Exam 2: Action Potentials Continued Flashcards
When the cell is hyperpolarized, does it take more or less stimulus to turn the cell back on?
More
T/F If sodium channels don’t reset, they can still be used
False; they need to be reset to be used again
During depolarization, what are the two important factors seen in the Goldman equation?
- Concentration gradients for ions
- Permeability for ions
T/F Chloride is found in the nervous system and hyperpolarizes/suppresses electroactivity
True
What occurs in GABA receptors?
GABA receptors open up chloride channels in neurons which allows chloride to flood in and make the cell more negative
How many binding sites does acetylcholine have?
2
What connects the neurotransmitter to a neurotransmitter receptor?
Neuromuscular junction
Where are nicotinic acetyl choline receptors found?
Skeletal muscles and brain
Do both binding sites for Ach have to be occupied to allow current to run through it?
Yes
What is a nicotinic acetyl-choline receptor? (nACh)
Donut shape protein in the cell wall that is lined w/ amino acids that have a negative electrical charge; the negative charge repels negatively charged electrolytes from moving through the channel
Which electrolyte easily gets through nACh receptors?
Sodium; majority of the current that goes through is sodium b/c it is the easiest to get through since it moves down its concentration gradient
How is potassium prevented from leaking out of the cell?
Sodium wants to flow in so badly that it prevents the potassium from leaking
Which other ion can move into the cell to also depolarize it?
Calcium
Why doesn’t calcium just flow into the cell?
Because it is large and “clunky” per Schmidt
Describe how a neuron talks to skeletal mm.
A motor neuron is connected to skeletal muscles via the NMJ (neuromuscular junction), where ACh (neurotransmitter) is released to bind to 2 sites on the receptor. Once ACh binds, this causes an action potential to spread along the muscle fiber on both sides and signals to the muscle to contract and move.
Where do paralytics work?
NMJ (Neuromuscular junction)
What is another example of how to turn on neurons?
Via physical pressure
Where can physical pressure turn on neurons?
Anywhere in the body where we sense pressure
How does pressure turn on neurons?
We have a specialized structure with an oval sensor that notices a change in pressure and causes the stimulus to be turned into an action potential, travels up the neuron, and sends the information back to the nervous system for processing.
Does pressure increase or decrease sodium permeability?
When pressure increases, the sensor (containing sodium channels) flattens, causing the wells of the sodium channels to become wider and allowing more sodium to come into the cell which leads to an action potential.
Can action potentials spread both ways or only one direction?
Action potentials can spread both in one direction as well in both directions
If an action potential spreads in both directions, does this excite cells much faster or slower?
Faster; spreading in one direction would excite cells slower
T/F Action potentials are examples of positive feedback
True; there is an initial stimulus, sodium comes into the cell which leads to more and more sodium coming in until it reaches the entire length of the action potential
What determines action potentials?
Threshold potentials
Threshold potentials are _____ from cell to cell.
Different
If a threshold is -70 and something passes the threshold, what occurs?
An action potential will be fired
What occurs when we experience a weak stimulus that barely passes the threshold?
The firing might cause a delay in an action potential being fired
T/F Action potentials are NOT specialized to whatever role the cell is doing
False
Why is the action potential of the heart sustained longer than that of a neuron?
The heart needs time to contract and push blood through the heart so action potential are longer
What type of channels open slowly after depolarization of an action potential of the heart?
Voltage gated calcium channels
Which ion is entered into the cell during depolarization of a heart action potential?
Calcium
T/F The length of the nerve does not affect the time it takes to send an electrical signal
False; when you have a long nerve, it takes longer for the electric signal to be sent compared to a short nerve
When a nerve is wider does is it faster or slower? Does it have more or less resistance?
Wider = FAster and less resistance
