• Functions of the Nervous System
1.
_____________________________________________________________________________
2.
_____________________________________________________________________________
3.
_____________________________________________________________________________
• Divisions of the Nervous System
– _________________________________________
• Brain and spinal cord
• Intelligence, memory, and emotion
– _________________________________________
• Paired spinal and cranial nerves carry messages from the CNS to the rest of the body and back
• Includes all the neural tissues outside of the CNS
• Functional Relationships of the PNS
– Two functional divisions
• _________________________________________
– Sensory information detected outside of the nervous system is transmitted by the afferent division of the PNS to the CNS
• _________________________________________
– The CNS sends motor commands via the efferent division to smooth/cardiac muscle, & glands
» Subdivided into the ______________________ and the ______________________
• ANS contains the _________________ and ___________________ divisions
• Histology of Nervous Tissue
– Two principal cell types
• Neurons—excitable cells that transmit electrical signals
• Neuroglia (glial cells)—supporting cells:
– ____________________ (CNS)
– ____________________ (CNS)
– ____________________ (CNS)
– ____________________ (CNS)
– ____________________ (PNS)
– ____________________ (PNS)
• Astrocytes
– Most abundant, versatile, and highly branched glial cells
– __________________________________________________________________________________________
– Create a framework for CNS neurons to perform repairs in damaged neural tissues
• Microglia
– Smallest and rarest of the neuroglia
– __________________________________________________________________________________________
• Ependymal Cells
– Range in shape from squamous to columnar
– Line the central cavities of the brain and spinal column
– The lining of the epithelial cells is called the ependyma
• _______________________________________________________________
• Oligodendrocytes
– Processes wrap CNS nerve fibers, forming insulating myelin sheaths
• The gaps between the adjacent myelinated areas are called ________________________
• _______________________________________________________________
• Satellite Cells and Schwann Cells
– Satellite cells
• Surround and support neuron cell bodies in the PNS
– Schwann cells
• Cover (myelinate) every axon outside the CNS
• Where a Schwann cell covers an axon , ___________________________________________________

• Neurons (Nerve Cells)
– Special characteristics:
• _________________________
• Several branching, sensitive ________________ (which receives incoming signals)
• An elongated ______________ (which carries outgoing signals toward 1 or more...)
• …Synaptic terminals
– Where a neuron communicates with another cell
• Cell Body
– Lack centrioles and as a result cannot divide for reproduction
• ________________________________________________________________
– Rough ER called Nissl bodies and mitochondria provide energy
– Projecting from the cell body are several dendrites and an axon
• Dendrites
– Short, tapering, and diffusely branched
– ___________________________________________________________________
– Convey electrical signals toward the cell body as graded potentials
• The Axon
– One axon per cell arising from the axon hillock
– Occasional branches (___________________)
– Axon function:
• ____________________________________________________________________
• Generates and transmits nerve impulses (__________________) away from the cell body
• White Matter vs. Gray Matter
– White matter
• Dense collections of _______________ fibers
– Gray matter
• Mostly neuron cell bodies and ________________ fibers
• Structural Classification of Neurons
– Three types:
• _____________________—1 axon and several dendrites
– Most abundant
– All the motor neurons that control skeletal muscles
• _____________________—2 processes, 1 axon and 1 dendrite with the cell body in between
– Rare, found in special sense organs
• _____________________—the dendrites and axon are continuous with the cell body off to one side
• Functional Classification of Neurons
– Three types:
• _______________________________________
– Transmit impulses from sensory receptors toward the CNS
• _______________________________________
– Carry impulses from the CNS to effectors
• _______________________________________
– Interconnect other neurons
– Responsible for the distribution of sensory information and the coordination of motor activity
• Membrane Potential
− Respond to adequate stimulus by generating an action potential (__________________)
– All the communications between neurons and other cells occur through their membrane surfaces which are polarized (_____________________________________________________)
• Because these charges are separated by a plasma membrane this is referred to as membrane potential
– Measured in millivolts (mV)
– The membrane potential of an undisturbed cell is known as its resting potential
» _____________________________________________

• Membrane Potential
– The negative symbol in -70mV indicates that the inside of the plasma membrane contains an excess of negative ions
• If the membrane potential shifts towards 0 mV meaning that there are more positive ions entering the plasma membrane then this is referred to as _________________
– ________________________________________________________
• If the membrane potential becomes more negative then this is referred to as ____________________
– ________________________________________________________
• Graded Potential vs. Action Potential
– ______________________________ – changes in the membrane potential that cannot spread far from the site of stimulation (local depolarization)
• Occur in response to environmental stimuli
• Often trigger specific cell functions
– ______________________________ – a propagated change in the membrane potential of the entire plasma membrane
• Generated in response to a graded potential
• Usually begins near the axon hillock and travels along the length of the axon toward the synaptic terminals, where its arrival activates the synapses
• Generation of an Action Potential
– 4 stages:
• ______________________
• ______________________
• ______________________
• ______________________
– When the process is done it returns to stage 1
• Propagation of an Action Potential
– Continuous propagation
• ________________________________
• Speeds of about 2 mph
– Saltatory propigation
• ________________________________
• The Synapse
• Action potential jumps from node to node skipping over the myelinated sections
• Speeds of 40-300 mph
– A junction that mediates information transfer from one neuron:
• _____________________________
• _____________________________
– Information transfer occurs through the release of chemicals called neurotransmitters from the synaptic terminal
– Presynaptic neuron—________________________________________________
– Postsynaptic neuron—_________________________________________________
• Neuronal Pools
– ________________________________________________________________
– Neurons and neuronal pools communicate with each other in several patterns, or neural circuits. The 2 simplest are:
• _________________
– Information spreads from 1 neuron (or pool) to several neurons (or pools)
• _________________
– Several neurons synapse on a single postsynaptic neuron

• Meninges
– Provide physical stability and shock absorption
– 3 layers of specialized membranes that cover and protect the CNS:
• ____________________________________________
– The outermost covering of the CNS (consists of 2 layers)
• The inner layer extends into the cranial cavity and creates dural folds (hold brain in place)
• ____________________________________________
– Contains lymphatic fluid to reduce friction
• ____________________________________________
– Bound to underlying neural tissue
– Contains the blood vessels servicing the brain and spinal cord
• Spinal Cord
– Functions to provides two-way communication to and from the brain
• ________________________________________ (ascending)
• ________________________________________ (descending)
– 31 segments on the spinal cord with 31 pairs of nerves
• Each with a pair of dorsal root ganglia, dorsal roots (_____________________________) and ventral roots (_____________________________________)
– Roots bound together into a spinal nerve
– Ends at 1 st or 2 nd lumbar vertebrae
• The Major Regions of the Brain
1.
Cerebrum
– Divided into cerebral hemispheres
2.
Diencephalon
3.
Midbrain (_____________________)
4.
Pons
5.
Medulla Oblongata
6.
Cerebellum
• Ventricles of the Brain
– Contain cerebrospinal fluid
• Two C-shaped lateral ventricles in the _______________________
• Third ventricle in the _______________________
• Fourth ventricle in the ____________________________________
• Connected to the third ventricle by the cerebral aqueduct
• Cerebral Hemispheres
– Cerebral cortex (blanket of neural cortex) covers the superior and lateral surfaces of the cerebrum
– Surface markings
• Ridges (gyri), shallow grooves (sulci), and deep grooves (fissures)
• _______________________________________________________________________
– Longitudinal fissure
• Separates the two hemispheres and contains the corpus callosum
– Five lobes
• ____________________
• ____________________
• ____________________
• ____________________
• ____________________

• Functional Areas of the Cerebral Cortex
– The three types of functional areas are:
• Motor areas—_______________________________________
• Primary motor cortex
• Sensory areas—________________________________________
• Primary sensory cortex
• Association areas—_________________________________________
• Somatic sensory association area
• Somatic motor association area (premotor cortex)
• Hemispheric Lateralization
– ______________________:
• Interpretive and speech centers
• Language-based skills
• Reading, writing, speaking
• Analytical tasks
• Mathematical calculations
• Logical decision making
• __________________________________________________________________
– ______________________:
• Analyzes sensory information
• Relates the body to the sensory environment
• Enables you to indentify familiar objects by touch, smell, taste, or feel
• Analyzes emotion
• Music/art
• Diencephalon
– Three paired structures
• ________________
• __________________________________________________________
• Final relay point for all ascending sensory information, except olfactory
• Plays a role in coordinating voluntary/involuntary motor commands
• ________________
• Subconscious control of skeletal muscle contractions
• Secretes a variety of hormones (ADH and oxytocin)
• __________________________________________________________
• Regulates body temperature and sleep cycle
• ________________
• Above the third ventricle (roof of diencephalon)
• __________________________________________________________
• Brain Stem
– Three regions
• ______________________
• Has 2 pairs of sensory colliculi involved in processing visual and auditory sensations
• Houses the reticular formation (regulates many involuntary functions)
• ______________________
• Connects cerebellum to the midbrain, diencephalon, cerebrum, and spinal cord
• Controls involuntary control of the pace and depth of respiration
• ______________________
• Connects the brain to the spinal cord
• Contains cardiovascular centers – adjust heart rate, strength of cardiac contractions, and flow of blood
• Contain respiratory rhythmicity centers – set breathing pace

• The Cerebellum
– 2 important functions:
• ___________________________________________________________________________
• ___________________________________________________________________________
– Can be permanently (trauma or stroke) or temporarily (alcohol) damaged
• These changes produce ataxia (a disturbance in balance)
• Cranial Nerves
– 12 pairs connected to the brain:
• N I – _____________________
• Only cranial nerves attached to the cerebrum
• Responsible for the sense of smell
• N II – _____________________
• Carry visual information from the eyes
• N III – ____________________
• Innervates 4 of the 6 muscles that move the eyeball
• N IV – ____________________
• Innervate the superior oblique muscles of the eyes
• Smallest cranial nerve
• N V – _____________________
• Provide sensory information from the head and face and motor control over chewing
• Largest cranial nerve
• N VI – ____________________
• The sixth of the eye muscles (lateral rectus)
• N VII – ___________________
• Provide deep pressure sensations, taste information, produce facial expressions, control tear/salivary glands
• N VIII – ___________________
• Monitor the sensory receptors of the inner ear
• N IX – ____________________
• Innervates the tongue (taste) and pharynx (swallowing)
• N X – ____________________
• Provides sensory info from the ear canal, diaphragm, pharynx, esophagus, respiratory tract
• N XI – ___________________
• Innervate structures of the neck and back
• N XII – ___________________
• Voluntary control over the tongue
• Reflexes
– _________________________________________________________________________
– Simple reflex steps:
1.
Arrival of a stimulus and activation of a receptor
2.
Activation of a sensory neuron
3.
Information processing by an interneuron
4.
Activation of a motor neuron
5.
Response by an effector (muscle or gland)
– Usually removes or opposes the original stimulus