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Cerebral Cortex
Cerebral Cortex
Cerebral Cortex - The outermost layer of the brain containing gray matter. Responsible for many "higher-order" functions like language and information processing.
Layers of the Cerebrum• Gray Matter
– Outer layer of the brain
– Composed of neuron cell bodies (site of nucleus)
– Includes regions of the brain involved in muscle control, sensory perceptions, like seeing and hearing, memory, emotions, speech and critical thinking/problem solving
Cell Body of Neuron
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
Axon of Neuron
Myelin = fatty outer covering of axons.
Allows for faster transmission of message.
Limbic System
• set of evolutionary primitive brain structures
• involved in emotions and motivations, like the ones related to survival– fear, anger, sexual
behavior
• also involved in feeling of pleasure– eating and sex
Limbic System Structures• Amygdala – linked to both fear
responses and pleasure. Anxiety, autism, depression, post-traumatic stress disorder, and phobias are linked to abnormal functioning
• Hippocampus – sends memories out to the appropriate part of the brain for long-term storage and retrieves them when needed.– damage to hippocampus can
cause an inability to form new memories
Amygdala shrinks by more than 30% in males upon castration – minimizes pleasure
Diencephalon – “Interbrain”
• Sits on top of the brain stem
• Enclosed by the cerebral hemispheres; well-hidden brain region
• Made of three parts– Thalamus Thalamus
– Hypothalamus Hypothalamus
– Epithalamus Epithalamus
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
Hypothalamus• Under the thalamus
• Controls organs by maintaining homeostasis
• Important autonomic nervous system center
– Helps regulate body temperature
– Controls water balance
– Regulates metabolism
The pituitary gland is attached to the hypothalamus. It releases hormones
which affect growth, sexual development, metabolism and
reproduction.
Epithalamus
• Helps to regulate the sleep/wake cycle by releasing hormones like melatonin from pineal gland
• Controls some parts of emotions and mood
Epithalamus
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
Brainstem• Midbrain = Smallest region of
the brain which relays auditory and visual information.
– Also controls eye movements, like blinking
• Pons = “bridge” of the brainstem. Controls Breathing.
• Medulla Oblongata = The lowest part of the brain stem– Merges into the spinal cord– Contains important control centers
• Heart rate control• Blood pressure regulation• Breathing• Swallowing• Vomiting
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
Cerebellum and other brain parts
Dura Mater: outermost meninges; tough and thick. Can restrict movement of the brain within the skull. Protects the brain from movements that may stretch and break brain blood vessels.
Meninges = three connective tissue membranes covering and protecting brain
Central Nervous System Disorders• Meningitis = inflammation of
meninges. Serious threat since bacteria or viruses can spread to brain.
• Concussion = injury is slight; dizzy, see stars, or lose consciousness briefly but no permanent damage.
• Stroke = blood circulation to a brain area is blocked from ruptured blood vessel or blood clot.
More Brain Disorders
• Hemorrhage = bleeding from ruptured blood vessels.
• Aneurysm = dilation, bulging or ballooning out of part of the wall of a vein or artery in the brain
– Can get larger over a lifetime
– Pushes on brain regions causing symptoms like blurred vision, stutter, etc.
– Can hemorrhage