Of the 11 major body systems, which is the least involved in maintaining homeostasis?

A. Movement: This is a primary function; skeletal muscles move the skeleton, and smooth muscles move substances through organs.

B. Protection: While muscles provide some padding, protection is considered a primary function of the skeletal system (rib cage, skull) and integumentary system (skin).

C. Heat production: Muscles produce a significant amount of heat as a byproduct of contraction (thermogenesis), which is vital for maintaining body temperature.

D. Posture: Skeletal muscles maintain partial contraction (tonus) to keep the body upright and stable.

Rationales for correct answers:

• Blood Cultures: The client is presenting with systemic symptoms of infection (fever, chills, fatigue). Blood cultures are standard practice when a lower respiratory infection is suspected to determine if the causative agent has entered the bloodstream (bacteremia) and to guide systemic antibiotic therapy.
• Complete Blood Count (CBC): A CBC is essential to evaluate the white blood cell (WBC) count. An elevation in WBCs (leukocytosis) and a "left shift" (increase in immature neutrophils) would support the diagnosis of an active bacterial infection like pneumonia.
• Sputum culture and sensitivity: The client reports a "productive purulent cough." Collecting and analyzing the sputum is the most direct way to identify the specific microorganism causing the respiratory infection and to determine which antibiotics will be most effective at treating it.

Rationales for incorrect answers

• Pulmonary Function Test (PFT): These are used to diagnose chronic conditions like COPD or asthma. They are not appropriate for a client in acute respiratory distress with a suspected infection, as the client would be unable to perform the necessary breathing maneuvers.
• Pulmonary angiography: This is an invasive procedure used to visualize blood flow in the lungs, typically to diagnose a pulmonary embolism. The client’s purulent cough and fever point toward an infectious process (pneumonia) rather than a vascular one.
• Preparation for chest tube insertion: There is no evidence of a pneumothorax (collapsed lung) or a large pleural effusion. Breath sounds are decreased, but the presence of crackles and purulent sputum suggests consolidation from infection rather than a need for surgical drainage.
• Peak flow meter: This is a tool used by patients with asthma to monitor their daily airway patency. It is not a diagnostic tool for acute infectious pneumonia.