1B: Biology Flashcards
What are the four parts of the neuron, and what are their functions?
dendrite, soma, axon, and axon terminals (synapse)
What are the three types of neurons, and what are their functions?
Sensory- Environment
Motor- Muscle
Interneurons- all other neurons in between
What is the resting potential? What causes the inside of the neuron to be more negative than the outside? How does the neuron maintain the resting potential?
- Net electrical difference between inside & outside of a neuron.
- about -60mV
- due to large negatively charged proteins inside the cell
- maintained by the selective permeability of the cell membrane
What is the Action Potential?
- Brief electrical charge that travels down an axon
- Generated by rapid movement of ions across the axon membrane
What are the 5 Steps to an Action Potential
1) resting state (- 60 mV)
2) excitatory input (positive charges) causes a slight depolarization
3) if threshold (-40 mV) is reached, Na+ channels briefly open, Na+ enters, & polarity becomes positive (+50 mV)
4) extra K+ channels open & K+ leaves, causing repolarization & hyperpolarization (e.g., -70 mV)
5) Na+/K+ pump pushes Na+ out and K+ in, returning cell to resting state (-60 mV)
Why is the action potential considered an all-or-none response? How is the strength of a response demonstrated by a neuron?
- an all-or-none response
- strength of response is determined by the firing rate
- # of APs/s (up to about 300/s)
What is synaptic transmission? Synapse?
- Junction between the axon of one neuron and the dendrite or cell body of another neuron
What are the Steps involved in Synaptic Transmission?
1) AP causes release of neuro- transmitters (NTs) into synaptic cleft
2) NTs bind to receptors on next cell
3) Ion channels on receiving cell open and allow ions in
4) NTs are metabolized or taken back into the presynaptic cell
What are Post-Synaptic Effects?
- Excitatory - positive ions increase the likelihood
that the post-synaptic neuron will fire - Inhibitory - negative ions decrease the likelihood that the post-synaptic neuron will fire
How does a neuron “decide” whether it will fire an action potential?
- Integration of Synaptic Input - the activity of a neuron is determined by a summation of multiple synaptic inputs at a given point in time
What is the distinction between cortical and subcortical brain structures?
Subcortical Structures - deep structures (including brainstem & cerebellum) responsible for basic, life- sustaining functions
What are the most important subcortical structures for sensation and perception?
- Thalamus -relays sensory information from
receptor organs to the cortex - superior & inferior colliculi (midbrain) -orientation toward sensory stimuli
What is meant by a baseline (spontaneous) firing rate?
- Information is conveyed through an increase or a decrease in the neuron’s firing rate (as seen in a “raster plot”)
What is the difference between static and functional brain imaging?
- Static Images - CT (computerized tomography) & MRI (magnetic resonance imaging)
- often used for diagnostic purposes
- Functional - PET (positron emission tomography)
& fMRI (functional MRI) - used in experimental research
What is Grey Matter?
- tissue closer to the cortical surface
- composed primarily of neural cell bodies
