Chapter 9

 Central Nervous System (CNS)  Brain and spinal cord  Peripheral Nervous System (PNS) ◦ nerves

 Nervous tissue contains masses of nerve cells called neurons. ◦ Specialized to react to physical and chemical changes. ◦ Transmit info in the form of electrochemical changes called nerve impulses. ◦ Bundles of axons make nerves. ◦ Also contains neuroglial cells that provide physical support, insulation, and nutrients for neurons.

 Brain and Spinal Cord ◦ Protected by layered membranes called meninges.  Dura mater (outermost layer- contains blood vessels)  Arachnoid mater (no blood vessels)  Pia mater (thin, contains nerves and b.v that nourish the cells of the brain and spinal cord)  Cerebrospinal fluid (CSF) –clear, watery fluid b/w the arachnoid and pia maters that is a shock absorber. Secreted by masses of specialized capillaries called choroid plexuses.

 Contains 100 billion multipolar neurons.

Brain areaLocationFunction Cerebrum Largest, most of cranial cavity Sensory and motor functions Higher mental functions -memory -reasoning Cerebellum Posterior and inferior region Coordination Balance Muscle tone

Brain areaLocationFunction Diencephalon 1.Thalamus 2.Hypothalamus MiddleLimbic system-controls emotional experience and expression 1.Process sensory info (pain, touch, temp) 2.Maintains homeostasis: appetite center, sleep- wake, water balance Brainstem 1.Medulla 2.Pons 3.Midbrain Base of brainConnect various parts of NS Regulates visceral activities 1.Breathing, heart rate 2.Origin of cranial nerves 3.Coordinate head/eye movements to sound& light

 Cerebral cortex is the outermost layer of gray matter that contains 75% of all neuron cell bodies of the NS.  Left & Right cerebral hemispheres are connected by a bridge of nerve fibers called the corpus callosum. ◦ Dominant hemisphere-controls the ability to understand language  Surface contains many ridges called gyri (gyrus) separated by grooves. Shallow groove is a sulcus and a deep groove is a fissure. ◦ Longitudinal fissure separates the right and left hemispheres. ◦ Transverse fissure separates the cerebrum from the cerebellum.

 5 lobes-frontal, parietal, temporal, occipital, insula (inner)  4 ventricles

NerveFunction  Olfactorysmell  Opticvision  Oculomotormoves/focus eye  Trochlearmoves eye  Trigeminalchewing  Abducensmoves eye  Facialfacial expression, taste  Vestibulocochlearequilibrium, hearing  Glossopharyngealswallowing  Vagusheart, digestion  Accessoryneck  Hypoglossalmove tongue

Oh, Oh, Oh, To Touch And Feel Very Good Velvet, AH

 SPINAL CORD ◦ Contains 31 segments, each giving rise to a pair of spinal nerves. Foramen Magnum -Where the spinal cord begins Cervical Enlargement -supplies nerves to upper limbs Spinal Cord Vertebral Canal Lumbar Enlargement - supplies nerves to lower limbs

 Cross section of spinal cord Posterior Sulcus: divides spinal cord into right and left halves. White Matter: myelinated neurons Contains CSF Unmyelinated neurons Anterior fissure Divides spinal cord into right and left halves

 Spinal Cord Functions (pg. 234)  Conducting impulses ◦ 2 way communication system ◦ Ascending tracts: carry sensory info to the brain ◦ Descending tracts: conduct motor impulses from the brain to effectors  Spinal reflex center ◦ Patellar and withdrawal reflex ◦ Reflex arc passes through the spinal cord

 Subdural hematoma: collection of blood from broken blood vessels that will increase pressure in the skull and will lead to functional losses or death.  Cerebral palsy: partial paralysis and lack of muscular coordination caused by damage to the cerebrum.