Activity of Neurons Flashcards
Information conducting unit of the nervous system
Neuron
What are the functions of dendrites? (2)
- Collect information from other cells
- Increase cell’s surface area
What are Dendritic spine?
Small protrusions that cover the dendrites
Describe the axon of a neuron. (4)
- Extends out from the cell body
- Axon hillock
- Axon collateral - branches of the axon
- Teleodendria - smaller branches toward the end
What are terminal boutons? Where do they sit?
- End foot’ at the end of each teleodendrion
- Sits close to the dendritic spine of another neuron
What is a synapse?
Space between the terminal button of one neuron and dendritic spine of another
What is a Neurotransmitter?
Chemical released from terminal buttons that carries the message across the synapse
Dopamine is an _____________ neurotransmitter.
inhibitory
What encapsulate the neurotransmitters in the terminal boutons?
Vesicles
What does the nucleus of a neuron contain?
Chromosomes and genes
What is intracellular fluid of a neuron?
Fluid in which the cell’s internal structures are suspended
What is the cell membrane in neurons?
membrane surrounding the cell
Extracellular fluid, fluid outside , c__________ the cell
cushions
What is another name for intracellular fluid?
Cytoplasm (Salty Water)
True or False:
Concentration of dissolved substances in extracellular and intracellular fluid is THE SAME
False Concentration of dissolved substances in extracellular and intracellular fluid is DIFFERENT, this difference is very important for allowing a neuron to conduct electrical signal
The cell membrane is impermeable, what does impermeable mean?
Does not allow liquid to pass (hydrophobic)
How do substances like potassium and sodium cross the neuron cell membrane?
From extracellular fluid, the substances cross the membrane via embedded proteins (channels, gates or pumps)
What are the five steps of a Nerve impulse?
- Resting potential
- Action potential (Depolarization Phase)
- Repolarization
- Hyperpolarization
- Restoration of Potential
Which step describe this nerve impulse step:
Cell membrane is polarized (i.e., electrical difference between inside & outside of cell)
Intracellular fluid has a negative charge relative to the extracellular fluid
Difference in charge is about -70mV
Maintained by efflux (i.e., exit) of Na+ and influx (i.e, entry) of K+
Sodium-Potassium pump works continuously exchanging 3 Na+ for 2 K+
Since more Na+ exits than K+ enters, intracellular fluid is negatively charged
The Resting potential
Which step describe this nerve impulse step: Na+ channels close
Voltage-sensitive K+ channels open causing rapid efflux of K+
Intracellular fluid develops a more negative charge relative to the extracellular fluid
Repolarization
Which step describe this nerve impulse step: K+ efflux overshoots
Causes brief period in which charge of intracellular fluid relative to extracellular fluid is even more negative than in resting state
Hyperpolarization
Which step describe this nerve impulse step: Cell membrane receptors activated by external or internal stimuli
If -50 mV threshold reached, there is a brief but extremely large flip in the polarity of cell membrane
Voltage-sensitive Na+ channels open causing rapid influx of Na+
Intracellular fluid develops a positive charge relative to the extracellular fluid
Depolarization
Which step describe this nerve impulse step: Sodium-Potassium pump reactivated (3 Na+ out for 2 K+ in)
Cell membrane polarized (-70 mV)
Restoration of Resting Potential
What are the two types of Refractory Period?
Absolute Refractory Period
Relatively Refractory Period
