MCAT® ExamBiological and Biochemical Foundations of Living SystemsEasy
A patient is diagnosed with a rare genetic disorder that results in a defect in the synthesis of hemoglobin. Specifically, the patient's red blood cells produce hemoglobin molecules that are unable to effectively bind oxygen at normal physiological partial pressures. This defect most directly impacts which function of the circulatory system?
- ARegulation of blood pressure
- BTransport of oxygen to tissues
- CTransport of nutrients to tissues
- DRemoval of metabolic waste products
Show answer & explanationAnswer & explanation
Correct answer: B. Transport of oxygen to tissues
Hemoglobin is the protein in red blood cells primarily responsible for binding and transporting oxygen from the lungs to the body's tissues. A defect that prevents hemoglobin from effectively binding oxygen directly impairs the circulatory system's ability to deliver oxygen.
Why the other options are wrong
- A. Blood pressure regulation involves vascular tone, heart rate, and blood volume, not directly hemoglobin's oxygen-binding capacity.
- C. Nutrient transport is primarily carried out by plasma and other blood components, not directly by hemoglobin.
- D. Waste product removal is handled by the kidneys and liver, and CO2 by hemoglobin, but the primary issue described is oxygen binding.
Hemoglobin Oxygen Transport
Hemoglobin is a metalloprotein in red blood cells that reversibly binds oxygen, primarily in the lungs, and transports it to tissues throughout the body. Its oxygen-binding affinity is influenced by factors like pH, temperature, and CO2 levels.
- Located in red blood cells.
- Binds oxygen in the lungs.
- Releases oxygen in tissues.
- Crucial for cellular respiration.
Memory trick: Circulatory System: 'Carry' 'Oxygen' and 'Nutrients', 'Clear' wastes.