EXCITABLE CELLS

Question 1

WHAT IS A MEMBRANE POTENTIAL?

Answer 1

The resting membrane potential is an
electrical charge/ voltage across
the plasma membrane, where the interior
of the cell is negative with respect to the
exterior

Question 2

describe the sodium potassium ATPase or action potential

Answer 2

This pump
pushes two potassium ions (K+) into the cell for every three sodium ions (Na+) it pumps out of the cell, at the cost of one ATP molecule, so its activity results in a net loss of positive charges within the cell.

Question 3

explain how ion channels work as transistors

Answer 3

they have a
gate and if the gate opens it creates a signal that is always the same).
They allow for the spread of the action potential without the loss of amplitude

Question 4

when do voltage and ligand gated channels open

Answer 4

A voltage-gated ion channel opens when there is change in membrane potential
Ligand-gated ion channels opens as a result of the binding of a neurotransmitter

Question 5

what does gated mean in terms of ion channels

Answer 5

they open in response to a specific stimulus

Question 6

what are the differences between voltage gated and ion gated channels

Answer 6

he voltage-gated ion channels allow permeation of only one type of ion
Ligand-gated channels are less selective and allow permeation of two or more types of ions through the channel pore.

Question 7

list some bodiily processes where a membrane potential is needed

Answer 7

signal transduction, muscle contraction, release of neurotransmitters, growth, motility, hormone secretion, volume regulation, and apoptosis

Question 8

what is the refractory period

Answer 8

Effectively more K+ leaving than Na+ coming in (leads to
hyperpolarization)

Question 9

label action potential graph

Answer 9

resting
threshold
depolarization
repolarization
refractory period or hyperpolarization

Question 10

what is the threshold potential?

Answer 10

-55V