Physiology Chapter 5

Receptors for lipophobic messengers are typically located where in the cell? A. rough endoplasmic reticulum B. cytosol C. nucleus D. plasma membrane

Which of the following are proteins on a target cell that specifically recognize and bind only one messenger or a class of messengers? A. neurotransmitters B. albumins C. enzymes D. receptors

Chemical messengers derived from cholesterol fall under which of the following categories? A. amine messengers B. steroid messengers C. peptide/protein messengers D. eicosanoid messengers

Which of the following chemical messengers is characteristically released from an endocrine gland? A. cytokines B. neurotransmitter C. hormone D. neurohormone

Hormones can be transported in blood in dissolved form or bound to __________. A. growth factors B. enzymes C. receptors D. carrier proteins

What type of hormones bind to receptors located on the cell membrane? A. lipid-soluble hormones, such as thyroid hormones and cortisol B. water-soluble hormones, such as insulin and epinephrine

Which intracellular substance degrades cAMP, thus inactivating the response to a hormone? A. phosphodiesterase B. adenylate cyclase C. phospholipase C D. protein kinase C

Growth factor hormones, such as insulin, bind to which type of receptor? A. intracellular receptors B. G proteins C. tyrosine kinase receptors

Which is the correct order of events for hormones activating Gs proteins? A. activation of G protein, binding of GTP, activation of phospholipase C, activation of DAG and IP3 B. activation of G protein, binding of GTP, activation of adenylate cyclase, conversion of ATP to cAMP C. activation of a G protein, tyrosine kinase receptor, phosphorylation of intracellular proteins

Which second messenger causes the release of calcium from the endoplasmic reticulum? A. tyrosine kinase B. IP3 C. cAMP D. DAG

Which of the following adrenergic receptors increase cAMP levels? A. β receptors B. α2 receptors C. α1 receptors

Where in the cell are receptors for cholesterol derived chemical messengers typically located? A. plasma membrane B. golgi apparatus C. microtubules D. nucleus/cytosol

The strength of binding between a messenger and its receptor is known as __________. A. specificity B. saturation C. up-regulation D. affinity

One of the striking features of second messengers is the ability to elicit a marked response on a target cell by small changes in the concentration of a chemical messenger. This phenomenon is known a(n) __________. A. signal amplification B. down-regulation C. signal transduction D. up-regulation

A chemical messenger that is released into the blood stream to travel to its target would be categorized as a(n) __________. A. neurotransmitter B. paracrine C. autocrine D. hormone

Chemical messengers that bind to a receptor, preventing a biological response are __________. A. agonists B enzymes C. antagonists D. blockers

Direct communication between adjacent cells is provided by __________. A. gap junctions B. tight junctions C. paracrines D. desmosomes

A change in electrical properties of the cell is most likely the result of a chemical messenger binding to which type of receptor? A. an enzyme-linked receptor B. a G-protein linked-receptor C. an intracellular receptor D. an ion channel

The binding of chemical messengers to receptors produces a response inside the target cell through a variety of mechanisms referred to as __________. A. feedback B. inhibition C. depolarization D. signal transduction

Neurohormones ________________. A. bind receptors located on neurons only B. are exocytosed by neurons C. travel a short distance to reach target cells D. are produced by epithelial cells

Which of the following chemical messengers communicate with neighboring cells? A. vasopressin B. epinephrine C. insulin D. vascular endothelial growth factor

A neuroscientist was running an experiment to determine how much dopamine was present in a group of dopaminergic (dopamine secreting) neurons in a particular brain region. She knew that some of the cells in a nearby brain region secreted norepinephrine. She took a sample of cells from the dopaminergic region and a sample of cells from the region where the cells secreted norepinephrine, keeping them separate from one another. She put them into a solution that degraded the phospholipids of the cells in order to release the intracellular contents into the solution. When she tested each of the two solutions of cellular contents, what do you think she found? A. Dopamine was present in the solution containing the dopaminergic cells and the cells that secreted norepinephrine. B. Dopamine did not appear to be present in either of the solutions because all the dopamine was contained in vesicles, preventing it from being measured. C. Dopamine was present only in the dopaminergic cells, but not in the cells that secrete norepinephrine.

Steroid hormones are exocytosed from the cells. A. true B. false

Why do lipophilic hormones require carrier proteins while being transported in the blood? A. Because lipophilic hormones are too small and the carrier proteins make them larger. B. Because lipophilic hormones are inactive without carrier proteins. They cannot bind to their target cell receptors without being bound to the carrier. C. Because lipophilic hormones make the blood too acidic and the carrier proteins act as a buffer to prevent acidemia. D. Because lipophilic hormones don't dissolve well in blood plasma.

If a person had a disease in which carrier proteins were nonfunctional, what might happen? A. The person's blood could not transport hydrophobic hormones, but would still be able to transport all hydrophilic hormones. B. The blood could not transport any hormones at all. C. The person's blood could not transport hydrophobic and some hydrophilic hormones. D. All hormones would be preserved in the blood for much too long (their half-lives would be overly extended).

Which of the following hormones has intracellular receptors? A. epinephrine B. insulin C. cortisol

What is the mechanism of action of lipid-soluble hormones? A. activation of genes, which increases protein synthesis in the cell B. increasing protein kinases C. phosphorylation of intracellular proteins

After a lipid-soluble hormone is bound to its intracellular receptor, what does the hormone complex do? A. hosphorylates a protein B. acts as a transcription factor and binds to DNA, activating a gene C. activates a protein kinase D. directly alters protein synthesis at the ribosome

Which hormone's receptor is always bound to DNA, even when the receptor is empty? A. thyroid hormone B. cortisol C. insulin

What keeps intracellular receptors from binding to DNA before a hormone binds to the receptor? A. chaperone proteins (chaperonins) B. Receptors can't enter the nucleus until the hormone is bound to it. C. transcription factors

G proteins are second messengers A. true B. false

If all the adrenergic receptors on a target cell are bound to ligand, this is referred to as __________. A. affinity B. saturation C. down-regulation D. up-regulation

Which of the following statements is FALSE regarding target cell receptors? A. Target cells can add receptors to their membranes in an effort to increase ligand binding and signal transduction. B. Target cell receptors are specialized phospholipids. C. Target cells may possess receptors for more than one type of chemical messenger. D. The response of a target cell increases as the concentration of chemical messenger increases.

If a patient were experiencing a less than ideal reaction to a drug, you could try to treat the patient with another drug which interfered with the first drug. Which of the following types of drug would be your best option for this? A. an antagonist drug with equal affinity B. an agonist drug with greater affinity C. an agonist drug with equal affinity D. an antagonist drug with greater affinity

Beta receptors are __________. A. cholinergic receptors B. G protein-linked receptors C. predominantly located in blood vessels D. nuclear receptors

Which type of receptor is also called a "fast channel"? A. enzyme-linked receptor B. G protein-linked receptor that opens or closes an ion channel C. ligand-gated ion channels D. G protein-linked receptor that activates an enzyme

Which of the following statements about G proteins is true? A. There is only one G protein associated with any given G protein-linked receptor. B. G proteins are located on both sides of the plasma membrane (facing the ECF and facing the ICF). C. G proteins can increase or decrease enzyme activity. D. G proteins can act as second messengers.

In which of the following hormones would signal transduction be impaired if there were an intracellular shortage of GTP? A. estrogen B. insulin C. thyroxine D. vasopressin

Which of the following second messengers activates protein kinase A? A. diacylglicerol (DAG) B. cyclic adenosine monophosphate (cAMP) C. cyclic guanosine monophosphate (cGMP) D. inositiol triphosphate (IP3)

Phospholipase C is an enzyme that functions to produce which of the following second messengers? A. calcium B. cyclic adenosine monophosphate (cAMP) C. diacylglicerol (DAG) D. cyclic guanosine monophosphate (cGMP)

Communication in the nervous system generally involves __________, which is very fast and typically of short duration. A. activation of second messengers like cAMP and cGMP B. altered mRNA transcription C. the opening and closing of ion channels D. altering enzyme concentrations within neurons

Which of the following correctly pairs the organ system with its appropriate characteristic? A. nervous system; secretory cell = endocrine cell B. endocrine system; longer duration of effect C. endocrine system; target cell = neuron, muscle, or gland D. nervous system; secreted messenger = hormone

Adenylate cyclase is __________. A. a class of chemical messenger B. activated by a second messenger C. an enzyme D. a G protein

The ultimate problem with cholera that can lead to death is __________. A. severe dehydration and electrolyte imbalance B. only water loss C. fluid loss with electrolyte concentrations remaining normal D. only electrolyte loss

The loss of chloride ions is occurring as a result of an continuously open __________, found in certain intestinal epithelial cells. A. sodium pump B. ATP dependent sodium/potassium pump C. chloride channel protein D. potassium pump

The main purpose of the chloride channel proteins on the apical surface of the intestinal epithelial cells is to create an osmotic gradient that ultimately causes __________ to move through the intestinal epithelium and into the intestinal lumen to assist in the formation of mucus. These are the same chloride channel proteins, adversely affected in cystic fibrosis. A. water B. sodium C. potassium D. calcium

The main physiologic mechanism used to control the opening of the chloride channel protein is through the use of __________. A. G protein-linked receptors B. potassium pump C. sodium pump D. enzyme-linked receptors

The main factor that causes cholera is the overstimulation of __________ by the __________. A. adenylate cyclase; cholera toxin B. guanylate cyclase; the bacterium Vibrio cholerae C. guanylate cyclase; cholera toxin D. adenylate cyclase; the bacterium Vibrio cholerae

The normal physiologic mechanism used by G protein-linked receptors is for a ligand to bind to the G protein-linked receptor; this in turn activates __________ located in the intracellular side of the plasma membrane, which eventually leads to the physiologic effector action. A. G protein B. diacylglycerol C. cyclic AMP D. inositol triphosphate

Cholera toxin bypasses the normal sequential cascade of events involving G protein activation. The __________subunit of cholera toxin enters into the cell and directly activates __________. This leads to a non-physiologic (non-homeostatic) action of inappropriately maintaining the chloride channel proteins open. This causes excessive __________, sodium, and water to leave the intestinal epithelial cells. A. A; diacylglycerol; chloride B. B; G protein; chloride C. A; G protein; chloride D. B; inositol triphosphate; calcium

A defect in the chloride channel protein, causing it to not open, will _________ the chloride, sodium, and water loss in cholera. However, it will also cause the individual to have __________ mucus. A. prevent; thick B. allow; thin C. allow; thick D. prevent, thin

A drug that prevents the cholera toxin from attaching to the __________ in the intestinal epithelial cell could be a useful treatment. A. AMP B. ganglioside C. protein D. phospholipid

The best method to reduce the spread of cholera is to __________. A. never travel to underdeveloped countries B. give everyone antacids C. provide properly treated water supplies D. give everyone antibiotics

A prostaglandin is a type of ____________, which is a type of lipid. A. steroids B. eicosanoid C. leukotrienes D. protein

There are different prostaglandins, some perform __________ functions and some perform __________ functions. A. no; homeostatic B. enzyme; inflammatory C. nerve; hormonal D. homeostatic; inflammatory

The enzyme phospholipase A2 is responsible for __________ the __________ acid from membrane phospholipids. This fatty acid acts as the precursor molecule to form prostaglandins. A. releasing; leukotrienes B. attaching; arachidonic C. releasing; arachidonic

__________ is acted upon by the enzyme __________ to form __________. A. Linoleic acid; cyclooxygenase; prostaglandins B. Arachidonic acid; cyclooxygenase; prostaglandins C. Arachidonic acid; phospholipase A2; leukotrienes D. Arachidonic acid; lipoxygenase; prostaglandins

There are __________ forms of cyclooxygenase (COX). A. four B. two C. three D. five

An NSAID (Non-steroidal Anti-Inflammatory Drug) is a type of enzyme inhibitor that __________ of cyclooxygenase. Thus, it __________ prostaglandin formation. A. inhibits the activity; increases B. inhibits the activity; decreases C. enhances the activity; decreases D. enhances the activity; increases

Aspirin is a type of __________. A. neurotransmitter B. eicosanoid C. steroidal anti-inflammatory drug (SAID) D. nonsteroidal anti-inflammatory drug (NSAID)

__________ is the cyclooxygenase that is associated with pain and inflammation. A. COX-1 B. thromboxane C. COX-3 D. COX-2

Aspirin inhibits __________, and has the side effect of gastric bleeding and ulcers. A. only COX-1 B. none of the COX enzymes C. both COX-1 and COX-2 D. only COX-2

Vioxx inhibits __________, and has the side effect of increasing the risk of __________. A. only COX-1; heart attacks and strokes B. only COX-2; heart attacks and strokes C. both COX-1 and COX-2; gastric bleeding and ulcers D. both COX-1 and COX-2; heart attacks and strokes