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Difficulty: MediumCirculatory and Transport Systems in Animals

Which of the following anatomical features prevents the mixing of oxygenated and deoxygenated blood in the mammalian heart?

  1. A complete muscular interventricular septum that fully divides the ventricle into two separate chambersAnswer
  2. B
    A central single ventricle equipped with a muscular ridge that partially separates blood flow during systole
  3. C
    A prominent sinus venosus that collects deoxygenated blood before discharging into the left atrium
  4. D
    A three-chambered heart arrangement where pulmonary and systemic venous returns merge in a shared atrium

Answer

A complete muscular interventricular septum that fully divides the ventricle into two separate chambers
In the mammalian heart, a complete muscular interventricular septum separates the ventricles into distinct right and left chambers. Deoxygenated blood arriving via the right atrium and right ventricle is pumped exclusively to the lungs, while oxygenated blood arriving via the left atrium and left ventricle is pumped to systemic tissues, maintaining complete separation.

Step-by-Step Solution

1
Analyze the circulatory requirement of mammals
Mammals are endothermic organisms requiring high metabolic rates and efficient oxygen delivery to body tissues.
High oxygen demands require complete double circulation with zero mixing of oxygenated and deoxygenated blood.
2
Examine cardiac anatomical adaptations across vertebrate classes
Fish have 2 chambers, amphibians have 3 chambers (2 atria, 1 ventricle), non-avian reptiles have partially partitioned 3-chambered hearts, and mammals/birds have 4 completely separate chambers (2 atria, 2 ventricles).
The complete interventricular septum isolates systemic deoxygenated blood in the right heart from pulmonary oxygenated blood in the left heart.

Key Concept

Cardiac chamber evolution and prevention of blood mixing in mammalian double circulation
Estimated Time:1m 0s
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Topics

Circulatory and Transport Systems in Animals

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