The document discusses the function of ion channels in excitable cells, emphasizing that their opening can cause rapid ion movement and electrical signaling. It explains membrane potential, noting that resting cells have a negative potential due to potassium leak channels and describes the patch clamp technique for studying ion channels. Additionally, it compares types of gated ion channels and outlines the effects of neurotransmitters on postsynaptic neurons.

1. Why do ion channels not function like open pores?
What is membrane potential?
How do K+ leak channels work? Why is the membrane potential of a resting cell negative?
What is patch clamp recording? What is one of the major insights gained from patch clamp
reporting experiments?
Compare and contrast the three types of gated ion channels.
Be familiar with the different parts of a neuron.
During an action potential, what happens to the membrane potential, voltage-gated Na+
channels, Na+ ions, voltage gated K+ channels, K+ ions, and Na+-K+ ion pumps?
When an action potential reaches a synapse, what happens to the Ca2+ channels, Ca2+ ions,
neurotransmitters, transmitter-gated ion channels, and the post synaptic neuron?
What effect do excitatory or inhibitory neurotransmitters have on postsynaptic cells?
What is an example of a mechanically gated ion channel?
Solution
1.Excitable cells, such as fast-acting neurons and muscle cells, have specialized channels that
open in response to a signal and permit rapid ion movement across the cell membrane. The
opening of just a single ion channel alters the electrical charge on both sides of the membrane.
The resulting charge differential then causes adjacent voltage-sensitive channels to open in
chain-reaction fashion, creating a self-propagating electrical signal that travels down the entire
length of the cell. Sometimes, this sequence of events is triggered when a chemical signal —
such as a neurotransmitter — binds to an ion channel receptor on cell's surface. Other times, a
cell's ion channels open in response to mechanical (rather than chemical) stimuli.
2.In cells of all types, there is an electrical potential difference between the inside of the cell and
the surrounding extracellular fluid. This is termed the membrane potential of the cell. When a
nerve or muscle cell is at "rest", its membrane potential is called the resting membrane
potential. In a typical neuron, this is about –70 millivolts (mV). The minus sign indicates that the
inside of the cell is negative with respect to the surrounding extracellular fluid.
3.The leak channels allow K+ to move across the cell membrane down their gradients (from a
high concentration toward a lower concentration).
With the combined ion pumping and leakage of ions, the cell can maintain a stable resting
membrane potential and create membrane potential of a resting cell negative.

2. 4.Patch clamp recording is an extremely useful technique for investigating the biophysical
properties of the ion channels that control neuronal activation.
The procedure involves pressing a glass micropipette against a cell in order to isolate a small
“patch” of membrane that contains one or more ion channels.
The experimental setup further allows scientists to “clamp” the electrical environment of the
patched area by precisely controlling the voltage across the cell membrane, which, depending on
the ion channels present, impacts the flow of ions through the membrane and allow for intricate
study of these channels.
5. Ion channels can be voltage-sensitive, ligand-gated, or mechanically-gated in nature.
Ligand-gated ion channels open when a chemical ligand such as a neurotransmitter binds to the
protein.
Voltage channels open and close in response to changes in membrane potential.
Mechanically-gated channels open in response to physical deformation of the receptor, as in
sensory receptors of touch and pressure
6.The primary components of the neuron are the soma (cell body), the axon (a long slender
projection that conducts electrical impulses away from the cell body), dendrites (tree-like
structures that receive messages from other neurons), and synapses (specialized junctions
between neurons).
7. The movement of a signal through the neuron and its axon is all about ions. An ion is a
charged particle, such as Na+, the sodium ion. It has a positive charge, because it is missing one
electron. Other ions, of course, are negatively charged.
9. An inhibitory postsynaptic potential (IPSP) is a kind of synaptic potential that makes a
postsynaptic neuron less likely to generate an action potential.[1] The opposite of an inhibitory
postsynaptic potential is an excitatory postsynaptic potential (EPSP), which is a synaptic
potential that makes a postsynaptic neuron more likely to generate an action potential.
10.An important example is the the acetylcholine receptor found in the membrane of skeletal
muscle cells. ... This ion channel plays a role in the secretion of insulin from the pancreas