Neurons, Synapses, and Signaling Flashcards
Presynaptic cell
- Cell body (has most neurons organelles)
- Dendrites (branches of trees, receive signals)
- Axon (a long extension, transmit signals)
- Glial cells/glia
Postsynaptic cell (receiver)
- Synapse
- Neurotransmitters pass info from the transmitting neuron to the receiving cell.
- synaptic terminals
- Glial cells/Glia
2 types of glial cells
- Astrocytes
- Oligodendrocytes
3 steps of information processing in neuron system
- Sensory input/sensory neuron
- Intergration/interneuron
- Motor output/motor neuron
What neuron carry out intergration
- Central nervous system (CNS)
What neuron carry out input and output
- Peripheral nervous system (PNS)
Membrane potential
- attracts opposite charges, potential energy (-50 to -100mV)
Resting potential
- not sending a signal ( -60 to -80mV)
What types of ions and pump play an important role in resting potential
- Potassium ions and sodium ions. Every 3 sodium out, 2 potassium in
- Their channels
Are there more Na channels or K channels
- K channels, thats why resting potential is closer to Ek than Ena
Ek negative or positive
- Negative
What is equilibrium potential (Eion)
- the membrane voltage for a particular ion at equilibrium and can be calculated using the Nernst equation
Ena is negative or positive
- Positive
What causes changes in membrane potential
- Gated ion channels that open and close in order to response a specific stimuli
What is hyperpolarization
- An increase in magnitude of membrane potential (more negative inside)
What is depolarization
- A decrease in magnitude of membrane potential (less negative inside)
Graded potential
- Cause a smal magnitude change by hyperpolarizations
Action potential
- A big jump cause by depolarization, conducted by the axons
Generation of action potentials
- Resting state: all K and Na channels closed, ungated channels maintain resting potential
- Gated Na channels opens as it becomes depolarization
- Rising phase
- Falling phase: most Na channels become inactivated, and most K channels open
- Undershoot: Na channels closed, some K channels still open
Refractory period
- After the action potential, further stimulus has no effect
What cause refractory period
- Temporary inactivation of Na channels
What site the action potential is generated
- Axon hillock
In what direction does action potential travel
Toward the synaptic terminals
What prevent action potential from travelling backwards
- Inactivated Na channels
The speed of action potential increase proportionally to what
- Axon’s diameter
What is myelin sheath
- It is made by glia oligodendrocytes in the CNS and Schwann cells in the PNS
Myelin sheath in action potential
- It insulates axons and help action potential speed increase
What position on the axons action potentials form
- Nodes of Ranvier (gaps between myelin sheath)
What is the process of action potentials jumping from node to node called
- Saltatory conduction
Where does the transmission of information from neurons to other cells occur
- At the synapses
At electrical synapses
- the electrical current flows from one neuron to another
- found in heart and brain
At chemical synapses
- a chemical neurotransmitter carries information across the gap junction
Most synapses are chemical or electrical
- Chemical
What gated channels involved in chemical synapses
- Ca channels
2 postsynaptic potentials
- Excitatory postsynaptic potentials: depolarization
- Inhibitory postsynaptic potentials: hyperpolarization
After being released from the synaptic vesicles, neurotransmitter will
- diffused out of the synaptic cleft
- taken up by surrounding cells
- degraded by enzymes
What is temporal summation
Two excitatory post synapsis potentials are produced and cause a jumping over threshold
Spatial summation
- Two spontaneous excitatory post synapsis produced
Five groups of neurotransmitters
- Acetylcholine
- Biogenic amines
- Amino acids
- Neuropeptides
- Gases
Some nervous system disorder
- Parkinson
- Alzheimer
