Question

Reptiles can change the flow of blood through their hearts. This is called shunting. Describe the two types of shunting and why they are used.

Answer 1

In times of oxygen deprivation (diving in some reptiles, consumption of large prey in snakes), reptiles can shunt blood away from the lungs. Right to left cardiac shunting in the non-crocodilian heart can be facilitated by an increase in pulmonary vascular resistance and action of the muscular and vertical ridge.

All ectothermic reptiles have the ability to shunt blood. A left-to-right intracardiac shunt occurs when oxygen-rich blood, which has entered the left atrium and moved into the cavum arteriosum in the left side of the ventricle, is pumped into the pulmonary artery, to be recirculated to the lung.

In reptiles:all reptiles, three great vessels arise from the ventricle: the pulmonary artery, the right aortic arch (RAo), and the left aortic arch (LAo).

In human: The different types of shunts used most commonly include ventriculoperitoneal (VP) shunts, ventriculoatrial (VA) shunts or a lumboperitoneal (LP) shunts (Koutoukidis et al. 2016). Shunts will generally consist of three components: An inflow catheter – This drains the CSF from the ventricles.

Functional role of shunting:

Cardiac shunting normally occurs in chelonians (turtles), squamates (lizards and snakes) and crocodilians (alligators, caimans, crocodiles). The magnitude of these shunts is affected by the ventilatory state and provides these animals with a flexibility in blood flow that cannot be achieved in mammals or birds. The differential distribution of blood flow into the pulmonary and systemic circulations has prompted physiologists to postulate the functional significance of such a circulatory design. But represent an important cardiovascular adaptation in extant reptiles. Nevertheless, while these hypotheses may be intuitively appealing, experimental evidence attesting the advantageous role of cardiac shunts in pulmonary gas exchange is lacking.In detail, the various hypotheses that explain the functional significance of cardiac shunts in pulmonary gas exchange in intermittently breathing reptiles.