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Regions and Organization of the CNS
Adult brain regions
1. Cerebral hemishperes
2. Diencephalon
3. Brain stem (midbrain,pons, and medulla)
4. Cerebellum
Spinal cord
Central cavity surrounded by a gray matter core
External white matter composed of myelinated fiber tracts
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Cerebral Hemispheres
Five lobes
1. Frontal
2. Parietal
3. Temporal
4. Occipital
5. Insula
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Cerebral Cortex
- Thin (2-4 mm) superficial layer of gray matter
- 40% of the mass of the brain
- Site of conscious mind: awareness, sensory perception, voluntay motor initiation, communication, memory storage, understanding
- Each hemisphere connects to a contralateral side of the body
- There is lateralization of cortical function in the hemispheres
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Functional Areas of the Crebral Cortex
The three types of functional areas are;
- Motor areas--control voluntary movement
- Sensory areas--conscious awareness of sensation
- Association areas--integrate diverse information
- Conscious behavior involves the entire cortex
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Primary Motor Cortex
Motor homunculi: upside-down caricatures representing the motor innervation of body regions
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Broca's Area
- A motor speech area that directs muscles of the tongue
- Is active as one prepares to speak
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Frontal Eye Field
Controls volutary eye movements
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Visual Areas
Visual association area
-Uses past visual experiences to interpret visual stimuli (e.g. color, form and movement)
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Auditory Areas
Primary auditory cortex
- Interprets information from inner ear as pitch loudness and location
Auditory association area
- Stores memories of sounds and permits perception of sounds
Olfactory Cortex
- Region of conscious awareness of odors
Gustatory Cortex
-Taste
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Visceral Sensory Area
Concious perception of visceral sensations i.e. upset stomach or full bladder
Vestibular Cortex
- Responsible for conscious awareness of balance (position of the head in space)
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Limbic Association Area
Provides emotional impact that helps establish memories
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Lateralization of Cortical Function
Left hemisphere --Controls language, math and logic
Right Hemisphere- Insight, visual0spatial skills, intuition and artistic skills
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Functions of the Basal Nuclei
-Influence muscular control
-Help regulate attention and cognition
-Regulate intensity of slow or sterotyped movements
-Inhibit antagonistic and unnecessary movements
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Thalmamic Function
Sorts, edits and relays information
Mediates sensation, motor activities, cortical arousal,learning and memory
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Hypothalmic Function
- Autonomic control center for many visceral functions (i.e. blood pressure, rate and force of heartbeat, digestive tract motility)
- Center for emotional response: Involved in perception, fear and rage and in biological rythms and drives
- Regulates body temperature, food intake, water balance and thirst
- Regulates sleep and sleep cycle
-Controls release of hormones by the anterior pituitary
-Produces posterior pituitary hormones
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Epithalamus
Pineal; glad--extends from the posterior border and secretes melatonin which helps regulate sleep-wake cycles
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Pons
Fibers of the pons
-connect higher brain centers and the spinal cord
-Relay impulses between the motor cortex and the cerbellum
-Muclei that help maintain normal rhythm of breathing
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Medulla Oblongata
Autonomic reflex centers
Cardiovascular center--which adjusts force and rate of heart contractions
Vasomotor center adjusts blood vessel diameter for blood pressure regulation
- Respiratory centers
- -Generate respirator rhythm
- -Contol rate and depth of breathing with pontine centers
Additional centers regulate
- Vomiting
- Hiccuping
- Swallowing
- Coughing
- Sneezing
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The Cerebellum
Subconsciously provides precise timing and appropriate patterns of skeletal muscle contaction
Funtions
Recognizes and predicts sequences of events during complex movements
Plays a role in nonmotor functions such as word association and puzzle solving
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