THE CENTRAL NERVOUS SYSTEM

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THE CENTRAL NERVOUS SYSTEM

• D. C. MIKULECKY
• PROFESSOR OF PHYSIOLOGY
• AND
• FACULTY MENTORING PROGRAM

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ORGANIZATION OF THE NERVOUS SYSTEM
BRAIN SPINAL CORD
CENTRAL NERVOUS SYSTEM (CNS)
AFFERENT NERVES
EFFERENT NERVES
PERIPHERAL NERVOUS SYSTEM
EXTERO- RECEPTORS
INTERO- RECEPTORS
SOMATIC
AUTONOMIC
EFFECTOR ORGANS
SKELETAL MUSCLES
SMOOTH AND CARDIAC MUSCLES AND GLANDS
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MAINTENANCE AND PROTECTION OF THE CNS

• Glial Cells physical and metabolic support
• Skull and Spinal Column
• Cerebrospinal fluid
• Blood-brain barrier
• Blood supply

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GLIAL CELLS OR NEUROGLIA

• PHYSICAL AND METABOLIC SUPPORT
• 90 OF CELLS IN BRAIN
• FOUR TYPES ASTROCYTES, OLIGODENDROCYTES,
  EPENDYMAL CELLS, AND MICROGLIA

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Skull and Spinal Column

• PROVIDE MECHANICAL SUPPORT
• PROTECTS THE NEURAL AND SUPPORTING TISSUE

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CEREBROSPINAL FLUID

• DENSITY IS THE SAME AS BRAIN
• SHOCK ABSORBER

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Blood-brain barrier

• LIMITS ACCESS OF BLOOD MATERIALS TO BRAIN TISSUE
• PROTECTS BRAIN FROM FLUCTUATIONS IN BLOOD LEVELS

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STRUCTURE OF THE BRAIN

• BRAIN STEM
• CEREBELLUM
• FOREBRAIN

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THE FOREBRAIN

• THE DIENCEPHALON
• THE CEREBRUM

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THE DIENCEPHALON

• HYPOTHALAMUS
• THALAMUS

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THE CEREBRUM

• BASAL NUCLEI
• CEREBRAL CORTEX

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WHITE AND GRAY

• GRAY MATTER - MAINLY CELL BODIES
• WHITE MATTER - MYELINATED AXONS

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SUBCORTICAL STRUCTURES

• BASAL GANGLIA
• THALAMUS
• HYPOTHALAMUS
• LIMBIC SYSYTEM

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BASAL GANGLIA

• PLAY A COMPLEX ROLE IN THE CONTROL OF MOVEMENT
• INHIBIT MUSCLE TONE THROUGHOUT BODY
• SUPPRESS USELESS OR UNWANTED PATTERNS OF MOVEMENT

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THALAMUS

• RELAY STATION
• HELP US DIRECT OUR ATTENTION
• FILTERS OUT INSIGNIFICANT SIGNALS

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HYPOTHALAMUS

• REGULATES HOMEOSTATIC FUNCTIONS
• THIRST AND URINE OUTPUT
• FOOD INTAKE
• HORMONE SECRETION
• BODY TEMPERATURE
• AUTONOMIC NERVOUS SYSTEMS COORDINATING CENTER

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LIMBIC SYSTEM

• COMPLEX NETWORK OF FOREBRAIN STRUCTURES
• EMOTIONS
• BASIC SURVIVAL
• SOCIOSEXUAL BEHAVIOR
• MOTIVATION
• LEARNING

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BEHAVIOR AND NEUROTRANSMITTERS

• NOREPINEPHRINE
• DOPAMINE
• SEROTONIN

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LEARNING AND MEMORY

• SHORT TERM VS LONG TERM
• WORKING MEMORY
• ASSOCIATIVE VS CONDITIONED
• MULTIPLE LOCATIONS

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THE MOTOR CORTEX

• SOMATOTOPIC ORGANIZATION
• DESCENDING PATHWAYS
• SENSORY FEEDBACK

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CORTICAL AREAS INVOVED IN MOTOR CONTROL
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SOMATOTOPIC ORGANIZATION OF THE MOTOR CORTEX
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THE SPINAL CORD IN SOMATIC SENSORY FUNCTION

• WHITE AND GREY MATTER
• SEGMENTAL ORGANIZATION

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SEGMENTAL STRUCTURE OF SPINAL NERVES
DERMATOMES
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SPINAL CORD
DORSAL HORN
DORSAL
GREY MATTER
DORSAL ROOT GANGLION
LATERAL
VENTRAL HORN
WHITE MATTER
SPINAL NERVE
VENTRAL
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THE SOMATOSENSORY CORTEX
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SOMATOTOPIC ORGANIZATION OF THE SENSORY CORTEX
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MOTIVATIONAL SYSTEMS

• HUNGER
• THIRST
• SEXUAL BEHAVIOR

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HUNGER
GLUCOSE RECEPTORS IN HYPOTHALAMUS
REDUCED AVAILABILITY OF GLUCOSE
SHORT TERM
MECHANO- RECEPTORS IN STOMACH
CONTRACTIONS OF EMPTY STOMACH
HUNGER
LACK OF FOOD
LOW TRIGLYCERIDE LEVELS IN FAT CELLS
LONG TERM
PANCREAS
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THIRST
OSMORECEPTORS IN SUPRAOPTIC AND
SUPRA- VENTRICULAR NUCLEI OF HYPOTHALAMUS
THIRST
WATER DEFICIENCY
WATER RETENTION BY KIDNEY
ADH SERETION BY PITUITARY
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SEXUAL BEHAVIOR

• ANTERIOR HYPOTHALAMUS ORGANIZES RESPONSES TO
  PHERMONES
• OLIFACTORY CUES SENT TO PYRIFORM CORTEX AND
  AMYGDALA AND INDIRECTLY TO HYPOTHALAMUS
• ANDROGENS DETERMINE RELEASE OF LEUTINIZING
  HORMONE- CONSTANT OR CYCLIC

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LEARNING AND MEMORY

• ASSOSCIATIVE VS NONASSOCIATIVE LEARNING
• SHORT AND LONG TERM MEMORY
• NEURONAL PATHWAYS
• SPLIT BRAIN STUDIES
• CELLULAR MANIFESTATIONS
• USE AND DISUSE

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LOCALIZATION OF LANGUAGE FUNCTIONS
ASSOCIATION
COMPREHENSION
MOTOR PROGRAMS
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LATERALITY OF BRAIN FUNCTION

• RIGHT AND LEFT BRAIN
• GENDER DIFFERENCES

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RIGHT AND LEFT BRAIN

• RIGHT HEMISPHERE SPATIAL ABILITIES
• LEFT HEMISPHERE MUSICAL ABILITY

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GENDER DIFFERENCES

• MALES TEND TO EXHIBIT MORE LATERALIZATION OF
  SPECIFIC TASKS
• FEMALES USE BOTH HEMISPHERES MORE SYMMETRICALLY

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ANATOMY OF THE CEREBELLUM
Lateral Zone
Intermediate Zone
Floculonodular Lobe
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SOMATIC SENSORY PROJECTIONS ONTO THE CEREBELLAR
CORTEX
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THE BASAL GANGLIA
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THE FLEXOR WITHDRAWAL REFLEX

• PAINFUL STIMULUS DETECTED
• IPSILATERAL EXTENSORS INHIBITED
• IPSILATERAL EXTENSORS EXCITED
• LIMB IS WITHDRAWN
• IF INVOLVING ONE FOOT WHILE STANDING,
  CONTRALATERAL SIDE EXTENSORS ACTIVATED AND
  FLEXORS INHIBITED TO SUPPORT GREATER WEIGHT

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FLEXOR WITHDRAWAL REFLEX
SENSORY SIGNAL TO SPINE
STEPON TACK
VIA INTERNEURONS
IPSILATERAL EXTENSORS INHIBITED IPSILATERAL
FLEXORS CONTRACT-LEG LIFTS CONTRALATERAL
EXTENSORS CONTRACT CONTRALATERAL FLEXORS
INHIBITED- MAINTAIN BALANCE AND SUPPORT WEIGHT