CHAPTER 11: NERVOUS SYSTEM II: DIVISIONS OF THE NERVOUS SYSTEM OBJECTIVES: 1. Outline the major divisions of the nervous system.

Transcription

1 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS OBJECTIVES: 1. Outline the major divisions of the nervous system. NERVOUS CENTRAL NERVOUS (BRAIN & SPINAL CORD) (INTERNEURONS) PERIPHERAL NERVOUS (CRANIAL NERVES & SPINAL NERVES) SENSORY (INPUT INTO CNS) (AFFERENT NEURONS) MOTOR (OUTPUT FROM CNS) (EFFERENT NEURONS) SOMATIC (EFFECTORS: SKELETAL MUSCLE) MUSCLE, (CONSCIOUS CONTROL) AUTONOMIC (EFFECTORS: SMOOTH CARDIAC MUSCLE, GLANDS) (UNCONSCIOUS CONTROL) PARASYMPATHETIC (HOMEOSTASIS) (NT: ACETYLCHOLINE) SYMPATHETIC (FIGHT-OR-FLIGHT) (NT: NOREPINEPHRINE) 11-1

2 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 2. Discuss how the organs of the central nervous system (CNS) are protected in terms of bones, membranes and fluid. Bones Protects the brain = 8 bones of cranium; Protects spinal cord = vertebral column Membranes (Meninges) Membranes that surround and protect the brain and the spinal cord Cerebrospinal cord Provides protective cushion, nourishes, maintains ion and NT concentrations 3. Name the three meninges and discuss the differences between how they are structured around the brain and spinal cord. Dura mater - outer most layer; DRCT; attached to bone of skull but not to bone of vertebrae = epidural space Arachnoid mater- middle layer = thin delicate, underside of dura mater Pia mater- inner layer that covers brain and spinal cord 4. Name the space that lies between two of the meninges surrounding both the brain and spinal cord, and name the fluid that fills this space. Subarachnoid space : filled with cerebrospinal fluid and lined by ependymal cells 5. Name the additional space that is found around the spinal cord, and name the fluid that fills this space. Epidural space, filled with loose CT and fat 6. Define the term meningitis. An inflammation of the meninges (caused by viral or bacterial infection) 7. Discuss the external structure of the spinal cord in terms of its length, start, end, number of segments, and enlarged areas. About 17 inches long, the start is the foramen magnum, it tapers to a point and terminates near the intervertebral disc that separates the first/ second lumbar vertebrae in a point called the conus medullaris Has 31 segments that give rise to 31 pairs of spinal nerves Enlargement are in the cervical and lumbar regions. About the thickness of thumb Remnant of distal pia mater = filum terminale 8. Name the terminal point of the spinal cord, the term used for how the remaining spinal nerves appear, and the point at which they terminate. Conus medullaris cauda equina filum terminale 11-2

3 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 9. Illustrate the cross-sectional anatomy of the spinal cord and label all parts. 11-3

4 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 10. Name the cells that line the central canal and identify the fluid that fills the central canal. Lined by ependymal cells, and is filled with cerebrospinal fluid 11. Distinguish between a "horn" and a "column" in the spinal cord. A horn is gray matter and they form inner butterfly A column is white matter and they lie on outside of spinal cord 12. Explain which portion of the spinal cord is the location for the major nerve tracts, and discuss their significance. Ascending tracts are sensory : lie primarily in posterior white columns Descending are motor: lie primarily in anterior white columns 13. Compare and contrast ascending and descending tracts. See #12 above 14. Discuss the general characteristics of nerve tracts. They are conduits for nerve impulse to and from the brain; cross-over at some point in spinal cord; are composed of 2-3 interneurons in sequence. 15. Discuss the features located on the periphery of the spinal cord in cross-section. PNS: Dorsal Root Ganglion (cell bodies of sensory neurons) leading to dorsal root into Posterior white columns in SC; ventral root leading away from Anterior white columns. Fusion of dorsal root and ventral root = spinal nerve. 16. Define the term ganglion and discuss the specificities of a dorsal root ganglion. A ganglion is a bundle of cell bodies outside in PNS. 17. Define the term nerve pathway. The route traveled by a nerve impulse through the nervous system. 18. List and discuss the components in a reflex arc. A sensory receptor which reacts to a stimulus A sensory neuron that conducts the afferent impulse to the CNS The integration center (in interneuron of CNS) The motor neuron that conducts the efferent motor impulse from the CNS to an effector The effector which is muscle fibers or glands that respond to the motor impulse 19. Discuss the significance of reflex arcs. They are used to show physician that all parts of nerve pathway are functioning from SR to effector; They are the simplest demonstration of a nerve pathway; most are protective 11-4

5 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 20. Fully discuss the three-fold function of the nervous system. A. Draw a simple nerve pathway that involves three neurons (with cell parts labeled), and track (on your diagram) the transmission of a nerve impulse throughout this pathway. 11-5

6 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 21. Name and locate the four major regions of the brain. Cerebrum- largest Diencephalon Brainstem Cerebellum 22. Discuss the structure of the cerebrum in terms of its size, two major divisions, surface appearance, major grooves, and lobal divisions. Largest; divided into two hemispheres; bumps on surface are convulsions; shallow grooves are sulci; deep grooves are fissures. Longitudinal Fissure separates two hemispheres; Transverse Fissure separates cerebrum from cerebellum Each hemisphere has a frontal lobe, a parietal lobe, an occipital lobe, and a temporal lobe 23. Identify the composition of the bulk of the cerebrum. The cerebral medulla is composed of white matter; and the cerebral cortex is composed of gray matter. 11-6

7 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 24. Define the term cerebral cortex and discuss its composition and significance. The outer cerebral cortex is composed of gray matter = bundles of cell bodies in CNS These cell bodies serve as the destination site for all incoming sensory impulses and the initiation site for all outgoing motor impulses. 25. Compare the major functional areas (sensory and motor) of the cerebral cortex in terms of location and function (a diagram may help here). Frontal Primary motor cortex initiates all motor impulses to skeletal muscles; Broca s Area in left frontal lobe controls muscles of speech Parietal cortex general sensation Occipital cortex sense of vision Temporal cortex sense of hearing 11-7

8 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 26. Explain what is meant by an association area of the cerebral cortex and name a few association traits. Any traits that are not motor or sensory; all four lobes of cerebrum are involved in association traits Personality, memory, emotions, problem solving, etc 27. Name the term referring to the measurement of brain activity. EEG 28. Explain what is meant by hemisphere dominance, and name the hemisphere that is dominant in most people. Left hemisphere is dominant on 90% of right handed people language related activities; Right hemisphere controls musical, art, etc 29. Define the term basal nuclei and explain their location and function. Many areas deep in brain working together as outgoing motor relay station 30. Name the interconnected cavities within the cerebrum and brain stem and identify the fluid that fills these spaces and name the cells that line these spaces. Ventricles- cerebrospinal fluid - ependymal cells 31. Name the specialized capillaries that secrete CSF and denote their location on a diagram. Choroid plexuses 32. Trace a drop of CSF from where it is secreted to where it is reabsorbed back into the blood stream. a. Choroid plexuses b. Lateral ventricles c. 3 rd ventricle d. Cerebral aqueduct e. 4 th ventricle f. Down central canal of spinal cord and/or g. Into subarachnoid spaces h. Arachnoid granulations reabsorb CSF into blood stream (dural sinuses) 33. Define the terms arachnoid granulations and dural sinuses. Extensions of arachnoid mater that extend into dural sinuses (venous blood). They reabsorb CSG back into bloodstream 34. Discuss the functions of CSF. Cushions Ion source for nerve impulses; neurotransmitters Circulation 35. Discuss the two important areas of gray matter within the diencephalon, in terms of location and function. Thalamus Incoming sensory relay station for all senses, except smell 11-8

9 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 36. Identify the three major parts of the brain stem. Midbrain- pupillary and auditory reflexes Pons- controls breathing rate Medulla - cardiac center, vasomotor center, center for rhythm of breathing 37. Discuss the midbrain in terms of its location, composition and function. Located between dicephalon and pons Reflexes activity, auditory and pupillary 38. Name the location of the pneumotaxic area (Pontine Area) of the respiratory center. See above: bulge = Pons controls rate of breathing 39. Discuss the importance of the medulla (oblongata). Maintains homeostasis through hypothalamic regulation: Cardiac center controls heart rate and rhythm, vasomotor center controls blood pressure, respiratory center controls rhythm of breathing. 40. Briefly explain the significance of the limbic system and reticular formation. Limbic system is composed of several areas that work together to control emotions and circadian rhythm Reticular formation controls brain alertness 11-9

10 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 41. Locate the cerebellum on a diagram, and discuss its structure and function. Arbor vitae = white matter within Gray matter. equilibrium. Cerebellum controls balance and 42. Discuss the general structure of a nerve. Endoneurium- around each myelinated axon Perineurium around each fascicle of axons Epineurium around each nerve. 43. Distinguish between a mixed, sensory, and motor nerve. Mixed nerves have both sensory and motor fascicles; CN V, VII, IX, X and all spinal nerves Sensory nerves have only sensory fascicles; CN I, II, VIII Motor nerves have only motor fascicles; CN III, IV, VI, XI, XII 11-10

11 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 44. Name the twelve pairs of cranial nerves, designate them by Roman numeral, discuss their function, and designate them as sensory, motor, or mixed. Summary Table for Cranial Nerves Numeral Name Function Sensory, Motor, or Mixed Nerve I OLFACTORY OLFACTION/SMELL SENSORY II OPTIC VISION SENSORY III OCULOMOTOR MOVE EYE MOTOR IV TROCHLEAR MOVE EYE MOTOR V TRIGEMINAL CHEWING/MASTICATION AND SENSORY FROM FACE MIXED VI ABDUCENS MOVE EYE MOTOR VII FACIAL FACIAL EXPRESSION; TASTE VIII VESTIBULOCOCHLEAR HEARING AND EQUILIBRIUM IX GLOSSOPHARYNGEAL MOVE MUSCLES OF TONGUE AND PHARYNX; TASTE X VAGUS INNERVATE VISCERAL SMOOTH MUSCLE; SENSATIONS FROM SAME MIXED SENSORY MIXED MIXED XI ACCESSORY MOVE NECK MUSCLES MOTOR XII HYPOGLOSSAL MOVE TONGUE MOTOR 11-11

12 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 45. Discuss the characteristics of spinal nerves in terms of number, coverings, and composition. Spinal nerves are all mixed nerves There are 31 pair of spinal nerves Connective Tissue coverings are same as above 46. Discuss how a spinal nerve is distributed. The major portion is called a ventral ramus, which we will term a spinal nerve. 47. Define the term nerve plexus and explain its significance. A branching network of spinal nerves: they do not extend directly to the body part but they form networks. Plexuses are efficient and prevent complete paralysis of a limb if damage to a spinal nerve occurs. 48. Name the three/four major nerve plexuses and briefly discuss the areas that each innervates. Cervical plexus (C1-C4)- the neck and Lumbosacral plexus (T12-S5) anterior diaphragm and medial thigh and posterior lower limbs Brachial plexus (C5-T1)- upper limbs 49. Compare the somatic and autonomic divisions of the NS in terms of motor neurons involved, the presence or absence of ganglia, neurotransmitter type, and effector type. Somatic Autonomic One motor neuron 2 motor neurons Effectors are skeletal muscle Effectors are cardiac muscle, smooth muscle, glands Voluntary control Involuntary control 50. Describe the general function of the ANS. The ANS regulates involuntary actions 51. Name the two major divisions of the ANS, and describe their general function. sympathetic parasympathetic Fight or flight Maintains homeostasis 52. Compare the length of a preganglionic and postganglionic neuron in the sympathetic and parasympathetic division of the ANS. sympathetic parasympathetic Pre is short Pre is long and extends to at or near effector Post is long Post is short 11-12

13 CHAPTER 11: NERVOUS II: DIVISIONS OF THE NERVOUS 53. Define the term ganglion, and compare the location of sympathetic and parasympathetic ganglia. Ganglion- a bundle of cell bodies in PNS; the two ANS motor neurons synapse at a ganglion (AT of first synapses with CB of 2 nd ) Sympathetic- are located on either side of the spinal cord. Parasympathetic - located at or near the effector 54. Compare the origin of a sympathetic preganglionic neuron with a parasympathetic preganglionic neuron. Preganglionic origination of sympatric fibers is from the thoracolumbar regions of the spinal cord Preganglionic origination of parasympathetic arises from either the cranial region of brain or sacral region of spinal cord 55. Distinguish between cholinergic and adrenergic fibers (axons). ACh is released by the cholinergic fibers Norepinephrine is released by the adrenergic fibers. 56. Describe the two types of cholinergic and adrenergic receptors. Cholinergic Receptors Adrenergic Nicotinic and muscarinic Alpha and Beta 57. Compare and contrast the two divisions of the ANS in terms of their name, general function, origin of preganglionic fiber, length of preganglionic fiber, location of ganglia, and type of neurotransmitter secreted by the postganglionic fiber. General Function Origin of Preganglionic fiber Length of Preganglionic fiber maintain homeostasis from cranial region of brain or sacral region of spinal cord Long to survive stressful or fight or flight situations from thoracic or lumbar region of spinal cord short Location of Ganglia at or near effector alongside spinal cord NT secreted by postganglionic fiber acetylcholine norepinephrine 11-13