Transcript Chapter 13 Supplement 3 The Central Nervous System

BIO 210 Chapter 13
Supplement 3
The Central Nervous System
PowerPoint by John McGill
Supplemental Notes by Beth Wyatt
CEREBRUM
 Largest, Uppermost Division
 STRUCTURE
 CEREBRAL HEMISHPERES
 LOBES
CEREBRAL HEMISHPERES
 2 Halves of the Cerebrum That are Joined
Sheep Brain: Cerebral
Hemispheres
LOBES of the CEREBRUM
 LOBES
 Cerebrum is Divided
into Lobes by Fissures
 Majority of Lobes
Named After Bones
 FRONTAL LOBE
 PARIETAL LOBE
 TEMPORAL LOBE
 OCCIPITAL LOBE
 INSULA
 Lies Hidden in the
Lateral Fissure
LOBES of the CEREBRUM: Insula
 Lies Hidden in the Lateral Fissure (a.k.a. lateral sulcus)
Insula Photos
Cerebral Fissures
 FISSURES (4 Major)
 LONGITUDINAL
FISSURE (next slide)
 CENTRAL SULCUS
(aka central fissure)
 LATERAL FISSURE
 PARIETALOCCIPITAL
FISSURE
Cerebral Fissures: Longitudinal
 Deepest; Divides Cerebrum into 2 Hemispheres
Cerebral Fissures: Central Sulcus
Cerebral Fissures: Lateral Fissures
Cerebral Fissures: Parietaloccipital
CEREBRAL CORTEX
 CONVOLUTIONS (GYRI) are Folds
 SULCI are Grooves
Cerebrum vs. Cerebellum
 Cerebral Cortex has Convolutions and Sulci as
Cerebellum, Both Larger in Cerebrum
Cerebral Tracts
 White Matter of the
Cerebrum
 Lies Below the Cortex
 Cerebrum Has 3 Major
Kinds of Tracts
 PROJECTION TRACTS
 ASSOCIATION TRACTS
 COMMISSURAL
TRACTS
PROJECTION
TRACTS are
 Extensions of Tracts of
Spinal Cord & Brainstem,
ascending & descending.
 Example of Ascending
(Sensory)
 spinothalamic
 Example of Descending
(Motor)
 corticospinal
Projection Tracts: Sensory/Ascending-spinothalamic
Projection Tracts: Motor/Descending-corticospinal
ASSOCIATION TRACTS
 Tracts That Extend From 1 Convolution to Another
Convolution in the SAME Hemisphere
 Most Numerous
COMMISSURAL TRACTS
 Tracts That Extend From 1 Convolution to a Corresponding
Convolution in the OPPOSITE Hemisphere
 Compose the Corpus Callosum
Additional Cerebral Structures
 CEREBRAL NUCLEI (BASAL GANGLIA)
 CORPUS CALLOSUM
 SEPTUM PELLUCIDUM
CEREBRAL NUCLEI (BASAL GANGLIA)
 Gray Matter Located Deep Within the
Cerebrum’s White Matter
CEREBRAL NUCLEI (BASAL GANGLIA)
CORPUS CALLOSUM
 White Curved Structure That Joins the 2 Cerebral
Hemispheres
 Composed of Commissural Tracts
SEPTUM PELLUCIDUM
 Membrane That Lies Below the Corpus Callosum
 Covers the Lateral Ventricles
FUNCTIONS OF THE CEREBRAL CORTEX
 Organized Into 3 Groups
 SENSORY, MOTOR, & INTEGRATIVE.
FUNCTIONS OF THE CEREBRAL CORTEX
SENSORY FUNCTIONS OF THE CEREBRAL CORTEX
 Cortex Involved in the Interpretation of Sensations
MAJOR SENSORY AREAS
OF THE CEREBRAL CORTEX
 PRIMARY SOMATIC
SENSORY AREA
(POSTCENTRAL GYRUS):
CONTAINS SOMATIC
SENSORY MAP
 VISUAL CORTEX
(OCCIPITAL LOBE)
 PRIMARY AUDITORY
AREA (TRANSVERSE
GYRUS)
 PRIMARY TASTE AREA
MAJOR SENSORY AREAS
 PRIMARY SOMATIC SENSORY AREA
 POSTCENTRAL GYRUS
 CONTAINS SOMATIC SENSORY MAP
 Major Area Involved in the Interpretation of General
Sensations
 Located in the Postcentral Gyrus (Parietal Lobe)
 Contains a Somatic Sensory (General Sense) Map
VISUAL CORTEX (OCCIPITAL LOBE)
 Major Area Involved in the Interpretation of Vision
 Located in the Occipital Lobe
PRIMARY AUDITORY AREA
(TRANSVERSE GYRUS)
 Major Area Involved in the Interpretation of Hearing
 Located in the Transverse Gyrus (Temporal Lobe)
PRIMARY TASTE AREA
 Major Area Involved in the Interpretation of Taste
 Located in the Postcentral Gyrus
ASSOCIATION AREAS
 Areas that Assist the Major Sensory Areas in the Interpretation
of Sensations
 In Addition, Other Areas of the Brain are Also Involved in the
Interpretation of Sensation (i.e., Mamillary Bodies, Corpora
Quadrigemina, Thalamus)
MOTOR FUNCTIONS OF THE
CEREBRAL CORTEX
 Cortex also Involved the Producing Normal
Voluntary Movements of Skeletal Muscles
MOTOR FUNCTIONS OF THE CEREBRAL CORTEX
 Movements of Skeletal Muscles
 PRIMARY SOMATIC MOTOR AREA (PRECENTRAL GYRUS):
CONTAINS SOMATIC MOTOR MAP
 Major Area Responsible for Producing Voluntary Movements (Nerve
Impulses Begin Here)
 Located in the Precentral Gyrus (Frontal Lobe)
 Contains a Somatic Motor (Skeletal Muscle) Map
Sensory & Motor Maps
Motor Functions continued…
 PREMOTOR AREA
 Assists the Major Motor
Area in Producing
Voluntary Movements
 Located in the Frontal
Lobe
 In Addition, Other Areas
of the Brain are Also
Involved in Producing
Normal Voluntary
Movements (i.e.,
Cerebellum, Cerebral
Nuclei, Thalamus)
Integrative Functions
 3 cerebral functions:
 Sensory
 Motor
 Integrative
 Integrative Functions




Reticular Activating System-awareness
Language-understanding & speech
Limbic System-emotions
Memory
INTEGRATIVE FUNCTIONS:
Awareness
 CONSCIOUSNESS
 RETICULAR ACTIVATING SYSTEM
 Awareness of One's Self, the Environment, Others
INTEGRATIVE FUNCTIONS: Awareness
 Involves the Reticular Activating System (RAS)
 RAS = Neuron Pathways of the Reticular Formation, Brainstem,
Hypothalamus, Thalamus, Areas of the Cerebral Cortex
 Mechanism: As NI are Continuously Conducted Over the RAS and Excite Key
Areas of the Cerebral Cortex, Consciousness Results
 RAS Functions as the Arousal (Alerting) Mechanism
Integrative functions: LANGUAGE (SPEECH CENTERS)
 The 2 major Speech
Centers Include:
 Wernicke's Area:
Sensory Speech
Area (Understanding
Language)
 Broca's Area: Motor
Speech Area (Use of
Language)
 Speech Centers Are
Usually Located in the
Left Cerebral
Hemisphere
Integrative functions: EMOTIONS (LIMBIC SYSTEM)
 Limbic System Structures Form a Curving Border Around the Corpus
Callosum
 E.g. Cingulate gyrus & Hippocampus
 Involved in Both the Experience and the Expression of Emotions
 There Are Other Areas of the Cerebral Cortex Important in the
Expression of Emotions
Integrative functions: Memory
 Considered a Major Function of the Cerebral Cortex
 Involves Many Areas of the Cerebral Cortex
 Also Appears to Involve the Limbic System
Memory Formation
Memory Involves Many Brain Areas
 Most activities involve multiple brain areas
 Consider hearing and then repeating words:
impulses start in the ear and end in the
precentral gyrus
GENERALIZATIONS ABOUT CEREBRAL FUNCTIONS
 LEFT AND RIGHT HEMISPHERES SPECIALIZE IN
DIFFERENT FUNCTIONS
 Left: Language, Right: Nonlanguage (i.e., Images or Nonspeech Sounds)
 Both Hemispheres Work Together to Accomplish Functions
CEREBRAL ACTIVITY GOES ON AS LONG AS
LIFE ITSELF (EEG)
 Cerebral Activity: Nerve Impulses (Measured as Brain
Waves)
 Absence of Brain Waves = Death (Brain Death)
 Evidence Comes From EEG Electroencephalogram:
Measures Brain Waves)
SENSORY PATHWAYS
 FOR THE CEREBRAL CORTEX TO
PERFORM ITS SENSORY FUNCTIONS,
IMPULSES MUST BE CONDUCTED TO
ITS SENSORY AREAS ALONG
SENSORY PATHWAYS
 Example: Spinothalamic
 Sensory Pathways: See Handout & Next Slide
 Sensory Pathways Are Crossed
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Motor Pathways
 FOR THE CEREBRAL CORTEX TO PERFORM
ITS MOTOR FUNCTIONS, IMPULSES MUST
BE CONDUCTED FROM ITS MOTOR AREAS
TO SKELETAL MUSCLES ALONG SOMATIC
MOTOR PATHWAYS
 Example: Corticospinal
 Somatic Motor Pathways: See Handout & Next Slide
 Most (Though Not All) Somatic Motor Pathways Are
Crossed
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LEFT BRAIN & RIGHT BRAIN
 LEFT AND RIGHT HEMISPHERES SPECIALIZE IN
DIFFERENT FUNCTIONS due to ascending and descending
pathways being crossed.