Nokea
Which of the following is the primary physical barrier the body uses to prevent infection?
- A. mucus membranes
- B. stomach acid
- C. skin
- D. urine
Correct Answer: C
Rationale: The correct answer is 'C: skin.' The skin is the primary physical barrier the body uses to prevent infection. It acts as a protective shield that prevents harmful microorganisms from entering the body. The outer layer of the skin, known as the epidermis, acts as a tough physical barrier that blocks the entry of pathogens. Additionally, the skin has special immune cells that can help fight off invaders that manage to breach the physical barrier. Choices A, B, and D are incorrect. While mucous membranes, stomach acid, and urine play important roles in the body's defense against pathogens, the primary physical barrier is the skin, which covers the entire body and provides a robust protective barrier.
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Which of the following chambers of the heart receives blood returning from the lungs during pulmonary circulation?
- A. left atrium
- B. right atrium
- C. left ventricle
- D. right ventricle
Correct Answer: A
Rationale: The correct answer is A, the left atrium. During pulmonary circulation, oxygenated blood returns from the lungs to the heart and enters the left atrium through the pulmonary veins. The left atrium then contracts, pushing this oxygen-rich blood into the left ventricle. The left ventricle subsequently pumps this oxygenated blood out to the rest of the body through the aorta. Choices B, C, and D are incorrect because the right atrium receives deoxygenated blood from the body, the left ventricle receives oxygenated blood from the left atrium, and the right ventricle pumps deoxygenated blood to the lungs for oxygenation, respectively.
Which of the following are the two major zones of the respiratory system?
- A. left bronchus and right bronchus
- B. nose and mouth
- C. larynx and pharynx
- D. conducting and respiratory
Correct Answer: D
Rationale: The two major zones of the respiratory system are the conducting zone and the respiratory zone. The conducting zone encompasses structures like the nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles, which serve to transport air into the lungs. On the other hand, the respiratory zone includes the respiratory bronchioles, alveolar ducts, and alveoli, where the crucial gas exchange process between the air in the lungs and the blood occurs. Choices A, B, and C are incorrect as they do not represent the major zones of the respiratory system but rather individual structures within the system.
Which of the following is a type of white blood cell that plays a key role in adaptive immunity by seeking out, attacking, and destroying targeted pathogens?
- A. memory B cells
- B. neutrophils
- C. antibodies
- D. cytotoxic T cells
Correct Answer: D
Rationale: The correct answer is cytotoxic T cells. Cytotoxic T cells are a type of white blood cell that is crucial in adaptive immunity. They are specialized in recognizing and destroying infected or abnormal cells in the body. Neutrophils are primarily involved in innate immunity, providing rapid response to infections. Antibodies are proteins produced by B cells and are essential in specific immune responses, but they do not directly attack pathogens. Memory B cells are part of the adaptive immune response, responsible for mounting a quicker and stronger response upon re-exposure to a pathogen. However, they do not directly seek out and destroy pathogens like cytotoxic T cells do.
Which of the following describes the muscular organ that processes food material into increasingly smaller pieces, mixes it with saliva to create a bolus, and creates a barrier to transport food into the esophagus?
- A. pharynx
- B. tongue
- C. diaphragm
- D. stomach
Correct Answer: B
Rationale: The tongue is the muscular organ responsible for manipulating food material in the mouth, breaking it down into smaller pieces, and mixing it with saliva to form a bolus. It also plays a crucial role in pushing the food bolus towards the back of the mouth to facilitate swallowing and transport the food into the esophagus. The pharynx is involved in swallowing and directing food to the esophagus after it passes the mouth. The diaphragm is a muscle involved in the breathing process, not food processing. The stomach is an organ responsible for further digestion of food after it passes through the esophagus.
Which of the following is the cartilaginous flap that protects the larynx from water or food while still allowing the flow of air?
- A. epiglottis
- B. bronchioles
- C. epithelium
- D. tongue
Correct Answer: A
Rationale: The epiglottis is the cartilaginous flap that protects the larynx from water or food while still allowing the flow of air. When we swallow, the epiglottis covers the entrance to the larynx, preventing food or liquid from entering the airway and instead directing them towards the esophagus for digestion. Choice B, bronchioles, are small airway branches within the lungs and are not involved in protecting the larynx from food or water. Choice C, epithelium, refers to the tissue that lines the surfaces of organs and structures in the body, but it is not the specific structure that protects the larynx as described. Choice D, tongue, plays a role in taste, speech, and swallowing, but it is not the cartilaginous flap that protects the larynx.