1. NERVOUS SYSTEM A IDS IN REMEMBERING, THINKING, MOVING, BEING AWARE, AND COORDINATING ALL OTHER BODY FUNCTIONS TO MAINTAIN HOMEOSTASIS. Chapter 9

2. 2 P ARTS OF THE N ERVOUS S YSTEM Central Nervous System (CNS)  Brain and spinal cord Peripheral Nervous System (PNS) nerves

3. N ERVOUS S YSTEM F UNCTIONS SENSORY Neurons contain sensory receptors (cells) at their ends. Detect changes inside and outside the body Convert information into nerve impulses that travel through the PNS to the CNS INTEGRATIVE In the CNS, impulses are brought together creating sensations, adding memory, producing thoughts, etc. Making conscious and subconscious decisions MOTOR Impulses are carried from the CNS to effectors (muscles and glands). 2 categories Somatic Nervous System Consciously controlled; skeletal muscle Automatic Nervous system Involuntary; heart, smooth muscle, glands

4.  SPINAL CORD (pg 247) ◦ 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

6. Cross section of spinal cord (pg. 233) 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

7. Spinal Cord Functions (pg. 234) 1. Conducting impulses 2 way communication system Ascending tracts: carry sensory info to the brain Descending tracts: conduct motor impulses from the brain to effectors 2. Spinal Reflexes

8. N EURONS 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.

9. T HE TYPICAL NEURON

10. R EVIEW OF KEY NEURON PARTS

11. CLASSIFICATION OF NEURONS Vary in structure, size, shape, and the number of connections they make with other neurons. 3 major structural groups (pg. 218) Bipolar : found in eyes, ears, nose Multipolar : found in brain and spinal cord Unipolar: lead to PNS and CNS, can form ganglia

12. 3 major functional groups of Neurons 1) Sensory neurons Carry impulses from PNS to CNS Receptor cells found at end of dendrites or in skin or sensory organs Most are unipolar 2) Interneurons In brain and spinal cord Transmit impulses from one part of the brain or spinal cord to another multipolar 3) Motor neurons Carry impulses out of brain or spinal cord to effectors multipolar

15. NEUROGLIAL CELLS (PG. 215) Outnumber neurons in CNS Can divide (neurons do not normally divide) 4 TYPES 1) Microglial cells Support neurons and phagocytize bacterial cells and cellular debris 2) Oligodendrites Align along nerve fibers Provide insulating layers of myelin 3) Astrocytes Found b/w neurons and blood vessels Provide structural support Regulate nutrient and ion concentration within tissue Form scar tissue that fill spaces following an injury in the CNS “blood-brain barrier” Shields delicate tissue from chemical fluctuations Some drugs can get in some can’t

16. 4.) Ependymal cells Forms an epithelia-like membrane that covers specialized brain parts Forms inner linings that enclose spaces within the brain and spinal cord * Schwann Cells : are neuroglial cells that form a myelin sheath around axons.

17. S O HOW DO N EURONS C OMMUNICATE WITH EACH OTHER ?????? I MPULSES TRAVEL FROM ONE NEURON TO ANOTHER TO REACH THE CNS BY CROSSING A SYNAPSE

18. THE SYNAPSE The junction between two communicating neurons Synaptic cleft : the gap between 2 communicating neurons. Synaptic transmission : -process of the impulse crossing the cleft -one-way process carried out by neurotransmitters -n.t. can be excitatory or inhibitory - about 50 neurotransmitters in n.s -pg. 226 chart

19. Steps of a Nerve Impulse/ Synaptic Transmission 1 2 3 4 5 6

20. NERVE IMPULSES NERVE IMPULSES – ACTION POTENTIAL o The surface of a cell membrane is polarized (electrically charged) o At rest, membrane potential is negative, membrane is polarized. Na+++++++++++++ K+++++++++++ Na++++++++++++++ When the membrane reached its threshold stimulus, Na/K channels open, ions diffuse, and membrane is depolarized. K+K+Na+Na+ N+Na+ K+K+ Na/K channels open again, ions diffuse, and the membrane repolarizes. Na+++++++ K++++++

23. A wave of action potentials is occurring throughout the membrane of a neuron. *This is an ALL-OR-NOTHING response*

24. NERVE PATHWAYS (PG. 229) Are routes nerve impulses follow as they travel through the nervous system. The simplest of these pathways includes only a few neurons called a reflex arc. Reflexes are automatic responses to stimuli that help maintain homeostasis. Heart rateblood pressure Coughing vomiting Breathingsneezing

25. Patellar reflex : uses only 2 neurons, helps maintain upright posture Withdrawal reflex : aids in limiting tissue damage caused by touching something harmful.

26. SYNAPSE AFFECTORS/OTHER PROBLEMS Caffeine : stimulates the nervous system by lowering the threshold at the synapse so neurons are more easily excited. Antidepressants: keeps the neurotransmitter, serotonin, in the synapse longer. Epileptic seizures : caused when nerve impulses reach the synaptic knob to fast, exhausting the neurotransmitter.

27. Multiple sclerosis (MS): is a disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelinization and scarring. The body’s immune system attacks and damages the myelin. Axons can no longer effectively conduct signals. Symptoms include muscle weakness, spasms, difficulty in moving, coordination, balance, speech, or swallowing, visual problems, fatigue, and bladder and bowel difficulties.

28. M ISCELLANEOUS /P ROBLEMS 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.

29. 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.

31. B RAIN S TRUCTURE AND F UNCTIONS Contains 100 billion multipolar neurons.

32. 4 MAIN PARTS OF BRAIN 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

33. 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

34. 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.

35. 5 lobes-frontal, parietal, temporal, occipital, insula (inner) 4 ventricles

36. 12 P AIRS OF C RANIAL N ERVES NerveFunction 1. Olfactorysmell 2. Opticvision 3. Oculomotormoves/focus eye 4. Trochlearmoves eye 5. Trigeminalchewing 6. Abducensmoves eye 7. Facialfacial expression, taste 8. Vestibulocochlearequilibrium, hearing 9. Glossopharyngealswallowing 10. Vagusheart, digestion 11. Accessoryneck 12. Hypoglossalmove tongue

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