a. Oxygenb. Ribosomesc. Amphipathic lipidsd. LigandsANS: DLigands are specific molecules that can bind with receptors on the cell membrane.Oxygen moves by diffusion; it does not bind to receptors.Ribosomes make proteins and are not involved in binding.Amphipathic lipids are a portion of the cell membrane.REF: p. 116A nurse is reviewing a report from a patient with metastatic cancer. What finding would support the diagnosis of metastatic cancer? Alterations in extracellular matrix that include:a. Decreased fibronectinb. Increased collagenc. Decreased elastind. Increased glycoproteinsANS: AReduced amounts of fibronectin are found in some types of cancerous cells, allowing cancer cells to travel, or metastasize.Collagen provides strength, and its breakdown is associated with osteoarthritis, not cancer.Elastin is found in the lungs and allows tissues to stretch; it is not associated with cancerous cells.Decreased, not increased, glycoproteins are associated with cancerous cells.REF: p. 87Which form of cell communication is used to relate to other cells in direct physical contact?a. Cell junctionb. Gap junctionc. Desmosomesd. Tight junctionsANS: ACell junctions hold cells together and permit molecules to pass from cell to cell.Gap junctions allow communication from the inside of one cell to the inside of another.Desmosomes are not involved in communication, but allow cells to hold together.Tight junctions are barriers that prevent movement of some substances and leakages of others.REF: p. 98Pancreatic beta cells secrete insulin, which inhibits secretion of glucagon from neighboring alpha cells. This action isan example of which of the following signaling types?a. Paracrineb. Autocrinec. Neurohormonald. Hormonal
ANS: AParacrine signaling involves the release of local chemical mediators that are quickly taken up, destroyed, or immobilized, as in the case of insulin and the inhibition of the secretion of glucagon.When cells produce signals that they themselves respond to, autocrine signaling is used.Neurohormonal signaling involves secretion of hormones into the bloodstream by neurosecretory hormones.Hormonal signaling involves specialized endocrine cells that secrete hormone chemicals released by one set of cellsthat travel through the tissue through the bloodstream to produce a response in other sets of cells.REF: p. 119In cellular metabolism, each enzyme has a high affinity for a:a. Soluteb. Substratec. Receptord. RibosomeANS: BEach enzyme has a high affinity for a substrate, a specific substance converted to a product of the reaction.Solutes are small particles that pass through the cell membrane.A receptor is a site on the cell wall that allows transport into the cell.Ribosomes are located inside the cell and are not related to the work of enzymes.