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BIOL 1102 Exam Three
Electrical Signaling Part 1
| Question | Answer |
|---|---|
| Which part of the neuron receives stimuli | dendrites and the cell body |
| Where are synpatic stimuli summed | at the axon hillock |
| What happens when the sum of the arriving signals reaching the threshold | action potential is triggered |
| Where are action potentials conducted | to the axon terminal |
| What do action potentials cause | release of neurotransmitters stored in vesicles |
| What do neurotransmitters bind to | receptors on the postsynaptic cell membrane |
| What are three types of neurons | sensory neuron, interneuron, and motor neuron |
| What are the three parts of the three types of neurons | dendrites, cell body, and axon |
| What does a resting potential reflect | baseline state of the neuron, the entire neuron exists int his state when it is inactive |
| What does graded potential reflect | temporary change in membrane polarity that formms when neuron interats all the different signals it has received |
| What is a graded potential proportional to | strength of the input signal |
| What does action potential reflect | once the graded potential has passed a certain threshold, |
| What happens during the action potential | large reversal of the membrane potential and is used to convey signals to other cells |
| What are three transmembrane proteins used to maintain membrane potential | sodium-potassium pump, potassium channel, sodium channel |
| What are the two electrochemical gradients | one for Na+, one for K+ |
| What does the Na+/K+ pump? | performs active trasnport, exports 3Na+ and imports only two K+ using ATp |
| What results from the sodium potassium pump | negative membrane potential |
| What type of channels are the two channels? | leak chanels, because they are open pores allowing ions to move down their concentrationg radients |
| Are there are more sodium or potassium channel and what does it do | more k+ channels, which further hyperpolarizes the membrane |
| What type of channels can K+ and Na also cross the membrane through | gated channels |
| What happens during resting state in the gated channels | both voltage-gated K+ and voltage-gated Na+ channels are closed -> don't contribute to membrane potential |
| What is the stimulus that opens a gated ion channel | stimulus is a change in membrane potential |
| What are two other types of gated ion channels | Ligand-gates and mechanically-gate |
| How are ligand-gated channels activated | specific molecule activates the ion channel |
| How are mechanically-gated channels activated | deformation of cell membrane activates ion channel |
| How do ion channels and open and close as the action potential speads | ion channels sequentially opens |
| Which channels open first to depolarize the membrane | voltage-gated sodium channels |
| Which channel opens second to hyperpolarize the membrane | voltage-gated potassium channel |
| What does each chemical signal produce as stimulation at the dendrites | a slight depolarization of the cell membrane at the axon hillock - they are alone insufficient to reach the threshold |
| What is the threshold potential | a certain membrane voltage that depolarization is graded up to |
| Once triggered can action potential stop | no, action potential is an all-or-none phenomonen - once triggered, it has a magnitude that is independent of the strength of the triggering stimulus |
| Where do action potentials travel along | signals that carry information along axons |
| How quick are action potentials | very brief, 1-2 milliseconds in duration, allows for production of high frequency of signals |
| How do neurons encode information | in terms of action potential frequency (how many occur per unit of time) NOT amplitude (amount of voltage change per action potential) |
| What are glial cells | support neurons across the nervous system, make up ove half the volume of human neural tissue |
| What are the four major types of central nervous system glia | ependymal cells, astrocytes, microglia, oligodendrocytes |
| What do ependymal cells produce | cerebrospinal fluid that cushions the brain and spinal cord - located in the ventricles (fluid-filled cavities of the CNS) |
| What do astrocytes contribute to | blood-brain varrier and nourish+repair nervous tissue; structurally support the brain to help maintain its shape |
| What do microglia do | abundant, represent up to 10% of brain cells; type of immune cell that clears out plaques, dead cells, and mcirobes |
| What do oligodendrocytes do | myelinate the cells of the CNS, insulate and metabolically support them |
| What does myelination of axons do | speeds up signal transmission |
| What are the only type of nerves that have gated ion channels | nodes of ranvier, so the action potential moves rapidely via saltatory conduction |
Created by:
goldengalleon