Physiology Exam 2 Ch. 6 Test Bank
Questions with Complete Answers
23) continuously monitors its environment for a specific variable - Answer-E. sensory
receptor
Peripheral cells sensitive to the presence of hormones are called ________. -
Answer-targets
A few gases are known to act as signal molecules, including ________, ________,
and ________. - Answer-nitric oxide, carbon monoxide, hydrogen sulfide
Before nitric oxide was identified, its action was observed in ________ and it was
given the name ________. - Answer-endothelial cells (blood vessel lining),
endothelial-derived relaxing factor (EDRF)
________ can be caused by alterations in receptors or by problems with G protein or
second messenger pathways. - Answer-Diseases
Lipid signal molecules that act in a paracrine fashion and combine with G-protein
coupled receptors include ________ and ________. - Answer-eicosanoids,
sphingolipids
________ is a process by which an extracellular signal molecule, called the
________, activates a membrane receptor that in turn alters intracellular molecules,
called the ________, to create a response. - Answer-Signal transduction, first
messenger, second messenger
A gap junction forms when opposing membrane-spanning proteins called ________
on two adjacent cells unite, creating a protein channel that is capable of opening and
closing. - Answer-connexins
A chemical that is secreted by a cell to act on cells in its immediate vicinity is called
a(n) ________. - Answer-paracrine
If the signal molecule acts on the cell that secreted it, the chemical is called a(n)
________. - Answer-autocrine
All molecules secreted by nerve cells (neuromodulators, neurotransmitters, and
neurohormones) are known as ________. - Answer-neurocrines
________ are molecules that bind to the receptor in such a way that they block the
normal ligand from binding and turning the receptor on. As a result, the signal
pathway remains inactive. - Answer-Antagonists (or Competitive inhibitors)
If the concentration of an endocrine ligand decreases, the target cell may insert more
receptors into the cell membrane in an attempt to keep its response at a normal
level, in a process known as ________. - Answer-up-regulation
, The nervous system has a role in preserving the "fitness" of the ________. - Answer-
Internal Environment
The ________ link membrane receptors to either ion channels or to membrane
enzymes located on the cytoplasmic face of the membrane. - Answer-G proteins
Many second messenger systems activate ________, enzymes that transfer a
phosphate group from ATP to a protein. The phosphorylation of proteins sets off a
series of intracellular events that lead to the ultimate cellular response. - Answer-
protein kinases
Explain how epinephrine can cause intestinal blood vessels to constrict and cause
skeletal muscle blood vessels to dilate. - Answer-Epinephrine can bind to different
isoforms of the adrenergic receptor. Epinephrine binds to the alpha receptor on the
intestinal blood vessels and beta receptors on the skeletal muscle blood vessels
(see Fig. 6.14).
To maintain ________, the body uses a combination of simple diffusion across small
distances; wide spread distribution of molecules through the circulatory system and
rapid, specific delivery of messages by the nervous system. - Answer-homeostasis
Most long-distance communication between cells takes place through the ________
and ________ systems with their combination of chemical and electrical signals. -
Answer-nervous, endocrine
An intracellular signal molecule that translates a signal from a neurotransmitter or
hormone into an intracellular response is called a ________. - Answer-second
messenger
The secretion of the hormone insulin in response to changes in blood glucose level
is an example of a(n) ________ reflex. - Answer-simple endocrine
Homeostatic regulation usually involves a(n) ________ that is sensitive to a
particular stimulus (variable) and a(n) ________ whose activity has an effect on the
same stimulus. - Answer-receptor, effector
When epinephrine combines with alpha adrenergic receptors on smooth muscle in
intestinal blood vessels, the blood vessels ________; however, when epinephrine
binds to beta-2 adrenergic receptors on certain skeletal muscle blood vessels, the
vessels ________. - Answer-constrict, dilate
What is the half-life of a signal? - Answer-the time required for a signal to lose half its
activity
What is an orphan receptor? - Answer-a receptor that has no known ligand
The intracellular effector in chemical signaling is often
A) a hormone.
B) a membrane receptor molecule.
Questions with Complete Answers
23) continuously monitors its environment for a specific variable - Answer-E. sensory
receptor
Peripheral cells sensitive to the presence of hormones are called ________. -
Answer-targets
A few gases are known to act as signal molecules, including ________, ________,
and ________. - Answer-nitric oxide, carbon monoxide, hydrogen sulfide
Before nitric oxide was identified, its action was observed in ________ and it was
given the name ________. - Answer-endothelial cells (blood vessel lining),
endothelial-derived relaxing factor (EDRF)
________ can be caused by alterations in receptors or by problems with G protein or
second messenger pathways. - Answer-Diseases
Lipid signal molecules that act in a paracrine fashion and combine with G-protein
coupled receptors include ________ and ________. - Answer-eicosanoids,
sphingolipids
________ is a process by which an extracellular signal molecule, called the
________, activates a membrane receptor that in turn alters intracellular molecules,
called the ________, to create a response. - Answer-Signal transduction, first
messenger, second messenger
A gap junction forms when opposing membrane-spanning proteins called ________
on two adjacent cells unite, creating a protein channel that is capable of opening and
closing. - Answer-connexins
A chemical that is secreted by a cell to act on cells in its immediate vicinity is called
a(n) ________. - Answer-paracrine
If the signal molecule acts on the cell that secreted it, the chemical is called a(n)
________. - Answer-autocrine
All molecules secreted by nerve cells (neuromodulators, neurotransmitters, and
neurohormones) are known as ________. - Answer-neurocrines
________ are molecules that bind to the receptor in such a way that they block the
normal ligand from binding and turning the receptor on. As a result, the signal
pathway remains inactive. - Answer-Antagonists (or Competitive inhibitors)
If the concentration of an endocrine ligand decreases, the target cell may insert more
receptors into the cell membrane in an attempt to keep its response at a normal
level, in a process known as ________. - Answer-up-regulation
, The nervous system has a role in preserving the "fitness" of the ________. - Answer-
Internal Environment
The ________ link membrane receptors to either ion channels or to membrane
enzymes located on the cytoplasmic face of the membrane. - Answer-G proteins
Many second messenger systems activate ________, enzymes that transfer a
phosphate group from ATP to a protein. The phosphorylation of proteins sets off a
series of intracellular events that lead to the ultimate cellular response. - Answer-
protein kinases
Explain how epinephrine can cause intestinal blood vessels to constrict and cause
skeletal muscle blood vessels to dilate. - Answer-Epinephrine can bind to different
isoforms of the adrenergic receptor. Epinephrine binds to the alpha receptor on the
intestinal blood vessels and beta receptors on the skeletal muscle blood vessels
(see Fig. 6.14).
To maintain ________, the body uses a combination of simple diffusion across small
distances; wide spread distribution of molecules through the circulatory system and
rapid, specific delivery of messages by the nervous system. - Answer-homeostasis
Most long-distance communication between cells takes place through the ________
and ________ systems with their combination of chemical and electrical signals. -
Answer-nervous, endocrine
An intracellular signal molecule that translates a signal from a neurotransmitter or
hormone into an intracellular response is called a ________. - Answer-second
messenger
The secretion of the hormone insulin in response to changes in blood glucose level
is an example of a(n) ________ reflex. - Answer-simple endocrine
Homeostatic regulation usually involves a(n) ________ that is sensitive to a
particular stimulus (variable) and a(n) ________ whose activity has an effect on the
same stimulus. - Answer-receptor, effector
When epinephrine combines with alpha adrenergic receptors on smooth muscle in
intestinal blood vessels, the blood vessels ________; however, when epinephrine
binds to beta-2 adrenergic receptors on certain skeletal muscle blood vessels, the
vessels ________. - Answer-constrict, dilate
What is the half-life of a signal? - Answer-the time required for a signal to lose half its
activity
What is an orphan receptor? - Answer-a receptor that has no known ligand
The intracellular effector in chemical signaling is often
A) a hormone.
B) a membrane receptor molecule.
