MISCELLANEOUS

Question 1

What stimuli are known to gate regulated ion-channels? (HINT: there’s 4 stimuli)

Answer 1

Voltage
 Ligand
 Stretch or Pressure-gated
 Light

Question 2

What parameters can we measure from a single channel recording? (HINT: there’s 4 parameters)

Answer 2

 Open probability
 Mean open times
 Mean closed times
 Conductance

Question 3

What is the equation used to calculate the probability of an ion channel being open?

Answer 3

P(open)=t(open)/t(total)

Question 4

What is ohms law?

Answer 4

V= IR

Question 5

What is the equation for conductance?

Answer 5

g = 1/R

Question 6

How you would experimentally obtain the necessary information in order to calculate the single-channel conductance for a given ion?

Answer 6

Under voltage-clamp conditions we can measure the single channel current amplitude at a given voltage. We can then construct a current-voltage relationship. The slope of the current-voltage relationship gives us the conductance

Question 7

What is conductance a measure of?

Answer 7

How “good” a channel is at letting current through

Question 8

Why is it important to study the basic biophysical properties of an ion channel?

Answer 8

The single channel properties are unique for a given ion channel and this enables us to functionally identify the channel. This is important particularly when we want to look at the action of a drug or the effect of a single point mutation which may underlie a given pathology as a result of altered channel function.

Question 9

Name the 5 longitudinal ligaments that pass between vertebral bodies and connect vertebral arches, and describe the function(s) of these ligaments.

Answer 9

Anterior longitudinal
Posterior longitudinal
Supraspinous
Interspinous
Ligamentum flavum
Allow some flexibility of the column as a whole
But prevent unwanted movements which are potentially damaging (hyperextension, hyperflexion)

Question 10

Describe the normal appearance of an erythrocyte under the light microscope and how it would differ in patients suffering from anemia due to severe iron deficiency

Answer 10

Normal erythrocytes will appear as small round cells with a red stain inside denoting the hemoglobin content. In severe anemia, the lower amounts of hemoglobin present will often be in a ring around the edge of the cell, leaving a clear central area. These cells may also be slightly smaller than normal healthy erythrocytes

Question 11

Describe the normal appearance of a neutrophil on a normal blood film, and how it would differ from a small lymphocyte

Answer 11

Neutrophils can easily be observed due to their multi-lobed nucleus and clearly visible cytoplasm, in marked contrast to small lymphocytes in which the single non-lobed nucleus occupies the majority of the cell, ie there is very little cytoplasm visible.

Question 12

What % of neutrophils would you expect to observe on a normal blood cell count?

Answer 12

50-70%

Question 13

What characteristic feature of basophils would you use to distinguish these rare cells on a normal blood film?

Answer 13

Very rare cells on a normal blood film, identifiable due to their very darkly stained granules which pack the cytoplasm, often obscuring the nucleus.

Question 14

What are the four criteria that a molecule must conform to in order to be considered a neurotransmitter?

Answer 14

1. Production pre-synaptically
2. Storage pre-synaptically
3. Released on demand not constitutively released
4. Must be inactivated somehow

Question 15

What are the three ways neurotransmitters are inactivated?

Answer 15

1. Diffusion
2. Enzymal breakdown
3. Re-uptake

Question 16

What role does the Na/K ATPase play in the action potential?

Answer 16

No direct role other than to maintain the Na and K gradients by pumping Na out and replacing K lost. It is the ionic gradients and changes in membrane permeability that give rise to the action potential. Activity of the Na/K ATPase, by maintaining the ionic gradients, creates the environment where the action potential can happen.