Chapter 2 Flashcards
NEURON
a specialized cell transmitting nerve impulses; a nerve cell.
DENDRITES
a short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.
CELL BODY
the nucleus-containing central part of a neuron exclusive of its axons and dendrites that is the major structural element of the gray matter of the brain and spinal cord, the ganglia, and the retina — called also perikaryon, soma.
AXON
the long threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells.
MYELIN SHEATH
the insulating covering that surrounds an axon with multiple spiral layers of myelin,
TERMINAL BUTTONS
Tiny bulblike structures at the end of the dendrites, which contain neurotransmitters that carry the neuron’s message into the synapse.
NEUROTRANSMITTERS
a chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure.
SYNAPSE
a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.
RECEPTOR
SITES
the part of a nerve that receives and reads chemical signals (neurotransmitters) from other nerves to transmit the electrical signals that transfer information through the brain and nervous system.
THRESHOLD
the level of strength a stimulus must reach to be detected.
ACTION POTENTIAL
threshold in a neuron is the point of depolarization at which the neuron fires, transmitting information to another neuron.
ALL-OR-NONE
PRINCIPLE
law is a principle that states that the strength of a response of a nerve cell or muscle fiber is not dependent upon the strength of the stimulus.
NEURAL FIRING
An action potential is part of the process that occurs during the firing of a neuron. During the action potential, part of the neural membrane opens to allow positively charged ions inside the cell and negatively charged ions out. … When the charge reaches +40 mv, the impulse is propagated down the nerve fiber.
EXCITATORY
NEUROTRANSMITTERS
Excitatory neurotransmitters are neurotransmitters that increase the likelihood that a nerve cell will produce an action potential, an electrochemical impulse that nerve cells use to transmit signals
INHIBITORY
NEUROTRANSMITTERS
A neurotransmitter that generally activates receptors that have reversal potentials more negative than threshold for action potential firing.
ACETYLCHOLINE
a compound that occurs throughout the nervous system, in which it functions as a neurotransmitter.
DOPAMINE
a compound present in the body as a neurotransmitter and a precursor of other substances including epinephrine.
ENDORPHINS
any of a group of hormones secreted within the brain and nervous system and having a number of physiological functions. They are peptides that activate the body’s opiate receptors, causing an analgesic effect.
SEROTONIN
a compound present in blood platelets and serum that constricts the blood vessels and acts as a neurotransmitter.
AFFERENT
NEURONS
are pathways that carry sensory information from the body to the central nervous system (the brain and spinal cord).
EFFERENT
NEURONS
are conducting cells that carry information from the central nervous system (the brain and spinal cord) to muscles and organs throughout the body.
CENTRAL
NERVOUS
SYSTEM
the complex of nerve tissues that controls the activities of the body. In vertebrates it comprises the brain and spinal cord.
SPINAL CORD
the cylindrical bundle of nerve fibers and associated tissue that is enclosed in the spine and connects nearly all parts of the body to the brain, with which it forms the central nervous system.
PERIPHERAL
NERVOUS
SYSTEM
the nervous system outside the brain and spinal cord.
SOMATIC
NERVOUS
SYSTEM
Major functions of the somatic nervous system include voluntary movement of the muscles and organs and reflex movements. In the process of voluntary movement, sensory neurons carry impulses to the brain and the spinal cord
AUTONOMIC
NERVOUS SYSTEM
the part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes.
SYMPATHETIC
NERVOUS
SYSTEM
the part of the autonomic nervous system that contains chiefly adrenergic fibers and tends to depress secretion, decrease the tone and contractility of smooth muscle, and increase heart rate — compare parasympathetic nervous system.
PARASYMPATHETIC
NERVOUS SYSTEM
The part of the involuntary nervous system that serves to slow the heart rate, increase intestinal and glandular activity, and relax the sphincter muscles. The parasympathetic nervous system, together with the sympathetic nervous system, constitutes the autonomic nervous system
LESIONS
a region in an organ or tissue that has suffered damage through injury or disease, such as a wound, ulcer, abscess, tumor, etc.
ELECTROENCEPHALOGRAM
a test or record of brain activity produced by electroencephalography.
COMPUTERIZED AXIAL TOMOGRAPHY
Tomography in which computer analysis of a series of cross-sectional scans made along a single axis of a bodily structure or tissue is used to construct a three-dimensional image of that structure.
MAGNETIC RESONANCE IMAGING
a form of medical imaging that measures the response of the atomic nuclei of body tissues to high-frequency radio waves when placed in a strong magnetic field, and that produces images of the internal organs.
POSITRON EMISSION
TOMOGRAPHY
positron emission tomography (PET) scan is an imaging test that helps reveal how your tissues and organs are functioning. A PET scan uses a radioactive drug (tracer) to show this activity. … The tracer may be injected, swallowed or inhaled, depending on which organ or tissue is being studied.
FUNCTIONAL MRI
Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled.
HINDBRAIN
the lower part of the brainstem, comprising the cerebellum, pons, and medulla oblongata.
MEDULLA
the inner region of an organ or tissue, especially when it is distinguishable from the outer region or cortex (as in a kidney, an adrenal gland, or hair).
PONS
the part of the brainstem that links the medulla oblongata and the thalamus.
CEREBELLUM
“Little brain” the part of the brain at the back of the skull in vertebrates. Its function is to coordinate and regulate muscular activity.
MIDBRAIN
a small central part of the brainstem, developing from the middle of the primitive or embryonic brain.
RETICULAR FORMATION
a diffuse network of nerve pathways in the brainstem connecting the spinal cord, cerebrum, and cerebellum, and mediating the overall level of consciousness.
