Biopsychology- Neurons and synpatic transmission Flashcards
What is the function of dendrites?
Receive signals from other neurons or sensory receptor cells- typically connected to the cell body
What is the function of the cell body?
Contains the nucleus (genetic info)
What is the function of an axon?
Long slender fibre that carries nerve impulses in the form of electrical signal known as action potential
What is the function of the Myelin sheath?
Most axons are surrounded by myelin sheath which insulates the axon so electrical impulses travel faster along the axon
What is the function of the axon terminal?
Connects the neuron to another neuron (or directly to organs using synaptic transmission
What are the 5 structures of a neuron?
- Dendrites
- Cell body
- Axon
- Myelin sheath
- Axon terminal
Neurons vary in 1.____ but all share the same basic 2.____
- Size
- Structure
What are the 3 types of neurons?
-Sensory neuron
-Relay (interconnecting) neurons
-Motor neuron
What is the function of sensory neurons?
-Carry nerve impulses to the spinal cord and brain
-Nerve impulses are translated into sensations
-Not all sensory neurons reach the brain as some neurons stop at the spinal cord allowing for quick reflex actions
Where are sensory neurons found?
-Found in receptor cells
What is the length of the fibre of sensory neurons?
-Long dendrites and short axons
Where are relay (interconnecting) neurons found?
-In between sensory and motor neurons
-Found in the brain and spinal cord
What is the function of relay neurons?
-Allow sensory and motor neurons to communicate
What is the length of the fibres on the relay neuron?
-Short dendrites and short axons
Where are motor neurons found?
-Found in the CNS
What is the function of motor neurons?
-Control muscle movements
-When motor neurons are stimulated they release neurotransmitters that bind to receptors on muscles to trigger a response
What is the length of fibres in a motor neuron?
-Short dendrites and long axons
What is synaptic transmission?
-A nerve impulse passes across the synaptic gap from one neuron (pre-synaptic neuron) to another (Post synaptic neuron)
What is a synapse?
Each neuron is separated from the next by a tiny gap- a conjunction of the end of the axon of one neuron and the dendrite or cell body of another neuron
What is the 1st step of Synaptic transmission?
-Action potential- information passed down the axon of the neuron as an electrical impulse or the contraction of a muscle
Define action potential
-The change in electrical potential that propagates along the axon of a neuron during the transmission of a nerve impulse or the contraction of a msucle
What is the 2nd step of Synaptic transmission?
Once the action potential reaches the end of the axon it needs to be transferred to another neuron/ tissue by crossing the synaptic gap
What is the 3rd step of synaptic transmission?
At the end of the neuronic (in the axon terminal) are the synaptic vesicles which contain neurotransmitters
What is the 4th step of synaptic transmission?
The electrical (nerve) impulse (action potential) stimulates the release of neurotransmitters from the synaptic vesicles
What is the 5th step of synaptic transmission?
Neurotransmitters then carry the signal across the synaptic gap, they bind to receptor sites on the postsynaptic cell (neuron) which then becomes activated
Which neurotransmitters make the postsynaptic cell/ neuron more likely to fire? (eg. noradrenaline)
Excitatory
What do inhibitory neurotransmitters do? (eg. GABA)
Make them less likely to fire
What is summation?
The net effect of the EPSPS and IPSPS (adding up the positive and negative charges)
When does excitation occur?
-When receptor stimulation results in an increase in the positive charge of the postsynaptic neuron and increases the likelihood of the neuron firing and passing on the electrical impulse (EPSP)
When does Inhibition occur?
When receptor stimulation results in an increase in the negative charge of the postsynaptic neuron and decreases the likelihood of the neuron firing and passing on the electrical impulse
How many neurons (nerve cells) are in the body?
100 billion nerve cells, 80% located in the brain
What are neurons?
Cells that conduct nerve impulses, transmit signals electrically and chemically
In a reflex arc, like the knee-jerk reflex, a stimulus such as a hammer hitting the knee is defected by sense organs in the 1.____ which conveys a message along a 2.___. The message reaches the 3.___ where it connects with a 4.____, this then transfers the message to a motor neuron which then carries the message to a 5._____ such as a muscle which causes the muscle to contract and the knee to jerk/move,
- PNS
- Sensory neuron
- CNS
- Relay neuron
- Effector
