M1 Lec 2 Flashcards
what does it mean for a neuron to be quiescent
it cant be replaced by the post miotic cells
what glial cells are found in the CNS (brain + spinal cord)?
astrocytes and oligodendrocytes (make myelanation)
what glial cells are found in the PNS?
Schwann cells
what do microglia do
immune cell - react to inflammation of nerves
what is the myelination? actions?
insheathment of the axon within neurons
* insulate axon
* increase conduction velocity
what are the 4 functional regions where a signal is generated
- input
- integrative
- conductive
- output
where does a neuroendocrine cell project to
it passes signal onto capillary
what is the flow of signals in a neuron
dendrites —> cell body —> axon —> axon terminal —> synapse
what are the 2 forms of electrochemical communication
- electrical signals - changes in membrane voltage
- chemical signals - release of neurotransmitters
what is the cell membrane
* 3 components of the membrane?
it is a lipid bilayer that acts as a filter and barrier for the cell. It is highly selective filter for ions
1. phospholipid bilayer
2. proteins
3. active na/k pumps
what is the phospholipid bilayer made up of
hydrophilic head (facing outward to solution) and hydrophobic tails (sandwhiched by the two heads)
electrical concepts: whats v, i, r
voltage (diff in electrical potential)
current (flow of electrical charge)
resistance (opposition of flow)
what are ions
charged atoms or molecules
k and na concentrations in and out of cell?
- k+ high inside cell
- na+ high outside cell
what is capacitance? how does the membrane act as a capacitor?
- the ability to store electrical charge
- the membrane stores charge via the separation of ions across the bilayer (has unequal ion distribution - neg inside pos outside cell)
the membrane acts as a resistor to the flow of ions. How do ions get around this?
they have ion channels and provide pathways for ions to cross the membrane which reduces resistance (open/leaky channels + gated channels)
what formula do you use to measure the difference in voltage across the membrane
Vm = V in - V out
what is the concentration gradient
differences in ion concentration across the membrane
* move from high to low conc
electrical gradients
differences in electrical potential across the membrane
electrochemical gradient
combined influence of concentration and electrical gradients on ion movement
* ex: elec gradient attracts K+ in, conc gradient pulls K+ out of cell
permeability of cell at rest
- most permeable to K+ bc of leaky channels
- few open Na+ channels bc limited
what is donnan equilibrium
overall distribution of diffusible ions is uneven, but electrical and chemical forces are balanced
What is the equation for chemical force?
What is the equation for electrical force?
what is the nernst equation and when is it used
used to calculate equilibrium potential for single ions (where elctrical and chemical forces are balanced)
how do neurons communicate
through electrochemical signaling
