Chapter 2 Flashcards
What are neurons?
The structure that transmits electrical signals in the body. Key components of neurons are the cell body, dendrites, and the axon or nerve fiber.
What is the cell body?
The part of a neuron that contains the neuron’s metabolic machinery and that receives stimulation from other neurons.
What are dendrites?
Nerve processes on the cell body that receive stimulation from other neurons.
What is the axon / nerve fiber?
The part of the neuron that conducts nerve impulses over distances. Also called the nerve fiber.
What are the two electrodes?
recording electrode, shown with its recording tip inside the neuron,
and a reference electrode, located some distance away so it is not affected by the electrical signals
What is the resting potential?
−70 millivolts
The difference in charge between the inside and the outside of the nerve fiber when the fiber is not conducting electrical signals. Most nerve fibers have resting potentials of about 270 mV, which means the inside of the fiber is negative relative to the outside.
What is the action potential?
Rapid increase in positive charge in a nerve fiber that travels down the fiber. Also called the nerve impulse.
What is a propagated response?
A response, such as a nerve impulse, that travels all the way down the nerve fiber without decreasing in amplitude.
once the response is triggered, it travels all the way down the axon without decreasing in size
How does stimulus intensity affect action potentials?
Comparing these three records leads to an important conclusion: Changing the stimulus intensity does not affect the size of the action potentials but does affect the rate of firing.
What is the refractory period?
The time period of about 1/1,000th of a second that a nerve fiber needs to recover from conducting a nerve impulse. No new nerve impulses can be generated in the fiber until the refractory period is over.
What is spontaneous activity?
Nerve firing that occurs in the absence of environmental stimulation.
What are neurons bathed in?
Neurons are bathed in a liquid solution rich in ions
What are ions?
Charged molecules. Sodium , potassium , and chlorine are the main ions found within nerve fibers and in the liquid that surrounds nerve fibers.
What is permeability?
A property of a membrane that refers to the ability of molecules to pass through it. If the permeability to a molecule is high, the molecule can easily pass through the membrane.
What is depolarization?
When the inside of a neuron becomes more positive, as occurs during the initial phases of the action potential. Depolarization is often associated with the action of excitatory neurotransmitters.
What is the rising phase of the action potential?
This quick and steep depolarization from −70 mV to +40 mV during an action potential
What is hyperpolarization?
When the inside of a neuron becomes more negative. Hyperpolarization is often associated with the action of inhibitory neurotransmitters.
