1. Allied Health I Hendersonville High School
Nervous System
Allied Health I
Hendersonville High School

2. Organization of Nervous System

3. 6 questions about the Neuron
What is it?
Where is it?
What does it do?
What are the different kinds of neurons?
What does a neuron look like?
What are the functions of the different parts of a neuron?

4. The Neuron What is it? Where is it? What does it do?
Nerve Cell that is the building block of the nervous system
Where is it?
Throughout the body
What does it do?
Transmits information in both electrical and chemical forms throughout the body
What are the different kinds of neurons
Sensory, Motor, Interneurons

5. The Neuron
What does a neuron look like?

6. The Neuron 8 parts of the neuron
What are the functions of the different parts?
Axon: Sending arm
Dendrite: Receiving fingers
Soma: Cell body not involved in transmission
Myelin Sheath: fatty insulatory
Schwann Cell: forms myelin sheath
Node of Ranvier: gaps in sheath to renew action potential
Synapse: gap separating neurons
Neurotransmitter: chemicals that allow message to “jump” across synapse

7. A Nerve What is it? Where is it? What does it do?
How is a nerve constructed?
What does a nerve look like?
What are the different kinds of nerves?
How does a nerve communicate with the brain?

8. What is it? Where is it? What does it do?
cordlike structure of the body, comprising a collection of nerve fibers
Where is it?
Throughout the body
What does it do?
Conveys impulses between a part of the central nervous system and some other body region.

9. A Nerve How is a nerve constructed? Like a muscle:
an outer covering: the epineurium.
Nerve fibers organize into bundles: fascicles
Each fascicle surrounded by the perineurium
Between individual nerve fibers is an inner layer of endoneurium.

10. AND… More about Nerves What is a glial cell? (neuroglia)
What is the difference between a stimulus, an impulse, irritability and conductivity?

11. A Nerve
What does a nerve look like?

12. A Nerve What are the different kinds of nerves?
Sensory, Motor, Autonomic
(afferent, efferent)
How does a nerve communicate with the brain?
plexus: interconnection of fibers which form new combinations
spinal cord tracts (exception: Cranial Nerves)
Sensory-somatic: conscious awareness of the external environment and all our motor
Autonomic: involuntary communication between brain and internal organs
Crossing Over of the Spinal Tracts
Impulses reaching the spinal cord from the left side of the body eventually pass over to tracts running up to the right side of the brain and vice versa

13. Regeneration Regeneration of Nerve Fibers (cut or compressed axons)
Separated ends seal off and swell
Axon and myelin sheath (of injured site) disintegrates
Schwann cells and macrophages migrate to site to phagocytize debris
Neurilemma remains intact and schwann cells proliferate
Axon "sprouts", guided by schwann cells, gap to original contact

14. Divisions of the Nervous System

15. Peripheral Nervous System
What is the peripheral nervous system?
What does it do?
Where are the nerves of the peripheral nervous system?
How do the nerves of the peripheral nervous system communicate with the brain?
What are the divisions of the peripheral nervous system?

16. Peripheral Nervous System
What is the peripheral nervous system?
One of the 2 divisions of the Nervous system
Central (brain and spinal cord) and Peripheral
What does it do?
connects the central nervous system (CNS) to the limbs and organs.

17. Peripheral Nervous System
3. Where are the nerves of the peripheral nervous system?
Cranial: directly from brain to head and neck
12 pairs
Either sensory, motor or mixed
Spinal Nerves: from spinal cord and extend throughout the body in dermatomes, pass out between the vertebrae
31 pairs

18. Cranial Nerves II. Optic III. Oculomotor IV. Trochlear V. Trigeminal
I. Olfactory
II. Optic
III. Oculomotor
IV. Trochlear
V. Trigeminal
VI. Abducens
VII. Facial
VIII. Vestibulocochlear
IX. Glossopharyngeal
X. Vagus
XI. Accessory
XII. Hypoglossal

19. Peripheral Nervous System
How do the nerves of the peripheral nervous system communicate with the brain?
Dermatomes: somatic or musculocutaneous areas served by fibers from specific spinal nerves
spinal cord tracts (exception: Cranial Nerves)
white matter of the spinal cord contains tracts which travel up and down the cord
White matter: bundles of axons each coated with a sheath of myelin
What are the divisions of the peripheral nervous system?
Sensory-somatic (sensory and motor)
Autonomic

21. Autonomic Nervous System
What is the Autonomic Nervous System?
What does it do?
What are the divisions of the Autonomic Nervous System?
What do each of the divisions control?

22. Autonomic Nervous System
What is the Autonomic Nervous System?
sensory neurons and motor neurons that run between the central nervous system and various internal organs
What does it do?
Monitors conditions in the internal environment and brings about appropriate changes in them
What are the divisions of the Autonomic Nervous System?
Sympathetic, Parasympathetic and Enteric

23. Autonomic Nervous System
What do each of the divisions control?
Sympathetic: prepares the body for emergencies: for "fight or flight" (and, perhaps, enhances the memory of the event that triggered the response)
prepares the body for violent activity
Parasympathetic: returns the body functions to normal after they have been altered by sympathetic stimulation
reverses these changes when the danger is over.
Enteric nervous system: meshwork of nerve fibers that innervate the viscera (gastrointestinal tract, pancreas, and gall bladder

24. Autonomic Nervous System
Sympathetic (Adrenalin)
stimulates heartbeat
raises blood pressure
dilates the pupils
dilates the trachea and bronchi
stimulates glycogenolysis — the conversion of liver glycogen into glucose
shunts blood away from the skin and viscera to the skeletal muscles, brain, and heart
inhibits peristalsis in the gastrointestinal (GI) tract
Inhibits contraction of the bladder and rectum

25. Autonomic Nervous System
Parasympathetic
slowing down of the heartbeat (as Loewi demonstrated)
lowering of blood pressure
constriction of the pupils
increased blood flow to the skin and viscera
peristalsis of the GI tract

26. Reflexes What is a reflex?
direct connection between stimulus and response, does not require conscious thought, a reflex is a quick involuntary action.
Where does a reflex come from?
spine
How does a reflex occur
the stimulus occurs
sensory neurons sense the stimulus
sends a message to your spinal cord (it doesn't reach the brain right then)
spinal cord sends a message to motor neurons
reflex occurs
While this is happening, message goes on to brain (which is why you feel the pain slightly after the event)

27. Reflex Reflex and Reflex Arc
Reflex = rapid, predictable motor response to a stimulus
Five components to reflex arc:
Receptor (site of stimulus)
Sensory neuron (transmits afferent impulses to CNS)
Integration Center:
Monosynaptic reflex (single motor or sensory neuron)
Polysynaptic reflex (multiple interneurons)
Motor neuron (conducts efferent impulses)
Effector (muscle or gland

28. Central Nervous System
What are the components of the central nervous system?
What are the functions of each structure in the CNS?
What is the difference between gray matter and white matter?
What are the names of the protective linings in the CNS?
What is the name of the fluid surrounding the structures in the CNS?

29. Nervous System

30. CNS What are the components of the central nervous system? Brain
Cranial Nerves
Spinal Cord

31. CNS What are the functions of each structure in the CNS? Spinal Cord
conducts sensory information from the peripheral nervous system (both somatic and autonomic) to the brain
conducts motor information from the brain to our various effectors
skeletal muscles
cardiac muscle
smooth muscle
glands
serves as a minor reflex center
Brain
receives sensory input from the spinal cord as well as from its own nerves (e.g., cranial nerves)
devotes most of its volume and power to processing its various sensory inputs and initiating appropriate — and coordinated — motor outputs

32. CNS What is the difference between gray matter and white matter?
white matter = bundles of axons each coated with a sheath of myelin
gray matter = masses of the cell bodies and dendrites
In the spinal cord, the white matter is at the surface, the gray matter inside.
In the brain, this pattern is reversed.

33. CNS What are the names of the protective linings in the CNS?
The Meninges
Both the spinal cord and brain are covered in three continuous sheets of connective tissue, the meninges
From outside in, these are:
the dura mater — pressed against the bony surface of the interior of the vertebrae and the cranium
Subdural space
the arachnoid
Subarachnoid space
the pia mater

34. CNS
What is the name of the fluid surrounding the structures in the CNS?
CSF flows uninterrupted throughout the central nervous system
through the central cerebrospinal canal of the spinal cord and
through an interconnected system of four ventricles in the brain