Week 1: Neurons, Action Potential, Synapic Connections Flashcards
(31 cards)
What are some roles of glia cells? (5)
- regulation of neuron to neuron communication
- transfer nutrients from blood to neuron
- cover axons to increase transmission speed of action potentials
- removal of pathogens and dead cell bodies from brain
- create high ways for neuron migration during development
What is the ratio of glia cells to neurons?
Outnumber neurons but 10:1
What does a dendrite do?
Receive input from other neurons
Why do dendrites grow like a dendritic tree?
Greater surface area allows it to receive more information
What is the soma and what happens there?
‘cell body’ where metabolic work occurs
What are the roles and features of an axon? (3)
send output to other neurons
transmits action potential
constant diameter
How do neurons communicate?
By chemicals. Axon of presynaptic neuron releases neurotransmitter and dendrite of postsynaptic neuron detects them to change its activity. Synaptic transmission is one-way communication.
What is Ohm’s law?
V=IR
V is voltage
I is current
R is resistance. (opposite of conductance)
What is the neuron membrane made of?
lipids (fats/oil)
When in contact with water/liquid, what does the neuron membrane form?
A phospholipid bilayer.
What are the other 2 terms for Equilibrium potential for a specific ion?
Nernst potential/Reversal potential
What creates the concentration gradient across the cell membrane?
When ions are present in different concentrations inside and outside of the cell. (Since K+ more concentrated inside cell, concentration gradient drives exit of K+ once gate opens.)
What is the role of protein in the cell membrane?
An ion channel that selectively allows passage of certain ions only (eg. only K+)
What creates the electrical gradient across the cell membrane?
When there is a charge imbalance inside and outside the cell. (+-). Overall charge inside and outside cell is 0.
Briefly describe the equilibrium potential for a specific ion (nernst potential, reverse potential)
when the 2 opposing forces of concentration vs electrical gradient eventually balance out and reach a point of equilibrium. (net flow of ions is 0)
What is the resting membrane potential?
the membrane potential at which overall flow of current (counting all ion species) equals 0. (ie. when multiple types of ions reach an equilibrium)
How does the cell maintain the difference in concentration of Na+ and K+ across the membrane.
Sodium-Potassium Pump (or Na+/K+ ATPase)
- a membrane protein that pumps K+ into the cell and Na+ out of the cell. Energy (ATP) is needed because the movement of both ions does against their concentration gradients. (active transport)
Resting membrane potential is close to the reverse potential of ___?
K+ (around -70mV)
At rest, K+ channels are ___ and Na+ channels are ___? (open/close)
open; closed.
How does the electrical and concentration gradient act on Na+ at rest?
Electrical gradient: Na+ is attracted to interior of cell which is negative
Concentration gradient: Na+ is more concentrated outside than inside. Flow in.
How does the electrical and concentration gradient act on K+ at rest?
Electrical gradient: pull K+ to negative interior of cell
Concentration gradient: drives K+ out as it is more concentrated inside the cell
What is the resultant force of electrical and concentration gradient of K+?
Small net flow out of cell. Sodium potassium pump continues pulling K+ into cell, so it’s always a little more concentrated inside.
What is an action potential?
refers to movement of changes in membrane voltage down the axon.
What is a voltage-gated channel?
Refers to an ion channel that opens in response to an increase of the membrane potential (depolarization) as long as this increase crosses a certain threshold.
