Download Ch. 48 - 49

Ch. 48
Nervous Systems
Nervous System
Central Nervous System
PNS
AUTONOMIC

Sympathetic

Stress (like

Parasympathetic

Peace
a “fight or
flight”
response)
(relaxed,
normal
functions)
Nervous
system
afferent
interneurons
efferent

PNS, CNS
INPUT:
Effector cells
Sensory Neurons (receptors)
INTEGRATION: CNS(brain & spinal cord) Interneurons
OUTPUT: Motor Neurons (effectors)
The Reflex Arc
The Neuron





Dendrites receive
the signal, axon
delivers the signal
away to another
neuron or to the CNS
Myelin sheaths (white matter) insulate the axon and
are made by Schwanns cells or oligodendrocytes
What is a Node of Ranvier?
What is saltatory conduction?
What is a synapse?
Anatomy of a Neuron
Makes myelin - PNS
>Speed of Transmission: Larger axons
& Myelin sheath (Saltatory conduction)
Think! Turn to your partner and
discuss…
1.
2.
3.
4.
5.
Name the three types of neurons and
their functions. Which make up the CNS
and the PNS?
Describe the main parts of a neuron.
Describe what happens in a Reflex Arc.
How are Nodes of Ranvier and Saltatory
conduction related?
What occurs at the synapse?

What makes a signal travel down the
axon ?
Action Potential
(“all or none” nerve
impulse)
K+ out of
the cell
Threshold Potential reached: -55mV
-70
-50
0
Na+
Gates
Open
…Na+
flood cell
-80
Na/K pump restores
Hyperpolarization IPSP
from too many K+ ions leaving
-90
Membrane potential (mV)
+35
EPSP
Na+ Gates Close
and K+ Open
0
1
2
3
4
Time (milliseconds)
resting state
restored (-70)
Hyperpolarization:
more negative inside
by K+ moving out—does
not cause an action potential
Depolarization: inside gains more
positive charge by Na+ rushing in
EXCITATORY (+)
-70
What is meant by all–or–none action potential?
Think! Turn to your partner
and discuss…
1.
2.
3.
What causes an action potential?
What significance is the -55mV?
Describe the differences between
depolarozation, repolarization, and
hyperpolarization.
The steps of an action potential…
Resting State
+
Na
gates closed,
K+ gate closed
Na/K pump is maintaining –70mV
thres
Depolarizing
Phase
Na+ gate OPENS, (fast gate)
+
K channels are still closed
(slow gate)
Na+ rushes into the neuron (+ + + +)
RE-polarizing
Phase
+
Na
inactivation gate closes,
K+ slow gate OPENS
K+ rushes out of the neuron
Undershoot
+
Na
channels closed,
K+ channels still OPEN
K+ still rushes out of the neuron
(Hyperpolarizing the inside - - - - - -)
Direction of
transmission?
Slow closing of
the K+ channels
prevents “backflow”
One way flow
of Electricity!
Chemical synapses

TERMS:

Vesicles
synaptic cleft
neurotransmitters
(Ca2+)
receptor
ion channel
Pre/post
synaptic
membrane
Enzymes to
degrade the
neurotransmitters







Summation of IPSP & EPSP
Inhibitory(-) & Excitatory(+) Post-Synaptic Potential
Temporal and Spatial Summation
The real thing . . . . . . . .
Cerebrum
Thalamus
Hypothalamus
Cerebellum
Brain stem: medulla
oblongata, pons, midbrain
Cerebrum
Right versus left Cerebrum
BRAIN STRUCTURES
AND FUNCTIONS

Brain Stem:

Medulla Oblongata & Pons = (autonomic,
homeostatic, data conduction)
 Midbrain = (receives and integrates sensory
information)
 Cerebellum: Automatic coordination of movements



and balance
Thalamus:integration of stimuli coming to the brain
Hypothalamus: important homeostatic regulation
(temperature, hunger, thirst) & hormones
Cerebrum: memory, learning , emotions, motor
movements, sensory cortex areas