Which structure produces releasing hormones? thyroid gland hypothalamus anterior pituitary posterior pituitary

it's hypothalamus

Releasing hormones are peptide hormones, which are produced within the hypothalamus and transferred via the hypothalamo-hypophyseal portal veins to the adenohypophysis, where they regulate the synthesis or release of adenohypophyseal hormones.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.