Changes

The position of the heart varies among [[:Category:Snake Species|species]] and, as there is no diaphragm, it is mobile within the [[Snake Musculoskeletal System|ribcage]].  Heart position varies slightly with its ecological niche and [[Snake Taxonomy|phylogenetic position]], and its mobility may facilitate the passage of relatively large prey (see [[Snake Feeding|snake feeding]]).  The heart has three chambers: right and left atria and one ventricle.  The right atrium receives deoxygenated blood from the systemic circulation and the left receives oxygenated blood from lungs via the left and right pulmonary veins.  The ventricle has internal ridges that enable a considerable functional separation between the oxygenated and deoxygenated blood.  It is divided into three subchambers: the cavum pulmonale, cavum venosum and cavum arteriosum.

The position of the heart varies among [[:Category:Snake Species|species]] and, as there is no diaphragm, it is mobile within the [[Snake Musculoskeletal System|ribcage]].  Heart position varies slightly with its ecological niche and [[Snake Taxonomy|phylogenetic position]], and its mobility may facilitate the passage of relatively large prey (see [[Snake Feeding|snake feeding]]).  The heart has three chambers: right and left atria and one ventricle.  The right atrium receives deoxygenated blood from the systemic circulation and the left receives oxygenated blood from lungs via the left and right pulmonary veins.  The ventricle has internal ridges that enable a considerable functional separation between the oxygenated and deoxygenated blood.  It is divided into three subchambers: the cavum pulmonale, cavum venosum and cavum arteriosum.

Snakes can control arterial pressure reflexly, but this is diminished when not within the [[POTZ]].  Oxygen dissociation curves of snake [[Lizard and Snake Haemotology|blood]] are also influenced by temperature.

Snakes can control arterial pressure reflexly, but this is diminished when the body temperature is outside the [[POTZ]].  Oxygen dissociation curves of snake [[Lizard and Snake Haemotology|blood]] are also influenced by temperature.

 

==Systemic arteries==

==Systemic arteries==

There are two aortae that leave the heart - the right aorta exits from the left side of the ventricle and the left aorta from the right side.  The aortae join caudal to the heart to form the abdominal aorta that extends caudally through the coelomic cavity.  The left systemic arch is larger than the right, the opposite to most tetrapods.   

There are two aortae that leave the heart - the right aorta exits from the left side of the ventricle and the left aorta from the right side.  The aortae join caudal to the heart to form the abdominal aorta that extends caudally through the coelomic cavity.  The left systemic arch is larger than the right, the opposite to most tetrapods.