Unit 3 Flashcards
Neuron
A nerve cell, the basic building block of the nervous system
Cell body
The part of a neuron that contains the nucleus; the cells life-support center
Dendrites
A neuron’s often bushy, branching extensions that receive and integrate messages, conducting the impulses toward the cell body
Axon
The neuron extension that passes messages through its branches to other neurons or to muscles or glands
Myelin Sheeth
A fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one node to the next
Glial Cells
Cells in the nervous system that support, nourish, and protect neurons; they also play a role in learning, thinking, and memory
Action Potential
A neural impulse; a brief electrical charge that travels down an axon
Threshold
The level of stimulation requires to trigger a neural impulse
Refractory period
In neural processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state.
All-or-none response
Neurons reaction of either firing (with a full-strength response) or not firing
Synapse
The junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or the synaptic cleft
Neurotransmitters
Chemical messengers that cross the synaptic gaps between neurons. when released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
Reuptake
A neurotransmitter’s reabsorption by the sending neuron
Endorphins
“Morphine within” - natural opiate like neurotransmitters linked to pain control and to pleasure
Agonist
A molecule that increases a neurotransmitter’s action
Antagonist
A molecule that inhibits or blocks a neurotransmitter’s action
Nervous system
The body’s speedy, electrochemical, communication network, consisting of all the nerve cells of the peripheral and central nervous systems.
Central nervous system (CNS)
The brain and the spinal chord
Peripheral Nervous system (PNS)
Th sensory and motor neurons that connect to the central nervous system (CNS) to the rest of the body
Nerves
Bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sense organs
Sensory (afferent) neurons
Neurons that carry incoming information from the body’s tissues and sensory receptors to the brain and spinal chord
Motor (efferent) neurons
Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands
Interneurons
Neurons within the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs
Somatic Nervous System
The division of the peripheral nervous system that controls the body’s skeletal muscles also called the skeletal nervous system
Autonomic nervous system
The part of the peripheral nervous system (PNS) that controls the glands and the muscles of the internal organs (heart) its sympathetic divisions arouses; its parasympathetic division calms
Sympathetic Nervous System
The division of the autonomic nervous system that arouses the body, mobilizing its energy
Parasympathetic Nervous System
The division of the autonomic nervous system that calms the body, conserving its energy
Reflex
A simple, autonomic response to a sensory stimulus, such as the knee-jerk response
Endocrine system
The body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream
Lesion
Tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue
EEG (electroencephalogram)
An amplified recording of the waves of electrical activity sweeping across the brain’s surface. These waves are measured by the electrodes placed on the scalp
MEG (magnetoencephalography)
A brain imaging technique that measures magnetic fields from the brain’s neural electrical activity
CT (computed tomography scan)
A series of x-ray photographs taken from different angels and combined by computer into a composite representation of a slice of the brain’s structure (also called CAT scan)
PET (positron emission tomography scan)
A visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task