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THE FUNCTIONS OF
THE NERVOUS
SYSTEM
The Central Nervous System: lower cortex to brain stem.
The cerebral cortex
•
•
•
•
Frontal lobe
Parietal lobe
Occiptial lobe
Temporal lobe
THE temporal lobe
• Temporal lobes
– Separated from the frontal and parietal
lobe by the lateral fissure
• Three important areas:
– Auditory projection area,
– visual and auditory association areas
– Additional language area: Wernicke’s
Area.
THE auditory or
temporal cortex
• Auditory cortex:
– receives sound information from the ears
– lies on the superior (uppermost) gyrus of the temporal lobe.
• Wernicke’s area
– Just posterior to the auditory cortex
– Left hemisphere only
– interprets language input arriving from the nearby auditory and visual
areas.
– also generates spoken language through Broca’s area and written
language by the way of the motor cortex.
• Inferior temporal cortex
– lower part of the lobe (as the name implies)
– plays a major role in the visual identification of objects.
THE occipital cortex
• Occipital lobes
– location of the visual cortex,
– visual information is
processed.
• contains a map of visual
space because adjacent
receptors in the back of
the eye send neurons to
adjacent cells in the visual
cortex.
THE Midbrain and
brainstem
• Older areas of the
brain
• More “animal-like”
in that regulate
more basic
(noncognitive)
functions
THE Thalamus
• Lies deep within the brain
• Located just below the lateral
ventricles,
• Receives information from
ALL of the sensory systems
EXCEPT olfaction (smell)
• Relays info to the respective
cortical projection areas.
THE hypothalamus
• Smaller than thalamus
• Inferior to the thalamus,
• Plays a major role in
controlling emotion and
motivated behaviors
• Controls the 4F;s:
– Feeding (eating and
drinking)
– Fighting
– Fleeing
– F….sexual activity.
THE hypothalamus
• Hypothalamus exerts influence largely through its
control of the autonomic nervous system
– Automatic system
– Sympathetic: fear/flight/fight
– Parasympathetic: feeding, sexual behavior
• Hypothalamus also influences the body’s hormonal
environment
– Controls the pituitary gland.
– The pituitary is known as the master gland because it controls other
glands in the body.
THE pineal gland
• Posterior to the thalamus
• Participates with other
structures in controlling
daily rhythms or circadian
rhythm in humans and
animals.
• Secretes melatonin,
related to sleep/circadian
rhythm
• Controls seasonal cycles
in nonhuman animals
corpus callosum
• Dense band of fibers that carry
information between
hemispheres
• Is found a couple of inches
below the brain’s surface where
the longitudinal fissure ends
• Implicated in gender
differences in brain function,
autism and other
developmental disorders
THE Ventricles
• Cavities in brain and central canal in spinal
cord which form during development
– Form a hollow interior of the nervous system.
– filled with cerebrospinal fluid or CSF,
• CSF carries material from the blood vessels to
the central nervous system
• CSF also transports waste materials in the
other direction.
THE midbrain areas
• Midbrain contains structures that have secondary
roles in vision, audition and movement.
– Superior colliculi: help guide eye movements and fixation of
gaze.
– Inferior colliculi: help locate the direction of sounds.
• Ventral tegmental area (VTA), which plays a role in
the rewarding effects of food, sex, drugs and so on.
Mid Brain
Motor functions
Corpus Striatum
•
Motor Habits
–
–
Behaviors you do “without thinking”
Walking, writing, proficient or well learned behaviors
•
Located between the cortex and the thalamus
•
Composed of three very large nuclei
–
–
–
–
Caudate nucleus
Putamen
Globus pallidus
collectively- called the striatum
Basal Ganglia and
Corpus Striatum
•
Basal Ganglia
–
–
Diffuse system of nuclei
Important for coordination of
body movement
•
Substantia Nigra
•
One of the structures involved in
movement, projects to the basal
ganglia to integrate movements.
•
Parkinson's disease,
Huntington's chorea both
involve damage to these area
Limbic System
•
Group of interconnected
structures
•
Amygdala:
–
•
Helps regulate states of
emotional arousal
Hippocampus:
–
Plays important role in the
formation of memories
The Hindbrain
THE hindbrain
• The hindbrain is composed of
–
–
–
–
the medulla
the pons
the cerebellum
Controls most basic life functions
• The medulla
– forms the lower part of the hindbrain.
– Set of nuclei involved with control of essential life processes
• cardiovascular activity
• respiration (breathing).
THE pons
• Means “bridge” in Latin
ˉ Bridges between upper and lower brain areas
• Serves as a major highway
ˉ sensory neurons pass through the pons on way to thalamus
ˉ motor neurons pass through between the cortex and the
cerebellum
• Contains centers related to sleep and arousal
• Pons is also part of reticular formation.
THE reticular formation
• Collection of several nuclei
• Runs through the middle of the hindbrain and the midbrain.
• Major role in sleep and arousal
• Contributes to attention
• Helps modulate aspects of motor activity
– Reflexes
– muscle tone
• Implicated in disorders such as autism, narcolepsy
THE CErebellum
• One of most distinctive appearing brain structure.
–
–
–
–
Perched on the back of the brain stem
wrinkled or striped- striated tissue
divided down the middle like the cerebral hemispheres –
Name means “little brain.”
• Critical for refining movements initiated by the motor
cortex
• Controls speed, intensity and direction of movement.
• It also plays a role in motor learning, and research implicates it
in other cognitive processes and in emotion.
THE CErebellum
THE spinal cord
• Finger-sized cable of neurons
• Carries commands from the brain to the muscles and organs
• Carries sensory information into the brain.
• Dorsal root: Sensory
– Sensory neurons enter the spinal cord through the of each spinal nerve.
• Ventral root: Motor
– The axons of the motor neurons pass out of the spinal cord through
the.
• Reflex Pathway:
– sensory neurons from the dorsal side connect with motor neurons,
either directly or through an interneuron.
– This pathway produces a simple, automatic movement in response to a
sensory stimulus, called a reflex.
Protecting the CENTRAL
NERVOUS SYSTEM
• Meninges:
– Covers both the brain and spinal cord
– Protective three-layered membrane called the.
– The space between the meninges and the CNS is filled with
cerebrospinal fluid,
– This cushions the neural tissue from the trauma of blows and
sudden movement.
• Blood-brain barrier:
– Limits the passage between the bloodstream and the brain
– Provides constant protection from toxic substances
– Prevents neurotransmitters from circulating in the blood.
THE PERIPHERAL
NERVOUS SYSTEM
• The peripheral nervous system (PNS)consists of:
– cranial nerves that enter and leave the underside of the
brain,
– Spinal nerves that connect to the sides of the spinal cord
at each vertebra.
• The PNS can be divided into the
– Somatic nervous system: voluntary behavior
– Autonomic nervous system (ANS): involuntary or
automatic behavior
THE somatic
nervous SYSTEM
• Motor neurons that operate the skeletal muscles –
– Neurons that move the body
– Typically refer to voluntary muscles rather than smooth
muscle movement
• Sensory neurons
– bring information into the central nervous system from
the body and the outside world.
– Includes all senses
THE autonomic
NERVOUS SYSTEM
• Regulates general activity levels in the body
• Controls smooth muscle:
–
–
–
–
–
–
Stomach
Blood vessels
Glands
Heart
Lungs
Other vital and “automatic” organs.
THE ANS has two divisions
• Sympathetic nervous system
– activates the body in ways that help it cope with
demands, such as emotional stress and physical
emergencies
– Fear/flight/fight.
• Parasympathetic nervous system
– slows the activity of most organs to conserve energy,
– also activates digestion to renew energy
– Which one modulates sexual behavior?
– Question: can you wet your pants when you are afraid?
Testing the ANS!