Which organ system(s) have a lumen that is considered part of the external Choos
ID: 3475168 • Letter: W
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Which organ system(s) have a lumen that is considered part of the external Choose all correct answers. environm ent? a. Cardiovascular Digestive c. Respiratory d. Urinary e. Reproductive f. Endocrine -2 13. The process where substances in the lumen of the nephron (kidney) leave it to enter the blood is called while the name of the process where substances from blood enter the lumen of the gastrointestinal tract is called a. Reabsorption; Filtration b. Reabsorption; Secretion c. Absorption; Filtration d.Absorption; Secretion e. Secretion; Reabsorption e. Secretion; Filtration . Ouabain (digitalis) is a drug that inhibits the Na+/K+ ATPase. If this drug is present and active, which the following would be true regarding the resting membrane potential? a Resting membrane potential would become less negative. b/ Resting membrane potential would become more negative. c. There would be no change in the resting membrane potential.Explanation / Answer
12.
The organs like heart, lungs, blood vessels and intestines are hollow. These organs within the body cavity enclose compartment called lumen. This lumen is filled with air or fluid. For example, blood vessels are filled with fluid called blood. In some organs, the lumen is extended into external environment. The substance carried in the lumen is truely a component of external environment but is not part of internal environment until they cross the wall of the organ. The lumen of digestive system is considered as the component of external environment. Therefore, option b is correct.
13.
The process of substances of nephron lumen entering into blood is called reabsorption. This is because, the excess solutes and water are absorbed once during filtration by kidneys and further in nephrons, the tubular reabsorption takes place to reabsorb the ions and water and are released into blood. The process of movement of substances from blood into lumen of gastrointestinal tract is known as secretion. Secretion is th eprocess of producing digestive enzymes, mucus and saliva to mix with the ingested food and further processed for digestion and absorption. Therefore, the option b is correct.
14.
The drugs such as Ouabain and Digitalis used in the treatment of the heart disease because they make the heart muscles to contract by inhibiting the Na+ pump in these cells. The Na+ pump when not in a position to work at its full capacity, the electro chemical gradient of Na+ pump generated is less steep in treated cells and the resting membrane potential becomes less negative. Therefore, option a is correct.
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