4. Nerve TissueGlial
Cells
Specialized cells in nervous system called
neuroglia, or glial cells, perform specialized
functions
Metabolic and
structural support
5. Nerve TissueGlial
Cells
Specialized cells in nervous system called
neuroglia, or glial cells, perform specialized
functions
Attack Microbes
and remove
debris
6. Nerve TissueGlial
Cells
Specialized cells in nervous system called
neuroglia, or glial cells, perform specialized
functions
Cover and line
cavities of
nervous system
7. Nerve TissueGlial
Cells
Specialized cells in nervous system called
neuroglia, or glial cells, perform specialized
functions
Makes lipid
insulation called
myelin
12. Nerve Tissue-The
Neuron
Each part of neuron has
specific function
Body/Soma: cell
Body/Soma
metabolism
Dendrites: receive
Dendrites
information from the
environment
Axon: generates and sends
Axon
signals to other cells
13. Figure 9-3
A neuron connecting to a
skeletal muscle.
Each part of neuron has
specific function:
Axon terminal: where
terminal
signal leaves cell
Synapse: where axon
Synapse
terminal and
receiving cell
combine
14. Neurons
Neurons are classified by how they look (structure)
Neurons are classified by how they look (structure)
or what they do (function)
or what they do (function)
15. How Neurons Work
Neurons can use their ability to generate
electricity to send, receive, and interpret
signals
16. How Neurons Work
Neurons are called
excitable cells; this
simply means that if cell
is stimulated it can carry
small electrical charge.
charge
Each time charged
particles flow across a
cell membrane, there is
tiny charge generated
17. How Neurons Work
All three muscle types are
excitable cells, as are
many gland cells
Cells are like miniature
batteries, able to generate
batteries
tiny currents simply by
changing permeability of
their membranes
18. The Action Potential
Series of
permeability
changes within the
cell and the
resultant changes in
the charge across
the cell membrane
20. Resting Cell-Polarized
A cell that is not
stimulated or excited is
called a resting cell; it
cell
is said to be polarized
It has a difference in
charge across its
membrane, being more
negative inside than on
the outside cell
21. Stimulated CellDepolarized
When cell is
stimulated, sodium
gates in the cell
membrane spring
open, allowing sodium
open
to travel across
membrane
Sodium bits are
positively charged, so
charged
cell becomes more
positive as they enter
22. Repolarization
Sodium gates close after a few minutes and
potassium gates open; potassium leaves cell,
open
taking its positive charge with it
23. Hyperpolarization
If cell becomes more
negative than resting
it is called
hyperpolarized
Action potential (AP)
is cell moving
through
depolarization,
repolarization, and
repolarization
hyperpolarization
24. Refractory Period
Cell cannot accept another stimulus until it
returns to its resting state, and this time
period when it cannot accept another stimulus
is called refractory period
28. Myelinated axon vs.
Unmyelinated
.5 meters/second
100 meters/second
Myelin is essential
for speedy flow of
Action potential down
the axon
Un-myelinated axon
has to depolarize
each and every
millimeter of axon
29. Figure 9-5
Wider axons conduct faster
Diameter of axon
also affects speed
of action potential
flow; wider the
diameter of axon,
faster the flow of
ions
30. Figure 9-5
Impulse conduction via
myelinated axon.
Nerve impulse
jumps from the
bare areas
between myelin
sheath called the
Nodes of Ranvier
which is FASTER
32. How Synapses Work
When AP* arrives at
axon terminal, terminal
depolarizes and calcium
gates open; calcium ions
flows into cell; when
calcium flows in, it
triggers change in
terminal
*Action potential
33. How Synapses Work
There are tiny sacs in terminal called vesicles
that release their contents from cell when
calcium flows in
Vesicles
Vesicles
34. How Synapses Work
Vesicles are filled
with molecules
called
neurotransmitters
that send signal
from neuron across
synapse to next
cell in line
35. How Synapses Work
Once released the
neurotransmitter
binds to
receptors on
postsynaptic
membrane. Each
neurotransmitter
has a specific
receptor
36. How Synapses Work
The specific
Sodium channels
neurotransmitter
determines
whether the
impulse continues
which is called
EXCITATION
allowing Sodium
(Na+) channels
to open and
membrane is
depolarized and
37. How Synapses Work
The specific
Potassium channels
neurotransmitter
determines
whether the
impulse is blocked
which is called
INHIBITION
allowing
Potassium (K+)
channels to open
and the impulse
STOPS
38. How Synapses Work
The receptor then
Enzymes
releases the
neurotransmitter
after which it is
reabsorbed by the
synaptic knobs and
recycled or
destroyed by
enzymes.
39. Chemical Synapse
Use of neurotransmitters is called chemical
synapse because chemicals carry information
from one cell to another
40. Chemical Synapse
Figure 9-6
. Step 1: The impulse travels down
the axon.
Step 2: Vesicles are stimulated to
release neurotransmitter
(exocytosis).
Step 3: The neurotransmitter
travels across the synapse and
binds with the receptor site of post
synaptic cell.
Step 4: The impulse continues
down the dendrite.
41. Neurotransmitters
Acetylcholine
Generally excitatory, but
sometimes excitatory
Norepinephrine
May be excitatory or
inhibitory depending on
receptor
Epinephrine
May be excitatory or
inhibitory depending on
receptors
Serotonin
Generally inhibitory
Endorphins
Generally inhibitory
42. Clean up at the
Synapse
After
neurotransmitters
create a nerve
impulse at the
synapse,
enzymes
“reuptake” or
clean up the
chemicals and
use them again
43. Antidepressants
Selective serotonin
reuptake inhibitors
(SSRIs) are
medications that
prevent cleanup of
neurotransmitter
serotonin from
synapses, thus
increasing effects
of serotonin on
receiving cell
44. Electrical vs Chemical
Synapse
Gap junction
•• Cells do not need
Cells do not need
chemicals to
chemicals to
transmit
transmit
information from
information from
one cell to another
one cell to another
•• Can transfer info
Can transfer info
because of special
because of special
connection called
connection called
GAP JUNCTION
GAP JUNCTION
47. In Class
WORKSHEET
Complete the worksheet using
ONLY YOUR NOTES-NO
TEXTBOOK or LAP TOPS,
TABLETS
You will not need to complete
the Chapter 9 worksheets for
credit but use simply for
STUDY GUIDE for your test
48. EXAM-Chapters 6 & 7
Your exam is Tuesday Oct 29 at 9:30
a.m. It will have questions from:
•Power Point Presentations on
Chapter 6 & 7
•Essay on functions of skeletal
system
•Explain osteoporosis and cells of
bone formation
•Step by step of Muscle contraction
•Diagram on specific joint
•Extra credit: MUSCLE TONE page
149 in your textbook
