Flashcards in Neurons and Synaptic transmission Deck (28):
The basic building blocks of the nervous system, They are nerve cells that process and transmit messages through electrical and chemical signals.
Define sensory neurons?
These carry messages from the PNS to the CS. They have a long dendrite and a short axon.
Define relay neurons?
These connect the sensory neurons to the motor neurons. they have a short dendrite and a short axons
Define motor neurons?
These connect the CNS to affect things such as muscles and glands. They have short dendrites and long axons
Where are neurotransmitters found?
There are a hundred billion neurotransmitters in the human NS - 80% of which are located in the brain
What do neurons provide the nervous system with?
It's primary means of communication by transmitting signals electrically and chemically
What are the three types of neurons?
What is similar across neurons and whats the same?
Vary in size (from less than a mm up to a M)A=
Share the same basic structure
What is the structure of a neuron like?
The cell body contains a nucleus which contains the genetic material of the cell
Branch like structures called dendrites protrude from the cell body
What do dendrites do?
Carry nerve impulses from neighbouring neurons towards the cell body
What do axons do?
Carries the impulses away from the cell body down the length of the new one
What is the axon covered in?
A fatty layer of mileage sheets that protects the axon at speeds of electrical transmission of the imports
What is electric transmission?
The firing of a neuron when you are on in a rested state the inside of the cell is negatively charged compared to the outside. When activated by a stimulus the inside of the cell becomes positively charged for a split second course of an action potential to occur. This creates an electrical impulse travels down the axon towards the end of a neuron
How do neurone communicate?
Neurons communicate with eachother within groups known as neural networks. Each neuron is separate from the next. Neurons will send signals which are transmitted electrically , however signals between neurons transmit chemically across the synapse. When the electrical impulse reaches the end of the neuron it triggers the release of neurotransmitter from tiny sacs called synaptic vesicles.
What are neurotransmitters?
The chemicals that are fired across the synapse to the next neuron in the chain.
What happens once the neurotransmitter crosses the synapse?
It is taken up to the post-synaptic receptors site (the dendrites of the next neuron) where the chemical message is converted back into an electrical impulse and the process of transmission begins again in this new road
How many types of neurotransmitter have been identified in the brain?
Several dozen types identified in the brain as well as in the spinal cord and some clamps
In what ways are neurotransmitters specific?
Each neurotransmitter has its own specific molecular structure that fits perfectly into the post-synaptic receptor site (like lock and key)
They also have specialist functions e.g CH is found at each point where a new motor neuron ... it will cause muscles to contract
What two affects can neurotransmitters have on the neighbouring neurons give examples?
Inhibitory or exhibitory e.g serotonin causes inhibition resulting in the neuron becoming more negatively charged and less likely to fire. Adrenaline causes excitation of the post-synaptic neuron by increasing its positive charge and making it more likely to fire
Define synaptic transmission?
The process by which neighbouring neurons communicate with eachother by sending chemical messages across the gap (the synapse) that separates them
Brain chemicals released from synaptic vesicles is what really signals across the synapse from one neuron to another. Neurotransmitters can be broadly divided inti those that perform an excitatory function and those that perform an inhibitory function
When a neurotransmitter such as adrenalin increases the positive charge of the post-synaptic neuron. This increases the likelihood that the neuron will fire and pass on the electrical impulse
When a neurotransmitter, such as serotonin increases the negative charge of the post-synaptic neuron. This decreases the likelihood that a neuron will fire and pass on an electrical impulse.
Define a hormone?
Hormones are chemicals that are produced by endocrine glands such as the pituitary gland . In response to signals from the brain hormones are secreted directly into the bloodstream where they travel to their target cells and exert their influence by stimulating receptors on the surface of or inside cells. The presence of a hormone causes a physiological reaction in the cells altering its activity.
Define a neurotransmitter (long)?
When a nerve impulse reaches the end of one neuron, a chemical called a neurotransmitter is released. It travels from one neuron to the next across a junction called a synapse. There are many different types of neurotransmitter, some of which trigger the receiving neuron to send an impulse and some stop it from doing so. Those neurotransmitters that trigger nerve impulses in the receiving neuron and stimulate the brain into action are called excitatory neurotransmitters. Those that inhibit nerve impulses in order to calm the brain and balance mood are called inhibitory transmitters.
What would happen if the ... was continuous?
It would have the reverse affect and slow down the electrical impulse
What is the neuron segmented by?
Gaps called nodes of Ranvier - these speed up the transmission of impulse bisphosphonate by forcing it to jump across the gaps along the axon