In chemical communication between cells, a ________ cell secretes a chemical messenger that binds to ________ on the ________ cell.
a. gap : connexons : secretory
b. secretory : connexons : gap
c. secretory : connexons : target
d. target : receptors : sec
e. secretory : receptors : target
Direct communication between cells in contact with one another is accomplished through ________.
a. ligands
b. receptors
c. gap junctions
d. paracrine chemical messengers
e. endocrine hormones
c. gap junctions
Which is the most general type of chemical messenger that is released from one cell and binds to receptors on neighboring cells?
a. paracrine
b. autocrine
c. hormone
d. cytokine
e. neurotransmitter
a. paracrine
Which type of chemical messenger, when released, binds to receptors on the cell that released the chemical messenger?
a. paracrine
b. autocrine
c. hormone
d. cytokine
e. neurotransmitter
b. autocrine
Which type of chemical messenger is released into the bloodstream by an endocrine gland where it can affect target cells throughout the body?
a. paracrine
b. autocrine
c. hormone
d. cytokine
e. neurotransmitter
c. hormone
Which type of chemical messenger is released from the axon terminal of a neuron and directly stimulates other cells?
a. paracrine
b. autocrine
c. hormone
d. cytokine
e. neurotransmitter
e. neurotransmitter
Communication across a synapse is initiated by the release of a neurotransmitter from the ________ region of the neuron.
a. postsynaptic
b. axon terminal
c. perisynaptic
d. dendritic
e. axon hillock
b. axon terminal
Vasopressin (antidiuretic hormone), which is released from the posterior pituitary, is an example of this type of chemical messenger.
a. cytokine
b. autocrine
c. paracrine
d. neurohormone
e. neurotransmitter
d. neurohormone
Interleukins and interferons are examples of ________ released from white blood cells.
a. paracrine
b. autocrine
c. hormone
d. cytokine
e. neurotransmitter
d. cytokine
Which of the following classes of chemical messengers moves to the target cell by diffusion?
a. paracrine
b. hormone
c. neurotransmitter
d. both paracrine and neurotransmitter
e. all of these
d. both paracrine and neurotransmitter
Which of the following classes of chemical messengers travels in the bloodstream to the target cell?
a. paracrine
b. hormone
c. neurotransmitter
d. both paracrine and hormone
e. all of these
b. hormone
Which of the following chemical messengers is lipophilic?
a. glutamate
b. histamine
c. norepinephrine
d. prostaglandin
e. gamma-amino butyric acid
d. prostaglandin
Histamine acts as a(n) ________ in its role in inflammation.
a. paracrine
b. autocrine
c. hormone
d. neurotransmitter
e. cytokine
a. paracrine
Which of the following chemical messengers is NOT derived from an amino acid?
a. epinephrine
b. testosterone
c. histamine
d. thyroid hormones
e. both testosterone and thyroid hormones
b. testosterone
For which of the following chemical classes do all the messengers function as hormones?
a. amines
b. peptides/proteins
c. steroids
d. eicosanoids
e. amino acids
c. steroids
Release of which of the following classes of chemical messengers occurs by exocytosis?
a. catecholamines
b. steroids
c. eicosanoids
d. both catecholamines and eicosanoids
e. both steroids and eicosanoids
a. catecholamines
Catecholamines are derived from what amino acid?
a. glutamate
b. tryptophan
c. tyrosine
d. histidine
e. glycine
c. tyrosine
Thyroid hormones are synthesized from what amino acid?
a. glutamate
b. tryptophan
c. tyrosine
d. histidine
e. glycine
c. tyrosine
Which of the following classes of chemical messengers is stored in secretory vesicles?
a. catecholamines
b. peptides/proteins
c. steroids
d. eicosanoids
e. both catecholamines and peptides/proteins
e. both catecholamines and peptides/proteins
Once a steroid is synthesized, it is ________.
a. immediately capable of diffusing across the membrane
b. stored in a vesicle until released
c. bound to albumin until released from the cell
d. stored in a unique protein structure that maintains steroids i
a. immediately capable of diffusing across the membrane
Where in a cell are peptide/protein messengers packaged into secretory vesicles?
a. nucleus
b. rough endoplasmic reticulum
c. smooth endoplasmic reticulum
d. Golgi apparatus
e. lysosomes
d. Golgi apparatus
An equilibrium exists between a hormone that is bound to a carrier protein and a free hormone such that, as the amount of free hormone increases, ________.
a. the amount of bound hormone will not change
b. more hormone must be synthesized to directly repl
d. more free hormone will become bound to carrier proteins
Hormones that are dissolved in blood typically exhibit a half-life on the order of ________, whereas hormones that are bound to carrier proteins can remain undegraded for ________.
a. seconds : hours
b. seconds : minutes
c. minutes : hours
d. hours : minu
c. minutes : hours
The adrenergic receptor has the greatest affinity for ________.
a. norepinephrine
b. epinephrine and norepinephrine equally
c. epinephrine
d. dopamine
e. serotonin
b. epinephrine and norepinephrine equally
Chronic exposure to a ligand (messenger) ________ the receptor population for that chemical messenger on the target cell.
a. decreases the specificity of
b. decreases the affinity of
c. upregulates
d. downregulates
e. changes the conformation of
d. downregulates
Lipophilic hormones are transported in blood ________ and bind to receptors located ________.
a. dissolved in the plasma : on the plasma membrane of the target cell
b. dissolved in the plasma : inside the target cell
c. bound to carrier proteins : on the
d. bound to carrier proteins : inside the target cell
A molecule that is similar in structure to a ligand (messenger) and binds with that ligand's receptor to stimulate a response from the target cell is called a(n) ________.
a. blocker
b. synergist
c. antagonist
d. agonist
e. protagonist
d. agonist
The affinity of a receptor for its ligand is a measure of ________.
a. the strength of binding between ligand and receptor
b. the number of binding sites available for the ligand
c. the ability of the ligand to permeate the plasma membrane and reach its r
a. the strength of binding between ligand and receptor
________ describes ion channels that are coupled to membrane receptors such that their gating properties (opening and closing) are altered by messenger binding.
a. Enzyme-linked receptors
b. G protein-linked channels
c. Voltage-gated channels
d. Ligand-ga
d. Ligand-gated channels
Which of the following ions can act as a second messenger?
a. sodium
b. potassium
c. calcium
d. both sodium and potassium
e. both sodium and calcium
c. calcium
Opening channels for which of the following ions can trigger exocytosis?
a. sodium
b. potassium
c. calcium
d. both sodium and potassium
e. both sodium and calcium
c. calcium
Which of the following ions binds to calmodulin to ultimately activate a protein kinase?
a. sodium
b. potassium
c. calcium
d. chloride
e. both sodium and potassium
c. calcium
The function of a second messenger is to ________.
a. buffer a cells response to a ligand
b. isolate the response to the inside of a cell c. keep calcium involved in these responses d. amplify the response of the first messenger
e. facilitate the process
d. amplify the response of the first messenger
In its active form, a G protein will have ________.
a. the alpha and beta subunit separated from the gamma subunit
b. the gamma subunit separated from the alpha and beta subunit
c. the beta subunit separated from the alpha and gamma subunit
d. the alpha s
d. the alpha subunit separated from the gamma and beta subunit
The enzyme that catalyzes synthesis of cAMP is called ________ and is activated by ________.
a. adenylate cyclase : a Gs protein
b. adenylate cyclase : a Gi protein
c. phosphodiesterase : a Gs protein
d. phosphodiesterase : a Gi protein
e. phosphoprotein
a. adenylate cyclase : a Gs protein
What enzyme is activated by cAMP?
a. phosphodiesterase
b. adenylate cyclase
c. tyrosine kinase
d. protein kinase A
e. protein kinase C
d. protein kinase A
In order to terminate a cAMP-mediated response, the enzyme ________ can be activated to degrade cAMP.
a. cAMP decarboxylase
b. cAMP hydrolase
c. cAMP hydrogenase
d. cAMP phosphodiesterase
e. cAMP protein kinase
d. cAMP phosphodiesterase
Which of the following is a second messenger?
a. cAMP calcium
b. inositol triphosphate
c. both cAMP and inositol
d. triphosphate
e. all of these
e. all of these
Which of the following chemical messengers communicates over mm or longer distances?
a. neurotransmitters
b. neurohormones
c. hormones
d. both neurohormones and hormones
e. all of these
d. both neurohormones and hormones
Typical responses to ______ messengers require a long time to develop because they necessitate transcription of mRNA and translation of that mRNA into a functional protein.
a. amino acid
b. protein
c. peptide
d. lipophilic
e. lipophobic
d. lipophilic