U5 Lecture 34 Flashcards
what are the two cell types in neuronal tissue
nerve cells (neurons) and glial cells (neuroglia)
what do nerve cells (neurons) do
involved in the generation and interpretation of electrical signals
what do glial cells (neuroglia) do
support neuronal cell activity
what do dendrites do
collect information
what does the cell body do
process information
what do axons do
propogate info
what do synapses do
transmit info
what are the two ‘parts’ to bioelectricity
- resting membrane potential
- action potential
what does resting membrane potential depend on
- transmembrane ion gradients (Na+ and K+)
- membrane permeability to those ions
what happens in ion gradients
Na, K-ATPase develops and maintains steady-state ion gradients for ALL cells
what happens extracellularly in resting membrane potential
- pumping creates ionic gradient for K+
- K+ leaks out down its concentration gradient so that the inside of the cells becomes more negative
- now two kinds of forces pull/push on K+ (chemical and electrical)
what are the two opposing forces in resting membrane potential
- chemical force (K+ gradient) tends to push K+ out
2. developed electrical force (inside negative) tends to pull K+ in
In a typical cell what two things are nearly in balance
chemical and electrical forces for K+
What does it mean when chemical and electrical forces for K+ are in balance
outwardly-directed K+ gradient results in an inside negative electrical potential
what is the electrical potential difference (PD) measure in
volts
-typically -50 to -100 millivolts
What is a characteristic of all cells at rest
K+ dominated inside negative membrane potential
what two ions are typically inside the cell in resting membrane potential
phosphate ion and potassium ion
what two ions are outside of the cell in resting membrane potential
chloride ion and sodium ion
what happens to the membrane during rest
it is polarized
what do changes in membrane permeability produce
large changes in the membrane potential
what does the regulation of channel mediated ion permeability allow
cells to generate electrical signals
what are the keys to manipulation of membrane potential
- maintain(stable) Na+ and K+ gradients (Na/K ATPase)
2. vary the activity of specific ion channels
what are the three ‘important’ things to remember about ion channels
- integral membrane proteins
- channels can be open or closed
- some channels are routinely open
- some channels have their open states regulated
what are the 3 types of channels that are regulated
- chemically (ligand) gated channels
- mechanically gated channels
- voltage gated channels
what happens in chemically (ligand) gated channels
they open when a signal molecule binds to the channel protein ( example ACh)
what happens in mechanically gated channels
they open when membrane gets stretched
what happens during voltage gated channels
they open when the membrane potential gets less negative or depolarized
