Chapter 3: Neuroanatomy

the brain and the spinal cord

Autonomic nervous system and somatic nervous system

soma: is the cell body and is essentially the nucleus of the neuron intracellular fluid: is what it sounds lie its the space inside the neural membrane Axon: the long tale fiber of the neuron which neurotransmitters and electrical impulses travel down Terminal buttons: the end of the axon where neurotransmitters are releases into the synaptic gap onto the next neuron Dendrites: the extra fibers opposite the axon which receive neurotransmitters and increase the neurons surface area Myelin: lipid which insulates the membrane of the axon and allows for better conduction from one neuron to the next, white matter is called white because it consists of myelinated axons while grey matter is grey because it consists mainly of neural cell bodies node of ranvier: the gaps inbetween the myelinated pockets of the axon extracellular fluid: the space outside of the neural membrane

a neuron

A neural network is a pathway of neurons which collaborate to perform specific types of communication; they can change over time and because of enviorment or genertics; one example is

Reception, Integration, Transmission Reception is taking the chemical signal from one neuron Integration is when the soma processes the signal and decides to fire or not Transmission: when the neuron sends a neurotransmitter to the next neuron, essentially passing on the message or sending a transfiugured message

Senory nerves are the nerves that carry sensory info inside the body to the CNS, these can be on organs and provide touch, sight, smell, etc Somatosensory nerves are a kind of sensory nerve which are on your skin and muscles and connect with the sense of touch

These neurons direct muscle control to relax or constrict muscles and produce movement; these are usually located in the CNS

a semipermeable neural membrane is crucial to neural activity and communication because it allows ions channels to let specific ions in and out of the neuron when receiving or sending an electrochemical signal

A primary inhibitory neurotransmitter which increases the amount of potassium (anions) inside a neuron; preventing an action potential from firing

Primary excitatatory neurotransmitter which opens receptors allowing more cations into the neuro - making it a excitatory neurotransmitter

Sérotonin, dopamine, norepinephrine, acetylcholine as they can open reception to either cations or anions— which one it is more receptive to is based on the protein make up of the receptors themselves

An action potential is an electrical pulse that runs from the soma and down the axon to the terminal buttons which sends a message across the synaptic gap and to the post synaptic neuron An action potential is fired when the electrical charge of the neuron changes to more negative than the extracellular space to more positive than the extracellular space through the increase of soduim ions that overtake the potassium ions

• The soduim gates in the cell membrane open allowing sodium ions to rush in, increasing the poositive charge of the neuron • in turn the potassuim channels move the potassuim ions out of the neuron which also puts the neuron in a more postive charge, causing depolarization • When the neuron reaches a postive threshold the sodium channels close as repolarization begins and more potassuim flows into the neuron, increasing its negative charge • Resting membrane potential is restored as the neuron shifts back to its normal slightly negative state

A cation is a positively charged ion that moves through the sodium channels An anion is a negatively charged molecule which moves through the potassuim channels

An excitatory neurotransmitter is one that increases the soduim ion reception of a neuron, increasing the likelihood of an action potential aka it decreases polarization An inhibitory neurotransmitter is one that decreases the soduim ion recpetion or increases the potassuim ion recpetion, decreasing the likelihood of an action potential aka it increases polarization

Resting membrane potential is the neutral state of a neuron also known as a polarized state where theres slightly more negative ions in the intracellular space than in the extracellular space

Depolarization is a decrease in potassium ions and conversely an increase of sodium ions in a neuron that shifts its charge from slightly negative to more positive; this occurs before an action potential Repolarization is the process of a neuron returning to its slightly negative state after an action potential

Potassium

Presynaptic is essentially the neuron that is sending the neurotransmitter over the synapticv gap Post synaptic is the neuron which receives said neurotransmitter

the all or nothing principle states that a neuron is like a binary switch, it is either firing or not– a discrete processes rather than continuous

A neurotransmitter is an electrochemical signal that gets passed from one neuron to the next. These can either inhibit the neuron from relaying the message (firing) or excite the neuron to fire

• The Neurotransmitter is made in the soma, and stored within vesicles in the terminal buttons waiting to be released. • When released, these molecules bind to receptors on the postsynaptic neuron’s membrane– a neurotransmitter can only bind to the receptor of which it is made for, like a puzzle piece. • depending on what neurotransmitter it is, the post synaptic neuron can either open or close its ion channels to positive or negative ions, producing an excitatory or inhibitory response

1) Reuptake, where the neurotransmitter gets released from the terminal buttons into the synaptic gap, but is then recycled by the terminal buttons before it can reach the post synaptic receptors 2) enzyme deactivation, When an enzyme breaks down the NT beforer it can reach the postsynaptic recptors 3) Autoreception, this usually happend when too much of as neurotransmitter is being released so the NT binds to the receptors of its parent neuron (presysnaptic) instead of the post synaptic