NERVOUS SYSTEM Aids in remembering, thinking, moving, being aware, and coordinating all other body functions to maintain homeostasis. Chapter 9

2 Parts of the Nervous System Central Nervous System (CNS) Brain and spinal cord Peripheral Nervous System (PNS) nerves

Neurons 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.

Central Nervous system 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.

Brain Structure and Functions Contains 100 billion multipolar neurons.

4 main parts of brain Brain area Location Function Cerebrum Cerebellum Largest, most of cranial cavity Sensory and motor functions Higher mental functions -memory -reasoning Cerebellum Posterior and inferior region Coordination Balance Muscle tone

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

STRUCTURE OF CEREBRUM 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

12 Pairs of Cranial Nerves Nerve Function Olfactory smell Optic vision Oculomotor moves/focus eye Trochlear moves eye Trigeminal chewing Abducens moves eye Facial facial expression, taste Vestibulocochlear equilibrium, hearing Glossopharyngeal swallowing Vagus heart, digestion Accessory neck Hypoglossal move 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 Anterior fissure Divides spinal cord into right and left halves Unmyelinated neurons

Conducting impulses Spinal reflex center 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

Miscellaneous/Problems 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.