Which is NOT a basic method of cell-to-cell communication?
Mechanical Signals
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The most significant difference between a paracrine and an autocrine is
the cell that responds to it
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Neurotranmitters and neurohormones both
are released by neurons and affect only cells with specific receptors
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Why do some normal cells fail to respond to a chemical signal?
some cells lack the necessary receptors
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Receptor molecules on the surface of a cell
determine that cell's response and may allow a particular ligand to bind
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Receptor molecules are located
outer membrane, cytosol, nucleus, and cells surface
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Down-regulation may allow a target cell to
only decrease its number of receptors for a ligand
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Lipophilic hormones
bind to receptors inside the cytoplasm or nucleus
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When adenylyl cyclase is activated,
cAMP is formed
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Second messenger molecules directly
change the regulation of ion channels, increase intracellular calcium concentration, change enzyme activity, and change regulation of gene expression
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An integrating center
evaluates incoming signals and compared it with the setpoint
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Which of the following are considered differences between endocrine and neural control systems?
specificity, nature of the signal, speed, and duration of action
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The desired target value for a parameter
setpoint
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Receives information about the regulated variable and initiates a response
integrating center
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The minimum stimulus to trigger a response
thershold
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The organ or gland that performs the change
effector
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Continuously moniters its environment for a specific variable
sensory receptor
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Peripheral cells sensitive to the presence of hormones are called
targets
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\____________________ can be caused by alterations in receptors or by problems with G protein or second
messenger pathways
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\_________________ 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
signal transduction, first messenger, second messenger
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A chemical that is secreted by a cell to act on cells in its immediate vicinity is called a(n)
paracrine
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If the signal molecule acts on the cell that secreted it, the chemical is called a(n)
autocrine
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All molecules secreted by nerve cells (neuromodulators, neurotransmitters, and neurohormones) are known as
neurocrines
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\_______________ 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.
antagonists
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The nervous system has a role in preserving the "fitness" of the \________________________.
internal environment
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The \____________ link membrane receptors to either ion channels or to membrane enzymes located on the cytoplasmic face of the membrane.
g proteins
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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.
protein kinases
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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.
homeostasis
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Most long-distance communication between cells takes place through the \___________ and \____________ systems with their combination of chemical and electrical signals.
nervous, endocrine
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An intracellular signal molecule that translates a signal from a neurotransmitter or hormone into an intracellular response is called a \_______________________.
second messenger
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The secretion of the hormone insulin in response to changes in blood glucose level is an example of a(n) \_____________ reflex.
simple endocrine
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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.
receptor, effector
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What us the half-life of a signal?
the time required for a signal to lose half its activity
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The intracellular effector in chemical signaling is often
a protein kinase
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The most important factor determining which type of receptor a signal molecule will bind to is
the lipid solubility of the ligand
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An ion widely important in intracellular signaling is
calcium
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When calcium becomes available inside a cell, it comes from
extracellular fluid and intracellular storage
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One intracellular calcium-binding protein is
calmodulin
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Signal molecule receptors exhibit
specificity, competition, and saturation
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The binding of lipophilic messengers, such as steroid hormones, to their receptors triggers
gene expression
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Both insulin and glucagon are peptide hormones that target liver cells. The response of the target cells to each of these two hormones is opposite. This information implies that
the two hormones bind to different receptors and use a different second messenger
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Homeostatic control that takes place at the tissue or cell by using paracrine or autocrine signals is called
local control
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What general action is shared by about half of the medical drugs currently in use?
these drugs act on membrane receptor proteins
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The link between a first messenger and a second messenger in a cell that responds to peptide hormones is usually
g protein
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When adenylyl cyclase is activated
cAMP is formed
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Typically, when steroid hormones bind to their receptors,
gene transcription may increase or decrease
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Each of the following hormones is an amino acid derivative EXCEPT one. Identify the exception
thyroid-stimulating hormone
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The majority of hormones in the body are
peptide hormones
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The most complex endocrine responses involve the
hypothalamus
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The posterior pituitary gland secretes
ADH
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The pituitary hormone that controls the release of glucocorticoids from the adrenal cortex is
ACTH
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The pituitary hormone that controls hormone synthesis and release from the thyroid gland is
TSH
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The pituitary hormone that stimulates milk production by the mammary gland is
prolactin
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Lipophobic molecule that interacts with receptors on cell surface
peptide hormone
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Site of vasopressin synthesis
hypothalamus
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True endocrine gland of epithelial origin
anterior pituitary
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Cannot be stored in secretory vesicles
steroid hormone
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Storage and release site for oxytocin
posterior pituitary
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Primary source of adrenal medulla
epinephrine
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Primary source of pancreas
insulin
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Primary source of anterior pituitary
prolactin
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Primary source of pineal
melatonin
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The \____________________ of a hormone is an indicator of how long a hormone is active in the body,
half-life
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A circulatory route that has two sets of capillaries is known as \___________________.
portal system
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The \_______________ gland sits along the superior border of the kidney
adrenal
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The outer layer of the adrenal gland is called the \___________.
adrenal cortex
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The adrenal cortex produces a steroid hormone called \____________ that controls Na+ and K+ homeostasis and another steroid hormone called \_____________ that controls blood glucose levels.
aldosterone, cortisol
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The term for two hormones that have additive effect is
synergists
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The term that describes the need for one hormone to be present for a second hormone to produce a full effect is called \__________.
permissive
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Two hormones that have opposing effects are called
antagonists
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Chemical signals released into the blood by neurons are called \______________.
neurohormones
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When stimulated by a particular hormone, there is marked increase in the activity of G proteins in the membrane. The hormone is probably
a steroid
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In a simple endocrine reflex, the endocrine cell is the
sensor and integrating center
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Synergism occurs when
hormones working together produce a larger effect than predicted
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Hormones acting through signal transduction pathways elicit a \________________ response compared to hormones that produce genomic effects.
faster
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A cell's or tissue's response to a hormone primarily depends on \______________ and \___________________.
cell receptors, signal transduction pathways
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The signal molecule produced by one animal that may affect the behavior of another animal of the same species is the \________________.
pheromone
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A signal molecule that is secreted into the external environment, instead of into the blood, is called a(n) \___________.
pheromone
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The portions of a neuron that extend off of the roughly spherical cell body are usually collectively called
processes
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Information coming into the central nervous system is transmitted along\_____________ neurons.
afferent and sensory
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The afferent and efferent axons together form the
peripheral nervous system
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The brain and spinal cord together compose the
central nervous system
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Exocrine glands, smooth muscles, and cardiac muscles are controlled by the
autonomic nervous system
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autonomic motor neurons are subdivided into the
sympathetic and parasympathetic divisions
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In general, the nervous system is composed of which two types of cells
neurons and glial
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Interneurons are found
only in the CNS
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The multi thin, branched structures on a neuron whose main function is to receive incoming signals are the
dendrites
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The collection of axons that carries information between the central nervous system and the peripheral effector is called
nerve
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The region where the axon terminal meets it target call is called the
synapse
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The axon is connected to the cell body by the
axon hillock
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Clusters of nerve cell bodies in the peripheral nervous system are called
ganglia
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Glial cell communicate primarily using
chemical signals only
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Myelin is formed by
schwann cells and oligodendrocytes
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These glial cells act as scavengers
microglia
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Which ions is/are higher in concentration inside the cell compared to outside
potassium
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Ion channel inactivation is
closing of the channel even when the stimulus continues
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Which of the following is the most common location where action potentials originate
axon hillock
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The rising phase of the action potential is due to
Na+ flows into the cell body
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The falling phase of the action potential is primarily due to
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Flashcard (67)