the structure and function of neurons Flashcards
what do neurons generally do?
receive information and transmit it to other cells
how many neurons are thought to be in the CNS?
-100 billion in the brain
-1 billion in the spinal chord
what are the 3 types of neurons?
-sensory
-relay
-motor
what do sensory neurons do?
tell the rest of the brain about the external and internal environment by processing info taken from one of 5 senses
what do relay neurons do?
carry messages from one part of the CNS to another
they connect sensory and motor neurons
what do motor neurons do?
carry signals from the CNS which help organs, glands and muscle functions
what are the main components of a neuron?
-nucleus
-dendrites
-cell body
-axon
-myelin sheaths
-nodes of ranvier
-terminal buttons
what neurons are multipolar and what ones are unipolar? what does this mean?
multipolar = sends and receives messages, motor and relay
unipolar = only sends messages, sensory
what is synaptic transmission?
the process by which electrical nerve impulses are transmitted chemically by neurotransmitters across the synapse between one neuron and another
what are neurotransmitters?
chemical messengers transmitted in cerebral fluid that convey information between neurons and from neurons to muscles
describe the process of synaptic transmission
the electrical nerve impulse travels down the neuron, prompting the release of neurotransmitters at the pre-synaptic terminal
these chemicals are released into the synaptic fluid in the synapse
the adjacent neuron must quickly take up the neurotransmitters from the fluid and convert them to an electrical impulse to travel down the neuron to the next pre-synaptic terminal
research on neurons
-Yamamoto & Kitazawa 2001 - why cant be easily perceive when we’re touched in two places simultaneously? argued to be because of the inability of the nervous system to transmit that info accurately as the distance from the brain for the neurons receiving the message is different (eg shoulder v foot)
what does action potential mean?
only certain neurotransmitters can ‘unlock’ a message channel in certain receptors, like a lock and key system
when the right key (neurotransmitter) meets the right lock (receptor) a specific ion channel in the membrane is opened. ions flow through the membrane into the neuron
the flooding of ions can cause a ‘potential’ which can either be excitatory or inhibitory
what are excitatory potentials?
make it more likely for the neuron to fire
what are inhibitory potentials?
make it less likely for the neuron to fire, so if the message is likely to stop at the post-synaptic neuron
