Download Startup: CST Prep Nervous System

Startup: CST Prep
Nervous System
•
Which statement is true about the
nervous system?
A. It is made up of cells called the peripheral
cells.
B. It has two major parts: the brain and the
central nervous system.
C. Its messages are carried by the
bloodstream.
D. It controls functions throughout the body.
Startup: CST Prep
Nervous System
• What is a role of the central nervous
system?
A. receiving messages from sense
organs
B. receiving messages from the brain
C. transmitting messages from sense
organs
D. transmitting messages to the brain
Communication is the key to
success
• On any team, communication essential
for success
• The same is true in your body
• The Nervous System controls and
coordinates functions throughout the
body and responds to internal and
external stimuli
The Nervous System
• Structures:
– Brain
– Spinal Cord
– Peripheral Nerves
• Function/Purpose
– Recognize and coordinate the body’s
response to changes in the internal and
external environments
– Communication System for the Body
Can You think of Examples of
a message being transmitted
from your body to your brain
or vice versa?
Basic Unit of the Nervous
System
• Neurons
– Cell that carries messages throughout the
Nervous System
– What kind of tissue is made of Neurons?
• Nervous Tissue
Nucleus
Axon terminals
Cell body
Myelin sheath
Nodes
Axon
Dendrites
Parts of the Neuron
• Cell Body
– Contains nucleus & cytoplasm. Center of
metabolic activity
• Dendrites
– Carry impulses from the environment or
other neurons TOWARD the cell body
• Axon
– Long fiber that carries the impulse away
from the cell body
Parts of the Neuron
• Myelin Sheath
– Insulating membrane that surrounds the
Axon
• Nodes
– Gaps in the Myelin Sheath. Helps impulse
travel down neuron faster
• Axon Terminals
– Branches at the end of the Axon through
which the nerve impulse leaves the nerve.
Nucleus
Axon terminals
Cell body
Myelin sheath
Nodes
Axon
Dendrites
3 Kinds of Neurons
• Classified according to the
DIRECETION in which an impulse
travels
– Sensory Neurons
• Carry impulses from the sense organs to the
spinal cord and brain (senses to brain)
– Motor Neurons
• Carry impulses from the brain and spinal cord
to muscles and glands (brain to muscle)
– Interneurons
• Connect sensory and motor neurons and carry
impulses between them. (neuron connectors)
Quick Quiz
• What part of the neuron carries the
message into the cell body of th
neuron?
• What part of the neuron sends the
message out of the neuron?
• What type of neuron carries messages
from the environment to the brain?
• What type of neuron carries messages
from the brain to the muscles?
Color and Label your Neuron
• You will get a worksheet with a neuron
on it
– It must be fully colored
– Fully Labeled
– Complete definitions on back
The Nerve Impulse
• So, what the heck is this “impulse” we
keep talking about?
Startup: CST Prep
Nervous System
• What is the function of motor
neurons?
A. Carrying impulses from sensory
neurons to interneurons
B. Carrying impulses from sense organs
to the spinal cord and the brain
C. Carrying impulses from the brain and
spinal cord to muscles and glands
D. All of the above
Classroom Business:
• Weekly quiz on Friday!
• Week 5 grades are posted!
• Open house on Thursday
–+5 for the class with the highest
attendance
–+5 if we beat my record of 40
parents
• Outline 35-2 and 35-3 due this
week!
Nerve Impulse
• Stimulus
• Impulse travels through neuron from
Dendrite through Cell Body to Axon and
out Axon Terminals
• Neurotransmitters relay message to
next neuron
Stimulus
Stimulus
– A signal to which an organism responds
– Stimulus - From senses to brain:
• Touching a hot stove
• Turning the lights out
– Response - From brain to muscles:
• Brain tells muscles to contract to pull your
hand away from the hot stove
• Brain tells pupils to dialate (get big) so you
can see better in the dark
Quick Quiz
• Give an example of a stimulus
The Nerve Impulse
• A stimulus excites nerve endings
(Dendrites) which sends an impulse,
like an electrical current, through the
neuron
The Resting Neuron
• When there is no impulse traveling
through a neuron
– Resting Potential
• Electrical charge across the cell membrane of a
resting neuron
• Negative on the Inside
• Positive on the outside
Resting Neuron
Positive Charge
Positive Charge
Negative
Charge
Negative Charge
Positive Charge
Positive Charge
The Moving Impulse
• When a neuron receives an impulse
– From the environment OR from another
neuron
– The impulse must be strong enough to
stimulate a response
– Impulse is ALL OR NOTHING
The Moving Impulse
• Action Potential
– A.K.A. a nerve impulse
– A rapid reversal of charges, from negative
to positive along the neruon - from
Dentrites to Axon Terminals.
Figure 35-7 An Impulse
Section 35-2
Action Potential
At rest.
As the action potential passes, potassium
gates open, allowing K+ ions to flow out.
Action Potential
At the leading edge of the impulse, the
sodium gates open. The membrane becomes
more permeable to Na+ ions and an action
potential occurs.
The action potential continues to move along
the axon in the direction of the nerve impulse.
The Action Potential is an “all or
nothing” response
The Action Potential moves down the
neuron from dendrite to axon then to
the synapse
----++++++++++++++++++
++++++++++++++++++++
++++++++++++++++++---++++++++++++++-------++
++++++++-------- +++++++
++++-------++++++++++++
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
The Synapse
• A gap between the Axon Terminals of a
neuron and another cell through which
the impulse is transferred.
– For example, where the Axon Terminal of
one neuron ends, and the Dendrite of
another neuron begins
Neurotransmitters
• Chemicals used by a neuron to transmit
an impulse across a Synapse to another
cell
– Neurotransmitters are secreted from the
end of the Axon Terminals and stimulate an
adjacent cell.
Quick Quiz
• What direction does an impulse travel
through a neuron?
• What is an Action Potential? What is
happening when the neuron is
experiencing Action Potential?
Startup: CST Prep
Nervous System
• Which type of neuron transmits
messages to the central
nervous system?
A. Sensory neuron
B. Interneuron
C. Motor neuron
D. Synaptic neuron
Figure 35-8 The Synapse
Direction of Impulse
Dendrite of
adjacent neuron
Axon
Receptor
Vesicle
Axon
terminal
Synaptic cleft
Neurotransmitter
Classroom Business
• Open House Tonight!!!
• Reading Quiz Tomorrow: 35-2
Today’s Assignment
Three Choices!
• 1. Outline 35-2 and Outline 35-3
– Due Tomorrow
– 5 HP/section
• 2. Action Potential Travel Brochure
– You are a tour guide through the neuron.
– 10 HP. Due Monday.
– 20 HP if you do it in a word document or PowerPoint
presentation
• Workbook Chapter 35-2 thru 35-5
– 5 HP per section
– Due Thursday after the CAHSEE
Quiz Tomorrow!
• Reading Quiz on 35-2
• Structures and Functions of a
Neuron
• The Nerve Impulse
• The synapse
• Pay close attention to figures and
examples from the book!!
Startup: CST Prep
Nervous System
•
A nerve impulse begins when
A. Positive ions move across the cell
membrane of a neuron.
B. Neurotransmitters flow down an axon of a
neuron.
C. Dendrites let negative ions pass through an
axon of a neuron.
D. Negative ions flow down an axon and
change the electric charge of a neuron.
Questions, Comments,
Concerns, Queries?
• Structure of a Neuron
• Types of Neurons
• Nerve Impulse
• Synapse
Homework
• LAST WEEK
– WORKBOOK 38
– OUTLINE 35-2
– OUTLINE 35-3
• THIS WEEK
– ACTION POTENTIAL BROCHURE/PPT
– OUTLINE 35-4
– OUTLINE 35-5
• NEXT WEEK
– OUTLINE 19-1
– OUTLINE 19-2
– READ CH. 40