Module 2 - Cells of the Nervous System Flashcards
Central Nervous System
Made up of the brain and spinal cord
Peripheral Nervous System
Made up of nerves and sensory organs
Nerves
Lots of neurons bundles together which transmit information from sensory organs to the brain and send information from the brain to the muscle or gland
Sensory Neuron
Detect environmental changes and send information about the changes to the CNS for processing
Motor Neuron
Contract muscles and glands to control motor behaviour
Interneuron
Found inbetween sensory and motor neurons in the CNS
Neuron
Transmit information
Soma
Cell nucleus & other important machinery for the neuronal function. Shape will vary in different neuron types
Membrane
The cell border made up of lipid (fatlike substance) that contain lots of protiens with various functions:
- Substance detectors and security guards
- Transporting substances in and out of the cell
Cytoplasm
What fills the space inside the membrane
Nucleus
Contains chromosomes with genetic information. They contains instructions for producing proteins
Mitochondria
Produce ATP (adenosine triphosphate) which is the energy sourse for the neuron
Dendrites
Like and antenna
Receive chemical messages sent from other neurons
Synapse (Synaptic Cleft)
The messages transmitter from neuron to neuron. They are made between the terminal buttons and dendrites
Cleft - Contains the fluid through which the neurotransmitter travels
Presynaptic Cell
The cell sending the message
Postsynaptic Cell
The cell receiving the message
Axon
Long tube (wrapped in myelin sheath)
Transmits an electrochemical message on its surface from the cell body of the neuron down to the terminal buttons
Action Potential
The message that transmits along the axon
Caused by a rapid burst of depolarisation followed by hyperpolarisation
Axoplasmic Transport
The axon stansports substances that a neuron needs that are only produced in the soma but need to get down to the terminal body.
Anterograde Transport
Where substances start from the soma and are transported to the terminal button
Retrograde Transport
Where substances start from the terminal button and are transported to the soma
Microtubules
Vesicles where axoplasmic transport occurs, located inside the axon.
Myelin Sheath
Over the top of the axon, acts like an insulator
Stops neuron messages interfering with one another
Terminal Button
Located at the end of the axon
Secrete chemicals into the synapse
Neurotransmitter
Chemical released into the synapse
Glial Cell
Support for neurons that store nutrients and provide protection. Acts as a glue to keen neurons together, control chemical and nutrient supply, insulate, destroy & remove dead neurons
Glial Cell - CNS - Astrocyte
Provide chemical regulation and production, act as a neuron glue, contain the neurotransmitters to the synapse
Glial Cell - CNS - Oligodendrocyte
Myelin maker for insulation. Produce little myelin tubes that cover axons with miniscule gaps inbetween called Nodes of Ranvier
Glial Cell - CNS - Microglia
Damage control (phasocytosis) and immune function
Glial Cell - PNS - Schwann Cell
Myelin makers for PNS. Each Schwann Cell makes 1 piece of myelin
Nodes of Ranvier
The little myelin tubes that cover the miniscule gaps on the axon
Blood Brain Barrier
Barrier between the blood and the fluid that surrounds the brain cells.
Important for controlling extracellular composition and protecting the brain from pathogens
Intracellular & Extracellular Fluid
Contains Ions
Intracelluar - inside the neuron
Extracellular - outside of the neuron
Area Postrema
Withdrawal Reflex
A reflex intended to protect the body from damaging stimuli.
Neurons work in a circuit
Sensory neuron > Interneuron > Motor neuron
Membrane Potential
The difference in electrical potential inside versus the outside neuron
Resting Potential
Neuron resting potential is negative (-70mv)
Hyperpolarisation
More negative electrical charge in neuron
Makes it less likely that action potential to occur
Depolaritasion
More positive electrical charge in neuron
Makes it more likely that an action potential will occur
Threshold of Excitation
The threshold of depolarisation where an action potential will occur
Diffusion
Molecules that move from regions if high concentration to regions of low concentration.
Electrostatic Pressure
When particles with same charge repel each other, but particles with different charges are attracted to eachother, its the force exerted by attraction and repulsion. The pressure can also more ions from place to place across the cell membrane
Ion
Small charged particles
Cation
Positively charged ions
Anion
Negatively charged ions
Organic Anions
Negatively charged ions that are only found inside the neuron
They cannot pass through the cell membrane and contribute to the negative charge
Chloride Ions
Negative charge (anion) found mostly outside the neuron
Concentrated outside
Diffusion pushes it into the neuron, but electrostatic pressure pushes it out
(Inside of the neuron is negative, and like charges repel)
Potassoim Ions
Positive charge (cation) found mostly inside of the neuron
Concentrated inside
Diffusion pushes it out of the neuron, but elctrostatic pressure pushes it in
(Outside of neuron is positive and like charges repel)
Sodium Ions
Positive charge (cation) found mostly outside of the neuron
Concentrated outside
Diffusion pushes it into the neuron, as does the electrostatic pressure
(inside of the neuron is positive, opposite charges attract)
Sodium-Potassium Pump & Transporters
Pushes sodium ions out of the cell
Made up of transporters (proteins which push ions across the cell membrane)
For every 3 sodium ions the proteins transport out of the neuron, two potassium ions go back in
The pump used a ton of energy
Voltage Dependant Ion Channel
Special proteins embedded into the membrane of the neuron
Ion channels can be open or closed depending on the charge of the cell at a given moment in time
The opening/closing cause the action potential to occur
All or None Law
Rate Law
Changes to indicate differences in intensity, the rate at which action potentials are egenrated in a neuron changes
Firing Rate
Saltatory Conduction
Postsynaptic Potential (PSP)
Brief changes in charge of the postsynaptic cell (depolarisation or hyperpolarisation)
Can cause a postsynaptic neuron to reach the threshold of excitation and generate its own action potential
Binding Site
On the receptor proteins located on the membrane of the postsynaptic cell
Neurotransmitters fit to the binding sites like a key that fits the lock
Ligand
If a chemical fits the binding site of the receptor protein
Axodendritic Synapse
Dendritic membrane of the receiving cell (smooth dendrite or dendritic spine)
Axosomatic Synapse
Somatic membrane of the receiving cell
Axoaxonic Synapse
A terminal button of the reciving cell
Presynaptic & Postsynaptic Membrane
Presynaptic membrane - Border of the sending cell
Postsynaptic membrane - Border of the receiving cell
Synaptic Vesicle
Containers made up of membrane that contain molecules of neurotransmitters to be released into the synapse
Dendritic Spine
Neurotransmitter Dependant Ion Channel
Open when the neurotransmitter molecules bind to a binding site on a postsynaptic receptor
Ionotropic Receptor
Class of neurotransmitter dependant receptor
Open ion channel directly
Have a neurotransmitter binding site and an ion channel that opens up neurotransmitter binding
Metabotropic Receptor
Class of neurotransmitter dependant receptor
Open ion channels indirectly
Have neurotransmitter binding site, but no ion channel. Instead upon binding, a series of events happen which eventually cause an ion channel somwhere in the cell membrane to open.
Calcium Ion Channel
Excitatory PSP
When ion movement causes an increase in charge (depolarisation)
Inhibitory PSP
When ion movement causes an decrease in charge (hyperpolarisation)
Reuptake
Occurs when neurotransmitter molecules in synapse are taken back up into the terminal button of the presynaptic
Achieved by special transporter proteins embedded into the membrane of the terminal button
Enzymatic Deactivation
Removes neurotransmitters from the synapse by breaking it down into smaller parts
Once neurotransmitter molecules are split up into their component parts, they cannot bind to binding sides on postsynaptic receptos.
Neural Integration
The process by which the inhibitory and excitatory potentials sent to a neuron are added toegther at the axon hillock
A neuron can have several connections with other neurons that are active
These connections could be a mix of excitatory or inhibitory
Crucial for a neuron to combine the messages sent from several other neurons
Axon Hillock
Between the axon and the soma
Autoreceptors
Receptor proteins on the membrane of the presynaptic cell
Autoreceptors on the presynaptic neuron respond to neurotransmitter that is released by that presynapthic neuron
They influence neurotransmitter production and release to help regulate neurotransmitter levels
Neuromodulators
They diffuse across extracellular fluid more broadly and can influence the activity of several neurons at once. Similar to neurotransmitters
Hormones
Chemicals released by the endrocrine glands as well as cells in various organs, which are distribruted through the bloodstream and can influence neuronal activity
Modulate activity to shape behaviour
Endocrine Glands
Produce chemicals eg; pancreas, thyroid gland
Target Cells
Neurons with special receptors for particular hormones
