Exam #3 W 4/2 in class Review T 4/1 from 5-7pm in PAI 3.02 Before Exam #3: the nervous system, movement and the immune system

Two ways to think about the world: atoms molecules organelles cells tissues organs systems organisms environment Reductionism

Two ways to think about the world: atoms molecules organelles cells tissues organs systems organisms environment Reductionism Wholism

Sensing and reacting to the environment is critical

Failure to properly sense and react to the environment can be fatal

CB 48.3 Nerves allow us to perceive the environment while the brain integrates the incoming signals to determine an appropriate response.

CB 48.5 Neurons: cells specialized for transmitting signals

Axon Parts of a neuron Signals

CB 48.7 In the brain neurons are shorter and highly interconnected

CB 48.5 Neurons: signals move through neurons electrically and between neurons chemically

Nervous System Signaling Stimulus Transduction Response

Na + /K + pump plasma membrane Na + K+K+ ATP–>ADP CB Ionic gradients in neurons

CB At rest, the Na + /K + gradient is maintained

CB Depolarization occurs with the opening of Na + channels

CB An action potential starts when the local depolarization causes other Na + channels to open

CB Action potentials only occur when the initial depolarization is above the threshold

CB An action potential starts when the local depolarization causes other Na + channels to open

CB Repolarization is achieved via closing Na + and opening K + channels

CB 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 CB 48.14

CB 48.8 Myelination: allows the depolarization to travel faster

CB Myelination: allows the depolarization to travel faster…it jumps

CB 48.5 Neurons: signals move through neurons electrically and between neurons chemically

CB At the end of the neuron, neurotransmitters are released signaling the next neuron to depolarize

Neurotransmitters can be excitatory or inhibitory (+) (–) (+) (+/–) (–) CB tbl 48.1

electrical at synapse chemical At the synapse the electrical signal is converted to a chemical signal

CB Neurons are commonly connected to many other neurons, and the effect of the different incoming signals determines what the neuron will do.

CB 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.

Neuron videos:

CB The brain and the central nervous system integrate the various incoming signals