Examkin

Question

Difficulty: HardCirculatory and Transport Systems in Animals

A red blood cell returning from the lower limb muscle of a mammal travels toward the lungs to release carbon dioxide and pick up oxygen. Which of the following is the correct sequential order of anatomical structures through which this cell passes?

  1. 1Inferior vena cava
  2. 2Tricuspid valve
  3. 3Pulmonary semilunar valve
  4. 4Pulmonary artery

Answer

The correct sequence of blood flow from the lower body to the lungs is: Inferior vena cava → Tricuspid valve → Pulmonary semilunar valve → Pulmonary artery.
Systemic venous return from lower tissues enters the heart through the inferior vena cava into the right atrium. During atrial emptying, blood passes through the tricuspid valve into the right ventricle. Upon right ventricular systole, high pressure opens the pulmonary semilunar valve, propelling blood into the pulmonary artery toward the lungs.

Step-by-Step Solution

1
Identify the entry vessel for systemic venous blood returning from the lower body.
Deoxygenated blood flows through systemic veins into the inferior vena cava.
The inferior vena cava collects venous blood from organs and muscles located below the diaphragm and empties into the right atrium.
2
Trace the pathway of blood moving from the right atrium to the right ventricle.
Blood flows through the open tricuspid valve into the right ventricle.
The tricuspid valve acts as the gateway between the right atrium and right ventricle, preventing ventricular-to-atrial backflow during systole.
3
Determine the valve through which blood is ejected out of the right ventricle.
Right ventricular contraction forces blood past the pulmonary semilunar valve.
The pulmonary semilunar valve opens in response to increased ventricular pressure, allowing blood to leave the heart without backflowing during diastole.
4
Identify the vessel conveying blood directly from the heart to the lungs.
Blood flows into the pulmonary artery toward the pulmonary capillary beds.
The pulmonary artery is the primary vessel transporting deoxygenated blood away from the heart to the respiratory exchange surfaces.

Key Concept

Mammalian Right Heart Deoxygenated Blood Pathway
Rate this question

Topics

Circulatory and Transport Systems in Animals

More questions from this topic