Exam 1 Flashcards
Explain who Golgi and Cajal are and why they’re important?
They both argued about the structure of the neuron and the nervous system
Golgi: Who was responsible for reticular theory believed that all neurons were connected directly together
He is also responsible for the golgi stain
Cajal: Founder of the neuron doctrine which stated that Neurons communicated with electrical and chemical signals (What we use today)
He also is responsible for discovering the law of dynamic polarization
What is the Law of Dynamic Polarization? What are the parts of a neuron and their
function?
The law of dynamic polarization, developed by Cajal, states that the direction of electrical signals in a neuron is unidirectional. The signal starts is received at the dendrites, then moves to the cell body, then finally leaves through the axon
What are the three most common glia cells and what are their functions?
Astrocytes: They regulate the chemical content of the brain
Oligodendrocytes: Produce and maintain myelin in the CNS
Schwann cells: Produce and maintain myelin in the PNS
What is the formula for Ohm’s Law?
Voltage = Current x Resistance
How are capacitance and resistance related to neurons?
Capacitance refers to the ability of a system to store charge. In neurons, capacitance primarily comes from the cell membrane, which acts like a capacitor by separating charges across its lipid bilayer.
Resistance refers to the opposition to the current flow. In neurons, resistance is associated with two main factors: Axial resistance and Membrane resistance
How would you describe axial resistance?
Axial (or Internal) Resistance: The resistance to the flow of ions within the cytoplasm of the neuron, especially along the axon. (Ex. As signals travel down an axon it gets weaker)
How would you describe membranal resistance?
Membrane Resistance: The resistance to the flow of ions through the cell membrane (via ion channels). (Ex. When ion channels are closed resistance skyrockets)
What is the “Time constant” of a neuron?
The time constant (𝜏) is a measure of how quickly a neuron’s membrane potential changes in response to a current. (How fast it gets to 63%) (𝜏 = Membrane capacitance x Membrane resistance)
What is the “Length constant” of a neuron?
The length constant (𝜆) determines how far a change in membrane potential (such as a depolarization or hyperpolarization) spreads along a neuron before decaying significantly (To about 37% of the original value)
What is the equilibrium potential?
The equilibrium potential is the membrane potential at which there is no net movement of a particular ion across the membrane. (Electrical driving force = concentration gradient) (Ions still move across cell membrane)
How do you calculate driving force?
Driving force = Membrane potential - equilibrium potential of the ion
How do conductance and driving force interact to affect membrane potential?
These factors work together to regulate ion movement across the membrane, which in turn affects the membrane potential. I (Ion movement) = G (Conductance) x (Driving force)
What are the steps of an action potential? (Stages)
- Resting potential, 2. Depolarization, 3. Repolarization, 4. Hyperpolarization, 5. Resting potential
What are the steps of an action potential? (Ion movement)
First sodium channels open and sodium enters the cell (Raising the voltage), then sodium channels close and potassium channels open, Then potassium slowly leaves the cell (Lowering the voltage), then potassium slowly re-enters the cell returning the voltage back to the resting potential
What are the two types of refractory periods and why do they occur? Can an action
potential be generated during either one of these periods?
Absolute refractory period: NO NEW ACTION POTENTIALS (Na channels are inactive)
Relative refractory period: There can be an action potential if there is a stronger-than-normal stimulus (Some Na channels have recovered and are just closed instead of inactive)