The Nervous System

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The Nervous System
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Do Now:
 Get Your Clicker!
 Contract a K-W-L chart on loose-leaf
 List everything you already Know about the
Nervous System in the K-column
 List everything you Want to know in Wcolumn
Functions
 Monitors internal and external environments
 Integrates sensory information
 Coordinates voluntary and involuntary
responses of other organ systems
 2 subdivisions:

CNS – brain and spinal cord


Intelligence, memory, emotion
PNS – all other neural tissue

sensory, motor
Receptors and Effectors
 Receptors – receive sensory info
 Afferent division – carries info from sensory
receptors to the CNS
 Efferent division – carries info from CNS to PNS
effectors (muscles, glands, adipose)
 Somatic Nervous System (SNS)
 Controls skeletal muscles (voluntary)
 Autonomic Nervous System (ANS)
 Controls involuntary actions
 Sympathetic Division (increase heart rate)
 Parasympathetic Division (decreases heart rate)
Classwork:
 Construct a flow chart detailing the direction
in which information flows in the nervous
system
The sensory part of the PNS is...
1.
2.
3.
4.
5.
6.
Somatic division
Sympathetic division
Parasympathetic
Afferent division
Efferent division
Control center
17%
1
17%
2
17%
17%
3
4
17%
5
17%
6
The fight or flight response is the...
1.
2.
3.
4.
5.
6.
Somatic division
17%
Sympathetic division
Parasympathetic division
Afferent division
Efferent division
Control Center
1
17%
2
17%
17%
3
4
17%
5
17%
6
A change in ambient temperature
would be detected by
1.
2.
3.
4.
5.
Somatic division
Sympathetic division
Afferent division
Efferent division
Control Center
33%
33%
22%
11%
0%
1
2
3
4
5
Label Neuron
 Read the functions to determine the structure
of a typical neuron
Neurons




Communicate w/other neurons
Soma-Cell body
Dendrites - receive info
Axon- sends signal to synaptic
terminals (terminal buds)
 Synapse – site of neural
communication (gap)
 Myelin – fatty insulation
 Node of Ranvier – exposed axon
between myelin
 3 structural types:



Multipolar – multiple dendrites &
single axon (motor neurons)
Unipolar – continues dendrites &
axon, cell body lies to side
(sensory neurons)
Bipolar – one dendrite and one
axon w/cell body between them
(special senses)
Types of Neurons
 3 functional types
 Sensory – afferent division
 info about surrounding environment
 position/movement skeletal muscles
 digestive, resp, cardiovasc, urinary, reprod, taste, and
pain
 Motor – efferent division (response)
 skeletal muscles
 cardiac and smooth muscle, glands, adipose tissue
 Interneurons
 Brain and spinal cord - memory, planning, and
learning
Neuroglia
 Regulate environment around
neurons; can be phagocytes;
actively divide
 Functions in CNS:
 maintains the blood-brain
barrier
 create myelin (lipid) to coat
axon
 Nodes – gaps between
myelinated sections
 Internodes – areas
covered in myelin
 Phagocytic cells
 Secrete cerebrospinal fluid
(CSF)
The most common type of neuron is
multipolar
2. bipolar
3. unipolar
1.
94%
0%
1
2
6%
3
The part of the neuron that has
receptor proteins on its surface is
Dendrites
2. soma
3. axon
4. Myelin sheath
1.
33%
33%
17%
1
2
3
17%
4
The part of the neuron that increases
the speed of transmission is the
Dendrites
2. soma
3. axon
4. Myelin sheath
1.
44%
38%
13%
6%
1
2
3
4
Complete Action Potential POGIL
Remember:
•Discuss each question and answer
with your group
•Use the information from the models
to support your responses
•You may use any resources to assist
you
Membrane Potential
 Cells are polarized (measured in volts)
 Resting potential of neuron -70mV
 Remains stable due to Na+/K+ Pumps
Leak channels – always open (K+ diffuses out)
Na+
Cl-
K+
Proteins-
Net - charge
Gated channels – open/closed under specific
circumstance
Changes in Membrane Potential
 Depolarization
Stimulus opens Na+ gated
channels
 increase +charge of cell towards
0mV
 Action Potentials
 Affects entire surface of cell
membrane
 (+) feedback as nerve impulse
continues
 Hyperpolarization
 Stimulus opens K+ gated
channels
 Increases –charge (from -70mV
to -80mV)
 Restores resting potential

Action Potential:
All or Nothing Principal


Only skeletal muscle fibers and neuron
axons have excitable membranes
Graded potential increases pressure
until sufficient enough to reach action
potential




Continuous Propagation



Resting potential (-70mV)
Reaches Threshold (-60mV)
Refractory Period – cell cannot
respond to stimulation
 Depolarization
 Repolarization
chain rxn until reaches cell memb
Unmyleinated – 1m/s (2mph)
Salatory Propagation



Myelinated (blocks flow of ions
except at nodes)
Action potential jumps from node to
node
18-40m/s (30-300mph)
Neural Communication
 Nerve impulse – info moving
in the form of action potentials
along axons
 At end of axon the action
potential transfers to another
neuron or effector cell by
release of neurotransmitters
from synaptic terminal (only
occur in 1 direction)
 Activity of neuron depends on
balance between:
 Excitatory
neurotransmitters depolorization
 ACh & Norepinephrine
 Inhibitory
neurotransmitters hyperpolarization
 Dopamine, Seratonin,
GABA
An excitatory neurotransmitter
Increases electrical
impulse
2. Causes the release
of more
neurotransmitters
3. Is released in a
synaptic cleft
4. All of the above
1.
0%
1
0%
0%
2
3
0%
4
The resting membrane potential
inside a neuron is
0mV
2. 30mV
3. -60mV
4. -70mV
1.
0%
1
0%
0%
2
3
0%
4
After stimulus, the rush of sodium
ions into the cell is called
depolarization
2. repolarization
3. hyperpolarization
1.
0%
1
0%
2
0%
3
The action potential is propagated by
More Na+ rushing
into the cell
2. K+ leaving the cell
3. Neurotransmitters
binding to dendrite
4. Vesicles release
neurotransmitters
1.
0%
1
0%
0%
2
3
0%
4
The cell’s charge at the peak
depolarization is
0mV
2. 30mV
3. -60mV
4. -70mV
1.
0%
1
0%
0%
2
3
0%
4
During repolarization
The resting potential
is restored
2. K+ diffuse out of cell
3. The cell membrane
becomes negatively
charged again
4. All of the above
1.
0%
1
0%
0%
2
3
0%
4
Once the action potential reaches the
axon terminal, the signal will be carried
to the next neuron by
Na+ ions
2. Neurotransmitters
3. K+ ions
4. All of the above
1.
0%
1
0%
0%
2
3
0%
4
If an excitatory neurotransmitter binds
to neuron number one, how will that
affect the number of neurotransmitter
released?
more
2. less
3. No effect at all
1.
0%
0%
0%
If previous neuron releases GABA,
an inhibitory neurotransmitter, how
will that affect neuron #2
1.
2.
3.
4.
5.
6.
Increase electrical stimulus
Decrease electrical stimulus
Increase neurotransmitters
released
decreased neurotransmitters
released
1&3
2&4
0%
0%
0%
0%
2
3
4
0%
0%
5
6
0 of 30
1
Reflexes
 Reflex – involuntary response to





stimulus w/o requiring the brain
Reflex arc- sensory neuron
Interneuron motor neuron
(opposes initial stimulus)
Ex. Knee jerk reflex
Babinski reflex (infants only)
 Stroke sole of foot  toes fan
out
Plantar reflex (adults only)
 Stroke sole of foot toes curl
Signals sent to brain by
interneurons allow for control
 Ex. Toilet training, gag, blink
Testing reflexes activity
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