Chapter 3 Flashcards
Identify different parts of a Neuron
- dendrites
- soma
- axon
- myelin sheath
- terminal buttons
- synapse
Identify the main functions of Glial Cells
- supply nourishment to neurons
- remove waste from neurons
- provide insulation around axons
- specialist glial cells help make the Myelin Sheath
- support development of nervous system in embryos
- may transmit signals to other glial cells
Describe the Neural Impulse
- a complex neurochemical reaction
- an electrical impulse that travels along the axon
Dendrites
branches of the neuron that receive messages from other cells.
Axon
a long fibre that transmits signals from the soma to other neurons
Myelin Sheath
insulates axons and allows information to be transmitted faster.
-stabilises axon structure
Synapse
the junction where information is moved from one neuron to the next neuron
Glia
cells found throughout the nervous system and support the neurons
Synapse
- the junction where information is moved from one neuron to the next neuron
- where neurons meet
Glia
cells found throughout the nervous system and support the neurons
ions
positive and negative electrically charged molecules that flow back and forth across the cell membrane.
Resting Potential
is the stable negative charge of a cell when the cell is inactive.
Action Potential
the very brief shift in a neuron’s electrical charge that travels along the axon.
Absolute refractory period
the minimum length of time after an action potential and when another action potential cannot occure
All or None Law
either a neuron fires or it doesnt. if there is not enough charge to cause the axon charge above -55 it does not fire and the neural impulse will not pass to the next axon.
Absolute refractory period
the minimum length of time after an action potential and when another action potential cannot occur
Na+
Sodium
K+
Potassium
Cl-
Chloride
Steps in Neural Impulse
- Polarisation of the Neuron membrane: Sodium is on the outside and potassium is on the inside
- Resting potential gives the neuron a break
- Action Potential: K+ gates open and Sodium ions move inside the membrane
- Repolarisation: Potassium ions move outside and sodium ions stay inside the membrane
- More potassium ions are on the outside that sodium ions on the inside.
- Refractory Period - puts everything back to normal Potassium returns inside, sodium returns outside.
Explain how neurons communicate at chemical synapses
- synthesis of NT chemicals into synaptic vesicles
- vesicles released into synaptic cleft
- vesicles bind to receptor sites in next neuron
- if not passed on then they are removed or made inactive by enzymes
- reuptake of inactive vesicles NTs absorbed by presynaptic membrane.
Synaptic Cleft
a microscopic gap between the terminal button on one neuron and cell membrane of the next neuron
Synaptic Vesicles
- contains neurotransmitters
- stored in the terminal buttons
Reuptake
- a process where NTs are absorbed from the synaptic cleft back into the presynaptic membrane.
