Midterm 2: Neurons and Nervous System Slides Flashcards
Why are neurons different from other body cells?
They’re excitable cells that exhibit electrical activity (receive, process, and send it)
Cell body structure and function
Contains nucleus and abundant protein synthesis organelles; main component of cell; 5-140 micrometers in diameter
What are other names for the cell body?
Perikaryon, soma
Dendrite function and structure
Extensions from cell body where electrical signals are received
Axon hillock function
Site where electrical activity is generated (then sent down axon to axon terminals)
Axon function, structure, and other name
Function: generate and conduct signals away from soma
Structure: abundant microtubules for transport
Also called nerve fibers
Axon terminal structure
Contain neurotransmitter-filled vesicles
Myelin sheath function and structure
Speed up electrical activity (lipid sheath that wraps around axon)
What are Nodes of Ranvier?
Gaps in myelin sheaths along axon (in between the “bundles”)
What do afferent/sensory neurons do?
Send information to the CNS
What do interneurons do?
Connect neurons within CNS
What do efferent/motor neurons do?
Send information from CNS
What do multipolar neurons look like and what function do they usually have? Where are they found?
Many dendrites and one axon; motor neurons and interneurons; found in brain and spinal cord
What do bipolar neurons look like and what function do they always have? Where are they found?
Only two extensions from cell body; uniquely sensory/afferent neurons; found in ears, nose, eyes
What do unipolar neurons look like and what function do they usually have?
Have short single process and divide into two long branches; function as sensory neurons
What is a synpase?
Junction formed by two neurons - allows communication to continue from one neuron to another
Axosomatic synapse
Axon terminal of one neuron meets body of another
Axodendritic synapse
Axon terminal of one neuron meets dendrites of another
In diffusion, what pushes molecules to move?
Chemical driving force (set by concentration differences across cell)
What are the ingredients for diffusion to occur?
Driving force (always there) and membrane permeability (not always there)
What happens at the threshold/critical point of an action potential (very generally)?
Slow change in voltage suddenly speeds up
What is a graded potential and where does it occur?
Slight fluctuation in electrical activity in the cell body and dendrites (action potentials do not occur here)
Where do charges come from in the ECF?
Positive from Na+, negative from Cl-
Where do charges come from in the ICF?
Positive from K+, negative from large protein anions
What is the function of a membrane with regards to electrical activity?
Serve as a charge separator (physically separates charges from meeting)
What is the overall charge inside a cell?
Negative (relative to outside)
Which ions move into and out of the cell (at rest)?
Na+ wants in, K+ wants out
Function of sodium/potassium pump
Maintain concentration gradient and never let cell reach equilibrium and lose excitability
Depolarization
Cell becomes more positive (less negative than resting potential)
Hyperpolarization
Cell becomes less positive (more negative than resting potential)
Repolarization
Membrane potential returns to resting value
What is the purpose of action potentials?
Facilitate communication
What is divergence in neurons?
Input from multiple neurons at once; neuron sends and receives multiple signals at any time
When is a VGSC at each of its states?
Closed at resting potential (-70 mV)
Open from -55 mV to 30 mV
Inactive from 30 mV back to -70 mV
When is a VGKC at each of its states?
Closed at resting potential (-70 mV) to 30 mV
Open from 30 mV to -80 mV
What triggers the opening of the voltage-gated channels?
When threshold is reached: VGSC opens right away, VGKC has delayed opening)
Schwann cells function
Make myelin in PNS
Oligodendrocyte function
Make myelin in CNS
What are the channel types from least to most permeable?
Leak, ligand-gated, voltage-gated
What is an EPSP?
Excitatory postsynaptic potential: NT binds to ligand channel and positive ions flow through
What is an IPSP?
Inhibitory postsynaptic potential? NT binds to ligand channel and negative ions flow through
