CHP 5 HUMAN A&P 2

In chemical communication between cells, a ________ cell secretes a chemical messenger that binds to ________ on the ________ cell. A) target : receptors : secretory B) gap : connexons : secretory C) secretory : connexons : target D) secretory : receptors : target E) secretory : connexons : gap

Direct communication between cells in contact with one another is accomplished through A) paracrine chemical messengers. B) gap junctions. C) endocrine hormones. D) ligands. E) receptors

The number of bound receptors on a target cell depends on what two things? A) the type and concentration of receptors B) the secretory cell and target cell C) the concentration of the messenger and the distance it has to travel D)the concentration of the messenger and signal transduction E) the concentration of the messenger and the concentration of receptors on the target cell

Which type of chemical messenger, when released, binds to receptors on the cell that released the chemical messenger? A) autocrine B) neurotransmitter C) cytokine D) hormone E) neurohormone

Which type of chemical messenger is released into the bloodstream by an endocrine gland where it can affect target cells throughout the body? A) autocrine B) paracrine C) neurotransmitter D) cytokine E) hormone

Which type of chemical messenger is released from the axon terminal of a neuron and directly communicates with other cells? A) autocrine B) cytokine C) paracrine D) hormone E) neurotransmitter

Communication across a synapse is initiated by the release of a neurotransmitter from the ________ region of the neuron. A) dendritic B) axon hillock C) axon terminal D) postsynaptic E) perisynaptic

Vasopressin (antidiuretic hormone), which is released from the posterior pituitary, is an example of what type of chemical messenger? A) cytokine B) neurotransmitter C) neurohormone D) autocrine E) paracrine

Inflammation is characterized in part by redness and swelling. In inflammation, ________ increases blood flow to affected tissues (producing redness) and causes fluid to leak out of the blood vessels and into the tissue (producing swelling). A) clotting factor B) histamine C) pyruvic acid D) growth factor E) amine

The more specific a drug is for a certain ________ type, the more specific the therapeutic actions of the drug and the fewer the side effects. A) target cell B) neurotransmitter C) ligand D) hormone E) receptor

Which of the following chemical messengers is lipophilic and is therefore able to cross the cell membrane? A) amines (excluding thyroid hormone) B) proteins C) peptides D) eicosanoids E) amino acids

Histamine acts as a(n) ________ in its role in inflammation. A) neurotransmitter B) autocrine C) paracrine D) hormone E) cytokine

What molecules are hydrophobic and can easily cross the plasma membrane? A) hydrophilic B) hyperdermic C) amino acids D) lipophilic E) lipophobic

All the messengers in what class are derived from cholesterol? A) eicosanoids B) amino acids C) peptides/proteins D) amines E) steroids

Most amines are ________, meaning they dissolve in water and therefore cannot cross the cell membrane. The ________ hormones are an exception because they are ________ and can easily cross the cell membrane. A) hydrophobic : steroid : hydrophilic B) lipophilic : thyroid : lipophobic C) amino acids : steroid : lipophilic D) lipophobic : thyroid : lipophilic E) lipophilic : protein : lipophobic

Peptide hormones are made________, stored and released via ________. A) in advance : receptor-mediated endocytosis B) in advance : pinocytosis C) on demand : simple diffusion D) in advance : exocytosis E) on demand : active transport

Cells that secrete dopamine must contain which enzymes? A) dopamine β-hydroxylase only B) tyrosine β-hydroxylase C) dopa decarboxylase only D) dopamine β-hydroxylase and dopa decarboxylase only E) tyrosine β-hydroxylase and dopa decarboxylase

Cells that secrete epinephrine must contain which enzymes? A) phenylethanolamine N-methyl transferase and dopa decarboxylase only B) dopamine β-hydroxylase, tyrosine β-hydroxylase, phenylethanolamine N-methyl transferase, and dopa decarboxylase C) dopamine β-hydroxylase, tyrosine β-hydroxylase, and dopa decarboxylase only D) tyrosine β-hydroxylase and phenylethanolamine N-methyl transferase only E) dopamine β-hydroxylase and dopa decarboxylase only

Catecholamines are derived from what amino acid? A) histidine B) tyrosine C) tryptophan D) glycine E) glutamate

Thyroid hormones are synthesized from what amino acid? A) tryptophan B) histidine C) glycine D) glutamate E) tyrosine

Aspirin is a nonsteroidal anti-inflammatory drug (NSAID) that relieves pain. Which mechanism best describes how NSAIDs work? A) Aspirin decreases the production of thromboxane A2, a chemical involved in blot clot formation, and COX inhibits A2 and, therefore, blood clots do not form and cause pain. B) Prostaglandins (PG) are eicosanoids that produce pain and inflammation. Cyclooxygenase (COX) is an essential enzyme in the production of PG and aspirin inhibits COX and therefore relieves pain due to the reduced production of PG. C) The COX receptors have a greater affinity for aspirin and these speed up the reactions of healing. D) When aspirin dissolves in the interstitial fluid it causes a concentration gradient and fluid is pulled from the cell reducing inflammation. E) Leukotrienes are eicosanoids that produce pain and inflammation. COX is used in the lipoxygenase pathway and therefore NSAIDs stop the conversion of arachidonic acid to leukotrienes thereby reducing inflammation.

Doctors often prescribe baby aspirin (82 mg) to guard against the formation of blood clots instead of a higher dose of 350 mg found in a regular aspirin. Which statement best describes the distinction in dosages? A) Aspirin is an allosteric modulator that activates COX-2 in the body and it is COX-2 that primarily inhibits blood clot formation. B) Aspirin causes several side effects, some good and some bad. Aspirin decreases thromboxane A2 which causes blood clots; however, at higher dosages, it also decreases the production of PGI2 (prostacyclin) that inhibits production of blood clots. Thus, higher dosages of aspirin would actually promote the formation of blood clots. C) Low dosages of aspirin inhibit a critical enzyme in the production of prostaglandins called cyclooxygenase (COX). There are two forms of COX: 1 and 2. Low dosages enhance the production of COX-2 which reduces blood clots. COX-1 receptors only reduce pain. D) Both dosages actually do the same thing to prevent blood clots but 82 mg of aspirin is much cheaper than 350 mg. E) Aspirin inhibits the production of PGE2 in the stomach, which protects the stomach lining from stomach acid causing ulcers. Lower dosages do not inhibit PGE2 and do not harm the stomach.

Once a steroid hormone is synthesized, it is A) stored in a vesicle until released. B) bound to albumin until released from the cell. C) stored in a unique protein structure that maintains steroids in the cell. D) immediately capable of diffusing across the membrane. E) bound to the mitochondria until released

What organelle packages peptide/protein messengers into secretory vesicles? A) smooth endoplasmic reticulum B) lysosomes C) rough endoplasmic reticulum D) nucleus E) Golgi apparatus

In order to synthesize eicosanoids, ________ catalyzes the release of ________ from a membrane phospholipid. A) phospholipase A2 : cholesterol B) phospholipase C : cholesterol C) phospholipase C : arachidonic acid D) phospholipase A2 : arachidonic acid E) phospholipase C : inositol biphosphate

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) cells will be stimulated to secrete more free hormone. B) the amount of bound hormone will not change. C) more bound hormone will be released from its carrier proteins. D) more free hormone will become bound to carrier proteins. E) more hormone must be synthesized to directly replace the free hormones

Lipophilic chemical messengers are poorly soluble in water. However, many of these lipophilic messengers are transported throughout the body. Their transport in blood (water) is facilitated by A) chylomicrons. B) carrier proteins. C) white blood cells. D) red blood cells. E) lipoproteins.

What enzyme catalyzes synthesis of prostaglandins from arachidonic acid? A) cyclooxygenase B) phospholipase A2 C) tyrosine β-hydroxylase D) lipoxygenase E) phospholipase C

A half-life, in terms of a chemical messenger, refers to A) the amount of time the messenger is bound to a protein. B) the time it takes for half of the chemical messenger in the blood to be degraded. C) the amount of time it takes to cross the plasma membrane. D) the radioactivity of the chemical messenger. E) how long the chemical messenger will be effective in the body

Androgens are precursor molecules for the synthesis of A) estradiol. B) cortisol. C) cholesterol. D) progesterone. E) aldosterone

Progesterone is a potential precursor for the synthesis of A) dehydroepiandrosterone. B) androstenedione. C) cortisol. D) testosterone. E) estradiol

Aspirin decreases inflammation by inhibiting the actions of what enzyme? A) lipoxygenase B) cyclooxygenase C) protein kinase A D) phospholipase A2 E) dopa decarboxylase

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 : minutes B) hours : minutes C) minutes : hours D) seconds : hours E) minutes : seconds

The location of receptors on a target cell depends on the solubility of the chemical messenger. Where would the receptors for lipophilic messengers be located? A) only in the nucleus of the cell B) at a free floating ribosome C) on the outside of the cell D) on the inside of the cell E) It depends on if it is an alpha, beta, or delta type receptor

The β1 adrenergic receptor has the greatest affinity for what messenger? A) serotonin B) dopamine C) norepinephrine D) epinephrine E) epinephrine and norepinephrine equally

The α1 adrenergic receptor has the greatest affinity for what messenger? A) dopamine B) epinephrine C) serotonin D) norepinephrine E) epinephrine and norepinephrine equally

Which of the following will NOT affect the magnitude of a cell's response to a specific hydrophilic ligand? A) affinity of the receptor for the ligand B) ligand concentration C) receptor upregulation D) number of receptors E) lipid solubility of the ligand

Chronic exposure to a ligand (messenger) ________ the receptor population for that chemical messenger on the target cell. A) decreases the affinity of B) down regulates C) upregulates D) changes the conformation of E) decreases the specificity of

Which of the following statements best describes the release of lipophobic messengers? A) Lipophobic messengers are stored in vesicles and released by exocytosis in response to a stimulus. B) Lipophobic messengers are stored free in the cytosol and released by simple diffusion in response to a stimulus. C) Lipophobic messengers are stored in vesicles and released by simple diffusion in response to a stimulus. D) Lipophobic messengers are stored in vesicles and released by exocytosis immediately after synthesis. E) Lipophobic messengers are released immediately upon synthesis by simple diffusion

Which of the following statements best describes the release of a lipophilic messenger? A) Lipophilic messengers are stored in vesicles and released by simple diffusion in response to a stimulus. B) Lipophilic messengers are released immediately upon synthesis by simple diffusion. C) Lipophilic messengers are stored in vesicles and released by exocytosis immediately after synthesis. D) Lipophilic messengers are stored free in the cytosol and released by simple diffusion in response to a stimulus. E) Lipophilic messengers are stored in vesicles and released by exocytosis in response to a stimulus

Lipophilic hormones are transported in blood ________ and bind to receptors located ________. A) bound to carrier proteins : inside the target cell B) inside red blood cells : inside the target cell C) bound to carrier proteins : on the plasma membrane of the target cell D) dissolved in the plasma : inside the target cell E) dissolved in the plasma : on the plasma membrane of the target cell

Much evidence suggests that depression might be associated with deficiencies in the biogenic amines serotonin and norepinephrine. If this is true and the body has reduced concentrations of these amines, one might predict the body would ________ in order to adapt to these lowered levels. A) reduce the affinity B) increase the half life C) increase the concentration of chemical messenger D) upregulate E) downregulate

What is a molecule that is similar in structure to a messenger and binds with that messenger's receptor to stimulate a similar response from the target cell? A) agonist B) antagonist C) protagonist D) synergist E) blocker

As a general rule, the magnitude of a target cell's response to a chemical messenger depends on which three factors? A) (1) the concentration of the messenger, (2) the percent saturation of the receptor, and (3) the specificity of the receptor for the chemical messenger B) (1) the concentration of the messenger, (2) the number of receptors, and (3) the affinity of the receptor for the messenger C) (1) the half life of the messenger, (2) the number of receptors, and (3) the percent saturation of those receptors D) (1) the solubility of the chemical messenger, (2) the location of the receptor, and (3) the class of the receptor E) (1) the solubility of the chemical messenger, (2) the location of the receptor, and (3) the affinity of the receptor to the messenger

The affinity of a receptor for its ligand is a measure of the A) percent of receptors on a specific target cell with bound ligand. B) ability of the ligand to permeate the plasma membrane and reach its receptor. C) strength of binding between ligand and receptor. D) response produced in the target cell when the ligand binds to the receptor. E) number of binding sites available for the ligand

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) protein B) lipophobic C) amino acid D) peptide E) lipophilic

Insulin is a peptide hormone and therefore lipophobic. When insulin is released due to high blood glucose levels, the response of the cells to this hormone will be ________ because it causes ________. A) fast : enzyme-linked receptors to catalyze intracellular reactions B) neutral : transcription of mRNA and translation of that mRNA into a functional protein C) slow : amplification of proteins D) slow : a second messenger system to be activated E) fast : new protein synthesis

Heroin overdose is usually treated with an opioid ________ such as naloxone (Narcan) or naltrexone, an opioid, which prevents heroin from binding to mu receptors and reverses the effects of heroin on the body. A) antihistamine B) agonist C) antagonist D) ligand E) second messenger

Differences in the rate of activity between fast and slow ligand-gated channels are caused by 49) ______ A) ligands gating both channels to the closed state. B) ligand selectivity. C) G protein activity gating the slow channel. D) ligand affinity. E) G protein activity gating the fast channel

Opening channels for which of the following ions can trigger exocytosis? A) sodium B) chloride C) calcium D) potassium E) magnesium

Which of the following ions binds to calmodulin to ultimately activate a protein kinase? A) calcium B) potassium C) sodium D) chloride E) magnesium

A first messenger is an extracellular messenger that binds to its receptor on the ________ of the cell and therefore activates a second messenger system. A) outside B) G protein C) ribosome D) endoplasmic reticulum E) inside

Which of the following statements best describes the function of tyrosine kinase? A) It sequesters calcium in the cytosol. B) It catalyzes the phosphorylation of a protein in the extracellular fluid. C) It catalyzes the formation of norepinephrine from dopamine. D) It catalyzes the phosphorylation of a protein inside a cell. E) It catalyzes the formation of dopamine from L-dopa

Cholera is the leading cause of death in children in developing countries, characterized by massive diarrhea. The effects stem from an extracellular toxin that the bacterium Vibrio cholerae releases into the gut. The toxin acts on a ________ that overstimulates ________ which causes a cascade of events that leads to electrolytes leaving the cell and causing water to follow them into the lumen of the intestine, resulting in severe diarrhea. A) protein-P : GTP B) cAMP : G proteins C) G proteins : adenylate cyclase D) protein kinases : calmodulin E) calcium : muscles

Which of the following is the most common second messenger in the human body? A) DAG B) calcium C) IP3 D) cAMP E) cGMP

What terminates the cAMP second messenger system? A) the release of the first messenger from the receptor B) the degradation of cAMP by the enzyme cAMP phosphodiesterase C) degradation of cAMP by the liver D) a G protein E) the axon terminal

Cyclic AMP (cAMP) stimulates one's metabolic rate. Many supplement companies offer products claiming to increase the levels of this chemical within the body. If you had a patient on this supplement and they had high levels of cAMP in their body, what symptoms would you expect them to display? A) weight loss and a high temperature B) high G protein and sugar levels in their urine C) weight gain and lethargy D) hypoglycemia and low blood pressure E) increased heart rate and shallow breathing

The function of a second messenger system is to A) keep calcium involved in these responses. B) isolate the response to the inside of a cell. C) amplify the response of the first messenger. D) facilitate the process of covalent modification of a protein. E) buffer a cell's response to a ligand

Based on your knowledge of signal amplification, which type of chemical messenger can have relatively small concentrations within the bloodstream and still get a large response? A) paracrine B) lipophilic C) autocrine D) lipophobic E) steroid

Functionally, G proteins are classified into what three types? A) slow, fast, and opened or closed B) those that affect proteins, those that affect enzymes, and those that affect specific genes C) those that affect ion channels, stimulatory G proteins, and inhibitory G proteins D) alpha, beta, and gamma E) first, second, and third messengers

When the alpha subunit of the G protein is activated, it can stimulate ion channels to do what? A) alter the ion that travels through the channel B) open only C) either open or close D) degrade E) close only

The enzyme that catalyzes synthesis of cAMP is called ________ and is activated by ________. A) phosphodiesterase : a Gs protein B) phosphoprotein phosphatase : a Gi protein C) adenylate cyclase : a Gi protein D) adenylate cyclase : a Gs protein E) phosphodiesterase : a Gi protein

What enzyme is activated by cAMP? A) phosphodiesterase B) adenylate cyclase C) protein kinase C D) protein kinase A E) tyrosine kinase

In order to terminate a cAMP-mediated response, the enzyme ________ can be activated to degrade cAMP. A) cAMP protein kinase B) cAMP phosphodiesterase C) cAMP decarboxylase D) cAMP hydrogenase E) cAMP hydrolase

When associated with G protein, guanylate cyclase will activate what enzyme? A) protein kinase A B) protein kinase C C) phospholipase C D) protein kinase G E) phosphodiesterase

What molecule, whose synthesis is catalyzed by phospholipase C, triggers the release of calcium from the endoplasmic reticulum? A) inositol triphosphate B) cGMP C) diacylglycerol D) inositol biphosphate E) phosphatidylinositol biphosphate

Which of the following proteins is directly activated by a G protein? A) phospholipase A2 B) calmodulin C) tyrosine kinase D) adenylate cyclase E) protein kinase G

Which of the following are second messengers? A) cAMP only B) calcium only C) inositol triphosphate only D) both cAMP and inositol triphosphate E) cAMP, calcium, and inositol triphosphate

What two systems primarily control homeostasis due to their ability to communicate over long distances? A) nervous and cardiovascular B) nervous and endocrine C) endocrine and respiratory D) cardiovascular and respiratory E) endocrine and cardiovascular

The chemical messenger of the nervous system is ________ and chemical messenger of the endocrine system is ________. A) neurotransmitter : neurohormone B) hormone : neurotransmitter C) autocrines : paracrines D) neurotransmitter : hormone E) neurohormone : adrenocorticoid

The target cells of the nervous system are A) glial cells. B) other neurons. C) muscle cells. D) all the cell types in the body. E) neurons, muscles, or glands

The nervous system communicates via the ________ and the endocrine system communicates via the ________. A) glial cell : hormone B) synapse : bloodstream C) muscle cells : specific target cells of hormones D) neuron : endocrine gland E) electrical signals : chemical signals or paracrine cells

Which of the following statements is true for the nervous system but NOT the endocrine system? A) A messenger is transported in the bloodstream. B) Communication occurs over long distances. C) Effector organs are scattered throughout the body. D) A messenger communicates to target cells by binding to specific receptors. E) There is a special anatomical arrangement between the secretory cell and the target cell.

What part of a neuron releases neurotransmitter by exocytosis? A) axon hillock B) dendrites C) soma D) axon terminal E) All of the answers are correct

What chemical messenger diffuses to neighboring cells to exert an effect? A) hormone B) neurotransmitter C) neurohormone D) autocrine E) paracrine

What chemical messenger is released from endocrine glands into the bloodstream? A) paracrine B) autocrine C) neurotransmitter D) hormone E) neurohormone

What chemical messenger is released by a presynaptic cell? A) neurotransmitter B) neurohormone C) paracrine D) hormone E) autocrine

Which of the following enzymes catalyzes phosphorylation of a protein? A) phospholipase A2 B) tyrosine β-hydroxylase C) adenylate cyclase D) tyrosine kinase E) phosphodiesterase

Which of the following enzymes catalyzes synthesis and release of arachidonic acid? A) tyrosine β-hydroxylase B) adenylate cyclase C) phospholipase A2 D) tyrosine kinase E) phosphodiesterase

Which of the following enzymes catalyzes synthesis of epinephrine from norepinephrine? A) phenylethanolamine N-methyl transferase B) phosphoprotein phosphatase C) dopa decarboxylase D) phospholipase C E) dopamine β-hydroxylase

Which of the following enzymes catalyzes synthesis of cAMP? A) phospholipase A2 B) phosphodiesterase C) tyrosine kinase D) adenylate cyclase E) tyrosine β-hydroxylase

Which of the following enzymes catalyzes synthesis of prostaglandins and thromboxanes? A) dopamine β-hydroxylase B) phenylethanolamine N-methyl transferase C) phosphoprotein phosphatase D) cyclooxygenase E) phospholipase C

Which of the following enzymes catalyzes dephosphorylation of a protein? A) dopamine β-hydroxylase B) phospholipase C C) phosphoprotein phosphatase D) phenylethanolamine N-methyl transferase E) cyclooxygenase

Which of the following enzymes catalyzes synthesis of diacylglycerol and inositol triphosphate? A) dopamine β-hydroxylase B) phenylethanolamine N-methyl transferase C) phospholipase C D) phosphoprotein phosphatase E) cyclooxygenase

A target cell will respond to a chemical messenger once that molecule has bound to a A) complex in the nucleus. B) protein kinase. C) G protein. D) receptor. E) calcium channel

A(n) ________ is transported in the bloodstream. A) glial cell B) paracrine C) neurotransmitter D) autocrine E) hormone

Histamine is an example of a(n) A) autocrine. B) hormone. C) neurotransmitter. D) glial cell. E) paracrine

Lipid-soluble molecules are not only hydrophobic, but are also A) disaccharides. B) cellulose. C) lipophilic. D) lipophobic. E) amino acids

Catecholamines, such as dopamine, norepinephrine, and epinephrine, are derived from the amino acid A) glutamate. B) glycine. C) isoleucine. D) leucine. E) tyrosine

Identify the two enzymes involved in converting tyrosine into dopamine. A) andenylate cyclase and phospholipase C B) cyclooxygenase and lipoxygenase C) tyrosine β hydroxylase and dopa decarboxylase D) dopamine β-hydroxylase and propeptide E) cortisol and dehydroepiandrosterone

Eicosanoids are derived from what phospholipid? A) prostoglandins B) thromboxanes C) leukotrienes D) arachidonic acid E) prostacycline

Steroid messengers are derived from what precursor molecule? A) calmodulin B) tyrosine C) cholesterol D) histamine E) arachidonic acid

Catecholamines are released from the secretory cell by A) simple diffusion. B) exocytosis. C) active transport. D) endocytosis. E) signal transduction

Steroids are released from the secretory cell by A) endocytosis. B) signal transduction. C) simple diffusion. D) exocytosis. E) active transport

What protein in the blood that is relatively non-specific with respect to its ability to bind and transport chemical messengers in the blood? A) albumin B) cytokine C) protein kinase D) hemoglobin E) corticosteroid-binding globulin

As free hormones bind to their receptors and no more hormone is released from their cell of origin, the concentration of hormone bound to carrier proteins will A) become saturated. B) decrease. C) increase. D) denature. E) have a greater affinity

The strength with which a ligand (chemical messenger) will bind with a receptor is referred to as its A) prepropeptide. B) enzyme-substrate complex. C) affinity. D) prohormone. E) binding strength

As the concentration of receptors on the cell membrane decreases, the response of the target cell will A) remain the same due to saturation. B) increase its affinity. C) increase. D) oscillate with the concentration of the chemical messenger. E) decrease

Which of the following chemical messengers are lipophilic? A) thyroid hormones B) eicosanoids C) peptides/proteins D) steroids E) steroids, eicosanoids, and thyroid hormone

Which of the following chemical messengers are lipophobic? A) amino acids B) peptides/proteins and steroids C) steroids D) peptides/proteins E) thyroid hormones

Lipophobic chemical messengers communicate a message to the target cell by binding to receptors on that cell's membrane. (T/F)

The target cell of a neurotransmitter is the postsynaptic cell (T/F)

Endocrine glands secrete neurohormones (T/F)

Tyrosine is one of four amino acids that function directly as chemical messengers (T/F)

Steroid hormones are produced within cells and stored in vesicles until they are released (T/F)

Steroid hormones are derived from the hormone testosterone (T/F)

All catecholamine-secreting cells synthesize dopamine (T/F)

Eicosanoids are released immediately upon synthesis (T/F)

The location of the receptor depends on whether the messenger is lipophilic or lipophobic (T/F)

A single cell can have receptors for different messengers (T/F)

Most receptors are relatively non-specific for the ligand that will bind to them (T/F)

Receptors for lipophilic chemical messengers are only located on the surface of a cell's membrane

Tyrosine kinases are enzymes that add a phosphate group to tyrosine residues on other proteins, changing the conformation of those proteins (T/F)

The higher concentration of messenger, the greater the response in the target cell.

Enkephalin is an opiate produced in the body. When enkephalin binds to opioid receptors, it produces analgesia (a lack of pain sensation). Morphine can also bind to opioid receptors and produce analgesia. Morphine is an opiate antagonist

Thyroid hormones alter the transcription of mRNA in the target cell (T/F)

If calcium channels open in the plasma membrane, calcium ions enter the cell (T/F)

An amplifier enzyme catalyzes the synthesis of a second messenger (T/F)

In its active form, a G protein has a GDP bound to its alpha unit (T/F)

Generally, the nervous system is a more rapid means of communication than the endocrine system (T/F)

The site of communication between two neurons is called a synapse (T/F)