CNS and neurotransmitters (AO1) Flashcards
Define “the nervous system”.
A system of organs and cells that is specialised for coordinating behaviour
What are the 2 sections of the nervous system?
Central Nervous System (CNS) - The brain, spinal cord and neurone cells
Peripheral Nervous System (PNS) - a series of nerves that carry information between CNS and the rest of body
What are the two sections of the peripheral nervous system?
Somatic nervous system - voluntary skeletal muscles
Autonomic nervous system - involuntary muscles i.e. organs
What are the two sections of the autonomic nervous system?
Parasympathetic - ‘rest & digest”
Sympathetic - “fight or flight”
What are the 3 functions of the central nervous system?
Detecting environmental changes and stimuli
Eg. sound and smell
Processing information to produce a response
Eg. emotional reactions to significant life events
Co-ordinating muscles to produce a response
Eg. moving away from a falling object
What are the 6 parts of the neuron and what are their functions?
Dendrites - receive electrical impulses from neighboring neurons
Soma - cell body which contains most of the cell’s organelles
Nucleus - contains cell’s DNA
Axon - transfers electrical impulse signals from cell body to synapse
Myelin sheath- insulates axon to help keep electrical signals inside the cell, allowing them to move faster
Synapses - sends electrical impulses to neighboring neurons
Define “Schwann cells” and “Node of Ranvier”.
Schwann cells- cells that form the myelin sheath
Node of Ranvier - a gap in the myelin sheath on the axon
Define “saltatory conduction”.
Propagation of action potentials (electric impulses) along myelinated axons from one node of Ranvier to the next, increasing electrical transmission speed
Describe the stages of neurotransmission before and including diffusion. (4 points)
Action potential arrives at presynaptic neurone
Calcium channels open - influx of Ca+ ions into the presynaptic neurone
Neurotransmitter-carrying vesicles move to the presynaptic membrane and fuse with the cell membrane
Exocytosis of neurotransmitter into synaptic cleft - neurotransmitter diffuses across
Describe the stages of neurotransmission after diffusion. (4 points)
Neurotransmitter binds to receptors on the postsynaptic membrane
Ligand-gated ion channels on postsynaptic membrane open - influx of Na+ ions at postsynaptic membrane causes depolarisation
Action potential in postsynaptic membrane is stimulated
Neurotransmitter broken down and taken back into synaptic vesicles - occurs via receptors in presynaptic membrane
Define “agonist” and “antagonist”.
Agonist - a drug that occupies receptors and activates them
Antagonist - a drug that occupies receptors but doesn’t activate them, effectively blocking them
What is an “excitatory synapse”?
+ Increases the activity of post synaptic membrane
+ By depolarisation
+ Due to influx of Na+ ions
+ Causing an action potential to be fired
What is an “inhibitory synapse”?
+ Decreases activity of postsynaptic membrane
+ By hyperpolarisation
+ Due to influx of Cl- ions
+ Causing no action potential to be fired
