Lecture 3 Flashcards
Creating action potentials in the nervous system are necessary for
Muscle contraction
What is Osmoregulation?
Controlling concentration of ions and water in and out of the cell
What are Action Potentials?
Electrical signals that are used by cells of the nervous system to communicate
Action Potentials are made when
Charged ions move from one side of the membrane to the other, down their concentration gradient
What produces electrical signals?
Movement of charged ions from one side of the membrane to the other
For Action Potentials to be made, there needs to be
A concentration gradient
What is the Resting membrane potential?
-70 mV
The Goldman Equation is used to
Calculate the resting membrane potential
What does the Goldman Equation consider?
- Concentration of ions on each side of the cell membrane
- The relative permeability of the membrane to these ions
- The charges of these ions
Action potentials used by the nervous system are created by
Altering the permeability of the membrane to ions
Facilitated diffusion occurs when the
Gates of ion channel proteins open
Action potentials are started by weaker electrical signals called
Graded Potentials
When do Graded Potentials form?
When a stimulus causes gates on Sodium Ion Channels to open
What are the different stimuli used to open Na+ channels?
- Binding of a specific molecule
- Change in pressure
Ligand-Gated Sodium Channel open in response to the
Binding of a specific molecule
Mechano-Gated Sodium Channel open in response to
A change in pressure
Neurotransmitters (like acetylcholine) or chemicals used in sense of taste / smell use which kind of Sodium channels?
Ligand-Gated Sodium Channels
Sense of touch or changes in blood pressure use which kind of Sodium channels?
Mechano-Gated Sodium Channel
What happens when sodium channels open?
The movement of sodium into neuron causes for a graded potential
What happens as Na+ rushes into the cell?
The inside of the cell becomes more positively charged
Why is there a Plateau at +60mV?
At this potential, the concentration of Na+ is equal on both sides of the membrane, so there is no concentration gradient
If enough sodium moves into the neuron during the graded potential, the membrane potential will
Cross the threshold potential (-50mV)
Crossing the threshold potential results in the
Triggering of AP
What are the Phases of AP?
Depolarization
Repolarization
Hyperpolarization
Each phase of the action potential is caused by the
Opening and closing of new ion channels
