Nokea
Which muscle has involuntary cells that are branched and striated and connected by intercalated discs with gap junctions?
- A. Smooth muscle
- B. Cardiac muscle
- C. Skeletal muscle
- D. Epithelial muscle
Correct Answer: B
Rationale: The correct answer is B: Cardiac muscle. Cardiac muscle cells fit the description provided in the question; they are involuntary, striated, and branched, with intercalated discs containing gap junctions that allow for synchronized contractions of the heart. Smooth muscle (choice A) lacks striations and is found in the walls of internal organs. Skeletal muscle (choice C) is voluntary and attaches to bones for movement. 'Epithelial muscle' (choice D) is not a valid muscle type, making it an incorrect choice.
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Which valve prevents backflow into the atrium when the ventricles contract?
- A. Pulmonary valve
- B. Tricuspid valve
- C. Mitral valve
- D. Aortic valve
Correct Answer: B
Rationale: The tricuspid valve (right atrioventricular valve) prevents backflow into the right atrium when the right ventricle contracts. This valve ensures that blood flows in the correct direction, preventing regurgitation into the atrium. The pulmonary valve is responsible for preventing backflow into the right ventricle from the pulmonary artery. The mitral valve prevents backflow into the left atrium, and the aortic valve prevents backflow into the left ventricle from the aorta. Therefore, the correct answer is the tricuspid valve as it specifically addresses the scenario of backflow into the atrium during ventricular contraction.
Which of the following lists the structures found beneath the rib in descending order?
- A. Nerve → Artery → Vein
- B. Vein → Nerve → Artery
- C. Vein → Artery → Nerve
- D. Artery → Nerve → Vein
Correct Answer: C
Rationale: The correct order of structures found beneath the rib in descending order is Vein → Artery → Nerve. This sequence is important to remember for medical procedures like inserting a chest tube to ensure precision and avoid complications. Choice A is incorrect because the nerve is not typically the structure closest to the rib. Choice B is incorrect as the vein is usually closer to the rib than the nerve. Choice D is incorrect as the artery is usually closer to the rib than the nerve.
What type of macromolecule is hemoglobin?
- A. Carbohydrate
- B. Lipid
- C. Protein
- D. Nucleic acid
Correct Answer: C
Rationale: The correct answer is C: Protein. Hemoglobin is a protein responsible for carrying oxygen in the blood. Proteins are macromolecules made up of amino acids and play a vital role in various biological functions, including the transportation of molecules like oxygen. Choices A, B, and D are incorrect because carbohydrates, lipids, and nucleic acids are different types of macromolecules that have distinct structures and functions. Carbohydrates are mainly involved in energy storage and structural support, lipids are essential for energy storage and cell membrane structure, and nucleic acids are responsible for storing and transmitting genetic information.
Which of the following functions corresponds to the parasympathetic nervous system?
- A. It stimulates the fight-or-flight response.
- B. It increases heart rate.
- C. It stimulates digestion.
- D. It increases bronchiole dilation.
Correct Answer: C
Rationale: The parasympathetic nervous system is often referred to as the 'rest and digest' system because it promotes activities that occur when the body is at rest, such as digestion. This system helps stimulate digestion by increasing gastrointestinal motility, secretion of digestive enzymes, and blood flow to the digestive organs. Choices A, B, and D are incorrect because they are functions associated with the sympathetic nervous system, which is responsible for the 'fight-or-flight' response, increasing heart rate, and dilating bronchioles to facilitate more oxygen intake during stressful situations.
Smooth muscle is the only ____________ muscle in the body.
- A. Voluntary, striated
- B. Involuntary, non-striated
- C. Involuntary, striated
- D. Voluntary, non-striated
Correct Answer: B
Rationale: Smooth muscle is the only involuntary, non-striated muscle type in the body. It is found in organs like the intestines and blood vessels, where it controls movements without conscious effort. Choice A is incorrect because voluntary muscles are under conscious control, while smooth muscle is involuntary. Choice C is incorrect because striations are not present in smooth muscle, unlike skeletal muscle. Choice D is incorrect because smooth muscle is not voluntary and lacks striations, making it different from skeletal muscle.