biology 210 chapter 13 the central nervous system edited by john mcgill supplemental notes by beth...
TRANSCRIPT
Biology 210 Chapter 13The Central Nervous System
Edited by John McGill
Supplemental Notes by Beth Wyatt
Original PowerPoint By: Jack Bagwell
Last Updated: April 10, 2023
DIVISIONS OF THE NERVOUS SYSTEM
There Are Several Ways That the Nervous System Can Be Organized BASED ON LOCATION
OF ORGANS CENTRAL NERVOUS
SYSTEM (CNS) PERIPHERAL NERVOUS
SYSTEM (PNS)
DIVISIONS OF THE NERVOUS SYSTEM
Organs centrally located
CENTRAL NERVOUS SYSTEM (CNS) BRAIN SPINAL CORD
DIVISIONS: Peripheral Nervous System
Organs (Nerves) Peripherally Located 2 Kinds of Nerves
CRANIAL NERVES (Originate From Brain) SPINAL NERVES (Originate From Spinal Cord)
Classification Based on Pathways
BASED ON DIRECTION IN WHICH PATHWAYS CARRY INFORMATION NEURONS CONDUCT NERVE IMPULSES) AFFERENT (aa ferent)
DIVISION: All Afferent Neurons
EFFERENT (ee ferent) DIVISION: All Efferent Neurons
Classification Based on Effectors
BASED ON EFFECTORS INNERVATED/REGULATED
SOMATIC NERVOUS SYSTEM (SNS)
AUTONOMIC NERVOUS SYSTEM (ANS)
Somatic: Voluntary Effectors SOMATIC NERVOUS SYSTEM
(SNS)Effectors: Skeletal Muscles
Voluntary Somatic Effectors
Autonomic: Involuntary Effectors
BASED AUTONOMIC NERVOUS SYSTEM (ANS) Effectors: Cardiac and Smooth Muscle,Glands
Involuntary Autonomic/Visceral Effectors)
Autonomic: 2 Divisions
SYMPATHETIC DIVISION-Response of Autonomic Effectors During Stress PARASYMPATHETIC DIVISION-Response of Autonomic Effectors During
Nonstress
COVERINGS OF THE BRAIN AND SPINAL CORD
Coverings Provide Protection 2 Kinds
OUTER COVERING - BONE CRANIAL BONES: BRAIN VERTEBRAE: SPINAL CORD
INNER COVERING – MEMBRANES (MENINGES) LAYERS OF MENINGES
DURA MATER ARACHNOID MEMBRANE PIA MATER
BONE COVERS THE BRAIN AND SPINAL CORD
CRANIAL BONES: BRAIN VERTEBRAE: SPINAL CORD
Vertebra & Spinal Cord
INNER COVERING MEMBRANES (MENINGES)
LAYERS OF MENINGES DURA MATER ARACHNOID MEMBRANE PIA MATER
LAYERS OF MENINGES
DURA MATER Outermost Layer of Meninges Tough, White An Extension of Periosteum
Dura Mater of Inferior Sheep BrainDura Mater of Inferior Sheep Brain
Pituitary
Op
tic
Ch
iasm
a
LAYERS OF MENINGES ARACHNOID MEMBRANE
Middle Layer of Meninges Delicate
LAYERS OF MENINGES
PIA MATER Innermost Layer of
Meninges Thin Transparent Adheres to CNS Contains Blood
Vessels
Pia Mater of Superior Sheep BrainPia Mater of Superior Sheep Brain
SPACES BETWEEN MENINGES
EPIDURAL SPACE SUBDURAL SPACE SUBARACHNOID SPACE
EPIDURAL SPACE “Space Above Dura” (Between Bone & Dura Mater) Contains Connective Tissue (Adipose)
Epidural Space
SUBDURAL SPACE “Space Below Dura”
(Between Dura Mater & Arachnoid)
Contains a Serous Fluid That Provides Lubrication
SUBARACHNOID SPACE
SPACES “Space Below the Arachnoid” (Between Arachnoid & Pia Mater)
Contains Cerebrospinal Fluid
CEREBROSPINAL FLUID
The Fluid That Circulates In and Around the CNS FUNCTION
Protection (A Cushion of Fluid)
FLUID SPACES The Spaces Where Cerebrospinal Fluid Circulates
CEREBROSPINAL FLUID: FLUID SPACES WITHIN BRAIN
VENTRICLES 4 Fluid Spaces Within the
Brain LATERAL (FIRST
AND SECOND) VENTRICLES
THIRD VENTRICLE FOURTH
VENTRICLE CEREBRAL AQUEDUCT
WITHIN SPINAL CORD CENTRAL CANAL
CEREBROSPINAL FLUID within the BRAIN
VENTRICLES: 4 Fluid Spaces Within the Brain LATERAL (FIRST AND SECOND) VENTRICLES
2, Located in Each Cerebral Hemisphere The Largest of the Ventricles
CEREBROSPINAL FLUID within the BRAIN
VENTRICLES: 4 Fluid Spaces Within the Brain THIRD VENTRICLE
Lies Inferior and Medial to the Lateral Ventricles
CEREBROSPINAL FLUID within the BRAIN
VENTRICLES: 4 Fluid Spaces Within the Brain FOURTH VENTRICLE
Diamond Shaped Space, Located Between the Brainstem and the Cerebellum
CEREBROSPINAL FLUID within the BRAIN
CEREBRAL AQUEDUCT Canal That Connects the Third and Fourth
Ventricles
CEREBROSPINAL FLUID within the SPINAL CORD
CENTRAL CANAL Passageway Within the Spinal Cord Continuous With the Fourth Ventricle
CEREBROSPINAL FLUID Circulation
AROUND BRAIN AND SPINAL CORD SUBARACHNOID
SPACE
CEREBROSPINAL FLUID Formation
FORMATION FROM BLOOD Choroid Plexuses: Capillary Networks Located in
Each of the Ventricles As Blood Flows Through Choroid Plexuses, Some of the Fluid from Blood Filters Through the
Plexuses and into the, Ventricles, The Fluid is Now Known as CSF
Choroid Plexuses
CEREBROSPINAL FLUID Circulation
FROM LATERAL VENTRICLES
THIRD VENTRICLE CEREBRAL AQUEDUCT FOURTH VENTRICLE* CENTRAL CANAL SUBARACHNOID SPACE BACK TO BLOOD
(ARACHNOID VILLI)
CEREBROSPINAL FLUID Circulation 2nd Pathway
*NOTE: ADDITIONAL PATHWAY:
ONCE IN FOURTH VENTRICLE
SUBARACHNOID SPACE BACK TO BLOOD
(ARACHNOID VILLI) Arachnoid Villi: Fingerlike
Extensions of Arachnoid That Project into Blood Vessels
SPINAL CORD STRUCTURE LOCATION,
EXTENT, SHAPE Spinal Cavity Extends from
Foramen Magnum to Lower Border of the First Lumbar Vertebra (approx. 18 inches)
Oval Cylinder
SPINAL CORD STRUCTURE: Grooves
ANTERIOR MEDIAN FISSURE Deep Groove in the
Anterior Midline
POSTERIOR MEDIAN SULCUS Groove in the Posterior
Midline
Anterior Median Fissure
1.Anterior median fissure 2.Olive 3.Pyramids 4.Cerebellum
Posterior Median Sulcus: 400X+
Posterior Median Sulcus & Others
SPINAL CORD: NERVE ROOTS
NERVE ROOTS/SPINAL NERVES Spinal Nerves Attached to Spinal Cord by
Nerve Roots (example nerves) DORSAL NERVE ROOT: NF OF AFFERENT
NEURONS VENTRAL NERVE ROOT: NF OF EFFERENT
NEURONS
DORSAL NERVE ROOT: NF OF AFFERENT NEURONS
Unipolar Receptors/Dendrites in Sense Organs Axons (Peripheral Portion) in Spinal Nerve Cell Bodies in Dorsal Root Ganglion Axons (Central Portion) in Dorsal
Nerve Root
VENTRAL NERVE ROOT: NF OF EFFERENT NEURONS
Efferent Neurons: Multipolar Dendrites/Cell Bodies in Gray Matter of Spinal Cord Axons in Ventral Nerve Root and S. Nerve
Spinal Cord Cross Section
http://www.uoguelph.ca/zoology/devobio/210labs/ecto2.html
Spinal Cord: Afferent (unipolar) & Efferent (multipolar) Neurons
Spinal Cord: Spinal Cord: Gray and White MatterGray and White Matter
The spinal cord consists of Gray Matter:
Consists of cell bodies of interneurons and motor neurons
White Matter Consists of axons of
neurons originating in the spinal cord and brain.
SPINAL CORD: Gray Matter
GRAY MATTER In Spinal Cord, Gray Matter Primarily Consists of Cell
Bodies of Interneurons and Motor Neurons
SPINAL CORD: Gray Matter
LOCATION: Central Portion of Spinal Cord, Resembles Letter “H” DIVISIONS: GRAY HORNS (COLUMNS), ANTERIOR, POSTERIOR,
& LATERAL
SPINAL CORD: White MatterSPINAL CORD: White Matter
White MatterWhite Matter Consists of axons of neurons originating in the spinal cord Consists of axons of neurons originating in the spinal cord
and brain.and brain.
SPINAL CORD: White Matter
LOCATION: Peripheral to Gray Matter DIVISIONS
WHITE COLUMNS: ANTERIOR, POSTERIOR, LATERAL
TRACTS White Columns Further Subdivided into Tracts
Names of Tracts Often Indicate 2 Things About Tract: Where Tract Begins/Ends White Column in Which Tract Located
SPINAL CORD: White Matter
WHITE COLUMNS ANTERIOR POSTERIOR LATERAL
Gray and White Matter
SPINAL CORD: White Matter
FUNCTIONS PROVIDES CONDUCTION ROUTES (2
WAY) FOR NERVE IMPULSES TRAVELING TO AND FROM THE BRAIN (WHITE MATTER)
White Matter of the Spinal Cord (Tracts) Conducts Impulses Toward and Away from the Brain Ascending tracts conduct impulses up the SC
toward the brain Descending tracts conduct impulses down the SC
away from the brain
SPINAL CORD: ASCENDING TRACTS
Conduct Impulses Up the SC Toward the Brain
FUNCTION Ascending Tracts Have a Sensory Function (Carry
Impulses Related To General Sensations: Hot, Cold, Pain, Pressure, Touch & Kinesthesia)
IMPORTANT ASCENDING TRACTS SPINOTHALAMIC TRACTS FASCICULI GRACILIS AND CUNEATUS SPINOCEREBELLAR TRACTS
SPINAL CORD: DESCENDING TRACTS
DESCENDING TRACTS Elaboration Conduct Impulses Down the SC Away from the
Brain FUNCTION Descending Tracts Have a Motor Function
(Carry Impulses that Will Result in Voluntary Movement of Skeletal Muscles)
IMPORTANT DESCENDING TRACTS CORTICOSPINAL TRACTS RETICULOSPINAL TRACTS RUBROSPINAL TRACTS
Spinal Cord TractsSpinal Cord Tracts
Ascending TractsAscending Tracts Spinocerebellar tracts
Impulses from stretch receptors are carried to the spinal cord. These tracts originate in the spinal cord and transmit signals to
the cerebellum Involved in regulation of muscle tone without reaching
consciousness. Spinothalamic tracts
Fibers concerned with pain, thermal sense, and light touch Originate in the spinal cord. Convey sensory impulses to the thalamus.
Dorsal column: Fasciculi Gracilis and Cuneatus Tracts Arise from spinal ganglion cells The fasciculi terminate upon large nuclear masses (the nuclei
gracilis and cuneatus) in the medulla. Conveys signals associated with tactile, pressure, and
kinesthetic (or positional) sense to sensory areas of the cerebral cortex.
Descending TractsDescending Tracts Corticospinal tract
Concerned with skilled voluntary activity, the corticospinal tract originates from premotor, primary motor, and primary sensory cortex.
Synapse with interneurons and motor neurons. Rubrospinal tract
Arises from cells in the midbrain. Fibers of this tract descend the spinal cord and terminate on
interneurons. Cells of the midbrain receive input from the motor cortex and from
the cerebellum (via the superior cerebellar peduncle). The rubrospinal tract brings flexor muscle tone under the control of
these two regions of the brain. Reticulospinal tract
Arises from the reticular formation of the pons and medulla Fibers of this tract influence voluntary movements, muscle tone, and
a variety of spinal reflexes. Fibers terminate at all spinal levels. Receive input from regions of the motor cortex.
Spinal Cord TractsSpinal Cord Tracts
SPINAL CORD : Reflexes
REFLEX CENTER FOR ALL SPINAL REFLEXES (GRAY MATTER) Gray Matter of the Spinal Cord Functions as Reflex Centers for
Spinal Reflexes Reflex Center: Center of a Reflex Arc Spinal Reflexes: Reflexes Whose Arcs Pass Through the SC
SPINAL CORD : Reflexes
SPINAL CORD : Reflexes
THE BRAIN
DIVISIONS BRAINSTEM
MEDULLA OBLONGATA PONS MIDBRAIN
CEREBELLUM DIENCEPHALON CEREBRUM
SIZE In Adults, Weighs Approx.
3 Pounds
THE BRAIN: Brainstem
BRAINSTEM Extension of SC into
the Cranial Cavity STRUCTURE
MEDULLA OBLONGATA Lowermost Division
PONS Middle, Swollen
Division MIDBRAIN
Uppermost Division
THE BRAIN: Brainstem
MIDBRAIN: Uppermost Division; Has 2 Important External Landmarks
CEREBRAL PEDUNCLES: Form Floor of Midbrain CORPORA QUADRIGEMINIA
Cerebral Peduncles
Midbrain: Copora Quadrigemina
CORPORA QUADRIGEMINIA Forms Roof of Midbrain CQ Consists of 4 Rounded Structures
SUPERIOR COLLICULI (2): Visual Centers INFERIOR COLLICULI (2): Auditory Centers
CORPORA QUADRIGEMINIA
THE BRAIN: Reticular Formation
LOCATIONS OF GRAY AND WHITE MATTER IN BRAINSTEM WHITE MATTER –outside RETICULAR FORMATION – inside
Reticular Formation = Mixture of Gray and White Matter Located in the Core of the Brainstem
Reticular Formation http://www.medinfo.ufl.edu/year2/neuro/neuroexam/nems5000.html
Reticular Formation http://www.medinfo.ufl.edu/year2/neuro/neuroexam/nems5000.html
THE BRAIN: Brainstem Tracts (white matter)
FUNCTIONS The Functions of the Brainstem are
Similar to the Functions of the SC PROVIDES CONDUCTION
ROUTES (2 WAY) FOR NERVE IMPULSES TRAVELING BETWEEN SPINAL CORD AND BRAIN (WHITE MATTER)
The White Matter of the Brainstem is Organized into Tracts (Ascending & Descending Which are an Extension of The Tracts of the Spinal Cord
http://brainimaging.waisman.wisc.edu/~mlazar/TRAVIS_2.html
THE BRAIN: Reticular Formation
REFLEX CENTER FOR BRAIN REFLEXES (GRAY MATTER) Portions of Gray Matter Located Within the
Reticular Formation Functions as Reflex Centers for Brain Reflexes
(Brain Reflexes: Reflexes Whose Arcs Pass Through the Brainstem)
THE BRAIN: Brain Reflexes 2 Kinds of Reflex Centers in Brainstem
VITAL REFLEX CENTERS (MEDULLA) Reflex Centers for Vital Reflexes Vital Reflexes: Reflexes that are Essential for
Survival; Examples: Breathing, Heart rate, BP
Names of Vital Reflex Centers: Respiratory Centers, Cardiac Control Centers,
Vasomotor Center
All of the Vital Reflex Centers are Located in the Medulla (Medulla Associated with Basic Survival)
THE BRAIN: Brain Reflexes
NONVITAL REFLEX CENTERS (MEDULLA, PONS, MIDBRAIN) Reflex Centers for Nonvital Reflexes (Not
Essential for Basic Survival: Vomiting, Coughing, Hiccuping, Swallowing,
Sneezing, etc.); Centers Have Same Names as Reflexes
Nonvital Reflex Centers Located in All Parts of the Brainstem
Brain Illusions and Information
http://www.exploratorium.edu/exhibits/changingill/
http://www.wnet.org/archive/closetohome/animation/neuron-main.html
http://videocast.av.com/default.cfm?FeatureID=105640