter that induces feelings of pleasure and reinforces particular behaviours in the reward pathway in the brain
What does the reward pathway involve?
Neurons which secrete or respond to dopamine
When is the reward pathway activated?
When an individual engages in our behaviour that is beneficial to them, for example eating when hungry
What are the two types of drugs used to treat neurotransmitters related to disorders?
Agonists and antagonists
What is agonist?
Chemicals that bind to and stimulate specific receptors mimicking the action of a neurotransmitter at a synapse
What are antagonists?
Chemicals that bind to specific receptors blocking the action of a neurotransmitter at the synapse
What do other drugs do?
Inhibits the enzymes which break down neurotransmitters or inhibit reuptake at the signups causing an enhanced effect
What are some disorders caused by changes in neurotransmitter release?
Alzheimer’s, Parkinson’s and some anxiety disorders
What can recreational drugs also do?
Act as agonists or antagonists
What do recreational drugs to?
Affect neurotransmission at synapse in the brain altering an individual’s mood, cognition, perception and behaviour
What do most recreational drugs affect?
Neurotransmission in the reward pathway of the brain
What do antagonists do?
Block specific receptors causing nervous system to increase sensitivity and number of receptors and as a consequence results in addiction
What do agonists do?
Stimulate specific receptors causing the nervous system to decrease sensitivity and number of receptors and as a consequence results in drug tolerance also known as desensitisation
