3.1 Flashcards
What is a neuron?
Cells that receive, integrate, and transmit information in the nervous system. They are powered by electrical impulses and communicate with other nerve cells through chemical signals.
How do neurons communicate?
They communicate selectively with other neurons to form neural networks.
Entire nervous system divided into which two units? What do they consist of?
Central Nervous System (CNS) - brain + spinal cord
Peripheral Nervous System (PNS) - all other nerve cells in rest of body
3 Types of Neurons
Sensory Neurons: (afferent neurons) detect information from the physical world and pass that information to the brain
Motor Neurons: (efferent neurons) direct muscles to contract or relax, thereby producing movement.
Interneurons: Only communicate with other neurons (instead of other brain structures or body organs)
What are the 4 structural regions of neurons?
Dendrites, Cell Body, Axon, Terminal Buttons
Dendrites
Branchlike extensions of the neuron that detect information from other neurons
*Dendrites (Dentures/teeth) where food is put in and received )
Cell Body
(Soma) Site in the neuron where information from thousands of other neurons is collected and integrated.
Axon
A long narrow outgrowth of a neuron by which information is transmitted to other neurons.
*(Ax)on -Axes cut down branches…Axons branch out to other nuerons
Terminal Buttons
Small nodules, at the end of axons, that release chemical signals from the neuron into the synapse.
Synapse
The site at which chemical communication occurs between neurons.
Synaptic Cleft
The gap between the axon of a “sending” neuron and the dendrites of a “receiving” neuron; it contains extracellular fluid.
What are neurons in the chain of communication referred to as?
Presynaptic or Postsynaptic
Myelin Sheath
A fatty material, made up of glial cells, that insulates the axon and allows for the rapid movement of electrical impulses along the axon.
Nodes of Ranvier
Small gaps of exposed axon, between the segments of myelin sheath, where potentials are transmitted.
Resting Membrane Potential
The electrical charge of a neuron when it is not active
Polarization
- When the electrical charge inside a neuron is different from the electrical charge outside.
- A neuron at rest is polarized
2 types of ions that contribute to a neuron’s resting membrane potential
Sodium Ions
Potassium Ions
Permeability of cell membrane
Acts like a “bouncer” at a night club. Only allows certain types of ions to cross membrane. (More Potassium than Sodium is inside the neuron)
Sodium-Potassium Pump
Works to increase potassium and decrease sodium inside the neuron.
Action Potential
(Neural Firing) The neural impulse that passes along the axon and subsequently causes that release of chemicals from the terminal buttons.
- Neuron starts off slightly negative–>Fires & allows more positive ions in (depolarization)—> returns to slightly negative resting state (repolarization)
2 types of signals that arrive at dendrites
Excitatory: depolarize the cell membrane (reduce polarization—>increasing the likelihood that a cell will fire)
Inhibitory: Hyper polarize the cell (increase polarization—>
decreasing the likelihood that the neuron will fire.
Propagaion
The wave movement when the neuron fires and moves along the axon.
All-or-none Principle
The principle where a neuron fires with the same potency each time, although frequency can vary. A neuron either fires or not. It can’t “partially” fire.
Presynaptic Neuron
Sends the signal
