Lecture 2 - Water, membrane and ions / electrochemical gradient

What is an ion?

Atom or molecule that has gained or lost e-

State the physiological roles of ions.

Carry signal / energy stores / biochemical function

What is Ficks law?

Number of molecules moving across an interface is proportional to: area of interface / conc gradient

In the Ficks law equation: Rate = D∙A∙dc/dx. What is D?

Diffusion coefficient

What is the diffusion coefficient of Ficks law?

Properties of ion and friction in the channel

In the Ficks law equation: Rate = D∙A∙dc/dx. What is A?

Area - size and number of channels

In the Ficks law equation: Rate = D∙A∙dc/dx. What is dc/dx?

Conc. gradient

Simple definition of electrophoresis

Ion movement in electric field

What does chemical gradient refer to?

Differences in concentration

What does electrical gradient refer to?

Differences in charge across membrane

What is the electrochemical gradient the sum of?

Chemical gradient + electrical gradient

What is the direction of ion movement determined by?

Electrochemical gradient

What is the rate of ion movement determined by?

EC gradient size / nature of ion / no. of open channel / property of channel

What is current?

Flow of ions

What is another reference to ‘potential difference’ / voltage (flagged)

Gradient

What is the equation linking current, volt & resistance?

I = V/R / V=IR

What is the equation linking current, volt & conductance?

I = VG

What is the equation linking conductance & resistance?

G = 1/R

What is the ionic gradient (outside - inside) of Na+ of a ‘typical’ mammalian cell?

150 - 15 mM

What is the ionic gradient (outside - inside) of K+ of a ‘typical’ mammalian cell?

5 - 100 mM

What is the ionic gradient (outside - inside) of Cl- of a ‘typical’ mammalian cell?

150 - 13 mM

What is the ionic gradient (outside - inside) of Ca2+ of a ‘typical’ mammalian cell?

2 - 0.002 mM

How are gradients set up (in a cell?)

Combinations of pumps / leak though ion channels

How much E does sodium-potassium ATPase use in neuron?

70%

What type of protein is sodium-potassium ATPase?

Transmembrane

What is the location of L type calcium channels?

Heart / smooth & skeletal muscles / CNS / retina / cochlear

What is the location of P/Q type calcium channels?

Neurons

What is the location of N type calcium channels?

Neurons

What is the location of R type calcium channels?

Neurons

What is the location of the T type calcium channels?

Neurons / heart / smooth muscles

What is the L type calcum channel?

Long lasting

What is the P/Q type calcium channel?

Purkinje

What is the N type calcium channel?

Neuronal

What is the R type calcium channel?

Residual

What is the T type calcium channel?

Transient

What is the alpha subunit of the L type calcium channel?

Cav 1.1-1.4

What is the alpha subunit of the P/Q type calcium channel?

Cav 2.1

What is the alpha subunit of the N type calcium channel?

Cav 2.2

What is the alpha subunit of the R type calcium channel?

Cav 2.3

What is the alpha subunit of the T type calcium channel?

Cav 3.1-3.3