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176 Cards in this Set
- Front
- Back
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The Nervous system
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the master controlling and communicating system of the body.
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Sensory Input
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The gathered information from stimuli
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Integration
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When the nervous system processes and interprets the sensory input and decides what should be done at each moment
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Motor Output
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When the nervous system effects or causes a response by activating muscles or glands
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The Central Nervous System
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Consists of the brain and the spinal cord, which occupy the dorsal body cavity and act as the integrating and command centers of the nervous system
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The peripheral nervous system
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The part of the nervous system outside the CNS. Consists mainly of the nerves that extend from the brain and the spinal cord.
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Sensory, or Afferent Division
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Consists of the nerves that convey impulses to the central nervous system from the sensory receptors located in various parts of the body.
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Motor, or Efferent Division
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Carries impulses from the CNS to effector organs, the muscles, or the glands. These impulses activate muscles and glands or EFFECT a motor response
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What are the two subdivisions of the Motor Division
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The somatic nervous system
The autonomic nervous system |
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Somatic Nervous System (Voluntary nervous system)
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Allows us to consciously or involuntarily control our skeletal muscles
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Autonomic Nervous System (Involuntary nervous system)
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Regulates events that are automatic, or involuntary, such as the activity of smooth and cardiac muscles and glands.
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Two parts of the Autonomic Nervous system
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Sympathetic and Parasympathetic
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Neuroglia
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Supporting cells in the CNS that are lumped together. Literally means "nerve glue"
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Types of Neuroglia
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1. Astrocytes
2. Microglia 3. Ependymal cells 4. Oligodendrocytes 5. Schwann cells |
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Astrocytes
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abundant star-shaped cells that account for nearly half of the neural tissue. They form a living barrier between capillaries and neurons, help determine
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Microglia
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Spider-like phagocytes that monitor the health of nearby neurotransmitters
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Ependymal cell
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gliial cells that lines the central cavities of the brain and the spinal cord. The beating of their cilia helps to circulate the cerebrospinal fluid that fills those cavities and forms a protective cushion around the CNS
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Oligodendrocytes
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glia that wrap their flat extensions tightly around nerve fibers, producing fatty insulating coverings called myelin sheaths
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Myelin sheaths
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Fatty insulating converings around nerve fibers
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Schwann Cells
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form the myelin sheaths around nerve fibers that are found in the PNS
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Satellite cells
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Act as protective cushioning cells
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Neurons (Nerve cells)
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highly specialized cells that transmit messages from one part of the body to another. They are all structurally different from one another, but have many common features
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Cell body
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the metabolic center of the neuron
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Neurofibrils
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Intermediate filaments that are important in maintaining cell shape. The are abundant in the cell body
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Nissl bodies
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Rough ER that are abundant in the cell body
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Processes (fibers)
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fibers that vary in length from microscopic to 3 to 4 feet. The longest ones go from the lumbar region of the spine to the great toe
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Dendrites
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Neuron processes that convey incoming messages toward the cell body. Neurons may have hundreds of these
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Axons
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Neuron processes that generate nerve impulses and generally conduct them away from the cell body.. Neurons only have one of these
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Axon hillock
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a cone-like region of the cell body from which axons arise from
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Axon terminals
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terminals that contain hundreds of tiny vesicles, or membranous sacs, that contain chemicals called neurotransmitters
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Neurotransmitters
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chemical released by neurons that may, upon binding to receptors of neurons or effector cells, stimulate or inhibit them
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Synaptic Cleft
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the fluid-filled space at a synapse between neurons
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Synapse
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The region of communication between neurons, or a neuromuscular junction between a neuron and a muscle cell
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Myelin
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a whitish, fatty material that covers most long nerve fibers. They protect and insulate the fibers and increase the transmission rate of nerve impulses
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Myelin Sheath
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A tight coil of wrapped membranes. The product of the wrapping process
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Nuclei
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cell bodies found in clusters in the CNS. They are well protected within the bony skull or vertebral column and are essential to the well-being of the nervous system
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Ganglia
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Small collections of cell bodies that are found in few sites outside the CNS in the PNS
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Tracts
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Bundles of nerve fibers (neuron processes) that run through the CNS
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Nerves
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Bundles of nerve fibers (neuron processes) that run through the PNS
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White Matter
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consist of dense collections or myelinated fibers (tracts). They are everything that has been myelinated
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Gray matter
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Contains mostly unmyelinated fibers and cell bodies
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Functional Classification
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groups neurons according to the directions the nerve impulse is traveling relative to the CNS. On this basis, there are sensory, motor, and association neurons
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Sensory or Afferent neurons
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Neurons carrying impulses from sensory receptors (in the internal organs or the skin) to the CNS. Cell bodies of sensory neurons are always found in a ganglion outside the CNS. The keep us informed about what is happening inside and outside the body
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Receptors
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Associated with the dendrite endings of the sensory neurons and are activated by specific changes occurring nearby
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Motor or Efferent neurons
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Neurons carrying impulses from the CNS to the viscera and/or muscles or glands. The cell bodies are motor neurons are usually found in the CNS.
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Interneurons or Association neurons
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Connect the motor and sensory neurons in neural pathways. Like motor neurons, their cell bodies are always located in the CNS
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Structural Classification
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Based on the number of processes extending from the cell body.
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Multipolar neuron
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Neurons with several processes extending from the cell body
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Bipolar neurons
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Neurons with two processes; an axon and a dendrite.
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Unipolar neurons
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have a single process emerging from the cell body. It is very short and divides almost immediately into proximal (central) and distal (peripheral) processes
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Reflex arc
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neural pathway where reflexes occur and involve both CNS and PNS structures
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Two major functional properties of a neuron
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Irritability and Conductivity
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Irritability
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the ability to respond to a stimulus and convert it into a nerve impulse
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Conductivity
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the ability to transmit the impulse to other neurons, muscles, or glands
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Polarized
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The plasma membrane of a resting, or inactive neuron. Meaning that there are fewer positive ions sitting on the inner face of the neuron's plasma membrane than there are on its outer face. As long as the inside remains more negative than the outside, the neuron will stay inactive
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K+ (Potassium)
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the major positive ions inside the cell
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Na+ (Sodium)
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the major positive ions outside the cell. Normally sodium ions cannot diffuse through the plasma membrane, but when the neuron is stimulated, the "gates" of sodium channels in the membrane open.
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Depolarization
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The inward rush of sodium ions that change the polarity of the neuron's membrane at that site
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Graded Potential
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When the inside is more positive and the outside less positive it creates this local electrical situation
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Action Potential (Nerve Impulse)
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A long distance signal transmitted and initiated by graded potential
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Repolarization
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When the potassium ions flow out from the cell and restore the electrical conditions at the membrane to polarized, or resting state
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Sodium-Potassium Pump
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Restores the ionic conditions of the resting state by ejecting three sodium ions for every two potassium ions that are carried back into the cell
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Reflexes
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Rapid, predictable, and involuntary responses to stimuli
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Somatic Reflexes
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All reflexes that stimulate the skeletal muscles. Ex. quickly pulling your hand away from a hot object.
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Autonomic Reflexes
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regulate the activity of smooth muscles, the heart, and glands. Ex. Secretion of saliva and changes in the size of the pupils
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What are the five elements of a reflex arc
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1. Sensory receptor
2. Effector Organ 3. Sensory neurons 4. motor neurons 5. integration center |
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1. Sensory receptor (reflex arc)
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Reacts to s stimulus
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2. Effector organ (reflex arc)
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the muscle or gland eventually stimulated
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3. Sensory
4. Motor neurons (reflex arc) |
Connect the two
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5. Integration center
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The synapse or interneurons between the sensory and motor neurons represent the central element
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Four major regions of the Brain
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1. Cerebrum
2. Diencephalon 3. Brain stem 4. Cerebellum |
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Cerebrum
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The largest part of the brain; consist of the right and left cerebral hemispheres. The most superior part of the brain.
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Gyri (singular: twisters)
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Elevated ridges on the entire surface of the cerebrum
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Sulci
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Shallow grooves that separate the gyri
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Fissures
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Less numerous and deeper grooves than sulci which separate large regions of the brain
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Longitudinal Fissure
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a single fissure that separates the cerebral hemispheres
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Lobes
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divisions of the cerebral hemispheres created by fissures and sulci
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Three basic regions of the cerebral hemisphere
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1. Cortex: superficial gray matter which looks gray
2. White matter: An internal area 3. Basal nuclei: islands of gray matter situated deep within the white matter |
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Cerebral Cortex
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Speech, memory, logical and emotional response, as well as consciousness, interpretation of sensation, and involuntary movement are all functions of neurons from this area
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Primary Somatic sensory area
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Located in the parietal lobe posterior to the central sulcus. Impulses traveling from the body's sensory receptors are localized and interpreted in this area of the brain. Allows you to recognize pain, coldness, or a light touch
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Sensory homunculus
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A spatial map that represents the body in an upside-down manner in the sensory area
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Occipital lobe
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Area of the brain where the visual area is located (posterior part of the occipital lobe)
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Temporal lobe
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Area of the brain where the auditory area is located. More specifically bordering the lateral sulcus, and the olfactory area is found deep inside the temporal lobe
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Primary motor area
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Allows us to consciously move our skeletal muscles. Located anterior to the central sulcus in the frontal lobe
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Corticospinal or Pyramidal tract
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The major voluntary motor tract formed from the axons of these motor neurons
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Motor Homunculus
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The body map on the motor cortex
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Broca's area
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A specialized cortical area that is very involved in the ability to speak. Found at the base of the precentral gyrus (anterior to the central sulcus)
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Anterior association area
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Areas involved in higher intellectual reasoning and socially acceptable behavior are in the anterior part of the frontal lobes. Complex memories appear to be stored in the temporal and frontal lobes
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Posterior association area
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Encompasses part of the posterior cortex. This area plays a role in recognizing patterns and faces, and blending several different inputs into an understanding of the whole situation
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Speech area
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Located within the posterior association area at the junction of the temporal, parietal, and occipital obes. Allows you to sound out words. Like Broca's area is usually in only one cerebral hemisphere.
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Cerebral White Matter
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composed of fiber tracts carrying impusles to, from, or within the cortex.
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Corpus Callosum
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One very large fiber that connects the cerebral hemispheres. Such fiber tracts are called commissures
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basal nuclei (basal ganglia)
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islands of gray matter buried deep within the white matter of the cerebral hemispheres. They help regulate voluntary motor activities by modifying instructions sent to the skeletal muscles by the primary motor cortex
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Diencephalon or Interbrain
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Sits atop the brain stem and is enclosed by the cerebral hemispheres. It's major structures are the thalamus, hypothalamus, and epithalamus
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Thalamus (gray matter)
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Encloses the shallow third ventricle of the brain and is a relay station for sensory impulses passing upward to the sensory cortex. Determines whether impending sensations are going to be pleasant or not.
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Hypothalamus
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Make up the floor of the diencephalon. Plays a role in the regulation of body temperature, water balance, and metabolism. Center for many drives and emotions such as thirst, appetite, sex, pain, and pleasure centers.
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Limbic system
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The emotional-visceral brain where the hypothalamus works
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Pituitary gland
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an endocrine organ that is regulated by the hypothalamus. It hangs from the anterior floor of the hypothalamus.
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Mammillary bodies
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reflex centers involved in olfacation (sense of smell). They bulge from the floor of the hypothalamus posterior to the pituitary gland
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Epithalamus
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Forms the roof of the third ventricle. Important parts are the pineal gland and the choroid plexus.
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Choroid Plexus
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knots of capillaries withing each ventricle that form cerebrospinal fluid
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Brain Stem
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About the size of a thumb in diameter. Its structures are the midbrain, pons, and the medulla oblongata. It provides a pathway for ascending and descending tracts, and has many small gray matter areas
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Midbrain
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a relatively small part of the brain stem that extends from the mammillary body to the pons inferiorly.The cerebral aquedact connects the third ventricle of the diencephalon to the fourth ventricle below. Anteriorly composed of two bulging fiber tracts called the cerebral penducles
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Cerebral Aqueduct
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a tiny canal that travels through the midbrain
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Cerebral penducles
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towo bulging fiber tracts that convey ascending and descending impulses.
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Corpora Quadrigemina
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located dorsally in the midbrain. They are four rounded potrusions that are reflex centers involved with vision and hearing
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Pons
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The rounded structure that protrudes just below the midbrain. Composed of mostly fiber tracts, however, it does have important nuclei involved in the control of breathing
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Medulla Oblongata
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The most inferior part of the brain stem. It merges into the spinal cord. Like the pons it is an important fiber tract area. Contains many nuclei that regulate vital visceral activities. Contains centers that control heart rate, blood pressure, breathing, swallowing, and vomiting.
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Reticular Formation
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Extends the entire length of the brain stem and is a diffuse of gray matter. Its neurons are involved in motor control of the visceral organs
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Reticular Activating System
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A special group of reticular formation that plays a role in consciousness and the awake/sleep cycle. Damage to this area con result in permanent unconsciousness (coma)
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Cerebellum
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A large, cauliflower-like part of the brain that projects dorsally from under the occipital lobe of the cerebrum. It has two hemispheres and a convoluted surface. It provides precise timing for skeletal muscle activity and controls our balance and equilibrium
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Meninges
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Three connective tissue membranes covering and protecting the CNS structures
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Dura Mater
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The outermost layer. It is a double layered leathery membrane where it surrounds the brain. One of its layers is attached to the inner surface of the skull, forming the periosteum (periosteal layer).
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Meningeal Layer
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Forms the outermost covering of the brain and continues as the dura mater of the spinal cord
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Falx Cerebri and Tentorium cerebelli
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A fold where the inner dural membrane extends inward that attaches the brain to the cranial cavity separates the cerebellum from the cerebrum
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Arachnoid mater
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The middle meningeal layer that is web-like
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Subarachnoid space
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arachnoid mater spans this space to attach it to the innermost membrane, the pia mater. It is filled with cerebrospinal fluid
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Pia mater
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The inner most membrane. It clings tightly to the surface of the brain and spinal cord, following everyfold
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Arachnoid villi
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Specialized projections of the arachnoid membrane that protrude through the dura mater
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Miningitis
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an inflammation of the meninges that is a serious threat to the brain because bacterial or viral meningitis may spread into the nervous tissue of the CNS
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Encephalitis
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A condition of brain inflammation
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Cerebrospinal fluid
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a watery "broth" similar in its makeup to blood plasma, from which it forms.
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Hydrocephalus
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When something obstructs the drainage of cerebrospinal fluid and it begins to accumulate and exert pressure on the brain
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Blood-Brain Barrier
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Keeps neurons separated from bloodborne substances. It is composed of the least permeable capillaries in the whole body.
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Concussion
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Occurs when brain injury is slight. The victim may seem dizzy or "see stars" No permanent brain damage occurs
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Contusion
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The result of marked tissue destruction
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Intracranial hemorrhage
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bleeding from ruptured blood vessels in the head that may cause death. Caused by a blow to the head
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Cerebral edema
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Swelling of the brain due to inflammatory response to injury
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Cerebrovascualr accidents
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The thrid leading cause of death in the U.S. Occur when blood circulation to the brain area is blocked, as by a blood clot or a ruptured blood vessel, and vital brain tissue dies.
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Hemiplegia
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A one-sided paralysis
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Aphasis
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A common result of damage to the left cerebral hemisphere, where the language areas are located.
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Transient ischemic attack
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Temporary brain ischemia or restriction of blood flow. Last from 5 to 15 minutes.
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Spinal cord
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Approximately 17 inches long, it is a glistening white continuation of the brain stem. It provides a two way conduction pathway to and from the brain and is a major reflex center.
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Cauda equina
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A collection of spinal nerves at the inferior end of the vertebral canal. Called this because it looks like a horses tail.
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Dorsal (Posterior) Horns
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two posterior projections located in the gray matter of the spinal cord and spinal roots
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Ventral (anterior) Horns
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two anterior projections located in the gray matter of the spinal cord and spinal roots
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Central canal
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Surrounded by gray matter. It contains cerebrospinal fluid
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Dorsal root
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Cell bodies of sensory neurons fibers enter the chord through this. Found in an enlarged area called the dorsal root ganglion
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Dorsal root ganglion
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An enlarged area where the dorsal root is located
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Ventral root
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Ventral horns of the gray matter that contain cell bodies of motor neurons of the somatic nervous system send their axons out this part of the cord
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Spinal nerves
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Formed by the fusion of the dorsal and ventral roots
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Flaccid paralysis
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Results from damage to the ventral root. Nerve impulses do not reach the muscles affected. Thus, no voluntary movement of those muscles is possible
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Dorsal, lateral, and ventral columns
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Three regions of the white matter on each side of the cord. Each contains a number of fiber tracts made up of axons with the same destination and function.
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Spastic Paralysis
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Results when the spinal cord is crushed or cut. The affected muscles stay healthy because they are stimulated by spinal reflex arcs and movement of those muscles does not occur. However, movements are involutary and out of control.
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Peripheral Nervous System
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Consists of nerves and scattered groups of neuronal cell bodies (ganglia) found outside the CNS
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Endoneurium
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Within a nerve, neuron fibers or processes are wrapped in protective connective tissue coverings. Each fiber is surrounded by a delicate connective tissue sheath called this
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Perineurium
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a coarser connective tissue wrapping than the Endoneurium
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Fascicles
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FIber bundles formed from groups of fibers wrapped in Perineurium
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Epineurium
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A tough fibrous sheath that inds together all the fascicles. It forms a cordlike nerve.
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Mixed nerves
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Nerves carrying both sensory and motor fibers
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Sensory (Afferent) Nerves
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Nerves that carry impulses toward the CNS only
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Motor (Efferent) Nerves
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Nerves that carry only motor fibers
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Cranial Nerves
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There are 12 pairs of these. The serve primarily the head and neck.
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Spinal Nerves
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There are 31 pairs of these nerves. They are formed by the combination of the ventral and dorsal roots of the spinal cor
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Dorsal and ventral rami
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The spinal nerves divides into these two areas making each spinal nerve only about 1/2 inch long. These (like the spinal nerves) contain both motor and sensory fibers.
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Plexuses
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When the ventral rami of all other spinal nerves form complex networks of nerves this form. They serve the motor and sensory needs of the limbs
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Types of Plexuses
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1. Cervical
2. Brachial 3. Lumbar 4. Sacral |
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Autonomic Nervous System (Involuntary Nervous System)
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the motor subdivision of the PNS that controls body activities automatically
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Preganglionic neuron
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The first of two motor neuron pairs. Located in the brain or spinal cord
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Preganglionic axon
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The axon of the preganglionic neuron leaves the CNS to synapse with the second motor neuron in a ganglion outside the CNS
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Postganglionic axon
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Extends to the organ it serves
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Sympathetic division (Thorocolumbar Division)
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mobilizes the body during extreme situations (fear, exercise, rage) Also know as the Thorocolumbar Division because its preganglionic neurons are in the gray matter of the spinal cord. Often referred to as "fight or flight" system
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Parasympathetic division (Craniosacral division)
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allows us to "unwind" and conserve energy. Also known as the Craniosacral division because the preganglionic neurons of this division are located in the brain nuclei of several cranial nerves.
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Terminal Ganglion
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The areas where the ganglionic motor neuron synapses with the axons of the neurons in the cranial region.
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Ramus communicans
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a small communicating branch where the preganglionic axons pass through after leaving the cord in the ventral root
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Sympathetic trunk ganglion
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Lies alongside the vertebral column on each side.
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Splanchnic Nerves
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Partly formed when preganglionic axons pass through gnaglion without synapsing. They travel to the viscera to synapse with the ganglionic neuron found in a collateral ganglion
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Collateral Ganglion
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found anterior to the vertebral column. Splanchic nerves travel here to synapse with the ganglionic neurons found here. The major ones supply the abdominal and pelvic organs
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Why is Sympethetic Division referred to as the E division?
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Exercise, excitement, emergency, and embarrassment
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Why is the Parasympathetic division referred to as the D division?
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Digestion, defecation, and diuresis
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Cerebral palsy
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A neuromuscular disability in which the voluntary muscles are poorly controlled and spastic because of brain damage
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Anencephaly
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a failure of the cerebrum to develop, resulting in a child who cannot hear, see, or process sensory inputs, and spina bifida
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Spina Bifida
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results when the vertebrae form incompletely.
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Orthostatic hypotension
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a type of low blood pressure resulting from changes in body position.
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Arteriosclerosis
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Decreased elasticity of the arteries. Results in a decreasing supply of oxygen to the brain neurons
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Senility
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A gradual lack of oxygen due to the aging process leads to this. It is characterized by forgetfulness, irritability, difficulty in concentrating and thinking clearly, and confusion
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