Variant 7- equilibrium and diffusion potential in model systes

Question 1

AIM

Answer 1

Investogation on the dependence of diffusion potential on the cincentration gradient and estomate ratio of mobilities in the system

Question 1

Describe the conditions under which the diffusion potential can arise. (7 points)

Answer 1

Membrane is fully permeable for all ions
* In the system a concentration gradient exists (ions from high conc. Move to
lower conc.)
* The ions have different mobilities (u->u+
)

Question 2

Describe shortly the experimental work and measurements performed in this practice. (8
points)

Answer 2

• Set up the model system where diffusion potential can arise using HCL as 1:1 electrolyte
• Measure the diffusion potential at different concentration gradients
• Taking the value of the potential for the steady state condition
• Calculate the slope (α) of the Henderson equation using
• Work out the mobilities from (α)
• Examine the time dependence of the diffusion potential for one concentration gradient of the

Na+ and Cl-

Question 3

4. Which situation is modelled with the experimental set-up in this practice? (5 points)

Answer 3

resting membrane potential?

Question 4

lipid monolayer with maximal molecular packing

Answer 4

90 degree tails

Question 5

List the factors, which determine the blood flow in the circulation. (7 points)

Answer 5

• Heart works as a pump, establishes a hydrostatic pressure difference (Δρ) between the
  ends of a blood vessel (the gradient of hydrostatic pressure- Δρ/l)
• The geometry of the blood vessels
• The mechanical properties of the blood vessel.
• BLood viscosity- hematocrit, deformability, cell aggregation

Question 6

Write the equation for the solute flux (Js) transported through a membrane by facilitated
diffusion. Explain the parameters involved. (7 points)

Answer 6

J=dm/Sdt

S is area of membrane
Dt is change in time
dm is transported solute mass
j is flux

Question 7

Plot as graph the following experimental data. The dependence of specific viscosity of
erythrocyte suspension (Ƞsp) on the haematocrit (Hct). (5 points)

Answer 7

linear starght graph

Question 8

In the above graph draw the line according to Einstein’s law with a slow the form factor (α)
for the RBC in the suspension, which should be calculated as a mean value for the ratio Ƞsp /
Hct. Comment the obtained value for α. (5 points)

Answer 8

a= n spec/hct avergaed

therefore just divide the numbers from graph table then avergae them out

Question 9

Calculate the following parameter. (4 points)

Answer 9

0.005 v

Question 10

Is the normal RBC aggregation in blood under physiological conditions reversible or
irreversible? Which cellular factors determine the aggregation behaviour of this cells? (7)

Answer 10

Normal RBC aggregation is reversible under physiological conditions

surface charge density= eg sialic acid, causes decrease aggregation bc more repulaion

Glycocalx= causes steric hinderance therefore less aggregation

RBC shape and deformability=

Question 11

6. Sketch an action potential of a nerve cell. Which are the main phases and which processes
   take place during them? (7)

Answer 11

time on x axid, potential (mV) on y axis

draw from -70mv to 40mv then down

explain depo repo hyper

Question 12

8. Plot the dependence of the absorbance of the erythrocyte suspension with haemolytic agent
   with time, based on the values from the table (5)

What is t50%

Answer 12

baso from the hughest value of absorbance, HALF IT , then follow the value along to time on x axs

its the time for when the absorbance reduced by 50%