Which valves are connected to chordae tendineae?
A
B
C
D
E
Correct Answer : A,C
A. Sinoatrial (SA) node: This structure is located in the right atrium near the opening of the superior vena cava. It initiates the electrical impulse that starts each heartbeat. Because it has the highest intrinsic firing rate (about 60–100 beats per minute), it determines the heart’s rhythm and is therefore called the pacemaker of the heart.
B. Atrioventricular (AV) node: The AV node is located in the lower part of the right atrium near the interatrial septum. Its main function is to delay the electrical impulse coming from the atria before passing it to the ventricles. This delay allows the ventricles time to fill with blood before they contract. It can act as a backup pacemaker, but its intrinsic rate is slower (40–60 bpm), so it is not the primary pacemaker.
C. Atrioventricular (AV) bundle (Bundle of His): This structure carries the impulse from the AV node into the interventricular septum. It is the only normal electrical connection between the atria and ventricles. It conducts impulses but does not normally initiate them, so it is not the pacemaker.
D. Bundle branches: These pathways run down the right and left sides of the interventricular septum. They rapidly conduct electrical impulses toward the apex of the heart. Their role is conduction, not impulse generation, so they are not pacemakers.
E. Purkinje fibers spread throughout the ventricular myocardium. They distribute the impulse to ventricular muscle cells, causing coordinated ventricular contraction. Although they have an intrinsic firing ability, it is very slow (20–40 bpm) and only takes over if higher pacemakers fail. Therefore, they are not the normal pacemaker.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. Heme does not get converted into amino acids. Instead, heme is split into iron and a porphyrin ring. The iron is stored or reused, and the porphyrin ring is converted into biliverdin and then bilirubin for excretion. This pathway is completely different from protein hydrolysis.
B. Globin: The blue box leads to a pathway labeled “hydrolyzed to free amino acids.” This describes what happens to the globin portion of hemoglobin. Globin consists of protein chains, and when red blood cells are broken down, these protein chains are hydrolyzed into individual amino acids. The body then reuses these amino acids to build new proteins or for other metabolic functions. Therefore, box 2 represents globin.
C. Erythropoietin is not part of hemoglobin structure. It is a hormone that regulates red blood cell production. It is not broken down during
Correct Answer is B
Explanation
A. Tongue: This muscular organ facilitates mechanical digestion and bolus formation within the oral cavity. It contains gustatory receptors and serous glands but lacks hepatocytes for biochemical synthesis. It does not participate in the production or secretion of biliary salts or pigments.
B. Liver: Hepatocytes synthesize bile acids from cholesterol to facilitate the emulsification of dietary lipids. This accessory organ secretes the fluid into the biliary tree for eventual transport to the duodenum. It is the primary site for the biochemical production of bile.
C. Pancreas: This dual-function gland secretes alkaline juice containing digestive enzymes and bicarbonate into the small intestine. Its exocrine component focuses on proteases, lipases, and amylases rather than bile. It regulates blood glucose via endocrine secretions but does not produce biliary fluids.
D. Salivary glands: These exocrine glands produce saliva containing ptyalin and lingual lipase for initial chemical digestion. They maintain oral hygiene and lubricate the food bolus for deglutition. They lack the specialized metabolic machinery required to synthesize bile acids or bilirubin.
E. Gallbladder: This hollow organ functions exclusively as a reservoir for the concentration and storage of bile. It undergoes cholecystokinin-induced contraction to release bile into the common bile duct. While it manages bile distribution, it possesses no secretory tissue for bile synthesis.
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