Exam 2 - Lecture 1 Flashcards
When you deviate from resting charge, cells can be turned ____ or _____
on, off
Repolarization is to reset ____
Fast sodium channels
what ion has the same Voltaged-gated structure as fast Na+ channels? How do they differ?
Calcium (L-type), they are slower.
Calcium channels can be blocked by ______. Where are these channels found and what are they called?
Dihydropyridine (DHP) calcium channel blockers, specifically found in smooth muscle and the heart. Also called L-type channels.
Chloride permeability is adjusted to
Hyperpolarize or suppress electrical activity in excitable cells, typically through GABA receptors
GABA receptors
Opens up chloride channels for chloride to enter the cell, make them more negative and difficult to excite.
Process of action potential
initial resting state = inside pos, outside neg.
Stimulus (e.g. maybe outside electrical stimulus, cop shoots you with a taser, causing AP) causes depolarization in one area of cylinder, opening fast sodium channels, making cell more positive (depolarization), triggering more fast Na+ channels.
Causes a wave in cell of depolarization outward away from initial trigger, opening Na+ channels across the entire cell.
Na+ channels close, while slow V-G K+ opening, repolarizing the cell in the same wave direction/pattern of depolarization.
Neurons that talk to skeletal muscles
Motor neurons.
Action potential is __________ cycle.
Positive feedback: due to sodium coming in, causing more sodium to come in.
Skeletal muscle tends to be
striated
Process of communication between brain and skeletal muscle
Brain/spinal cord decides to contract muscle -> motor neuron activated (somewhere in spinal cord) -> that activation produces an action potential from brain/spinal cord to neurotransmitters that are connected to skeletal muscle inside motor neuron.
Neuromuscular junction
NMJ. Area that connects neurotransmitters and receptors on the skeletal cell surface.
What type of receptors does skeletal muscle have? Where are they also found?
nACh: nicotinic acetlycholine receptors, excitatory.
also found in brain, but mostly skeletal muscle cells.
nACh have ___ binding site(s)
2, must be occupied simultaneously.
Acetylcholine is a type of ______
neurotransmitter
Nicotine can mimic
Acetylcholine being released from motor neurons.
nACh receptor characteristics
Donut shaped protein in cell wall. Lined with amino acids with negative charges. These negative charges repel/prevent negatively charged electrolytes from moving through channel.
nACh channels are specific for _________ ions
Positively charged. Mostly sodium current.
Small amounts of ___ leaks out through these nACh receptor channels
Potassium. Mostly prevented from coming out due to sodium flowing in so fast.
Small amounts of ____ come in through nACh receptor channels with Na+
Calcium. It will also depolarize the cell with Na+, but much much much less comes in. Calcium is BIG and CLUNKY.
When nACh channels are exposed to depolarization, ______ are opened up nearby.
Fast Na+ channels, allowing more sodium to come in.
Paralytics work on the
NMJ.
Skeletal muscle is part of the intracellular or extracellular container?
Intracellular.
mACh-R, and where are they found? What do they do?
Muscarinic acetylcholine receptors. Found in heart, smooth muscle, lungs. Influence hyperpolarization by opening potassium channels.
In the heart, mACh-r are found where?
SA and AV node
Vagus nerves
come in contact with pacing structures in the heart
Right vagus nerve = predominantly SA node, left side of heart.
Left vagus nerve = predominantly AV node, septum
They release: acetlycholine
mACh-r are what type of receptors?
GPCRs
mACh-r work by opening which channels?
Open K+ channels to hyperpolarize the heart, influencing pacemaker ability. They lower the Vrm.
Heart has an abnormally large amount of _______
Sodium leaking in, giving pacemaker activity and generating an action potential (heartbeat)
Acetylcholine is released from vagus nerves all the time to
Keep the heart rate down.
Absence of muscarinic activity in the heart causes _____
HR to go up
How does atropine work?
Inhibiting muscarinic activity
Another receptor on heart that antagonizes mACh-r activity
Beta receptors (B-R)
Another way to turn a neuron on
Physical pressure (anywhere we can sense pressure)
Baroreceptors
Pressure sensor in heart
When theres not alot of pressure on sensor, there is ______ sodium permeability
minimal.
(not alot of sodium going into cell, may or may not be enough to cause an action potential and send signal to brain)
When theres a ton of pressure on sensor and sensor flattens/widens, then _________ comes in and causes an action potential to send signal to brain.
More sodium
How is an action potential measured in a neuron? What about the heart?
Milliseconds and seconds
