Stimulus Response Lab
Research…
• Each student should pick from the following list of
disorders to research & answer the questions on the
worksheet. Be prepared to share with the class.
o
o
o
o
o
o
o
o
o
o
o
o
Bells Palsy
Cerebral Palsy
Multiple Sclerosis
Parkinson’s Disease
Huntington’s Disease
Tay-Sach’s
Amyotrophic lateral sclerosis (Lou Gherig’s Disease)
Epilepsy
Meningitis
Alzheimer’s Disease
Muscular Distrophy
Any other nervous disorder you may find on the internet!
Do Now
• Take out your research on your disease/disorder.
• Explain your disorder to a partner.
• Each partner is going to share what they learned
from each other!
The Nervous
System
Chapter 9
Objectives
• To identify the basic structure of a neuron.
• To explain the main components of the nervous
system.
• To compare and contrast the central nervous
system and the peripheral nervous system.
• To differentiate between the somatic and
autonomic nervous systems.
Nervous System
• Think back to when we talked about nervous tissue.
What is it’s function? How does it go about doing
this?
• General Functions:
o Sensory (detect change)
o Integrative (make sense of it)
o Motor (cause a response)
Structure of a Neuron
• Neuron= Nerve Cell
• Reacts to physical/chemical
changes in surroundings
• Transmit information through
nerve impulses to other
neurons and other cells.
Structure of a Neuron
CNS vs. PNS
• CNS (Central Nervous System):
o Brain
o Spinal Cord
• PNS (Peripheral Nervous System):
o Cranial nerves
o Spinal Nerves
PNS
• Contains a sensory division and a motor division.
• Sensory Division:
o Contains sensory receptors that convert info into a nerve impulse
and transmit it back to the CNS to make sense of it.
o Monitors environmental changes such as light and sound
o Detects changes in homeostasis ( ex: temperature, oxygen level)
Motor Division
• Utilize peripheral neurons to carry impulses from the
CNS to an effector which will cause a response
o Ex: muscle contraction, gland secretion, etc.
Motor Division
• Somatic Nervous System:
o Controls skeletal muscle and
voluntary movement.
• Autonomic Nervous System:
o Controls effectors that are
involuntary
• Ex: heart, smooth muscle,
certain glands
Lets put
that all
together…
Do Now
• What are the 2 divisions of the nervous system?
• Name as many parts of a neuron that you can
remember.
• What are the 3 main functions of the nervous
system?
Objectives
• To identify and explain the 3 different structures of
neurons.
• To compare and contrast sensory, motor, and
interneurons and explain a general pathway.
• To determine the functions of the 5 types of
neuroglia.
Lets Review…
• General Neuron structure and action potential
Types of Neurons
Multipolar:
o Many processes
stemming from cell
body.
o *most neurons in brain
and spinal cord are
multipolar
Types of Neurons
Bipolar:
o Only two processes (one
at each end.
o *found in eyes, nose,
ears..
Types of Neurons
Unipolar:
o One single process
extending from cell
body.
o one side of axon is the
peripheral process
associated with body
part, other side is the
central process that
enters brain or spinal
cord.
o Cell bodies create a
tissue mass called
ganglia.
Types of Neurons
Neuron Classification
• Sensory Neurons (afferent):
o Carry impulses from PNS to CNS
o Contain “receptor ends” at the
tips of dendrites
o Changes outside the body
stimulate receptor ends
triggering an impulse
o *Most are unipolar
Neuron Classification
• Interneurons (association):
o Completely in brain or spinal
cord.
o Link neurons together.
o *multipolar
Neuron Classification
• Motor Neurons (efferent):
o carry impulses out of brain or
spinal cord to the effector
and stimulate response.
General Pathway
Neuroglial Cells
*More numerous than neurons, support neurons in different
ways.
• Microglial Cells:
o Phagocytize bacterial cells and cellular debris
• Oligodendrocytes:
o Provide insulating layers of myelin
• Astrocytes:
o
o
o
o
Provide structural support
join parts (ex: neuroncapillary)
help regulate concentrations of nutrients and ions
Form scar tissue in the CNS
• Ependymal Cells:
o Forms membrane that covers specialized brain parts and forms inner linings
within the brain and spinal canal
• Schwann cells:
o Forms myelin sheath around axons.
Myelin
• A lipid that sometimes coats axons
o White matter = myelinated axons in CNS
o Gray matter = cell bodies & unmyelinated axons in CNS
• Produced by some neuroglial cells
• Insulates neurons & increases
efficiency of nerve impulses
Neuroglial Cells
• Oligodendron, astrocytes, and microglial cells
Neuroglial Cells
Do Now
• Which sub-division of the PNS is responsible
for your heart beating?
• What is the difference between afferent
and efferent neurons?
• What part of the neuron carries messages to
the CNS?
• Where are bipolar neurons commonly
found?
Objectives
• To explain how a nerve impulse occurs.
• To determine what types of stimuli elicit an action
potential.
• To explain different things that inhibit an action
potential.
• To understand components of a neuron that
contribute to impulse velocity.
Cell Membrane Potential
• The membrane is electrically charged, “polarized”
due to Na+ and K+ ions
o Greater concentration of sodium ions outside and potassium ions inside.
o Potassium ions pass through more easily
o Active transport (sodium/potassium pump) maintains balance
• This is essential in the propagation of a nerve
impulse.
Resting Potential
• When a nerve cell membrane is undisturbed, the
membrane remains polarized staying more
negative on the inside and positive on the outside.
Threshold Potential
• If the nerve cell detects a change in
light/temp/pressure it effects the resting potential
and the membrane begins depolarizing.
o Sodium channels open and + ions flow in, making the inside less negative.
• Change in potential is proportional to the intensity
of the stimulation.
• Stimulation + more stimulation before initial
stimulation subsides is called summation.
• Once the threshold is reached, an action potential
occurs.
Action Potential
Impulse Conduction
• Unmyelinated nerve = impulse conducted over the
entire surface.
•
Myelin insulates and prevents ion flow, would prevent conduction if it
were continuous and didn’t have the nodes of ranvier.
• Myelinated nerve= impulse jumps from node to
node and creates a saltatory response and is much
faster than unmyelinated.
All-or-None
• Nerve impulses create an “all or none response”.
Once the stimulus reaches threshold, it generates
an action potential.
Action Potential
Animation
• http://highered.mcgrawhill.com/sites/0072943696/student_view0/chapter8/
animation__action_potential_propagation_in_an_u
nmyelinated_axon__quiz_2_.html
PhysioEx Lab
• “Neurophysiology of Nerve Impulses”
o Complete the physioEx lab. Answer the questions. You
DON’T have to print the graphs.
o Complete the “review sheet” when you are done with your
lab.
o You will have a LAB QUIZ next lab day on this material.
(Next Wednesday)
Do Now
• How is an impulse generated?
• What are some ways to generate an
impulse?
• List the different inhibitors that can prevent
an action potential and how?
Objectives
• Identify the different components of a reflex
arc.
• Explain different autonomic reflexes found
throughout the body.
Article
• Read the article about impulses and answer the
questions!
Responses
• How would you explain how your body responds to
a stimulus? (use what you know about neurons)
Reflexes
• Ordinarily, a receptor sends a signal to the brain
where the brain coordinates a response.
• What happens when you touch something hot?
Reflex Arc
• A reflex is a rapid action that happens without
thought and does not involve the brain.
• Lets take a look…
o http://www.bbc.co.uk/schools/gcsebitesize/science/aqa_pre_2011/hum
an/thenervoussystemrev3.shtml
Reflex Arc
1) Receptor- sense organ in skin, muscle, or other
organ
2) Sensory Neuron- carries impulse towards CNS from
receptor
3) Interneuron- carries impulse within CNS
4) Motor Neuron- carries impulse away from CNS to
effector
5) Effector- structure by which animal responds
(muscle, gland, etc).
Reflex Arc
Types of Reflexes
Babinski Reflex
• http://vimeo.com/1471
4777
Study Guide
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Lab quiz Wednesday
Test on Ch. 9 on Friday
PhysioEx Lab due Wed
Brain dissection lab due Friday