Exam #3 W 4/7 in class (bring cheat sheet)
before Exam #3: the nervous system,
movement, and the immune system
Neurons: cells specialized for
transmitting signals
Fig 45.3
Neurons: signals move through neurons
electrically and between neurons chemically
the Na+/K+ pump reestablishes the resting state
Fig 45.11
Depolarization of one
part of the membrane
opens Na+ channels
further along so the
signal travels from one
end to the other
Fig 48.11
Neurons: signals move through neurons
electrically and between neurons chemically
Neurotransmitters can be excitatory or inhibitory
(+)
(+)
tbl 48.1
(–)
(+/–)
(–)
(–)
At the end of the neuron, neurotransmitters are
released signaling the next neuron to depolarize
Fig 48.15
At the synapse the electrical signal is
converted to a chemical signal
electrical
at synapse
chemical
electrical
Neurons are commonly connected to many
other neurons, and the effect of the different
incoming signals determines what the neuron
will do.
Fig 48.14
Neurons are commonly connected to many
other neurons, and the effect of the different
incoming signals determines what the neuron
will do.
Fig 48.16
Incoming signals move through neurons. Only signals
above the threshold are transmitted along the neuron.
Sensory and motor neurons are often
myelinated
Fig 48.12
Myelination allows faster movement of
the action potential
Fig 48.13
Nerves allow us to perceive the environment
while the brain integrates the incoming signals
to determine an appropriate response.
Fig 48.3
Response
Nervous System Signaling
Stimulus
Integration
Transduction
Transmission
Response
This stretch sensitive neuron transduces
different signals depending on the amplitude
of the stimulus
Fig 50.2
Smells are detected by receptor neurons in our nose.
Each receptor is sensitive to a different chemical
Fig 50.15
Light is
detected in
the eye by
receptors on
the retina
Fig 50.18
Some vision
problems arise
from misshapen
too long
eyeballs
too short
Fig 50.19
AAL 42.10
Light receptor neurons of
the eye:
Rods detect black and
white
Cones detect colors…one
type of cone for each color
- red, blue, and green
No light
No Signal
Inhibitory
neurotransmitter
Fig 50.22
Membrane depolarized
light
Signal sent
No
inhibitory
neurotransmitter
Fig 50.22
Polar Membrane
Vertebrate retina
structure
Fig 50.23
The brain and the
central nervous
system integrate
the various
incoming signals
Fig 49.4
Nerves allow us to perceive the environment
while the brain integrates the incoming signals
to determine an appropriate response.
Fig 48.3
Response
Responses can be
release of hormones,
change in cell activity,
or muscle contraction
Muscles allow
movement
An earthworm: without something to push
against, muscles are not much use.
The skeleton, made
of bones, gives
support
Fig 50.34
Bones (connective tissue) are alive
Connections
between bones and
muscles
Muscles can only contract. Therefore, two
muscles are needed for each range of motion.
Fig 50.32
2 nerve signals for
every movement:
excitatory and
inhibitory
Fig 50.32
How do
muscles
contract?
You should watch these animations about neurons:
http://www.youtube.com/watch?v=YwN9aCobCy8
http://www.blackwellpublishing.com/matthews/actionp.html
http://www.blackwellpublishing.com/matthews/nmj.html
And this muscle contraction animation:
http://www.blackwellpublishing.com/matthews/myosin.html