Glossary Of Terms Flashcards
Action potential
Brief change in the membrane potential caused by the rapid opening and closing of ion channels; the action potential is the nerve signals that moves down the axon of a neuron during neurotransmission
Acetylcholine
Primary neurotransmitter of the parasympathetic nervous system; effects include decreasing respiration, blood pressure, and heart rate, and increasing gastrointestinal secretions and motility
Afferent nerve
Sensory – nerve of the PNS that carry impulses from receptors in the body towards the central nervous system also called sensory nerves
Agonist
Substance that mimics the action of a neurotransmitter enhancing it’s intended effect; Agonists are often similar in structure and function to the naturally occurring neurotransmitter
Antagonist
Substance that blocks the actions of a neurotransmitter at its receptor site; by binding with the receptor antagonist prevent the neurotransmitter from causing it’s intended effect
Astrocytes
Most abundant type of glial cells; in addition to facilitate the exchange of nutrients between capillaries and neurons, they help mop up residual potassium ions and neurotransmitters
Autonomic nervous system ANS
Subdivision of the motor division of the peripheral nervous system; controls involuntary functions; e.g., conducts impulses to the heart smooth muscles in the digestive tract and blood vessels walls, and to glands
Axon
Part of a neuron that emerges from the cell body in a single long, slender process; nerve impulses travel down the axon and are transmitted to other neurons or cells of you find extensions at the end of the axon
Axon terminal
In the region of an axon; usually the site of synaptic contact with another cell; Also called the presynaptic terminal
Brainstem
Collective term for three structures of the brain
The midbrain , pons, medulla oblongata
Processes sensation from the skin and joints in the head, neck, and face; sensory input and motor output of the brainstem are carried out by the cranial nerves
Carotid sheath
Casing of fibrous tissue that encloses the Vegas nerve, along with the carotid artery, internal jugular vein, and sympathetic nerves that supply the head
Cell body
Area of a neuron containing the nucleus; region where metabolism occurs and where incoming signals are integrated
Central nervous system
One of the two main divisions of the nervous system; Consists of the brain and spinal cord
Cerebellum
Sometimes called the small brain - coordinates movements
Large, Cauliflower-like organ that is exceeded in size only by the cerebrum; provides the precise timing and patterns of skeletal muscle contraction needed for smooth coordinated movements
Cerebral cortex
Convoluted surface of the brain, covering the left and right cerebral hemispheres; origin of most cognitive abilities and conscious behavior
Cerebral hemispheres
Left and right hemispheres that are the most prominent features of the brain; collectively called the cerebrum includes three deep-lying structures – basal ganglia, hippo campus, and amygdaloid nuclei
Cerebrum
Collective term for the right and left cerebral hemispheres
Channel-linked receptor
Major type of neurotransmitter receptors composed of protein subunits around a central pore;
e.g., binding of neurotransmitters to the subunits causes the receptor to change its shape, thereby opening the central channel and allowing ions to enter the neuron
Complex partial seizures
Seizures that affect consciousness and a persons ability to interact normally with the environment
Corpus callosum
Large tract of myelinated nerve fibers that act as a bridge connecting the left and right hemispheres
Cranial nerves
12 pairs of nerves that originate in the brain and pass through various openings called foramina of the school other than the Vagus nerve which extends well into the abdomen, the cranial nerves serve only head and neck structures
Dendrites
Branching extensions from the neuronal cell body; receive information from other neurons and convey them to the cell body
Depolarization
Process during neurotransmission in which positive sodium ions rushing the axon through ion channels, reducing the negative potential of cell membrane and thereby creating an action potential (electrical signal)
Diencephalon
Structure located in the central core of the forebrain, surrounded by the cerebral hemispheres and above the brainstem; includes the thalamus and hypothalamus
Down-regulation
Decreased production of receptors by a neuron in response to, for example, excessive neurotransmitter levels in the synaptic cleft; also called desensitization
