Nokea
When a blockage forms in a coronary artery, reducing blood flow to the heart muscle, this condition is called:
- A. Atherosclerosis
- B. Myocardial infarction
- C. Angina pectoris
- D. Heart murmur
Correct Answer: B
Rationale: A myocardial infarction, commonly known as a heart attack, occurs when a blockage forms in a coronary artery, leading to reduced blood flow to the heart muscle. Atherosclerosis refers to the buildup of plaque in the arteries, which can lead to blockages but is not the name for this specific condition. Angina pectoris is chest pain or discomfort due to inadequate blood supply to the heart muscle, which is a precursor to a heart attack but not the name for this condition. A heart murmur is an abnormal sound heard during a heartbeat, often due to turbulent blood flow, and is not related to a blockage in a coronary artery.
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Which type of waves travel by causing particles in the medium to vibrate parallel to the direction of wave travel?
- A. Transverse waves
- B. Longitudinal waves
- C. Surface waves
- D. Electromagnetic waves
Correct Answer: B
Rationale: Longitudinal waves are waves in which particles of the medium vibrate parallel to the direction of wave travel. These waves are characterized by compressions and rarefactions in the medium, where particles move back and forth in the same direction as the wave. Transverse waves, on the other hand, cause particles to vibrate perpendicular to the direction of wave travel. Surface waves combine both longitudinal and transverse motion, making them different from pure longitudinal waves. Electromagnetic waves, unlike longitudinal and transverse waves, do not require a medium and can travel through a vacuum.
Endotoxins are toxic substances released by:
- A. Viruses
- B. Bacteria (gram-positive)
- C. Bacteria (gram-negative)
- D. Parasites
Correct Answer: C
Rationale: Endotoxins are toxic substances that are part of the outer membrane of the cell wall of gram-negative bacteria. These toxins are released when the bacteria are destroyed or during bacterial growth. Endotoxins can cause a variety of harmful effects in the host, including fever, inflammation, and septic shock. Viruses do not produce endotoxins; they are typically associated with producing viral proteins that can be toxic to host cells. Gram-positive bacteria produce exotoxins, which are different from endotoxins found in gram-negative bacteria. Parasites, though capable of causing diseases, are not typically associated with the production of endotoxins.
Which hormone is responsible for regulating blood sugar levels and is produced by the pancreas?
- A. Insulin
- B. Glucagon
- C. Testosterone
- D. Estrogen
Correct Answer: A
Rationale: Insulin is the correct answer. It is the hormone produced by the pancreas that regulates blood sugar levels by facilitating the uptake of glucose from the blood into cells for energy production or storage. Glucagon, also produced by the pancreas, has the opposite effect of increasing blood sugar levels by promoting the release of stored glucose from the liver. Testosterone and estrogen are sex hormones produced by the testes and ovaries, respectively, and are not directly involved in regulating blood sugar levels.
Which types of waves are capable of interference and diffraction?
- A. Longitudinal waves only
- B. Transverse waves only
- C. Electromagnetic waves only
- D. Both longitudinal and transverse waves
Correct Answer: D
Rationale: Both longitudinal and transverse waves are capable of interference and diffraction. Interference occurs when two or more waves overlap and combine, either constructively (increasing amplitude) or destructively (decreasing amplitude). Diffraction is the bending of waves around obstacles or through openings, which can occur with both longitudinal and transverse waves. Choice A is incorrect because only stating longitudinal waves can undergo interference and diffraction is inaccurate. Choice B is also incorrect as transverse waves, not just longitudinal waves, can exhibit these phenomena. Choice C is incorrect because electromagnetic waves are a broad category that includes both longitudinal and transverse waves, so it is not exclusive to either type. The correct answer is D because both longitudinal and transverse waves can demonstrate interference and diffraction.
What is the term for the process of exchanging gases (oxygen and carbon dioxide) between the blood and the tissues?
- A. Inhalation
- B. Exhalation
- C. External respiration
- D. Internal respiration
Correct Answer: C
Rationale: External respiration is the correct term for the process of exchanging gases (oxygen and carbon dioxide) between the blood and the tissues. It specifically refers to the exchange of gases that occurs in the lungs, where oxygen is absorbed into the bloodstream and carbon dioxide is released from the bloodstream to be exhaled. Inhalation and exhalation, choices A and B, are phases of the breathing process that involve the intake and expulsion of air into and out of the lungs, respectively. Internal respiration, choice D, is the process of gas exchange that happens at the cellular level between the blood and body tissues, not between the blood and the lungs or tissues as in external respiration. Therefore, external respiration is the most appropriate term for the described gas exchange process in the question.