1. The Nervous System
Unit K

2. Watch Youtube Video Introduction to Nervous System……. https://youtu

3. Nervous System
The nervous system is a complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body.
The nervous system is divided into the Central nervous system and Peripheral nervous system.

4. Watch Youtube Video Nervous System……. https://youtu.be/sjyI4CmBOA0

5. Neuron -Transmits a message from one cell to another
-Nerve cell
-Transmits a message from one cell to another
-Has a nucleus, cytoplasm, and cell membrane
Dendrites
Nerve cell processes that
carry impulse to cell body…may be one or more

6. Watch the following video and answer these questions:
1. What is a neuron?
2. What are the main parts of a neuron?
3. What is the path of action potential down a neuron?

7. Watch Youtube Video Basic Neuron……. https://youtu.be/mZdjQXrnTRo

8. Myelin Sheath Axon Myelin is a fatty substance that protects axon
speeds transmission along axon - Called neurilemma
Axon
-Carries impulses away from the cell body
-Only one on a neuron

9. SYNAPSE
A space between neurons, messages go from one cell to another.

10. Watch Youtube Video Synapse……. https://youtu.be/WmTXiLndbsc

11. NERVE IMPULSE A STIMULUS creates an IMPULSE.
Impulse to dendrite to cell body to axon to synapse (by neurotransmitters) to the next neuron (or muscle or gland).

12. Watch Youtube Video How a Neuron fires……. https://youtu.be/C4Gt322-XxI

13. SENSORY NEURONS (AFFERENT)
Emerge from the skin or sense organs.
Carry impulses to spinal cord and brain.

14. MOTOR NEURONS (EFFERENT)
Carry messages from brain and spinal cord to muscles and glands.

15. ASSOCIATIVE NEURONS (INTERNEURONS)
Carry impulses from sensory neurons to motor neurons.

16. Watch Youtube Video Nervous System……. https://youtu.be/M1E9Lm16cUs

17. NEUROGLIA Act as the “helper” cells of the nervous system.
Each neuron in the body is surrounded by anywhere from 6 to 60 neuroglia that protect, feed, and insulate the neuron.
They that insulate, support and protect the neurons, nerve glue.

18. CENTRAL NERVOUS SYSTEM
Divisions of the Nervous System
CENTRAL NERVOUS SYSTEM
Consists of the brain and spinal cord

19. Central Nervous System
The Central nervous system is made up of the brain and spinal cord and The Peripheral nervous system is made up of the Somatic and the Autonomic nervous systems.
Communication and coordination system of the body
Seat of intellect and reasoning.
Consists of the brain, spinal cord, and nerves.

20. Divisions of the Nervous System
PERIPHERAL NERVOUS SYSTEM
Consists of the autonomic and somatic

21. Peripheral Nervous System (PNS)
Includes all of the parts of the nervous system outside of the brain and spinal cord. These parts include all of the cranial and spinal nerves, ganglia, and sensory receptors.

22. Divisions of Peripheral Nervous System (PNS)
Somatic Nervous System (SNS) is a division of the PNS that includes all of the voluntary efferent neurons. The SNS is the only consciously controlled part of the PNS and is responsible for stimulating skeletal muscles in the body.
Autonomic Nervous System (ANS) is a division of the PNS that includes all of the involuntary efferent neurons. The ANS controls subconscious effectors such as visceral muscle tissue, cardiac muscle tissue, and glandular tissue. Peripheral nerves and ganglia
(ie: -Supplies heart muscle, smoother muscle and secretory glands
-automatic responses to injury like shock and increased heart rate)
Divisions of Peripheral Nervous System (PNS)

23. AUTONOMIC NERVOUS SYSTEM
Regulates activities of visceral organs (i.e. beating of heart)
Not subject to conscious control
Has two divisions:
SYMPATHETIC NERVOUS SYSTEM- the “fight or flight” system
&
Parasympathetic Nervous system

24. AUTONOMIC NERVOUS SYSTEM
SYMPATHETIC NERVOUS SYSTEM- the “fight or flight” system- when the body perceives danger, SNS sends message to adrenal medulla (above kidney) to secrete adrenaline - heartbeat increases, resp rate increases, etc

25. Parasympathetic Nervous system counters SNS – decreases heart rate, decreases respiratory rate, etc
REFLEX
Unconscious and involuntary
In a simple reflex, only a sensory nerve and motor nerve involved – example “knee-jerk” reflex

27. Watch Youtube Video Central Nervous System……. https://youtu

28. The Brain 3lb mass of soft nervous tissue 100 billion neurons
Protected by skull, 3 membranes called meninges, and cerebrospinal fluid (shock absorber)
Cerebrum

29. Adequate blood supply is needed, brain tissue will die in 4-8 mins without O2
Divided into 4 major parts: cerebrum, diencephalon (near midbrain), cerebellum, brain stem

31. Coverings of the Brain & Spinal Cord (MENINGES)
The meninges are the protective coverings of the central nervous system (CNS) (coverings of the brain and spinal cord).
. They consist of three layers:
dura mater,
arachnoid mater, and
pia mater.

32. Watch Youtube Video Brain……. https://

33. DURA MATER- outer brain covering, lines inside of skull, tough, fluid-containing - dense fibrous connective tissue
Layers = dura mater, subdural, arachnoid, subarachnoid, pia mater

34. Coverings cont’d Subdural space
is between the dura and arachnoid space
Next layer is the Arachnoid layer
- middle layer – resembles fine cob web

35. Watch Youtube Video Nervous System……. https://

36. Watch Youtube Video Nervous System……. https://

37. SUBARACHNOID SPACE- between arachnoid and pia mater, filled with CEREBROSPINAL FLUID which acts as a liquid shock absorber and as a source of nutrients for the brain

38. Watch Youtube Video Nervous System……. https://

39. Coverings cont’d
PIA MATER
innermost layer of the meninges
covers the brain’s surface, comprised of blood vessels held together by connective tissue

41. Watch Youtube Video Nervous System……. https://

42. Ventricles of the Brain
Brain contains four cavities filled with cerebrospinal fluid called CEREBRAL VENTRICLES.

43. Ventricles of the Brain (cont.)
CHOROID PLEXUS- network of blood vessels lining the ventricles which helps in the formation of cerebrospinal fluid.
CEREBROSPINAL FLUID
Forms inside ventricles of the brain.
Serves as a liquid shock absorber

44. Watch Youtube Video Nervous System……. https://

45. BLOOD-BRAIN BARRIER- choroid plexus capillaries prevent substances (like drugs) from penetrating brain tissue – this makes infections, like meningitis, difficult to cure.
LUMBAR PUNCTURE- removal of CSF from spinal canal, needle puncture between 3rd and 4th lumbar vertebrae.

47. Watch Youtube Video Nervous System……. https://

48. CEREBRUM Largest part of the brain
Divided into R and L hemispheres by deep groove
CONVULTIONS- elevated folds on the surface of the cerebrum, they increase the surface area of the brain

49. SULCI - fissure or grooves separating cerebral convolutions
Divided into four lobes – FRONTAL (voluntary muscle movement), PARIETAL, OCCIPITAL and TEMPORAL

50. Watch Youtube Video Nervous System……. https://

51. CEREBRAL FUNCTION
Conscious thought, judgment, memory, reasoning, and will power.
- responsible for maintaining consciousness,
decision making, recalling information
and normal speech
These people were not
using their cerebrum.

52. Located between cerebrum and midbrain
DIENCEPHALON
Located between cerebrum and midbrain
Composed of THALAMUS and HYPOTHALAMUS

53. Vital functions of the hypothalamus:
1. Autonomic nervous control
2. Temperature control
3. Appetite control
4. Emotional state
5. Sleep control

54. CEREBELLUM
2nd largest part of brain
Composed of two hemispheres
below the cerebrum
Controls all body functions related to skeletal muscles, including:
Balance, walking
Muscle tone
Coordination of muscle movements

55. Watch Youtube Video Nervous System……. https://

56. Controls all body functions related to skeletal muscles, including:
Balance, walking
Muscle tone
Coordination of muscle movements

57. BRAIN STEM Made up of PONS, MEDULLA and MIDBRAIN
Pons – in front of cerebellum, between midbrain and medulla – contains center that controls respiration
Midbrain – controls vision and hearing
Medulla oblongata – bulb-shaped structure between pons and spinal cord, inside the cranium above foramen magnum (opening in vertebral column)
- Responsible for:
1. Heart rate
2. Blood pressure
Click for picture…

58. Watch Youtube Video Nervous System……. https://

59. SPINAL CORD
Begins at foramen magnum and continues down to 2nd lumbar vertebrae
White and soft, in spinal canal
Surrounded by cerebrospinal fluid
FUNCTIONS AS:
Reflex center
Conduction pathway to and from the brain
Injury to spinal cord = difficulty with movement (paraplegia – paralysis of legs) and problems breathing

60. Peripheral Nervous System
All of the nerves outside the central nervous system
NERVES
Contains sensory and motor nerves (afferent and efferent)

61. Cranial Nerves 12 pairs Begin in the brain
Designated by number and name

62. Mnemonic for the 12 cranial nerves
Old
Olympus’
Towering
Top A
Finn
And
German
Vault
Hop
Mnemonic for the
12 cranial nerves

63. Watch Youtube Video Learn the 12 Cranial Nerves……. https://youtu

64. SPINAL NERVES
Originate at spinal cord and go through openings in vertebrae
31 pairs of spinal nerves
All are mixed (afferent and motor) nerves
Named in relation to their location on the spinal cord

65. Disorders of the Nervous System
MENINGITIS
Inflammation of the lining of the brain and spinal cord
May be bacterial or viral
Symptoms- headache, fever and stiff neck, nausea and vomiting
In severe form, may lead to paralysis, coma and death
If bacterial, may be treated with antibiotics
Dx by removing csf with a needle = lumbar puncture

66. EPILEPSY
Seizure disorder of the brain, characterized by recurring and excessive discharge from neurons
Seizures believed to be result of spontaneous, uncontrolled electrical activity of neurons
Cause – Uncertain
Victim may have hallucinations and seizures
Grand mal – severe, convulsive seizure
Petit mal - milder

67. Watch Youtube Video Epilepsy……. https://youtu.be/iYkWt1erux4

68. Watch Youtube Video Epilepsy First Aid……. https://youtu.be/men1or169Xo

69. CEREBRAL PALSY
Disturbance in voluntary muscular action due to brain damage.
May be due to birth injury or abnormal brain development
Spastic Quadriplegia- spastic paralysis in all four limbs.
Sx- head rolling, grimacing,
difficult speech and swallowing
No impairments of intellect.

70. POLIOMYELITIS DEMENTIA
Viral disease of nerve pathways of spinal cord- causing progressive muscle weakness leading to paralysis
Almost eradicated in USA (vaccine)
DEMENTIA
Loss of 2 areas of complex behavior, such as languages, memory, visual and spatial abilities, or judgment
Interferes with person’s daily life.

71. HYDROCEPHALUS
Increased volume of cerebrospinal fluid within ventricles of the brain.
Usually, blockage in 3rd and 4th ventricle
Enlargement of the head, usually noticed at birth.
Bypass or shunt performed to relieve pressure.

72. Watch Youtube Video Nervous System……. https://

73. Abnormal fibers build up creating tangles
ALZHEIMER’S DISEASE
Progressive disease that begins with problems remembering – characterized by early senility, confusion, and loss of recognition of persons
Nerve endings in cortex of brain degenerate and block signals that pass between nerve cells
Abnormal fibers build up creating tangles

74. Cause – Unknown
1st stage (2-4 yrs) involves confusion, short-term memory loss, anxiety, poor judgment
2nd stage (2-10 yrs) increase in memory loss, logic problems, and loss of social skills
3rd stage (1-3 yrs) inability to recognize oneself, weight loss, seizures, mood swings and aphasia

75. PARKINSON’S DISEASE
Symps - tremors, shuffling gait, pill-rolling, and muscular rigidity.
Decrease in neurotransmitter dopamine
RX- L-dopa and other drugs to treat symptoms.

76. (MS) Multiple Sclerosis- autoimmune, Chronic inflammatory disease of CNS -
Immune cells attack myelin sheath of axon-myelin sheath destroyed, leaving scar tissue on nerve cells…transmission of nerve impulses blocked.

77. Watch Youtube Video Nervous System……. https://

78. Cause- UNKNOWN
Sx- weakness of extremities, numbness, double vision, nystagmus, speech problems, loss of coordination, possible paralysis.
Typically strikes young adults age 20-40, mostly women
Rx- Avonex- slows progression

79. Cerebral Vascular Accident
Stroke or CVA
Interruption of blood and O2 to the brain – blockage of blood to the brain
Tissue death
Third leading cause of death in USA
PARALYSIS- loss of power of motion or sensation
HEMIPLEGIA- paralysis on one side of the body
(“hemi” means half)
Symptoms →

80. Risk Factors
Smoking
Hypertension
Heart disease
Family history
Causes of CVA
90% caused by blood clots
Clots lodge in carotid arteries, blocking the flow of blood to the brain
10% caused by ruptured blood vessels in the brain

81. SYMPTOMS Hemiplegia on the opposite side of the body
Sudden, severe headache
Dizziness
Sudden loss of vision in one eye
Aphasia
Dysphasia
Coma
Possible death