Neurons and synaptic transmissions Flashcards
1-How many neurons are in the nervous system
2-What percentage of them are located in the brain
- 100 billion
- 80%
What are the three types of neurons
- motor
- relay
- sensory
What is the basic structure of a neuron
- cell body, including the nucleus which contains dendrites these carry nerve impulses to the cell body
What does the axon do
- caries the impulse away from the cell body down the length of the neuron
1-What does the myelin sheath do
2-What is the myelin sheath segmented by to speed up electrical transmissions
- protects the axon and speeds up electrical transmissions of the impulse
- gaps called nodes of ranvier
The synapse includes a space between them as well as a __________ ________ ___ __________ _______ ____
- presynaptic terminal and postsynaptic receptor site
signals within neurons are transmitted electrically, however signals between neurons are transmitted __________ __ ________ _____________
- chemically by synaptic transmission
When the elctrical impulse reaches the end of the neuron it triggers the release of ________________ ____ ____ ____ ______ ________ ________
- neurotransmitter from tiny sacs called synaptic vesicles
What are neurotransmitters
- chemicals that diffuse across the synapse to the next neuron in the chain
What does each neurotransmitter have
- it’s own specific molecular structure that fits perfectly into a post-synaptic receptor site, similar to a lock and key
What does the neurotransmitter serotonin cause
- inhibition in the receiving neuron resulting in the neuron becoming more electrically charged and less likely to fire
What does adrenaline cause
- excitation of the postsynaptic neuron by increasing its positive charge and making it more likely to fire
What is the space between two synapses called
- synaptic cleft
How are signals within neurons transmitted
- electrically
How are signals between neurons transmitted
- chemically by synaptic transmission
