Experiments

Question 1

what is Bernstein’s Membrane Hypothesis?

Answer 1

1. asymmetric gradient of ions inside and outside cells
2. resting membrane potential more permeable to K+ ions
3. action potential due to transient increase in permeability to all ions

Question 2

what is Bernstein’s predictions?

Answer 2

1. action potential should be accompanied by increased membrane conductance.
2. voltage should approach 0mV at peak of action potential

Question 3

what did Galvani do?

Answer 3

1. He attached electric circuit to the nervous system of frogs.
2. He believed that the observed muscle twitch upon completion of electric circuit indicated that animals’ tissues could generate electricity.

Question 4

what did Volta do?

Answer 4

1. he disagreed with Galvani.

2. he argued that the current was produced by battery created from the combination of zinc with copper wires.

Question 5

what did Matteucci do?

Answer 5

1. he connected electric circuit to an injured muscle tissue and connected the injured muscle to an non-injured tissue.
2. he observed that both muscles contracted despite that injured contracted first.
3. he determined that excitable tissues can sense and generate electricity.

Question 6

what is the purpose of Hodgkin and Huxley experiment?

Answer 6

they tried to determine the relative permeability of ions at different points in the action potential by using Cole’s voltage clamp to measure membrane conductance during the action potential.

Question 7

what are the H&H observations?

Answer 7

1. hyperpolarization does not cause any channels to open, so there is no measurable current.
2. depolarizing activates voltage-sensitive ion channels, resulting in a measurable current.
3. step depolarizations reveal two current components: an transient inward current and a delayed outward current
4. they determined that the early transient current is due to sodium.