Neurons and Synaptic Transmission Flashcards
What is the neurons main function?
To transmit chemical and electrical signals around the body
Where are most neurons located in the body?
80% of neurons are located in the brain
What are the 3 types of neurons?
Sensory neurons
Relay neurons
Motor neurons
What does unipolar and bipolar mean in regards of neurons?
Unipolar - transmit messages
Bipolar - transmit and receive messages
What do sensory neurons do?
Collect and process information from 1 of the 5 senses and carry that info towards the CNS
Unipolar
What do relay neurons do?
Found within the CNS and connect sensory and motor neurons together.
Bipolar
What do motor neurons do?
Carry information/impulses away from the CNS to the rest of the body, effectors - muscles and glands
Bipolar
What are the different parts of a sensory neuron?
Receptor cell
Myelin sheath
Axon
Cell body
What are the different parts of a relay neuron?
Dendrites
Cell body
Axon
Pre-synaptic terminal
What are the different parts of a motor neuron?
Dendrites
Cell body
Myelin sheath
Axon
Node of Ranvier
What are dendrites?
These carry impulses from neighbouring neurons to the cell body
What is a cell body?
This contains the nucleus which holds the genetic information of the cell
What id the myelin sheath?
A fatty layer that protects the axon and speeds up transmission
What is nodes of ranvier?
These speeds up transmission by forcing a jump across the axon
What is the axon?
The stem which carries impulses away from the cell body
What are terminal buttons?
Pass impulses to neighbouring neurons across the gap between each neuron.
What is action potential?
When info from sensory neurons are passed to the dendrites of another neuron, then passed down to the cell body to the axon. When info arrives at the axon it travels down its length in the form of an electrical signal -called action potential.
What happens when action potential reaches the terminal buttons?
It transfers to another neuron or tissue over the synapse.
What is a synapse?
The gap between two neurons.
What are the parts in synaptic transmission?
Ends of the dendrites
Vesicle - contains 1 or more neurotransmitter
Presynaptic nerve - previous neurons terminal buttons
Neurotransmitters
Synaptic cleft
Receptors - specific to the neurotransmitters
Postsynaptic nerve - next neurons terminal buttons
Why can neurons only travel in one direction?
Vesicles containing NT are only found in the presynaptic membrane.
NT receptors are only found on the presynaptic membrane.
Binding of NT onto receptors allows the info to be transmitted,
Dendrites carry info to the cell body and the axon carries info away from the cell body.
What is the process of synaptic transmission?
- Action potential travels through the axon
- Causing vesicles to fuse with the membrane and release NT into synaptic cleft
- Chemical signals are passed through the synaptic cleft
- The neurotransmitters either bind to postsynaptic neurons receptors, reuptake back into the presynaptic neuron, diffuse away naturally, or gets digested by enzymes.
- the next neurons actions are determines by whether the NT is excitatory or inhibitory.
What are neurotransmitters?
Chemical messengers that travel through travel through neurons and instruct our nervous and endocrine system to perform certain physiological responses
What are some examples of neurotransmitters?
Adrenaline
Noradrenaline
Serotonin
Dopamine
Glutamate
GABA
What are the two types of neurotransmitters?
Excitatory and Inhibitory
What are excitatory neurotransmitters, and examples?
they excite the brain and keep the action potential going, passing the NT along to repeat the process of synaptic transmission.
Adrenaline and Glutamate
What are inhibitory neurotransmitters, and examples?
These calm the brain, preventing the action potential from moving along any further.
GABA and Serotonin
What is it called when an excitatory neurotransmitter binds with a postsynaptic receptor, and what does it do?
Excitatory postsynaptic potential (EPSP).
The next neuron is more likely to fire, which then the message continues its journey through the nervous system.
What is it called when an inhibitory neurotransmitter binds with a postsynaptic receptor, and what does it do?
Inhibitory postsynaptic potential (IPSP).
The next neuron is less likely to fire, which then the message may shortly end.
What does summation mean?
If both EPSP and IPSP arrive at the cell the soma gathers data from the dendrites to determine whether or not the cell fires.
