In medical terminology, what is the name for the condition in which there is a decreased level of oxygen in the blood?

Introduction / Context:
Medical terminology uses specific prefixes and roots to describe different conditions. Hypoxemia is a term that combines hypo, meaning low, with ox, referring to oxygen, and emia, referring to blood. This question asks you to identify which term correctly names decreased oxygen in the blood and to distinguish it from other similar sounding conditions.

Given Data / Assumptions:
- Several conditions involving blood are listed: hematemesis, hypercapnia, hemoptysis, and hypoxemia.
- The question focuses on reduced oxygen levels in blood.
- We assume standard meanings of these medical terms.

Concept / Approach:
Hypoxemia refers specifically to a lower than normal partial pressure of oxygen in arterial blood. It may result from lung diseases, ventilation perfusion mismatch, or high altitude. Hematemesis refers to vomiting blood, usually from a stomach or esophageal source. Hemoptysis refers to coughing up blood from the respiratory tract. Hypercapnia means elevated carbon dioxide levels in the blood. Only hypoxemia directly refers to decreased oxygen.

Step-by-Step Solution:
Step 1: Break down the term hypoxemia into hypo (low), ox (oxygen), and emia (blood), which indicates low oxygen in the blood. Step 2: Recognize that hematemesis combines hema (blood) with emesis (vomiting), describing vomiting of blood. Step 3: Understand that hypercapnia combines hyper (high) with capnia (carbon dioxide), describing excess carbon dioxide in blood. Step 4: Note that hemoptysis combines hema (blood) with ptysis (spitting or coughing), indicating coughing up blood. Step 5: Select hypoxemia as the correct term for decreased oxygen in blood.

Verification / Alternative check:
Medical dictionaries and physiology texts define hypoxemia as abnormally low oxygen content in arterial blood. They also list hematemesis under gastrointestinal bleeding, hemoptysis under respiratory symptoms, and hypercapnia as a respiratory failure sign related to carbon dioxide, not oxygen. This confirms that hypoxemia answers the question.

Why Other Options Are Wrong:
Option A: Hematemesis is vomiting of blood and does not refer to oxygen levels in blood.
Option B: Hypercapnia is elevated carbon dioxide in blood, which is a different gas and abnormality from low oxygen.
Option C: Hemoptysis is coughing up blood from the respiratory tract and does not directly describe blood gas levels.

Common Pitfalls:
Similar sounding terms can be confusing, especially when they share prefixes such as hema. Focusing on root meanings for each part of the word helps avoid confusion. Remember that ox in hypoxemia refers to oxygen and capnia refers to carbon dioxide. Matching prefixes and suffixes to their meanings is a useful strategy in medical vocabulary questions.

Final Answer:
The correct answer is hypoxemia, which is an abnormally low oxygen level in arterial blood because this term directly describes decreased oxygen in the blood.