IPHY 3430 Exam 2 Questions All
Solved.
Neuron anatomy - Answer Dendrites, cell body, axon hillock, axon, myelin sheath, axon
terminal
Synapse - Answer Junction between a neuron and another cell
What is the importance of cell membrane potential? - Answer Allows for electrical signaling of
excitable tissues (muscle and nervous) and secretion of neurotransmitters and hormones
What creates membrane potential? - Answer Separation of charge due to differing
concentrations of ions in the extracellular and intracellular fluid
Diffusional forces - Answer Chemical forces
When are ions subject to electrical forces? - Answer When the species are charged, because
positive charges are attracted to negative charges and vice versa
Equilibrium potential - Answer The chemical force is equal in magnitude but opposite in
direction to the electrical force; results in no net flow of ion in either direction
Which direction will Na+ (E=60 mV) flow if the cell membrane potential is -65 mV? What if it
were +65 mV? - Answer Into the cell, out of the cell
Mechanically-gated channel - Answer Has a structural apparatus that connects to the gate on
the channel
Chemically-gated channel - Answer Same as ligand gated, ligand binds and allows for ion flow
Voltage-gated channel - Answer Opens when a certain voltage is reached
Hyperpolarization - Answer Membrane potential becomes more negative than resting
potential
Depolarization - Answer Membrane potential becomes less negative than resting potential
, Repolarization - Answer Returning to resting potential from depolarization
Resting membrane potential - Answer Naturally occurring charge difference between the
inside of the cell and the outside; state when cell is not stimulated
What is resting membrane potential determined by? - Answer K+ concentration gradient, cell's
resting permeability to K+, Na+, and Cl-
What is the standard resting membrane potential? - Answer -70 mV
Excitatory postsynaptic potential (EPSP) - Answer Monovalent cation channels open and Na+
flows in, partially depolarizing the membrane (does not make it to threshold due to outward
movement of K+)
What is the result of an EPSP? - Answer Neuron is more excitable, more sensitive to any
stimulus, and occurrence of action potentials is greater
Inhibitory postsynaptic potential (IPSP) - Answer K+ and Cl- channels open (Cl- in, K+ out);
membrane is hyperpolarized
What is the result of an IPSP? - Answer There is a decreased chance of generating an action
potential because membrane potential is further from threshold
What gates are found on a voltage-gated Na+ channel? - Answer Activation and inactivation
gates
What does the activation gate do? - Answer Has a point of sensitivity to a particular voltage,
which is the threshold value; when threshold is reached activation gate opens and Na+ enters
the cell
What does the inactivation gate do? - Answer Important for refractory period of neuron;
closes as depolarization comes to an end to stop Na+ entry
Why does hyperpolarization occur? - Answer K+ gates are slow to close, resulting in excess K+
leaking out and cell hyperpolarizing
What are the two major types of electrical signals? - Answer Graded potential and action
potential
Solved.
Neuron anatomy - Answer Dendrites, cell body, axon hillock, axon, myelin sheath, axon
terminal
Synapse - Answer Junction between a neuron and another cell
What is the importance of cell membrane potential? - Answer Allows for electrical signaling of
excitable tissues (muscle and nervous) and secretion of neurotransmitters and hormones
What creates membrane potential? - Answer Separation of charge due to differing
concentrations of ions in the extracellular and intracellular fluid
Diffusional forces - Answer Chemical forces
When are ions subject to electrical forces? - Answer When the species are charged, because
positive charges are attracted to negative charges and vice versa
Equilibrium potential - Answer The chemical force is equal in magnitude but opposite in
direction to the electrical force; results in no net flow of ion in either direction
Which direction will Na+ (E=60 mV) flow if the cell membrane potential is -65 mV? What if it
were +65 mV? - Answer Into the cell, out of the cell
Mechanically-gated channel - Answer Has a structural apparatus that connects to the gate on
the channel
Chemically-gated channel - Answer Same as ligand gated, ligand binds and allows for ion flow
Voltage-gated channel - Answer Opens when a certain voltage is reached
Hyperpolarization - Answer Membrane potential becomes more negative than resting
potential
Depolarization - Answer Membrane potential becomes less negative than resting potential
, Repolarization - Answer Returning to resting potential from depolarization
Resting membrane potential - Answer Naturally occurring charge difference between the
inside of the cell and the outside; state when cell is not stimulated
What is resting membrane potential determined by? - Answer K+ concentration gradient, cell's
resting permeability to K+, Na+, and Cl-
What is the standard resting membrane potential? - Answer -70 mV
Excitatory postsynaptic potential (EPSP) - Answer Monovalent cation channels open and Na+
flows in, partially depolarizing the membrane (does not make it to threshold due to outward
movement of K+)
What is the result of an EPSP? - Answer Neuron is more excitable, more sensitive to any
stimulus, and occurrence of action potentials is greater
Inhibitory postsynaptic potential (IPSP) - Answer K+ and Cl- channels open (Cl- in, K+ out);
membrane is hyperpolarized
What is the result of an IPSP? - Answer There is a decreased chance of generating an action
potential because membrane potential is further from threshold
What gates are found on a voltage-gated Na+ channel? - Answer Activation and inactivation
gates
What does the activation gate do? - Answer Has a point of sensitivity to a particular voltage,
which is the threshold value; when threshold is reached activation gate opens and Na+ enters
the cell
What does the inactivation gate do? - Answer Important for refractory period of neuron;
closes as depolarization comes to an end to stop Na+ entry
Why does hyperpolarization occur? - Answer K+ gates are slow to close, resulting in excess K+
leaking out and cell hyperpolarizing
What are the two major types of electrical signals? - Answer Graded potential and action
potential
