Exam 5: Cell Signalling in Physiology

Type 2 diabetes mellitus is a disease in which the effect insulin has on the cell is reduced,despite consistent levels of circulating insulin (in the beginning of the disease).Which of the following could possibly explain this phenomenon?

Insulin is a protein hormone with mostly hydrophilic amino acids.Which is the most likely description of its receptor?

Which of the following is NOT typically true about G proteins?

Endogenous opioid molecules reduce pain sensation.Morphine,a common analgesic,is an agonist for endogenous opioid receptors.

Epinephrine activates the cyclic AMP pathway in liver cells.In this example,epinephrine is a(n)________ and cAMP is a(n)________.

Which of these is a lipid-soluble messenger?

With regard to the action of hormones and neurotransmitters on cellular receptors,which of these describes "amplification"?

Phosphorylation is a necessary component of any enzyme activation.

Designing a drug that blocked the release of eicosanoids would be an effective therapy for both pain and inflammation.

Which is NOT typically a step in the cAMP second-messenger system?

At very low concentrations,epinephrine causes an artery to dilate.At higher concentrations epinephrine causes the same artery to constrict.How can these different effects be explained?

One way that cells can increase their responsiveness to an external chemical regulator is by

Molecule X is some sort of chemical messenger.  Its receptor resides within the nucleus and once the receptor is bound to X,gene transcription occurs.  Molecule X might be a(n)

Amplification of a second-messenger cascade can take place at which level of a signal cascade?

Which of the following might be phosphorylated in a signaling pathway?

What is a role of calcium ions in the second-messenger cascade involving phospholipase C,diacylglycerol,and inositol trisphosphate?

An adipose (fat)cell responds to the presence of the hormone epinephrine by increasing cytosolic cyclic AMP production,which leads to the catabolism of both glycogen and fat.What is the most likely explanation for this phenomenon?

Amplification during a second-messenger cascade is beneficial because amplification

Naloxone (Narcan)is an antagonist to the opioid receptor,the same receptor to which heroin is an agonist.If both heroin and naloxone were in the bloodstream,what would the user experience?

Drug Y is a drug that is used to increase the force of contraction achieved by heart muscle tissue.In the absence of the drug,epinephrine increases heart contractility through a signaling pathway that involves a receptor and cAMP.Which of the following are plausible mechanisms of action for Y?