Bio 202 Notes

The Brain

• Regions and Organization of the Brain

– The adult brain is divided into the cerebral hemispheres, diencephalon, brain stem, and cerebellum. – The cerebral hemispheres and cerebellum have gray matter nuclei surrounded by white matter and an outer cortex of gray matter. – The diencephalon and brain stem lack a cortex.

Chapter 12

The Central Nervous System

• Ventricles of the Brain

– The brain contains four ventricles filled with cerebrospinal fluid (CSF). – The lateral ventricles (2) are in the cerebral hemispheres. – The third ventricle is in the diencephalon. – The fourth ventricle is in the brain stem and connects the central canal of the spinal cord.

• The Cerebral Hemispheres

– The two cerebral hemispheres exhibit gyri, sulci, and fissures. The longitudinal fissure partially separates the hemispheres. – Each cerebral hemisphere consists of the cerebral cortex, cerebral white matter, and the basal nuclei.

– Each cerebral hemisphere receives sensory impulses from, and dispatches motor impulses to, the opposite side of the body. – Functional areas of the cerebral cortex include: – 1) motor areas – 2) sensory areas – 3) association areas

– The cerebral hemispheres show lateralization of cortical function. – In most people, the left hemisphere is dominant, specialized for language and mathematical skills; the right hemisphere is more concerned with visual-spatial skills and creative endeavors.

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• The Diencephalon

– The diencephalon consists of the thalamus, hypothalamus, and epithalamus and encloses the third ventricle. – The thalamus is the major relay station for

• 1) sensory impulses ascending to the sensory cortex,

• 2) inputs from subcortical motor nuclei and the cerebellum traveling to the cerebral motor cortex, and • 3) impulses traveling to association cortices from lower centers.

– The hypothalamus is an important ANS control center. It maintains water balance and regulates thirst, eating behavior, gastrointestinal activity, body...