Module 2: Unit 3 Flashcards
Define potential
Stored energy
Cell membrane- the possibility of ions moving (in or out of cell) creating an action
Define electrical potential
Difference in the concentration of electrical charge from one point to another
Define current
Flow of charged particles form one point to another
Define polarized
When there is a difference in electrical charge from the inside of the cell membrane to the outside of the cell membrane
What is an excitable cell
Cells that have an ability to elicit a process (action potential) when there is a change in their resting membrane potential due to a stimulus. If a stimulus is put upon them, we can change the membrane potential
*skeletal muscle, cardiac and cloth muscle are the muscles or the excitable cells that we want to understand
What is a membrane potential?
Difference of electrical potential (voltage difference) between the ICF and ISF
*it is a measurement difference between the outside of the cell and the inside of the cell in regards to, millivots (voltage charge)
True or false: membrane potentials exist across every cell in the body
True
What are the three types of gated protein channels?
Mechanical
Ligand
Voltage
Define Resting Membrane Potential
Electrical potential difference across the plasma membrane when the cell is in a non-excited state. The membrane potential is at rest. *No Stimulus
What is the Resting Membrane Potentials of a non-excited neuron?
-70 mV
Is -70 mV to -90mV hyperpolarization or hypopolarization?
Hyperpolarization
*further from 0
What happens with depolarization?
Membrane potential decreases
RMP becomes a more positive number
What happens with hyperpolarization?
Membrane potential increases (Ex: -70 to -90mV)
RMP becomes a more negative number
What does an action potential do?
Lead as to the transmission of an electrical impulse (nerve impulse) that travels along the cell’s plasma membrane
All of the options are true regarding graded potentials, except?
A. They can be only depolarizing
B. It is a change in the membrane potential
C. The size of the change is proportional to the strength of stimulus
D. Occur due to gated protein channels
A,
It is a change in the membrane potential that occurs in the dendrites and soma of the cell body. It helps to stimulate or inhibit the formation of what we call an action potential
True or false: Every single cell in the body is excitable?
False
What are the three types of membrane potentials?
RMP, Graded potential, Action potential
What are the three influences of membrane potentials?
- Diffusion of ions down their concentration gradient (diffusion potential)
- Electrical attraction of cations and anions (Opposites attract)
-Electrical chemical gradient - Selective permeability of the membrane
- leak channels
*1 and 2 are referred to as the Electrochemical gradient
What is the ion concentration/composition of ISF?
Na+ (sodium)
Ca2+ (calcium)
Cl- (chloride)
HCO3- (bicarbonate)
What is the ion concentration/composition of ICF?
K+ (potassium)
Phosphates (-)
Proteins (-)
Which gated channel functions through binding from a neuro transmitter?
Ligand-gated
Which gated channel opens due to pressure?
Mechanically-gated
Which gated ion channel opens due to a response to a change in the charge inside of the cell?
Voltage-gated
What differentiates leak channels from gated channels?
Leak channels are always open.
*they are open to help achieve electrochemical equilibrium. Once this equilibrium is achieved it is called the equilibrium potential
How would you describe the chemical (concentration) gradient?
Concentration of an ion between the ICF and ECF
The drive to move down its concentration gradient
How would you describe electrical (electrostatic) gradient?
Charge of an ion (CATION = Positive charge) (ANION = Negative charge)
The drive for cations to be near anions
Which ion has a very high number of ion leak channels in the plasma membrane of neurons compared to other ion channels?
Potassium (K+)
*and it only allows K+ to leak through (selective)
What does the ATPase pump function to do?
It pumps sodium out of the cell and pumps potassium back in specifically three sodium ions and two potassium ions back in.
*this is an active transport pump (Using energy to pump ions against their concentration gradient)
True or false: All ions including K+ Na+ Cl- and Ca2+ have their own electrical chemical gradient?
True
What is the calculation used for the equilibrium potential for an ion at a given concentration difference across a membrane?
Nernst equation
What equation is used to calculate RMP?
Goldman Equation
What happens if an ion’s concentration changes in the ISF?
If it changes in the blood it changes in the ISF. Ex: if Ca2+ levels decrease in the blood because someone isn’t eating enough Ca2+ we will see that actually depolarizing or decreasing the membrane potential
What role does the Sodium-Potassium ATPase have in the RMP?
Creates and maintains the concentration gradient of K+ across the cell membrane
What is the electrochemical gradient?
It is the concentration gradient and the electrical gradient with ions wanting to move down their concentration gradient, and also wanting to be close to the opposite charged ion
What is the difference between the equilibrium potential and RMP?
EP is the calculation of the electrical chemical equilibrium. The EP is the balance of the electrical chemical gradient, and we can use the Nernst equation to provide an ion like charge to the equilibrium potential.
The RMP takes all of the equilibrium potentials, the equilibrium potential of all the ions around the cell and inside the cell, and calculates it into the Goldman equation to get the resting membrane potential.
*The RMP is a value of all of the ions equilibrium potential
True or false: a membrane potential is the difference in charge from the extracellular fluid to the intracellular fluid
True
True or false: all cells in the body are excitable
False
Where do graded potentials occur in a neuron?
A. Axon terminal
B. Axon
C. Dendrites and soma
D. Axon hillock
C
The equilibrium potential for an ion is achieved when:
A. The electrochemical gradient is neutralised
B. The net flow of ions through open channels in the plasma membrane is zero
C. The membrane potential reaches +70 mV
B
What does it mean when a cell membrane is polarized?
A. The electrochemical gradient is established
B. Only one type of ion can pass through the membrane simultaneously
C. There is no charge difference across the membrane
D. There is a difference in electrical charge between the inside and outside of the cell
D
What is an electrochemical gradient?
A. The combination of a chemical concentration gradient and an electrical gradient of an ion
B. The difference in electrical charge between cations and anions
C. The difference in charge between the ICF and ECF
A
True or false: Graded potentials involve local changes in the membrane potential of an excitable cell due to a stimulus
True,
It occurs at the dendrites of a neuron
How to you explain a graded potential?
It is either to stimulate or inhibit the formation of an action potential
How does a EPSP initiate action potentials?
For a EPSP to initiate an action potential, it must change the membranes potential to -55mV at the axon hillock
True or false: Graded potentials DEGRADE (lose strength) with Time and Distance
True
What are the two types of graded potentials and what do they do?
Excitatory Post-Synaptic Potential (EPSP): stimulates the formation of AP
*Makes the neuron “easier” to reach the potential threshold at the axon hillock to initiate an action potential.
*decreases membrane potential (Ex: -70mv to -60mv) = depolarization
Inhibitory Post-Synaptic Potential (IPSP): inhibits the formation of an AP *makes the neuron “harder” to reach the potential threshold at the o on hillock to initiate an action potential. *Increases membrane potential (Ex: -70 mV to -90 mV) hyperpolarization
Where do EPSPs and IPSPs occur on a neuron?
Only in the dendrites and soma region. They have to bind to neurotransmitter to open up that ion channel.
What happens when during EPSP when sodium (Na+) gated ligand channels open, and calcium (Ca+) gated ligand channels open?
Membrane becomes depolarized and is more likely to reach the membrane potential threshold
What happens during IPSP when potassium (K+) gated ligand channels open, and chloride (Cl-) gated ligand channels open?
Membranes becomes hyperpolarization and inhibits the ability to reach the membrane potential threshold
Name and describe the three types of summation.
Summation
The addition of the ESPS and ISPS at a given time. Determines if the neuron will undergo an action potential or become more inhibited
Cancellation Summation Type = IPSP and EPSP graded potentials cancel one another (RMP stays balanced)
Spatial summation type = The combination of IPSPs and EPSPs from MUTLTIPLE neurons simultaneously onto 1 neuron (can lead to cancellation summation type)
Temporal summation type = the combination of IPSPs and EPSPs from ONE neuron onto another neuron
*slide 55 of Mod 2: Unit 3 has action and graded potentials compare and contrast chart to look over.
What option is true regarding graded potentials with neurons?
A. EPSP or IPSP can lead to the development of action potentials
B. Occur in any location on the neuron
C. They degrade with time and distance
D. Associated with voltage gated channels
C
A graded potential changing a RMP from -70 to -90mv is referred to as?
Hyperpolarization
Which ligand gated channels, when opened, will lead to:
A. Depolarization
B. Hyperpolarization
Depolarization: Na+ and Ca2+
Hyperpolarization: K+ and Cl-
Two neuron synapse with another neuron simultaneously one neuron releases a neurotransmitter that causes the opening of a sodium ligand channels and the other causes the opening of potassium ligand gated channels. What will occur and what type of summation is this?
Cancellation summation
What is the threshold potential?
The level of membrane potential that needs to obtained to initiate an action potential
-55mV at the axon hillock
Define propagation
Once the AP is initiated, it causes depolarization at adjacent sites on the axon’s plasma membrane till it reaches the axon terminal
Define refractory period
Period during which another normal AP cannot be generated in an excitable cell.
The membrane cannot respond to further stimulation *specifically with the sodium voltage gated channels
Action POtenital Steps Slide 76, 79, 80, on mod 2 unit 3. *Look over
- need to understand the depolarization, repolarization and hyperpolarization phases of AP
Explain what happens during the depolarization phase
Membrane potential decreases and becomes more positive due to sodium voltage channels opening
Which option explains why the hyperpolarization phase occurs?
A. Calcium voltage gates open up
B. Sodium voltage gates stay open longer
C. Potassium voltage gates start open longer
D. Potassium ligand gates stay open longer
C
Explain what happens during the repolarization phase
Membrane potential increases and becomes more negative due to potassium voltage channels opening
How could an AP be inhibited?
IPSPs
An epidural procedure will introduce medication directly into the meninges the lower back.
True or false
False
Lidocaine must be in its charged form to be able to pass through the plasma membrane
T or False
False
This phase/aspect of the AP is associated with sodium-potassium ATPase pump
A. Initiation of the AP
B. Depolarization
C. Repolarization
D. Re-establishment of the RMP
D
What option defines why Jamal had his skeletal muscle weakness issues?
A. Jamal’s hypokalemia led to a hyperpolarized RMP
B. Jamal’s hyperkalemia led to a depolarization RMP
C. Jamal’s hypokalemia led to a depolarized RMP
A
What statement is TRUE regarding the case studies in laboratory 01.
A. Lidocaine blocks sodium voltage-gated channels from the IF side
B. Jamal’s hypokalemia disrupted the formation of graded potential, which blocked an AP
C. Changing potassium’s serum concentration will change the potassium’s equilibrium potential
C
