Can Kumustekin
Ms. Yorke
Psychology 12
22 May 2024
Biology of Psychology
In this class, I learned about 3 types of neurons in the peripheral nervous system: sensory, interneuron and motor neurons. Neurons are made of several parts: the nucleus, dendrites, the cell body, axon, Schwann’s Cells, Myelin Sheath, Node of Ranvier, and axon terminals.
(B is cell nucleus and the other line is cell body, it wasn’t visible in the image)
These neurons have an electrical charge called action potential that moves down the length of the neuron as a result of the movement of positive ions into and out of the axon. This potential has 3 parts to it: depolarization, repolarization, and the refractory period.
In the depolarization stage, channels in the membrane open allowing Na+ to flow into the axon and this incoming message stimulates the axon. With this, the voltage increases.
In the repolarization stage, along with the existing channels, new channels open that allows K+ to exit the axon which results in a voltage decrease.
Refractory period happens after repolarization and during this time Na+ is inside and K+ is outside of the axon. To be able to go through this cycle again, the pumps inside the axon push Na+ ions outside while K+ goes back inside, which was how this cycle started in the first place.
Synapse is the section between 2 nerve cells where a signal is sent from the axon to the dendrites. It has several parts like the axon terminal bulb, the synaptic gap, synaptic vesicle, pre-synaptic membrane, NT receptors and neurotransmitters, the axon of the sending neuron, dendrites, and post-synaptic membrane.
The axon terminal bulb produces neurotransmitters, and the synaptic vesicles store them. These neurotransmitters send signals by binding with the receptors on the post-synaptic membrane of the receiving neuron after moving in the synaptic gap after action potential gets transferred from the axon to the axon terminal bulb.
The receiving neuron decides to send its own action potential based on if the received NT message is excitatory or inhibitory. Excitatory means it stimulates AP while inhibitory represses AP. If the message is more excitatory than inhibitory, the receiving neuron will send its own action potential, but if inhibitory is more than excitatory, it will not.
