NSG 533 ADVANCED PHARMACOLOGY EXAM 2
QUESTIONS AND ANSWERS LATEST UPDATE
True or false: phosphorylation of intracellular proteins is a major mechanism of
action for many of our drugs.
True
Describe the effects after activation of a tyrosine kinase (enzyme)-linked receptor.
After the ligand binds, signals are sent to the intracellular tyrosine kinase domain of the
receptor and a conformational change, or allosteric activation, occurs (tyrosine kinase
domains swivel to face, and autophosphorylate, each other). Afterwards, other cellular
proteins are also susceptible to being phosphorylated by the activated enzymes.
Ligand-gated ion channels
Channel composed of simple proteins that act like a gate. When a ligand binds to the
receptor, the channel opens and a specific ion moves in or out of the cell according to
its concentration gradient. Those ions may potentiate or inhibit an action potential.
Intracellular receptors
Expressed only within the cytoplasm, such that any binding ligand must be lipid soluble
and diffuse according to its concentration gradient (often a steroid). Has 3 components -
a drug binding site, heat shock protein, and underlying DNA-binding domain.
Describe the mechanism by which activation of intracellular receptors produce
new proteins.
The ligand (steroid) binds to the receptor, which stimulates release of the heat shock
protein and exposes the underlying DNA-binding domain. The receptor then
translocates into the nucleus of the cell and activates a gene, transcribes mRNA,
translocates ribosomes, and produces new proteins.
True or false: after ligand binding, the response from a ligand-gated ion channel
is much faster than that of an intracellular receptor.
True; intracellular receptors involve the longer process of synthesizing new proteins.
Resting membrane potential
At rest, the interior of the cell has a voltage of approximately -70mV. This potential is
created, and driven by the Na+/K+ ATPase pump (3 Na+ out for every 2K+ in, making
, the inside more negative). Based on that gradient, Na+ and K+ also passively flow in
and out through leak channels, which are much more permissive for K+ than Na+.
Action potential
The sudden change in the normal resting potential from (-) to (+). Happens after Na+
ions entering the cell cause the membrane to reach threshold (-55mV) and voltage-
gated Na+ channels open. Na+ rushes in (depolarization) and membrane reaches
+40mV. Voltage-gated K+ channels open and K+ rushes out (repolarization). Cell
becomes hyperpolarized to -90mV and K+ channels close, then resting membrane
potential is restored to -70mV.
What is the stimulus that ends depolarization after Na+ rushes into the cell
through a voltage-gated ion channel?
Channel-inactivating segment blocks the channel and Na+ is prevented from entering
the cell. Triggers repolarization.
Absolute refractory period
The period from the initiation of an action potential to just after the peak of
depolarization, lasting 1-2 ms. All Na+ channels are blocked by the channel-inactivating
segment and cannot reopen, no matter how strong the stimulus.
Relative refractory period
When enough Na+ channels have reverted back to their resting state (without the
channel-inactivating segment) that they could respond to a strong stimulus.
True or false: refractory periods prevent hyperreactivity, which is important for
homeostasis.
True
What are the 2 divisions, and 3 principal functions of the autonomic nervous
system?
Parasympathetic and sympathetic; regulates heart, smooth muscles, and secretions.
Functions of the parasympathetic nervous system (PNS):
Rest and digest: slows heart rate, increases gastric secretions, empties bladder and
bowel, focuses eye for near vision, constricts pupil, constricts bronchi.
Functions of the sympathetic nervous system (SNS):
QUESTIONS AND ANSWERS LATEST UPDATE
True or false: phosphorylation of intracellular proteins is a major mechanism of
action for many of our drugs.
True
Describe the effects after activation of a tyrosine kinase (enzyme)-linked receptor.
After the ligand binds, signals are sent to the intracellular tyrosine kinase domain of the
receptor and a conformational change, or allosteric activation, occurs (tyrosine kinase
domains swivel to face, and autophosphorylate, each other). Afterwards, other cellular
proteins are also susceptible to being phosphorylated by the activated enzymes.
Ligand-gated ion channels
Channel composed of simple proteins that act like a gate. When a ligand binds to the
receptor, the channel opens and a specific ion moves in or out of the cell according to
its concentration gradient. Those ions may potentiate or inhibit an action potential.
Intracellular receptors
Expressed only within the cytoplasm, such that any binding ligand must be lipid soluble
and diffuse according to its concentration gradient (often a steroid). Has 3 components -
a drug binding site, heat shock protein, and underlying DNA-binding domain.
Describe the mechanism by which activation of intracellular receptors produce
new proteins.
The ligand (steroid) binds to the receptor, which stimulates release of the heat shock
protein and exposes the underlying DNA-binding domain. The receptor then
translocates into the nucleus of the cell and activates a gene, transcribes mRNA,
translocates ribosomes, and produces new proteins.
True or false: after ligand binding, the response from a ligand-gated ion channel
is much faster than that of an intracellular receptor.
True; intracellular receptors involve the longer process of synthesizing new proteins.
Resting membrane potential
At rest, the interior of the cell has a voltage of approximately -70mV. This potential is
created, and driven by the Na+/K+ ATPase pump (3 Na+ out for every 2K+ in, making
, the inside more negative). Based on that gradient, Na+ and K+ also passively flow in
and out through leak channels, which are much more permissive for K+ than Na+.
Action potential
The sudden change in the normal resting potential from (-) to (+). Happens after Na+
ions entering the cell cause the membrane to reach threshold (-55mV) and voltage-
gated Na+ channels open. Na+ rushes in (depolarization) and membrane reaches
+40mV. Voltage-gated K+ channels open and K+ rushes out (repolarization). Cell
becomes hyperpolarized to -90mV and K+ channels close, then resting membrane
potential is restored to -70mV.
What is the stimulus that ends depolarization after Na+ rushes into the cell
through a voltage-gated ion channel?
Channel-inactivating segment blocks the channel and Na+ is prevented from entering
the cell. Triggers repolarization.
Absolute refractory period
The period from the initiation of an action potential to just after the peak of
depolarization, lasting 1-2 ms. All Na+ channels are blocked by the channel-inactivating
segment and cannot reopen, no matter how strong the stimulus.
Relative refractory period
When enough Na+ channels have reverted back to their resting state (without the
channel-inactivating segment) that they could respond to a strong stimulus.
True or false: refractory periods prevent hyperreactivity, which is important for
homeostasis.
True
What are the 2 divisions, and 3 principal functions of the autonomic nervous
system?
Parasympathetic and sympathetic; regulates heart, smooth muscles, and secretions.
Functions of the parasympathetic nervous system (PNS):
Rest and digest: slows heart rate, increases gastric secretions, empties bladder and
bowel, focuses eye for near vision, constricts pupil, constricts bronchi.
Functions of the sympathetic nervous system (SNS):
