Neural Conduction And Synaptic Transmission Flashcards
Ramon y Cajal established the ____ ____, which states that the brain is made of many small, discrete cells.
Neuron Doctrine
There are almost ____ billion neurons in the human brain.
100
Neurons have four important regions
Dendrites
Soma (Cell Body)
Axon
Axon Terminal
Dendrites
Branching projections that collect information
Soma (Cell Body):
Contains the nucleus and integrates information
Axon:
Conducts the neural signal across a long distance
Axon terminals:
Small swellings that release signals to affect other neurons
Chemical signals, known as _____, cross small gaps, known as synapses.
neurotransmitters
It is estimated that there are about ___ trillion synapses in the adult brain.
500
A type of neuron that carry information to the brain.
Sensory neurons
A type of neuron that carry information from the brain to the muscles.
Motor neurons
A type of neuron that convey the signals around the nervous system.
Interneurons
A type of neuron that have many dendrites.
Multipolar neurons
A type of neuron that have one dendrite and one axon.
Bipolar neurons
A type off neuron that have only one projection from the soma, which branches to form the axon and the dendrite
Monopolar neurons
Glial Cells
- Speeding up the neuronal signaling
- Regulating extracellular chemicals
- Enabling neurons to modify their connections
In the glial cells, _______ , in the central nervous system, and ________, in the peripheral nervous system, _______ around axons to speed up signals.
Oligodendrocytes
Schwann cells
wrap myelin
Nodes of Ranvier
are small gaps in the myelin sheath.
Astrocytes .
regulate extracellular chemicals and regulate local blood flow
Microglia
provide immune system functions for the central nervous system.
The synaptic cleft is the _____ to _____ space between the cells.
20- to 30-nm
Monoamines
Serotonin
Epinephrine
Norepinephrine
Dopamine
Melatonin
Amino acids
Glutamate
Gaba
Glycine
Aspartate
Peptide Neurotransmitters
Cholecystokinin
Neuropeptide Y
Somatostatin
Gases
Nitric Oxide
Carbon Monoxide
Organic cation
Acetylcholine
Receptors
Specialized proteins in the cell membrane
Difference of Ionotropic receptors and Metabotropic receptors
Ionotropic receptors used ions to flow across the membrane which changes the charge of the cell membrane. It allows ions to move through a passage in the membrane. On the other hand, metabotropic receptors used proteins to relay information. It relays signals to proteins inside the cell.
Way to remove the receptors
Degradation, the neurotransmitter is broken apart. Diffusion the neurotransmitter moves down the concentration gradient and out of the synapse. Reuptake the neurotransmitter is transported back into the original cell.
The inside of the cell is more negative than the outside, about _____
-70 mV.
Difference between Excitatory Postsynaptic Potential and Inhibitory Postsynaptic Potential
EPSP alter the membrane voltage, moving the voltage closer to 0. Occurs when positive ions flow through an ionotropic receptor into the cell, causing depolarization. IPSP move the voltage further from 0. occurs when positive ions flow out of the cell, or negative ions flow in.
Explain the temporal and spatial summation
No summation occurs when EPSPs arrive with a delay between them; they, individually, cannot drive the membrane voltage to the threshold for a spike.
Temporal summation occurs when EPSPs arrive close in time and their contributions add up at the soma, leading to an action potential.
Spatial summation occurs when signals arrive on different branches of the dendrites, converging at the soma.
If an EPSP and an IPSP arrive at different locations at the same time, they will cancel each other’s effect at the soma.
How an action potential travels
In neurons at rest, there are more Na+ ions outside the cell and more K+ ions inside the cell.
At threshold, voltage-gated Na+ channels open, allowing Na+ ions to flow into the cell, down the chemical concentration and electrical gradients.
Voltage-gated K+ channels open, allowing K+ ions to flow out of the cell.
The current formed by the Na+ ions flows down the neuron, depolarizing the next part of the neuron.
There is a refractory period after the action potential, when the voltage-gated Na+ ion channels are less likely to open
Are neurons integrators or coincidence detectors?
Because neurons receive thousands of inputs, they may be better thought of as coincidence detectors. The cell body of the postsynaptic cell is unable to determine which presynaptic neuron sent which signal—instead, a postsynaptic spike will only signal the coincidence of many excitatory inputs arriving simultaneously.
