Circulatory system the areas above the heart) and the inferior vena cava (roughly speaking from areas below the heart). These two great vessels empty into the right atrium of the heart. The heart itself is supplied with oxygen and nutrients through a small "loop" of the systemic circulation and derives very little from the blood contained within the four chambers. The general rule is that arteries from the heart branch out into capillaries, which collect into veins leading back to the heart. Portal veins are a slight exception to this. In humans the only significant example is the hepatic portal vein which
Endometrial arteries body and they enrich the endometrium of the uterus. The joining of endometrial arteries and veins of the endometrium is known as arteriovenous. Endometrial arteries are also involved in the menstrual cycle. When the egg implants onto the endometrium and is not fertilized the endometrial arteries become narrow and the endometrium begins to disintegrate. This is when the endometrium sheds and results in menstruation. Endometrial arteries Arcuate arteries located in the uterus branch out and supply blood to different layers of the uterus. These arteries meet the myometrial-endometrial junction and lead to straight and endometrial arteries. The endometrium receives blood