2. The Nervous System 6
Lesson 6.1: Overview of the Nervous System Lesson 6.2: Transmission of Nerve Impulses Lesson 6.3: Functional Anatomy of the Central Nervous System Lesson 6.4: Functional Anatomy of the Peripheral Nervous System Lesson 6.5: Injuries and Disorders of the Nervous System

3. Overview of the Nervous System
Chapter 6: The Nervous System
Lesson 6.1
Overview of the Nervous System

4. Do Now
Pick three words and write the definition of each. All words are on page 201.
Central Nervous System
Peripheral Nervous System
Afferent Nerves
Efferent Nerves
Somatic Nervous System
Autonomic Nervous System

5. Today’s Objectives
Differentiate between the central nervous system and peripheral nervous system, and explain the function of each.
Explain the differences between afferent and efferent nerves.
Describe the functions of the somatic and autonomic branches of the nervous system.
Identify the general role of the glial cells.
Describe the anatomical structure of a typical neuron.

6. Nervous System Overview
The nervous system controls voluntary movement by activating skeletal muscle, but also directs the involuntary functions of smooth muscle in internal organs and cardiac muscle.
By automatically controlling the functions of smooth muscle and cardiac muscle, the nervous system ensures that these life functions are able to occur without conscious thought.

7. Nervous System Overview
organization of the nervous system
two major divisions categorized by:
Structural
Functional
the efferent nerves
nervous tissues
neuroglia
neurons

8. Organization of the Nervous System
Two major divisions
Central nervous system (CNS)
Peripheral nervous system (PNS)
Peripheral nervous system divided into subdivisions:
sensory receptors
afferent (sensory) nerves
efferent (motor) nerves

9. Two Major Divisions

10. Major Divisions Central Nervous System (CNS) Peripheral Nervous System
Includes the brain and spinal cord.
The CNS directs the activity of the entire nervous system.
Peripheral Nervous System
Includes spinal nerves that transmit information to and from the spinal cord
Cranial nerves transmit information to and from the brain.
Also includes sensory receptors which respond to stimuli such as pressure, pain, or temperature.

11. Afferent Nerves Efferent Nerves
Nerves that transmit impulses from the sensory receptors in the skin, muscles, and joints to the CNS
Efferent Nerves
Nerves that carry impulses from the CNS out to the muscles and glands.

12. The Efferent Nerves
There are two functional subdivisions of the efferent (motor) nerves
somatic nervous system
Stimulates skeletal muscles causing them to develop tension.
Voluntary control
autonomic nervous system
Controls the cardiac muscle of the heart and the smooth muscles of the internal organs.
Involuntary control
Includes two separate branches
sympathetic
parasympathetic

13. Nervous Tissues 2 Categories of tissues neuroglia neurons
also known as glial cells
support the neurons
protect the neurons
neurons
transmit nerve impulses

14. Neuroglia astrocytes microglia ependymal oligodendrocytes
Within the central nervous system there are 4 types of glial cells.
astrocytes
microglia
ependymal
oligodendrocytes

15. Central Nervous System Glial Cells
Astrocytes
Positioned between neurons and capillaries.
Protect the neurons from any harmful substances in the blood.
Microglia
Absorb and dispose of dead cells and bacteria
Ependymal
Form protective coverings around the spinal cord and central cavities within the brain.
Oligodendrocytes
Wrap around nerve fibers and produce a fatty insulating material called myelin.

16. Neuroglia peripheral nervous system includes 2 forms of glial cells
Schwann cells
Form the fatty myelin sheaths around nerve fibers
satellite cells
Serve as cushioning support cells

17. Neurons
Glial cells provide support and protection for the nervous system, but it is the neurons that transmit information in the form of nerve impulses.
Typical neuron has a long, tail-like projection called an axon.
dendrites
send information to cell body
cell bodies
Includes a nucleus and mitochondria
axons
send information away from cell body

18. Neuron Types by Function
sensory neurons (afferent)
send impulses toward CNS
Impulses from the skin and organs to the spinal cord and brain.
Provides information about the external and internal environments.
motor neurons
send impulses away from CNS
Transmits impulses from the brain and spinal cord to the muscles and glands, directing body actions.
interneurons
bridges between neurons

19. Neuron Structures bipolar unipolar multipolar
one axon and one dendrite
unipolar
one axon
multipolar
one axon and many dendrites

20. Review and Assessment
Match these words with 1–4 below: sympathetic nervous system, myelin, synapse, axon. 1. high alert 2. transmits impulses away from cell body 3. fatty insulating material 4. gap between neurons

21. END

22. Exit Ticket
Which of the following is not a major division of the nervous system?
a. Central Nervous System
b. Peripheral Nervous System
c. Afferent Nervous System

23. 2) T or F: The central nervous system has afferent nerves that carry impulses TOWARDS muscles and glands. 3) When sending nerve impulses, the purpose of the myelin sheaths are to: a. Decrease the speed of the transmission. b. Increase the speed of the transmission. c. Block any messages being sent. d. None of the above.

24. Transmission of Nerve Impulses
Chapter 6: The Nervous System
Lesson 6.2
Transmission of Nerve Impulses

25. Do Now Work on the “Learning the Key Terms” Worksheet
Chapter 6 Lesson 2 begins on page 202, or use the glossary which begins on page 579.
You have 8 minutes to complete the worksheet.
Turn the worksheet into Mr. B when you are finished.

26. Today’s Objectives Lesson 6.2 Transmission of Nerve Impulses
Define action potential and explain how action potentials are generated.
Explain the factors that influence the speed of neural impulse transmission.
Describe how impulses are transmitted across the synapse.
Discuss the roles played by neurotransmitters.
Describe the three types of reflexes and explain how they work.

27. Intro
Neurons have one behavior property in common with muscles: Irritability – the ability to respond to a stimulus.
However, neurons have an aspect of irritability that muscles DO NOT have: converting stimuli into nerve impulses.
Nerve impulse = a tiny electrical charge that transmits information between neurons.

28. Transmission of Nerve Impulses
Action Potentials
When a neuron is inactive, there are potassium ions (K+) inside the cell and sodium (Na+) ions outside the cell membrane.
Inside of the membrane is more negatively charged than the outside (Polarized).
When a stimulus is involved it changes the charge so the inside is more positive (Depolarized)
This change in charge is known as an Action Potential.
Following the discharge of the action potential, it goes back to it original charge (Repolarization)

29. Transmission of Nerve Impulses
Impulse Transmission
3 factors the sped at which a nerve impulse travels:
Myelin sheath
The presence of a myelin sheath acts as an electrical insulator and causes the action potentials to “jump”.
This increases the speed in which an impulse travels.
Diameter of Axon
The larger the axon, the more ions available to conduct the current.
Example: A large diameter pipe moves more water compared to a small diameter pipe.

30. Impulse Transmission Transmission at Synapses Neurotransmitters
Chemical messengers
excitatory effect
Activates muscle fibers
Inhibitory effect
Blocks pain messages

31. Transmission of Nerve Impulses
Temperature
Warm temperatures increase ion diffusion rates.
This increases the speed at which impulses will travel.
Cold temperatures decrease diffusion rates.
Example: when you hold an ice cube you have a numbing sensation. The cold area takes longer to send information about touch, pain, pressure, and temperature to your brain.

32. Reflexes Simple, rapid, involuntary, programmed responses to stimuli.
2 Categories of reflexes:
Somatic
Involve the skeletal muscles.
Example: withdrawing your hand quickly from something hot even before you realized that it was hot.
Autonomic Reflexes
Send involuntary stimuli to the cardiac muscle of the heart and the smooth muscle of internal organs.
Stimulates involuntary muscles.

33. Review and Assessment
Fill in the blanks with: reflexes, saltatory conduction, neurotransmitter, or action potential.
1. A(n) _______________ is an all or none response.
Action Potential
Saltatory conduction
2. _______________ occurs only in myelinated axons.
Reflexes
neurotransmitter
3. _______________ are rapid, involuntary responses.
4. The axon terminal has tiny vesicles filled with _______________.

34. END

35. Exit Ticket
Some factors that can influence the speed of a nerve impulse are:
a. body temperature
b. diameter of the axon
c. presence of a myelin sheath
d. all of the above
e. none of the above

36. 2) T or F: An action potential is generated when an electrical charge produced in a nerve or muscle fiber through stimulation. 3) Reflexes are ___: a. complex, slow, and voluntary responses b. complex, fast, and involuntary responses c. simple, rapid, and involuntary responses d. simple, slow, and voluntary responses.

37. 4) Somatic reflects involve which type of muscles and which type of action? a. Skeletal muscle, involuntary b. Skeletal muscle, voluntary c. Cardiac, voluntary d. Cardiac, involuntary

38. Functional Anatomy of the Central Nervous System
Chapter 6: The Nervous System
Lesson 6.3
Functional Anatomy of the Central Nervous System

39. The Brain cerebrum diencephalon brain stem cerebellum meninges
blood-brain barrier

40. Cerebrum cerebral cortex lobes primary motor cortex
gyrus
sulcus
fissure
lobes
frontal
parietal
occipital
temporal
primary motor cortex
primary somatic sensory cortex

41. Cerebrum

42. Diencephalon
thalamus
hypothalamus
epithalamus

43. Brain Stem
midbrain
pons
medulla oblongata

44. The Brain cerebellum meninges blood-brain barrier dura mater
arachnoid mater
pia mater

45. Spinal Cord

46. Review and Assessment
True or False? 1. The gyri divide the brain into 4 regions. 2. The hypothalamus regulates blood pressure. 3. The meninges has 3 layers. 4. The cerebellum coordinates balance. 5. The pons is also called the interbrain.

47. Functional Anatomy of the Peripheral Nervous System
Chapter 6: The Nervous System
Lesson 6.4
Functional Anatomy of the Peripheral Nervous System

48. Functional Anatomy of the Peripheral Nervous System
nerve structure
cranial nerves
spinal nerves and nerve plexuses
autonomic nervous system

49. Nerve Structure endoneurium perineurium epineurium covers axons
bundles fascicles
epineurium
wraps nerves

50. Cranial Nerves

51. Spinal Nerves and Nerve Plexuses
31 pairs
dorsal root
ventral root
dorsal ramus
ventral ramus
plexuses

52. Autonomic Nervous System
preganglionic and postganglionic neurons
sympathetic nerves
fight-or-flight action
parasympathetic nerves
resting or digesting action

53. Review and Assessment
Match these words with 1–4 below: efferent, ganglion, optic, perineurium. 1. wraps fascicles 2. motor 3. a cranial nerve 4. enlarged junction

54. Injuries and Disorders of the Nervous System
Chapter 6: The Nervous System
Lesson 6.5
Injuries and Disorders of the Nervous System

55. Injuries to the Brain and Spinal Cord
traumatic brain injury
cerebral palsy
spinal cord injury

56. Traumatic Brain Injury
violent impact to head
mild
moderate
severe

57. Cerebral Palsy damage to brain motor function impairment before birth
during birth
during infancy
motor function impairment

58. Spinal Cord Injuries C1–C3: usually fatal C1–C4: quadriplegia
C5–C7: paralysis of lower extremities
T1–L5: paraplegia
Corepics/Shutterstock.com

59. Common Diseases and Disorders of the CNS
meningitis
multiple sclerosis
epilepsy
Parkinson’s disease
dementia and Alzheimer’s disease

60. Review and Assessment
Match these words with 1–4 below: quadriplegia, multiple sclerosis, dementia, cerebral palsy. 1. inflammation destroys myelin sheath 2. loss of memory and thinking 3. loss of function below the neck 4. may begin before birth