<p>If I only had a brain………</p><p>Meninges –membranes between bone and tissue protecting brain and spinal cord</p><p>3 layers of meninges:</p><p>Dura mater-white fibrous CT, blood vessels and nerves, attaches to inside of cranial cavity, forms periosteum</p><p>Arachnoid mater-middle, weblike, no blood vessels</p><p>Pia mater-innermost, thin, contains nerves and blood vessels, hugs organs Cerebrospinal fluid-between arachnoid and pia mater, fill ventricles</p><p>Brain—3 lb mass 100 billion multipolar neurons</p><p>3 portions 1. Cerebrum-largest, nerve centers for sensory and motor, higher mental functions  Halves are cerebral hemispheres, connected by nerve fibers—corpus callosum, separated by longitudinal fissure  Ridges are convolutions (gyri)  Shallow grooves=sulci  Deep grooves=fissures  Lobes: Frontal (motor areas), parietal, temporal, occipital, insula  Outermost portion-cerebral cortex  Nerve fibers cross over—motor area on right controls left skeletal muscles  Hemisphere dominance—one side of cerebrum controls certain functions—Left hemi dom. In 90% of people.</p><p>2. Cerebellum-centers for voluntary muscle mvmt.  Posture, position of body parts 3. Brain stem-connect parts of nervous system and regulate visceral (organ) activities  Midbrain-reflex centers  Pons-relays impulses  Medulla Oblongata-cardiac, vasomotor, and respiratory centers</p><p>4. Diencephalon-contains Thalamus-sensation awareness Pituitary gland-growth hormones and reproductive hormones Hypothalamus-regulates visceral activity, overall homeostasis Limbic system-controls emotions</p><p>Spinal cord -Nerve column from foramen magnum to intervertebral disk between L1 and L2 vertebrae</p><p>-31 segments (spinal nerves)</p><p>White matter-myelinated fibers Gray matter-unmyelinated nerve fibers and neuron cell bodies Function of spinal cord: 1. Conducts nerve impulses 2. Center for spinal reflexes Ascending tracts carry info to brain Descending tracts carry info from brain</p><p>Peripheral Nervous system –nerves that branch off CNS, divided into Somatic and Autonomic Somatic N.S.-Connects CNS to skin and skeletal muscles for conscious activity</p><p>Autonomic Nervous system- Controls automatic processes, connects to viscera (organs) Regulates processes to keep body functioning 2 divisions Sympathetic division-prepares body for stress (fight or flight) Parasympathetic-active under ordinary, restful conditions, restores rest after stress </p>