What causes sudden feeling of sadness and anxiousness ?

One possible cause of persistent sadness could be depression

Explanation:

anything could trigger the sadness or anxiousness in a person, maybe thinking of a deceased loved one, a sudden break up, stage fright, anything

your answer should be c) enjoy!

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.