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Neurons: signals move through neurons electrically and between neurons chemically
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Exam #3 W 4/7 in class (bring cheat sheet)
before Exam #3: the nervous system, movement, and the immune system
Fig 45.3Neurons: cells specialized fortransmitting signals
Neurons: signals move through neurons electrically and between neurons chemically
Fig 45.11
the Na+/K+ pump reestablishes the resting state
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
Fig 48.15
At the end of the neuron, neurotransmitters are released signaling the next neuron to depolarize
electrical electricalat synapse chemical
At the synapse the electrical signal is converted to a chemical signal
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
Neurons are commonly connected to many other neurons, and the effect of the different incoming signals determines what the neuron will do.
Incoming signals move through neurons. Only signals above the threshold are transmitted along the neuron.
Fig 48.12
Sensory and motor neurons are often myelinated
Fig 48.13
Myelination allows faster movement of the action potential
Fig 48.3
Nerves allow us to perceive the environment while the brain integrates the incoming signals to determine an appropriate response.
Response
Nervous System Signaling
Stimulus
Transduction Transmission
Response
Integration
Fig 50.2
This stretch sensitive neuron transduces different signals depending on the amplitude of the stimulus
Smells are detected by receptor neurons in our nose. Each receptor is sensitive to a different chemical
Fig 50.15
Fig 50.18
Light is detected in the eye by receptors on the retina
Fig 50.19
Some vision problems arise from misshapen eyeballs too long
too short
AAL 42.10
Light receptor neurons of the eye:Rods detect black and whiteCones detect colors…one type of cone for each color - red, blue, and green
Fig 50.22
Inhibitoryneuro-transmitter
No light
Membrane depolarized
No Signal
Fig 50.22Polar Membrane
light
Noinhibitoryneuro-transmitter
Signal sent
Fig 50.23
Vertebrate retina structure
Fig 49.4
The brain and the central nervous system integrate the various incoming signals
Fig 48.3
Nerves allow us to perceive the environment while the brain integrates the incoming signals to determine an appropriate response.
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
Fig 50.32
Muscles can only contract. Therefore, two muscles are needed for each range of motion.
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