Chapter 10 & 11

1. Chapter 10 & 11 The Nervous System The Brain The Spinal Cord

2. Chapter 10Nervous System I Purpose - To generates and conducts electrical impulses !!! Coordinates all body systems by !!! electrochemical current The structural and functional unit of the nervous system is a NEURON (nerve cell)

3. Functions of Nervous System • Sensory Function • sensory receptors gather information • information is carried to the Central Nervous System (CNS) • Motor Function • decisions are acted upon • impulses are carried to effectors through the Peripheral Nervous System (PNS) • Integrative Function • sensory information used to create • sensations • memory • thoughts • decisions 10-6

4. Two Major Systems of the Nervous System • 1. Central Nervous System (CNS) • brain • spinal cord • 2. Peripheral Nervous System (PNS) • peripheral nerves (43 nerves) • cranial nerves (12 pair) • spinal nerves (31 Pair) 10-1

5. Two Divisions of Nervous System • Sensory Division • INPUT INTO CNS (afferent neurons) • picks up sensory information and delivers • it to the CNS. • 2. Motor Division(made up of two divisions) • OUTPUT FROM CNS to PNS (efferent neurons) • carries information to muscles and glands 10-4

6. Two Division of the Motor Division 1.Somatic – carries information to skeletal muscle. 2. Autonomic(made up of two divisions) – carries information to smooth muscle, cardiac muscle, and glands

7. Two Divisions of the Autonomic Division • PARASYMPATHETIC • Usually promotes those activities associated with a normal state. HOMEOSTASIS!!! • SYMPATHETIC • Effects are generally associated with emergency situations FIGHT OR FLIGHT!!!

8. Divisions Nervous System 10-5

9. The Brain and the Spinal Cord • The organs of the CNS are surrounded by bones, membranes and fluid. Bones: • Brain is encased by 8 skull bones • Spinal Cord is encased by 26 vertebra. Membranes: • The membranes that ground the brain and spinal cord are called Meninges

10. Meninges • Meninges • membranes surrounding CNS • protect CNS • three layers • dura mater – outer, attaches to skull • arachnoid mater – web like, middle layer • pia mater – inner, clings to brain 11-2

11. Meninges of the Spinal Cord 11-3

12. Ventricles Along with the meninges, there are ventricles. Ventricles – hollow areas of the brain that are filled with CSF and venous blood. 11-4

13. Cerebrospinal Fluid Functions – 1. Buoyancy 2. Protection 3. Waste removal 4. Maintenance of chemical environment • Secretion: • secreted by specialized capillaries • circulates in ventricles, central canal of spinal cord, and subarachnoid space • completely surrounds brain and spinal cord • About a liter is secreted daily to replenish itself Meningitis – inflammation of the meninges - bacterial and viral - Can be deadly 11-5

14. Subdural Hematoma • The collection of blood in between the dura and arachnoid mater. • Pressure builds and compresses the brain. • May lead to functional losses and death.

17. CT Scan of a Subdural Hematoma

18. Spinal Cord Structure • a nerve column extends foramen magnum to 2nd lumbar vertebra • about 17 inches long • Broken into 31 segments • 31 pairs of nerves • Like the brain, the spinal • cord is protected by • meninges 11-6

19. Cross Section of Spinal Cord 11-7

20. Spinal Cord Functions • Center for spinal reflexes 2. Provides a two-way communication system between the brain and the other parts of the body. 11-8

21. Reflex Arcs Reflexes – automatic, subconscious responses to stimuli 11-9

22. Knee-jerk Reflex • helps maintain posture 11-10

23. Withdrawal Reflex • protective 11-11

24. Brain • Functions • interprets sensations • determines perception • stores memory • reasoning • makes decisions • coordinates muscular movements • regulates visceral activities • determines personality • Major Parts • cerebrum • two cerebellar hemispheres • diencephalon • brain stem • cerebellum 11-16

25. Brain Development • Three Major Vesicles • Forebrain • Midbrain • Hindbrain • Forebrain (prosencephalon) • anterior portion (telencephalon) • cerebrum • basal ganglia • posterior portion (diencephalon) • thalamus • hypothalamus • posterior pituitary • pineal gland 11-17

26. Brain Development • Midbrain (mesencephalon) • midbrain • Hindbrain (rhombencephalon) • anterior portion (metencephalon) • cerebellum • pons • posterior portion (myelencephalon) • medulla oblongata 11-18

27. Structure of Cerebrum • corpus callosum • connects hemispheres 11-19

28. Functions of Cerebrum • interpretation • initiating voluntary movements • storing memory • retrieving memory • reasoning • center for intelligence and personality 11-21

29. Lobes of Cerebrum • Frontal • Parietal • Temporal • Occipital 11-20

30. Cerebral Cortex Cerebral Cortex – thin layer of gray matter that constitutes the outermost portion of cerebrum; responsible for all conscious behavior 11-22

32. Functional Regions of Cerebral Cortex Three kinds of functional areas: 1. Primary motor – involuntary movements and speech. 2. Primary sensory – senses (temp, touch, pressure, pain, vision, hearing, and taste) 3. Association – traits, memory, reasoning, verbalizing, judgment, and emotions.

33. Motor Areas • Primary Motor Areas • frontal lobes • control voluntary muscles • Broca’s Area • anterior to primary motor cortex • usually in one hemisphere • controls muscles needed for speech • Frontal Eye Field • above Broca’s area • controls voluntary movements of eyes and eyelids 11-23

34. Motor Areas 11-24

35. Sensory Areas • Cutaneous Sensory Area • parietal lobe • interprets sensations on skin • Visual Area • occipital lobe • interprets vision • Auditory Area • temporal lobe • interprets hearing 11-25

36. Sensory Areas 11-26

37. Association Areas • regions of cortex that are not primary motor or primary sensory areas • widespread throughout the cerebral cortex • analyze and interpret sensory experiences • provide memory, reasoning, verbalization, judgment, emotions 11-27

38. Association Areas • Frontal Lobe Association Areas • concentrating • planning • problem solving • judging • Temporal Lobe Association Areas • remember visual scenes • remember music • remember complex patterns • Parietal Lobe Association Areas • understanding speech • using words to express thought • Occipital Lobe Association Areas • combine visual images with other sensory experiences 11-28

39. Hemisphere Dominance • In over 90% of population, left hemisphere is dominant • Nondominant hemisphere controls • nonverbal tasks • motor tasks • understanding and interpreting musical and visual patterns • provides emotional and intuitive thought processes • Dominant hemisphere controls • speech • writing • reading • verbal skills • analytical skills • computational skills 11-29

40. Diencephalon • Structure: • between cerebral hemispheres and brainstem • surrounds third ventricle • Contains: • thalamus • hypothalamus • posterior pituitary • pineal gland 11-32

41. Diencephalon Functions • Thalamus • gateway for sensory impulses heading to cerebral cortex • receives all sensory impulses (except smell) • channels impulses to appropriate part of cerebral cortex for interpretation • Hypothalamus • maintains homeostasis (HR, temp) • links nervous and endocrine systems • Other Organs: • Pineal Gland – secretes melatonin • Pituitary Gland – control all hormones 11-33

42. Cerebellum • Structure: • - Large, cauliflower-like appearance • Located below the cerebrum and posterior to the brain stem. • Functions: • Communicates with other parts of the CNS. • integrates sensory information concerning position of body parts. • coordinates skeletal muscle activity • maintains posture • equilibrium (balance) 11-41

43. Brain Stem • Three Parts • Midbrain • Pons • Medulla Oblongata 11-35

44. Midbrain • Structure: • between diencephalon and pons. • contains bundles of fibers that join HIGHER parts of brainstem and LOWER part of brain • Function: • cerebral aqueduct • centers for visual and auditory reflexes 11-36

45. Pons • Structure: • rounded bulge on underside of brainstem • between medulla oblongata and midbrain • Function: • helps regulate heart rate and depth of breathing • relays nerve impulses to and from medulla oblongata and cerebellum 11-37

46. Medulla Oblongata • Structure: • enlarged continuation of spinal cord • Function: • conducts ascending and descending impulses between brain and spinal cord • contains cardiac, vasomotor, and respiratory control centers • contains various nonvital reflex control centers (coughing, sneezing, vomiting) 11-38

47. Cranial Nerves 11-46

48. DID YOU KNOW!!!

49. Life-Span Changes • Brain cells begin to die before birth • Over average lifetime, brain shrinks 10% • Most cell death occurs in temporal lobes • By age 90, frontal lobe has lost half its neurons • Number of dendritic branches decreases • Decreased levels of neurotransmitters • Fading memory • Slowed responses and reflexes • Changes increase risk of falling • Sleep problems common 11-71

50. Clinical Application Cerebral Injuries and Abnormalities • Concussion • brain jarred against cranium • loss of consciousness • temporary loss of memory • mental cloudiness • headache • recovery usually complete • Cerebral Palsy • motor impairment at birth • caused by blocked cerebral blood vessels during development • seizues • learning disabilities • Cerebrovascular Accident • stroke • sudden interruption in blood flow • brain tissues die 11-72