Unit 7 – The Nervous System

1. Unit 7 – The Nervous System

2. Contains 2 kinds of cells: • neurons: • cells that send and receive signals • neuroglia (glial cells): • cells that support and protect neurons Neural Tissue

3. Brain and spinal cord Sensory receptors of sense organs (eyes, ears, etc.) Nerves connect nervous system with other systems Organs of the Nervous System

4. Central nervous system (CNS) Peripheral nervous system (PNS) Anatomical Divisions of the Nervous System

5. The Central Nervous System

6. Consists of the spinal cord and brain Contain neural tissue, connective tissues, and blood vessels The Central Nervous System (CNS)

7. Are to process and coordinate: • sensory data: • motor commands: • higher functions of brain: • intelligence, memory, learning, emotion Functions of the CNS

8. The Brain

9. Ranges from 750 cc to 2100 cc Contains almost 98% of the body’s neural tissue Average weight about 1.4 kg (3 lb) The Human Brain

10. There are 3 layers (meninges) that surround the brain and spinal cord • Pia mater – covers the brain • Arachnoid – middle layer • Dura mater – outermost layer that is attached to the interior of the skull Meninges

11. Major Regions and Landmarks

12. Cerebrum Cerebellum Diencephalon Mesencephalon Pons Medulla oblongata 6 Regions of the Brain

13. Largest part of brain Controls higher mental functions Memory storage Divided into left and right cerebral hemispheres Surface layer of gray matter (neural cortex) Cerebrum

14. Also called cerebral cortex Folded surface increases surface area Elevated ridges (gyri) Shallow depressions (sulci) Deep grooves (fissures) Neural Cortex

15. Second largest part of brain Coordinates repetitive body movements 2 hemispheres Covered with cerebellar cortex Cerebellum

16. Located under cerebrum and cerebellum Links cerebrum with brain stem Contains thalamus and hypothalamus Diencephalon

17. Thalamus: • relays and processes sensory information • Hypothalamus: • hormone production • emotion • thirst/hunger • body temp. • controls circadian rhythms (day–night cycles) Thalamus and Hypothalamus

18. Processes infomation between: • spinal cord and cerebrum or cerebellum • Includes: • mesencephalon • pons • medulla oblongata The Brain Stem

19. Also called midbrain Processes sight, sound, and associated reflexes Maintains consciousness Mesencephalon

20. Connects cerebellum to brain stem Is involved in somatic and visceral motor control Pons

21. Connects brain to spinal cord • Relays information • Regulates autonomic functions: • Cardiovascular, respiratory, and digestive systems Medulla Oblongata

22. Divisions of the cerebrum

23. Is the largest part of the brain Controls all conscious thoughts and intellectual functions Processes somatic sensory and motor information The Cerebrum

24. The Cerebral Cortex Figure 14–12b

25. Gyri of neural cortex: • increase surface area (number of cortical neurons) Structures of the Cerebrum (1 of 3)

26. Longitudinal fissure: • separates cerebral hemispheres • Lobes: • divisions of hemispheres Structures of the Cerebrum (2 of 3)

27. Central sulcus divides: • anterior frontal lobe from posterior parietal lobe • Lateral sulcus divides: • frontal lobe from temporal lobe • Corpus Callosum • Connects left and right hemispheres Structures of the Cerebrum (3 of 3)

28. Each cerebral hemisphere receives sensory information from, and sends motor commands to, the opposite side of body The 2 hemispheres have different functions although their structures are alike Correspondence between a specific function and a specific region of cerebral cortex is not precise 3 Functional Principles of the Cerebrum

29. Sensory and Motor Areas of the Cerebrum

30. Central sulcus separates motor and sensory areas Motor and Sensory Areas of the Cortex Figure 14–15a

31. Precentral gyrus of frontal lobe: • directs voluntary movements Motor Areas

32. Postcentral gyrus of parietal lobe: • receives somatic sensory information (touch, pressure, pain, vibration, taste, and temperature) Sensory Areas

33. Visual cortex: • information from sight receptors • Auditory cortex: • information from sound receptors • Olfactory cortex: • information from odor receptors • Gustatory cortex: • information from taste receptors Special Sensory Cortexes

34. Sensory association areas: • monitor and interpret arriving information at sensory areas of cortex • Somatic motor association area (premotor cortex): • coordinates motor responses (learned movements) Association Areas

35. Somatic sensory association area: • interprets input to primary sensory cortex (e.g., recognizes and responds to touch) • Visual association area: • interprets activity in visual cortex • Auditory association area: • monitors auditory cortex Sensory Association Areas

36. Also called Wernicke’s area Present in only 1 hemisphere (left) Receives information from all sensory association areas Coordinates access to complex visual and auditory memories General Interpretive Area Wernicke’s area

37. Speech center (Broca’s Area): • is associated with general interpretive area • coordinates all vocalization functions • Prefrontal cortex of frontal lobe: • integrates information from sensory association areas • performs abstract intellectual activities (e.g., predicting consequences of actions) • Hippocampus • sorts and integrates emotions and memories • deep portion on the temporal lobe Other Integrative Areas

38. Hemispheric Lateralization • Functional differences between left and right hemispheres Figure 14–16

39. In most people, left brain (dominant hemisphere) controls: • reading, writing, and math • decision-making • speech and language The Left Hemisphere

40. Right cerebral hemisphere relates to: • senses (touch, smell, sight, taste, feel) • recognition (faces, voice inflections) The Right Hemisphere

41. The Spinal Cord

42. Adult Spinal Cord • About 18 inches (45 cm) long • 1/2 inch (14 mm) wide • Ends between vertebrae L1 and L2 • Carries signals between brain and PNS • Responsible for reflexes Spinal Cord

43. The Peripheral Nervous System

44. Includes all neural tissue outside the CNS The Peripheral Nervous System (PNS)

45. Deliver sensory information to the CNS Carry motor commands to peripheral tissues and systems Functions of the PNS

46. Also called peripheral nerves: • bundles of axons with connective tissues and blood vessels • carry sensory information and motor commands in PNS: • cranial nerves—connect to brain • spinal nerves—attach to spinal cord Nerves

47. Receptors: • detect changes or respond to stimuli • neurons and specialized cells • complex sensory organs (e.g., eyes, ears) • Effectors: • respond to efferent signals • cells and organs Receptors and Effectors

48. Afferent division: • carries sensory information • from PNS sensory receptors to CNS • Efferent division: • carries motor commands • from CNS to PNS muscles and glands Functional Divisions of the PNS

49. Somatic nervous system(SNS) Autonomic nervous system (ANS) The Efferent Divisions of the PNS

50. Includes all somatic motor neurons that innervate skeletal muscles • Controls skeletal muscle contractions: • voluntary muscle contractions • involuntary muscle contractions (reflexes) The Somatic Nervous System(SNS)