Key Terms – Nervous System
- action potential
- a momentary change in the electrical potential of a neuron (or muscle) membrane
- amygdala
- a structure within the limbic system that processes fear
- auditory ossicles
- (also, middle ear bones) the bones that transduce sounds from the air into vibrations in the fluid-filled cochlea
- autonomic nervous system
- the part of the peripheral nervous system that controls bodily functions
- axon
- a tube-like structure that propagates a signal from a neuron’s cell body to axon terminals
- basal ganglia
- an interconnected collections of cells in the brain that are involved in movement and motivation
- bolus
- a mass of food resulting from chewing action and wetting by saliva
- brainstem
- a portion of brain that connects with the spinal cord; controls basic nervous system functions like breathing and swallowing
- central nervous system (CNS)
- the nervous system made up of the brain and spinal cord; covered with three layers of protective meninges
- cerebellum
- the brain structure involved in posture, motor coordination, and learning new motor actions
- cerebral cortex
- the outermost sheet of brain tissue; involved in many higher-order functions
- cerebrospinal fluid (CSF)
- a clear liquid that surrounds the brain and fills its ventricles and acts as a shock absorber
- corpus callosum
- a thick nerve bundle that connects the cerebral hemispheres
- dendrite
- a structure that extends away from the cell body to receive messages from other neurons
- depolarization
- a change in the membrane potential to a less negative value
- endocrine gland
- the gland that secretes hormones into the surrounding interstitial fluid, which then diffuse into blood and are carried to various organs and tissues within the body
- exocrine gland
- the gland that secretes chemicals through ducts that lead to skin surfaces, body cavities, and organ cavities.
- frontal lobe
- the part of the cerebral cortex that contains the motor cortex and areas involved in planning, attention, and language
- ganglion
- a cluster of connected neurons (plural: ganglia)
- glia
- (also, glial cells) the cells that provide support functions for neurons
- hippocampus
- the brain structure in the temporal lobe involved in processing memories
- hormone
- a chemical released by cells in one area of the body that affects cells in other parts of the body
- hypothalamus
- the brain structure that controls hormone release and body homeostasis
- interstitial fluid
- the fluid found between cells in the body, similar in constitution to the fluid component of blood, but without the high concentrations of proteins
- limbic system
- a connected brain area that processes emotion and motivation
- membrane potential
- a difference in electrical potential between the inside and outside of a cell
- meninges
- (singular: meninx) the membranes that cover and protect the central nervous system
- myelin sheath
- a cellular extension containing a fatty substance produced by glia that surrounds and insulates axons
- myofibril
- the long cylindrical structures that lie parallel to the muscle fiber
- myofilament
- the small structures that make up myofibrils
- nephron
- the functional unit of the kidney
- neuron
- a specialized cell that can receive and transmit electrical and chemical signals
- occipital lobe
- the part of the cerebral cortex that contains visual cortex and processes visual stimuli
- parasympathetic nervous system
- the division of autonomic nervous system that regulates visceral functions during relaxation
- parietal lobe
- the part of the cerebral cortex involved in processing touch and the sense of the body in space
- peripheral nervous system (PNS)
- the nervous system that serves as the connection between the central nervous system and the rest of the body; consists of the autonomic nervous system and the sensory-somatic nervous system
- sensory-somatic nervous system
- the system of sensory and motor nerves
- set point
- the target value of a physiological state in homeostasis
- smooth muscle tissue
- the muscle that occurs in the walls of hollow organs such as the intestines, stomach, and urinary bladder, and around passages such as the respiratory tract and blood vessels
- spinal cord
- a thick fiber bundle that connects the brain with peripheral nerves; transmits sensory and motor information; contains neurons that control motor reflexes
- sympathetic nervous system
- the division of autonomic nervous system activated during stressful “fight-or-flight” situations
- synapse
- a junction between two neurons where neuronal signals are communicated
- synaptic cleft
- a space between the presynaptic and postsynaptic membranes
- temporal lobe
- the part of the cerebral cortex that processes auditory input; parts of the temporal lobe are involved in speech, memory, and emotion processing
- thalamus
- the brain area that relays sensory information to the cortex
- threshold of excitation
- the level of depolarization needed for an action potential to fire
- vertebral column
- (also, spine) the column that surrounds and protects the spinal cord, supports the head, and acts as an attachment point for ribs and muscles of the back and neck