It consists of all the arteries in body. The arteries carry blood away from the heart. The arterial system in frog beings with the truncus arteriosus which arises from top right region of ventricle.The truncus ascends, get curved towards left and divides into left and right branches or trunks, each of which subdivides into three major vessels or aortic arches: (1) Common carotid, (2) systemic and (3) pulmocutaneous.
1. Common carotid arch: It is a short vessel running forward and outward, but soon divides into 2 branches: external and internal carotids.
a. External carotid: It is the smaller inner branch carrying blood to the tongue and adjacent parts. It is also called lingual.
b.Internal carotid: It is the larger outer branch. At its base it forms a little swelling, the carotid labyrinth. Its lumen is converted into a labyrinth by folding of the walls. It is probably a sense organ and controls blood pressure in the internal carotid artery. The internal carotid divides into 3 branches: a palatine to the roof of buccal cavity, a cerebral to the brain, and an ophthalmic to the eye.
2. Systemic arch: It is the longest of the three arches and with greatest distribution of blood. The two systemic arches curve dorsally around the oesophagus and join with each other behind the heart to form the dorsal aorta. In its course each systemic arch gives off 3 arteries:
a. Oesophageal: A small inner artery to oesophagus.
b. Occipito-vertebral: A larger outer branch which immediately divides into an occipital branch to occiput or posterior part of head, and a vertebral branch to vertebral column and spinal cord.
c. Subclavain: It is a large outer artery supplying the shoulder region and extending into the forelimb as brachial artery.
Dorsal aorta: As already said, it is formed by the union of both the systemic arches. It runs posteriorly lying mid-dorsally just beneath the vertebral column. It gives off the following arteries:
a. Coeliaco-mesenteric: It is a single large artery arising from the left side of the junction of the two systemic arches. It has two main branches: the coeliac to stomach, pancrease and liver; and the
anterior mesenteric to spleen and small intestine.
b. Gonadial: A pair of short arteries to gonads, called spermatic in male frog and ovarian in female frog.
c. Renal: While passing between the two kidneys, dorsal aorta gives 5-6 pairs of small renal arteries in a series into both the kidneys.
d. Posterior mesenteric: It arises from the posterior end of dorsal aorta, or sometimes from anterior mesenteric. It goes to large intestine or rectum.
e. Common iliacs: The dorsal aorta finally bifurcates posteriorly into two common liliacs, each
supplying an epigastric to ventral body wall, rectovesicular to rectum and urinary bladder and
enters inside the hind limbs of own side and divides into femoral which supplies to hip and upper
thigh, and sciatic which supplies to lower leg.
3. Pulmocutaneous arch: It divides into two main arteries, pulmonary to the lung and cutaneous to skin of dorsal and lateral sides.