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 area Location Function

Cerebrum Largest, most of cranial cavity

Sensory and motor functionsHigher mental functions -memory -reasoning

Cerebellum Posterior and inferior region

CoordinationBalanceMuscle tone

Brain area Location FunctionDiencephalon1.Thalamus2.Hypothalamus

Middle Limbic system-controls emotional experience and expression1.Process sensory info (pain, touch, temp)2.Maintains homeostasis: appetite center, sleep-wake, water balance

Brainstem1.Medulla2.Pons3.Midbrain

Base of brain Connect various parts of NSRegulates visceral activities1.Breathing, heart rate2.Origin of cranial nerves3.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

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 cordPosterior Sulcus: divides spinal cord into right and left halves.

White Matter: myelinated neurons

Contains CSF

Unmyelinated neuronsAnterior fissureDivides 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.