Chapter 3 Neural Bases of Behaviour Flashcards
Define neurons
Basic building blocks of the nervous system - The cells that link together the bodies circuitry
What are the three main parts of the neuron?
- cell body
- dendrites
- axon
What is another term for the cell body of the neuron?
soma
Describe the cell body of the neuron
Contains the structure is necessary for the neuron to stay alive and the nucleus contains the genetic information that the neuron needs to function and develop - It also combines and processes incoming information.
Describe the dendrites of the neuron
Branch like fibres that emerge from the cell body that are specialized receiving units That provide input from neighbouring neurons and send the electrical impulse on to the cell body
Describe the axon of the neuron
Conducts electrical impulses away from the cell body to other neurons or muscles or glands
What branches out of the axon?
Axon terminal’s which may connect with other dendrites from other neurons
Describe the structural elements of a neuron
how are neurons supported in their functions?
glial cells
Describe glial cells
- surround neurons and hold them in place
- Manufacture or transport proteins
- Form the myelin sheath around some axons
- Absorb toxins and waste materials that might damage neurons
- Guide neurons to specialized positions during prenatal brain development
- Protects the brain from toxins
What keeps foreign substances from gaining access to the brain?
blood brain barrier - Glial cells and the small gaps in the blood vessels found in the brain
What two important things do neurons do?
- generate electricity
- release chemicals that allow them to communicate with other neurons and with muscles and glands
What are the three basic steps of nerve activation?
- at rest, neuron has a resting electron potiential due to distribution of positively and negatively charged chemicals otuside and inside of cell respectively
- When stimulated a flow of ions in and out through the cell membrane reverses the electrical charge of the resting potential, producing an action potential or nerve impulse
- the original distribution of ions is restored and the nueron is again at ret and capable of being activated again
describe ion channels
proteins embedded in the semipermeable neuron membrane that allow the passage of select substances
What creates a nerver impulse?
exhange of ions
Describe ions
electrically charged atoms
What ions are present in the fluid outside the neurons?
Na+ & Cl-
What ions are present inside the neurons?
A- (anions) & K+
Describe the neurons resting potential
An uneven distribution of ions inside and outside of cell that makes the inside more negative due to high concentration of negatively charged proteins interiorly and high concentration of positively charged Na+ exteriorly.
What state is the neuron in at resting potential?
State of polarization
When the neuron is not being stimulated what is the difference in the electrical charge?
-70mV between the interior and the surface of the cell
What maintains the negative interior of the neuron?
sodium-potassium pump - pumps out 3 Na+ for every 2 K+ that comes in
How does the electrical charge change during an action potential?
sodium is pumped into the axon and the charge changes from -70mV to +40mV
How does the action potential move down the length of the neuron?
Once neuron is stimulated, Na+ channels will open up in certain area changing the electrical charge and immediately after they close the K+ channel will open to pump K+ out restoring the resting charge and then adjacent Na+ pumps will open and this cycle will repeat down the length of the axon.
Show in a graph how the changes in potential would look
Describe action potential
sudden reversal in cells membrane voltage momentarily moves from -70mV ot +40mV inside the cell based off of the movement of Na+ and K+ movement across the cell membrane
Describe depolarization
shift from negative to positive voltage
Describe the reflex action
when Na+ channels close after depolarization and postively charged K+ flow out restoring the negative resting potential