copyright © 2006 pearson education, inc., publishing as benjamin cummings chapter 7 the nervous...
TRANSCRIPT
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Chapter 7
The Nervous System
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Organization of the Nervous System
Central Nervous System
Referred to CNS
Brain and Spinal cord
Integrative control center
Peripheral Nervous System
Referred to PNS
Nerves that extend outside the brain and spinal cord to the body’s extremities
Communicates between the CNS and the rest of the body
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Regions of the Brain
Cerebrum
Diencephalon
Cerebellum
Midbrain *
Pons *
Medulla Oblongata *
* Found in Brain Stem
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Cerebral Hemispheres (Cerebrum) Largest part of brain
Include more than half of the brain mass
Controls higher mental functions; conscious mind; MAKES US HUMAN
Allows us to sense, to communicate, to remember, and to understand, and initiate voluntary movements.
Outer layer of cerebrum (cerebral cortex) is made of gray matter
- Folded surface increases surface area- Elevated ridges (gyri)- Shallow depressions (sulci)- Deep Grooves (fissures)
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Cortex Roadmap
Gyri - ridges
Sulci – shallow grooves
Fissures – deep groves
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Lobes of the Cerebrum
Surface lobes of the cerebrum
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Sensory and Motor Areas of the
Cerebral Cortex
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Specialized Areas of the Cerebrum
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Layers of the Cerebrum Gray matter
Outer layer
Composed mostly of neuron cell bodies
Includes regions of the brain involved in muscle control, sensory perceptions, like seeing and hearing, memory, emotions and speech
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Layers of the Cerebrum White matter
Contains mainly long, myelinated axons
Involved in the relay of sensory information from the rest of the body to the cerebral cortex
Figure 7.13a
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Diencephalon Sits on top of the brain
stem
Enclosed by the cerebral hemispheres; well-hidden brain region
Made of three parts
Thalamus
Hypothalamus
Epithalamus
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Thalamus
The relay station for sensory impulses (switchboard)
Transfers impulses to the correct part of the cerebrum for interpretation
All incoming impulses get sorted here first and identified as pleasant or non-pleasant
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Hypothalamus Under the thalamus
Contains brain stem and controls organs by maintaining homeostasis
Important autonomic nervous system center
Helps regulate body temperature
Controls water balance
Regulates metabolism
An important part of the limbic system (emotions)
The pituitary gland is attached to the hypothalamus
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Hypothalamus An important part of the limbic system
(emotions)
The pituitary gland is attached to the hypothalamus which secretes hormones to maintain homeostasis
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Epithalamus
Makes the cerebrospinal fluid
Helps to regulate the sleep/wake cycle by releasing hormones like melatonin
Controls some parts of emotions and mood Epithalamus
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Brain Stem Attaches to the spinal
cord; primitive “rat brain”
Controls automatic behaviors necessary for survival (breathing)
Parts of the brain stem each about an inch long
Midbrain
Pons
Medulla oblongata
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Midbrain Smallest region of the brain that sort of works as a
relay station for auditory and visual information.
Also controls eye movements, like blinking
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Pons The bulging center part of the brain stem
Mostly composed of fiber tracts which relay messages to the brain
Includes control of breathing
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Medulla Oblongata The lowest part of the brain stem
Merges into the spinal cord
Includes important fiber tracts relaying messages
Contains important control centers
Heart rate control
Blood pressure regulation
Breathing
Swallowing
Vomiting
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Cerebellum contains ~70% of all the brain's neurons; yet is
only 10% of the volume of the brain!
contributes to precise timing of skeletal muscle activity (i.e. walking, running or standing on your hands)
controls our balance and equilibrium
Doesn’t function well under influence of alcohol
Works like ‘auto pilot’ – monitors body position and amount of tension in body parts
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Cerebellum and other brain parts