Psychology test - thursday Flashcards
What is synaptic transmission?
Synaptic transmission is a method of neurons communicating with each other, relaying information to the CNS across sensory neurons and carrying out responses dictated by the brain through sending information to effectors via motor neurons.
What are synapses?
Synapses are tiny gaps between nerve cells and at the synapse, the electrical signal which travels down the neuron is changed into a chemical signal. These chemicals called neurotransmitters diffuse across the synaptic gap.
What is the first step of the synaptic transmisson process?
Once an electrical impulse has arrived at the terminal button at the end of the axon (the pre-synaptic neuron), it needs to be transferred to another neuron (the post-synaptic neuron) or to tissue, to do this it must cross the synaptic gap.
What is the second step in the neurotransmission process?
At the end of the axon there are a number of sacs known as synaptic vessicles, these contain the chemical messengers (neurotransmitters) that assist the transfer of the impulse.
What is the third step of the synaptic transmission process?
As the action potential reaches the vessicles, it causes them to release their contents through a process called exocytosis.
What is the fourth step in the neurotransmission process?
The released neurotransmitters diffuse across the synaptic gap (down a concentration gradient), where they bind to specific receptors on the dendrite of the post-synaptic neuron.
What is the fifth step in the process of synaptic transmission?
Depending on the neurotransmitter, receptors then produce either an excitatory or inhibitory response on the postsynaptic neuron.
What is excitation or inhibition determined by?
Excitation or summation is determined by a process called summation.
What is the sixth step of the process of synaptic transmission?
Because the receptors are only on the postsynaptic membranes, synapses make sure impulses are unidirectional - the impulse can only travel in one direction.
What is the seventh step of the process of neurotransmission?
The effects of the neurotransmitters are then terminated by a process called re-uptake. Remaining neurotransmitters are broken down by enzymes or reabsorbed by the pre-synaptic neuron and stored for later use.
What are neurotransmitters?
Brain chemicals released from synaptic vesicles that relay signals across the synapse from one neuron to another.
How does an electrical impulse travel through a neuron?
Neurons transmit electrical impulses around the body. The cell body has dendrites that recieve information from other neurons, the info passes along the axon in the form of an electrical impulse that ends up as a synaptic knob. The myelin sheath insulates the axon to speed up nervous transmission. Neurotransmitters pass on the signal to the dendrites of the next axon.
How does information travel through and inbetween neurons?
The information travel electrically inside the neuron and chemically inbetween the neurons.
What is the function of sensory neurons?
Sensory neurons are the nerve cells that transmit electrical impulses from receptors to the CNS, when the signal reaches the brain it is translated into a sensation such as a visual imput, the signals dont have to reach as far as the brain as signals terminating at the spinal cord allows quick reflex responses.
What is the structure of sensory neurons?
Sensory neurons usually have long dendrites, short axons and the cell body is not central, they are usually found in the PNS.
What is the function of relay neurons?
Relay neurons are nerve cells that transmit electrical impulses between sensory neurons and motor neurons allwoing them to communicate with eachother.
What is the structure of relay neurons?
Relay neurons usually have short dendrites, short axons and are usually found in the CNS.
What is the function of motor neurons?
Motor neurons form synapses with muscles and control their contractions & are nerve cells that transmit electrical impulses from the CNS to effectors.
What is the structure of motor neurones?
Motor neurones usually have short dendrites, long axons and are found in the PNS.
What is excitation?
Excitation is when a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neuron. This increases the likelihood that the neuron will fire and pass on the electrical impulse.
What is inhibition?
Inhibition is when a neurotransmitter, such as serotonin, increases the negative charge of the postsynaptic neuron. This decreases the likelihood that the neuron will fire and pass on the electrical impulse.
What is summation?
The process of summation decides whether the post-synaptic neuron does fire. The excitatory and inhibitory influences are summed and if the net effect on the post synaptic neuron is inhibitory then the postsynaptic neuron is less likely to fire: if the net effect is excitatory it is more likely to fire - and momentarily, the inside of the postsynaptic neuron becomes positively charged. Once the electrical impulse is created it travels down the neuron. Therefore, the action potential of the postsynaptic neuron is only triggered if the sum of the excitatory and inhibitory signals at one time reaches the threshhold.
What is an action potential?
An action potential can occur when the inside of the neuron is negatively charged until it is activated by a stimulus; it then becomes poitively charged, which allows the action potential to occur.
