L03 Flashcards
Who won the Nobel prize in 1906 for their work on the structure of the nervous system?
Camillo Golgi and Santiago Ramon y Cajal.
Their work was made possible by the discovery of the Golgi stain that causes 2% of brain cells to darken in color.
What is the Golgi stain mixture made of?
Silver nitrate and potassium chromate
What is it that creates the Golgi stain?
The silver chromate that crystallizes inside of the brain cells
What is electrostatic pressure?
The attractive force between molecules that are oppositely charged (i.e., positive and negative) or repulsive force between molecules that are similar charged (e.g., positive and positive)
What are ion channels?
Specialized protein molecules (receptors) that sit in the cell membrane. They have a pore (hole) in them through which specific ions can enter or leave cells.
What are leak channels?
An ion channel protein that is in the membrane and has a pore that is always open (e.g., potassium leak channel).
Neurons sit in and are full of _____ _____.
salt water
What are the 2 proteins that are responsible for setting up and maintaining the resting membrane potential?
Sodium-Potassium transporters and the leak channels (potassium)
What is the function of the sodium-potassium transporter?
It is to pump Na+ atoms out of the cells and K+ atoms in.
What is diffusion?
If there is a concentration gradient and no forces or barriers to prevent free movement of molecules, then
molecules will move, on average, from regions of high concentration to regions of low concentration.
What is a membrane potential?
Electrical charge across a cell membrane; difference in electrical potential inside and outside the cell.
What is the resting potential?
Membrane potential of a neuron when it is not being altered by signaling molecules that cause excitatory or inhibitory postsynaptic potentials
What is the range of the resting membrane potential?
At rest, the membrane potential ranges between -40 and -90 mV across different types of neurons
What are receptors?
Proteins that act as sensors and that are specific to specific features of the extracellular environment.
What stimuli can receptor proteins detect in the external world?
- The presence of certain molecules (ex: neurotransmitters)
- Physical pressure (movement, touch)
- Electrical pressure (voltage)
- Temperature
- pH
- Electromagnetic radiation (light)
Are ion channels receptors?
Yes
What is depolarization?
When the membrane potential of a cell becomes less negative than it normally is at rest.
What 3 proteins are involved in the action potential?
- Voltage-gated sodium channels
- Voltage-gated potassium channels
- Voltage-gated calcium channels
Voltage-gated channels have _____ _____ on their doors, such that they open or close when the charge difference across the membrane is greater or smaller than some number.
electrical charges
What is the action potential?
A brief electrical impulse that provides the basis for conduction of information along the axon. It is a rapid change in the membrane potential caused by the opening and closing of voltage-gated ion channels.
What do we call the value of the membrane potential that must be reached to produce an action potential?
The threshold of excitation
Once the voltage-gated Na+ channels are open, how long does it take them to close again (get inactivated)?
1 ms
What is hard to do during the refractory period?
Trigger another action potential
When do voltage-gated calcium channels open?
When the axon terminal becomes depolarized
Is calcium more concentrated inside the cell or outside?
Outside the cell (1000x more concentrated)
What is the primary mean of communication between neurons?
Synaptic transmission
What is synaptic transmission?
The transmission of messages from one neuron to another via the presynaptic release of a chemical (neurotransmitter) that crosses the synapse and binds to receptors located on the post-synaptic membrane
What does the all-or-none law state?
That the action potential occurs or does not occur, and once triggered, will propagate down the axon without growing or diminishing in size, to the end of the axon.
Is the conduction of an action potential bidirectionnal or unidirectionnal?
Unidirectionnal
What do we call the movement of the information along the axon?
The conduction of the action potential
What does the rate law state?
That the strength of the stimulus is represented by the rate of the firing axon.
Does the size of the action potential remain constant or is it inconstant?
It remains constant
