1. Outline molecular mechanism of memory in
In the vertebrate brain, a form of learning, called long-term potentiation involves
an increase in the strength of synaptic transmission that occurs when presynaptic
neurons produce a brief, high-frequency series of action potentials. Because LTP
can last for days or weeks, it may be a fundamental process by which memories
are stored or learning takes place.
Sensitization involves interneurons that make synapses on the synaptic terminals
siphon sensory neurons. When the tail is shocked, the interneurons release
seratonin, which activates a signal transduction passageway that closes K
channels in the synaptic terminals of the siphon sensory neurons. As a result,
action potentials in the siphon sensory neurons produce a prolonged
depolarization of the terminals. That allows more Ca
to diffuse into the
terminals, which causes the terminals to release more of their excitatory
neurotransmitter onto the gill motor neurons. In response, the motor neurons
generate action potentials at a higher frequency, producing a more forceful gill
2. Outline events at a typical synapse
A synapse is the site of communication between a synaptic terminal and another
cell. Most synapses are chemical synapses, which involve the release of a
chemical neurotransmitter by the presynaptic neuron. The presynaptic neuron
synthesizes the neurotransmitter and packages it in synaptic vesicles, which are
stored in the neuron’s synaptic terminals. When an action potential reaches a
synaptic terminal, it depolarizes the terminal membrane, opening voltage -gated
calcium channels in the membrane. Calcium ions (Ca
) then diffuse into the
terminal, and the rise in Ca
concentration in the terminal causes some of the
synaptic vesicles to fuse with the terminal membrane, releasing the
neurotransmitter by exocytosis. The neurotransmitter then diffuses across the
synaptic cleft, which separates the presynaptic neuron from the postsynaptic cell.
Diagram muscle structure and outline how it works.
See page 1066, Figure 49.27 for the diagram
The action of a muscle is always to contract; muscles can extend only passively.
Therefore, the ability to move parts of the body in opposite directions requires
that muscles be attached to the skeleton in antagonistic pairs, each member of the
pair working against the other. We flex an arm by contracting the biceps, with the
hinge joint of the elbow acting as the fulcrum of a lever. To extend the arm, we
relax the biceps while the triceps on the opposite side contracts.
1066-1077 goes into specific detail on different muscle contraction, which isn’t
the question, but it’s there if you want to read it.
4. List major characters and plot outline in