Noteworthy Nervous System

1. Noteworthy Nervous System Part 1--The Basics

2. Divided into 2 Structural Systems • 1. Central Nervous System (CNS) • Made up of Brain and Spinal Cord • 2. Peripheral Nervous System (PNS) • Made up of Spinal and Cranial Nerves

3. 3 Types of Nervous Cell Tissue 1. Neurons 2. Supporting Cells --called Neuroglia (means nerve glue) 3. Nerves

4. Nerve A bundle of neurons and connective tissue.

5. Nerve Function Classification • **Based on the direction of the nerve impulse (sending of messages) to the CNS** • Sensory: From sense organs to CNS (informers) • Motor:Impulses from CNS to muscle, glands (doers) • Association (integration):Connect sensory and motor (may have many of these in the chain)

6. Closer Look at Nervous Tissue • A. Neurons • Function: To Transmit electrical and chemical messages • Don’t Reproduce • Made up of a cell body, nucleus, and 2 processes • 1. Axons: Take messages away from the cell body • 2. Dendrites: Take messages toward the cell body

7. B. Supporting Cells • Functions: Support, Insulate, Protect • Can Reproduce • Collectively called neuroglia--”nerve glue”

8. 6 KINDS OF SUPPORTING CELLS 1. Astrocytes 2. Microglia 3. Ependymal 4. Oligodentrocytes 5. Schwann cells 6. Satellite cells

9. Astrocytes • Anchor the neurons to blood supply

10. Microglia • They are Phagocytes that get rid of debris such as dead brain cells and bacteria Neurons stained blue, astrocytes: red and microglia: green

11. Ependymal • Circulate brain fluid

12. Oligodendrocytes • Form fatty, insulating covering around nerves of CNS, called myelin sheath)

13. Schwann cells • Same thing as oligodendrocytes except they are in the Peripheral nervous system not the CNS

14. Satellite Cells • Act as protective cushioning cells.

15. Physiology: 3 Basic Functions of the Nervous System 1. Monitors changes inside and outside the body (this information is called sensory input) 2. Interprets the sensory input and makes decisions (integration) 3. Responds by activating muscles, or glands (the response is called the motor output)

16. Simply Put: 3 Basic Activities of the Nervous System • Take in Sensory Input, • Integrate it, • and Respond.

17. Examples….. • Monitor: Sensory Input: See a red light • Interpret: Integration: red means stop • Make decision: Respond: put foot on brake

18. Noteworthy Nervous System Part 2--Fun Fun Fun Physiology

19. Irritability • Ability to respond to a stimulus and convert it to a nerve impulse

20. Conductivity • Ability to transmit the impulse to other neurons, muscles, or glands

21. I. Irritability (Electrical) • A. Polarized • Resting or inactive cell • Fewer positive ions inside the cell than outside • Inside is negative, compared to Outside. which is positive

22. I. Irritability (Electrical) • B. Stimulation • Light excites the eye receptors • Sound excites the ear’s receptors • Pressure excites the cutaneous receptors • Neurotransmitters (chemicals) excite other neurons

23. I. Irritability (Electrical) • C. Depolarization • Stimulation causes “sodium gates” to open • High concentration of sodium outside, so it rushes in • Now inside is more positive, outside is more negative • Action Potential (Nerve impulse)

24. I. Irritability (Electrical) • Repolarization • Permeability changes: • Impermeable to sodium • Permeable to potassium

25. Repolarization (cont.) • After repolarization, Sodium and Potassium concentrations are restored using a protein pump (ATP)

26. II. Conductivity (Chemical) • Neurons don’t touch!! They meet the Synaptic Cleft (Synapse)

27. II. Conductivity (Chemical) • Neurotransmitters--Chemicals that diffuse from one neuron to the next and bind on receptors • If enough neurotransmitter, the whole series of events happens again • Neurotransmitter is cleaned up

28. Noteworthy Nervous System Part 3--Rockin’ Reactions and Reflexes

29. I. Reactions • Voluntary responses to stimulation from the environment • Requires time • Visual: .25 sec • Hearing: .17 sec • Touch: .15 sec

30. II. Reflexes • A. Characteristics: • Take place without conscious control (often skip brain) • Quick • Purposeful and Involuntary • Always the same (predictable)

31. II. Reflexes • B. Types • 1. Autonomic Reflexes • Regulate smooth muscles, heart, and glands • EX. Secretion of saliva, change in pupil size (pupillary), digestion, elimination, blood pressure, sweating

32. II. Reflexes • B. Types • 2. Somatic Reflexes • Regulate skeletal muscles • EX. Knee jerk (patellar), Pulling away from hot stove

33. II. Reflexes • C. How They Work • 1. Sensory neuron reacts to stimulus • 2. Interneuron in brain or spinal cord reacts • 3. Motor neuron stimulates effector organ

35. Bravo! For the Bodacious Brain

36. What’s 3 lbs, pinkish-gray all over, wrinkled like a walnut, and has the texture of oatmeal?

37. I. Cerebral Hemispheres • Paired (left and right) • A. Anatomy • Gyri and sulci: elevated ridges and shallow grooves • Fissures: deep grooves, separated large regions of the brain • Lobes: sections named after the bones near them

38. A. Anatomy (cont) • *CORPUS CALLOSUM • Very large nerve tract, connects the two hemispheres, allows the two hemispheres to communicate

39. B. Functions • Interprets sensory information • Initiates voluntary muscle movements • Stores information (memory) • Uses memory for reasoning • Emotion • consiousness

40. II. Diencephalon (interbrain) • Located between cerebral hemispheres and above the midbrain • A. Thalamus: crude recognition of pleasant and unpleasant

41. B. Hypothalamus • “under the thalamus” • Regulates body temperature, water balance, metabolism, center for emotion (limbic system) • Thirst, appetite, sex, pain, pleasure

42. B. Hypothalamus (cont) • Pituitary: • Secretes lots of hormones “master gland” • Mammilary bodies: • Reflex center for smell (olfaction)

43. C. Epithalamus • Pineal Body • Regulates day and night cycles • Choroid plexis: • Knots of capillaries that make cerebrospinal fluid

44. III. Brain Stem • A. Midbrain • Corpora Quadrigemina • Reflex center for vision and hearing • B. Pons • Regulates depth and rate of breathing

45. III. Brain Stem • C. Medulla Oblongata • Merges into the spinal cord • Controls heart rate, blood pressure, breathing, vomiting • All nerve fibers connecting brain and spinal cord go through it

46. IV. Cerebellum • Looks like cauliflower • Precise timing for skeletal muscle activity • Controls balance and equilibrium

47. V. Protection….Meninges • A. Dura Mater • “tough or hard mother” • Double layer, one attached to inner surface of skull • Blood vessels

48. V. Protection…Meninges • B. Arachnoid Mater • “spider”, looks like spiderwebs • Surrounds spinal cord • No blood vessels

49. V. Protection…Meninges • C. Pia Mater • “gentle mother” • Thin blood vessels • Nourishes cells of the brain and spinal cord, attaches to surface