The nurse is assessing a newly admitted medical patient and notes there is a depression in the lower portion of the patient's sternum. This patient's health record should note the presence of what chest deformity?

Correct Answer: B

Rationale: The correct answer is B: A funnel chest. A funnel chest, also known as pectus excavatum, is characterized by a depression in the lower portion of the sternum. This deformity causes the chest to appear sunken or caved in. The other choices are incorrect because: A) A barrel chest is associated with COPD and is characterized by an increased anterior-posterior diameter of the chest. C) A pigeon chest, also known as pectus carinatum, is characterized by a protrusion of the sternum and ribs. D) Kyphoscoliosis is a combination of kyphosis and scoliosis, involving both a curvature of the spine and rotation of the vertebrae.

Correct Answer: C

Rationale: The correct answer is C because the surface tension of the pleural fluid creates a cohesive force that keeps the lungs adhered to the thoracic wall. This, combined with the negative pressure in the pleural cavity, creates a vacuum effect that maintains the lungs' position. A) The diaphragm and intercostal muscle contractions help with breathing but do not directly secure the lungs to the thorax. B) Tight junctions between the lungs and thorax do not play a significant role in holding the lungs in place. D) Atmospheric pressure does not hold the lungs against the thoracic wall; rather, it helps with breathing by aiding in lung expansion and contraction.

Correct Answer: D

Rationale: The correct answer is D (more than 90). At a PO2 of 70 mm Hg, hemoglobin is more than 90% saturated with oxygen due to the high oxygen affinity of hemoglobin at this partial pressure. Hemoglobin exhibits near-maximal saturation at this level, promoting efficient oxygen binding and transport. Choices A, B, and C are incorrect as they do not accurately reflect the high oxygen saturation levels associated with a PO2 of 70 mm Hg.

Correct Answer: D

Rationale: The correct answer is D because the Hering-Breuer reflex is a protective mechanism that prevents lung damage from overinflation by inhibiting inspiration. When the lungs are at risk of overinflation, stretch receptors in the lung tissue send signals to the brainstem to reduce or stop inspiration, preventing excessive stretching of the alveoli. Choices A, B, and C are incorrect as the Hering-Breuer reflex is not involved in changes in blood pressure, PO2, or PCO2 regulation.

Correct Answer: D

Rationale: The correct answer is D because all the choices are structural features of the trachea. A is correct as the trachea has C-shaped cartilage rings for structural support. B is correct as the trachea contains smooth muscle fibers that help regulate airflow. C is correct as the trachea is lined with cilia that help sweep mucus and foreign particles out of the respiratory tract. Therefore, all of the above choices are structural features of the trachea, making D the correct answer.