L4

Question 1

Przypomnienie sodium pump- przeczytac dokladnie

Answer 1

The activity of the sodium pump leads to the accumulation of potassium ions inside cells.

Some of these K+ ions leak out of the cells via potassium channels in the plasma membrane.

However, the membrane is much less permeable to sodium ions (10 – 100 times). So sodium ions are unable to replace all the lost potassium ions.

                                                                                             As the potassium ions diffuse out of the cell there is a build-up of negative charge inside the cells that can be detected as a potential difference across the plasma membrane - a membrane potential.

Question 2

Wzór Nernsta…!

Answer 2

E is the equilibrium potential,

ln is the natural logarithm

[C]o and [C]i are the extracellular and intracellular concentrations of the ion in question.

R is the gas constant (8.31 Joules °K-1 mol-1),

T the absolute temperature,

z the charge of the ion,

F the Faraday constant (96,487 coulombs. mol-1).

At 37°C the term RT/F = 26.7 mV

E=-61mV.log([C]i/ [C]o)

Question 3

Przypomnienie membrane potential

Answer 3

• All mammalian cells have a membrane potential.
• In quiescent cells it is called the resting membrane potential.
• The resting membrane potential is always negative with respect to the outside.

Question 4

The resting membrane potential is mainly determined by ………………

Answer 4

the potassium gradient across the plasma membrane.

Question 5

Ion Channels - w porównaniu do carriers prędkość

Answer 5

Generally have a high capacity for transport. K+ channel up to 10^8 ions/sec compared to 10^2-10^4 ions/sec via carriers.

Question 6

Ligand gated channels open in response to ….

Answer 6

specific chemical signals e.g. nicotinic acetlycholine receptor.

Question 7

Voltage-gated channels open in responses to ….

Answer 7

changes in the membrane potential e.g. sodium and potassium channels in the axon of a neuron.

Question 8

the membrane potential of the hepatocytes of the liver is about …

Answer 8

-40 mV.

Question 9

explain sodium - potasium gradient:

Answer 9

The activity of the sodium pump leads to an accumulation of potassium ions inside the cell. The plasma membrane, however, is not totally impermeable to potassium ions so that some are able to diffuse out of the cell down their concentration gradient via potassium channels. The membrane is much less permeable to sodium ions so the lost potassium ions cannot be readily replaced by sodium ions. The leakage of potassium ions from the cell leads to the build-up of negative charge on the inside of the membrane.

Question 10

ligand -

Answer 10

is a molecule that binds to another;

Question 11

agonist -

Answer 11

is a molecule that both binds to and activates a physiological system

Question 12

zwróć uwagę na wzór

Answer 12

Question 13

Podaj Resting potential:

skeletal muscle

smooth muscle cells

astroglia

neurons

erythrocytes

photoreceptors

Answer 13

Question 14

Przypomnienie sodium pump obrazek

Answer 14

Question 15

Przypomnienie obrazek

Answer 15