Download 4Central Nervous System (CNS)

Name _____________________________
The Nervous System
Functions of the Nervous System
 _______________ to internal and external stimuli
 _______________ nerve impulses to and away from CNS
 _______________ nerve impulses at the cerebral cortex
 Assimilate experiences in ______________________________
 Initiate glandular secretions and ______________________________
 Program ______________________________
Organs and Divisions of the Nervous System
 Central nervous system (CNS)— ______________________________
 Peripheral nervous system (PNS)—all _______________
 Autonomic nervous system (ANS) – ___________________________
_____________________________________________
Cells of the Nervous System
 _______________
 Consist of three parts
 _______________ of neuron—main part
 _______________—branching projections that
conduct impulses to cell body of neuron
 _______________—elongated projection that
conducts impulses away from cell body of neuron
 Neurons classified according to ________________________
_______________ of impulse
 Sensory neurons: conduct impulses ______________
_______________; also called afferent neurons
 Motor neurons: conduct impulses _______________________________ to muscles
and glands; also called efferent neurons
 Interneurons: conduct impulses from sensory neurons to motor neurons; also called
central or ______________________________
Nerves
 Nerve—bundle of peripheral _______________
 Tract—bundle of central axons
 White matter—brain or cord tissue composed primarily
of ______________________________ (tracts)
 Gray matter—brain or cord tissue composed primarily of
____________________________________________
 Nerve coverings—fibrous connective tissue
 _______________—surrounds individual fibers within a
nerve
 _______________—surrounds a group (fascicle) of nerve fibers
 _______________—surrounds the entire nerve
Reflex Arcs
 Nerve impulses are conducted from __________________________
over neuron pathways or reflex arcs
 Conduction by a reflex arc ______________________________ (i.e.,
contraction by a muscle or secretion by a gland)
 The simplest reflex arcs are two-neuron arcs—consisting of sensory
neurons synapsing in the spinal cord with motor neurons; threeneuron arcs consist of sensory neurons synapsing in the spinal cord
with interneurons that synapse with motor neurons
Nerve Impulses
 Self-propagating wave of ______________________________ that
travels along the surface of a neuron membrane; sometimes called
______________________________
 Mechanism
 At rest, the neuron’s ______________________________
_______________ on the outside—polarized—from a slight
______________________________ on the outside
 A stimulus triggers the opening of Na+ channels in the
plasma membrane of the neuron
 _______________ movement of Na+ depolarizes the
membrane by making the ____________________________
than the outside at the stimulated point; this depolarization is a
______________________________ (action potential)
 The stimulated section of membrane immediately repolarizes, but by that time the
depolarization has already triggered the next section of membrane to depolarize, thus
propagating a wave of electrical disturbances (depolarizations) all the way down the membrane
The Synapse
 Place where _____________________________________________________________________
______________________________ (the postsynaptic neuron)
 Synapse made of three structures—synaptic knob, synaptic cleft, and plasma membrane
 Neurotransmitters bind to specific receptor molecules in the membrane of a postsynaptic neuron,
opening ion channels and thereby stimulating impulse conduction by the membrane
Neurotransmitters
Actions
Disorder Involving It
_______________
-Triggers muscle contraction and stimulates
the excretion of certain hormones
-In CNS: involved in wakefulness,
attentiveness, anger, aggression, etc.
Alzheimer’s disease (lack of acetylcholine
in certain areas of the brain)
_______________
-Controls movement and posture,
modulates mood, and plays a central role in
positive reinforcement and dependency
Parkinson’s disease (loss of dopamine in
certain areas of the brain)
____________
(gammaaminobutyric acid)
-Contributes to motor control, vision, and
many other cortical functions; regulates
anxiety
Drugs that increase GABA in the brain
are used to treat epilepsy and
Huntington’s disease
_______________
-Learning and memory
Thought to be associated with
Alzheimer’s disease, whose first
symptoms include memory malfunctions
_______________
-Attentiveness, emotions, sleeping,
dreaming, and learning; also released as a
hormone into the blood, where it causes
blood vessels to contract and heart rate to
increase
Mood disorders like manic depression
_______________
-Regulating body temperature, sleep, mood,
appetite, and pain
Depression, impulsive behavior, and
aggressiveness
Central Nervous System (CNS)
 _______________
 Divisions
 Brainstem
 Cerebellum
 Cerebrum
 _______________
Brain – Brainstem
 Consists of three parts, named in ascending order: _______________________________________
 Structure—white matter with bits of gray matter scattered through it
 Functions
 All three parts of brainstem are two-way conduction paths
 Sensory tracts in the brainstem conduct impulses to the higher
parts of the brain
 Motor tracts conduct from the higher parts of the brain to the
spinal cord
 Many important reflex centers lie in the brainstem
 Medulla oblongata
 __________________________________________________
 Regulates _________________________________________________________________
_________________________________________________________________________
 Pons
 Helps ______________________________ from the cortex and the cerebellum
 Midbrain
 Associated with ____________________________________________________________
_________________________________________________________________________
Brain – Cerebellum
 Second largest part of the human brain
 _____________________________________________ to produce
coordinated movements so that we can maintain _____________________
___________________________________________________________
 Recent evidence shows the coordinating effects of the cerebellum may be
more extensive, also assisting the cerebrum and other regions of the brain
Brain – Cerebrum
 _____________________________________________
 Outer layer of gray matter is the cerebral cortex; made up of lobes; composed mainly of dendrites and
cell bodies of neurons
 Interior of the cerebrum composed mainly of white matter (i.e., nerve fibers arranged in bundles
called tracts)
 Functions of the cerebrum—mental processes of all types, including sensations, consciousness,
memory, and voluntary control of movements
Brain – Lobes of the Cerebrum
 ______________________________
 Personality, behavior, emotions
 Judgment, planning, problem solving
 Speech: speaking and writing (Broca’s area)
 Body movement (motor strip)
 Intelligence, concentration, self-awareness
 ______________________________
 Interprets vision (color, light, movement)
 ______________________________
 Interprets language, words
 Sense of touch, pain, temperature (sensory
strip)
 Interprets signals from vision, hearing,
motor, sensory and memory
 Spatial and visual perception
 ______________________________
 Understanding language (Wernicke’s area)
 Memory
 Hearing
 Sequencing and organization
Deep Structures of the Brain
 ______________________________: hunger, thirst, sleep, and sexual response, regulates body
temperature, blood pressure, emotions, and secretion of hormones
 ______________________________: known as the “master gland,” it controls other endocrine
glands in the body; produces many hormones
 ______________________________: regulates the body’s internal clock and circadian rhythms by
secreting melatonin
 _______________: serves as a relay station for almost all information that comes and goes to the
cortex
 ______________________________ (includes hypothalamus, amygdala, and hippocampus)
 _______________: emotional reactions
 _______________: memory
 ______________________________: allows for communication between hemispheres
Spinal Cord
 Columns of white matter, composed of bundles of myelinated
nerve fibers, form the outer portion of the H-shaped core of the
spinal cord; bundles of axons called tracts
 Interior composed of gray matter made up mainly of neuron
dendrites and cell bodies
 Spinal cord tracts provide _____________________________—
ascending and descending
 Spinal cord functions as the primary center for all spinal cord
reflexes; sensory tracts conduct impulses to the brain, and motor
tracts conduct impulses from the brain
Coverings and fluid spaces of the brain and spinal cord
 Coverings
 Cranial bones (_______________) and _______________
 Cerebral and spinal _______________
 Fluid spaces
 Subarachnoid spaces of meninges
 Central canal inside cord
 Ventricles in brain
 Fluid
 ______________________________ – cushions and provides immune protection
Peripheral Nervous System (PNS)
 ______________________________
 _______________—attached to undersurface of the brain
 Connect brain with the neck and structures in the thorax and abdomen
 ______________________________
 _______________—contain dendrites of
sensory neurons and axons of motor neurons
 Conduct impulses necessary for sensations
and voluntary movements
 After exiting the vertebral column, they split,
combine, and split again forming a plexus (there are 4)
 ______________________________
 ______________________________
 ______________________________
 ______________________________
Autonomic Nervous System
 Responsible for controlling ______________________________ (heartbeat, breathing, digestion)
 Composed of two divisions: the sympathetic system and the parasympathetic system
 Sympathetic nervous system
 Serves as the _____________________________________________, controlling visceral
effectors during strenuous exercise and when strong emotions (anger, fear, hate, or anxiety)
are elicited
 Group of changes induced by sympathetic control is called the ________________________
 Parasympathetic nervous system
 Dominates control of many visceral effectors under ______________________________