Answer:
lungs:
The blood first enters the right atrium.
The blood then flows through the tricuspid valve into the right ventricle.
When the heart beats, the ventricle pushes blood through the pulmonic valve into the pulmonary artery.
The pulmonary artery carries blood to the lungs where it “picks up” oxygen.
It then leaves the lungs to return to the heart through the pulmonary vein.
The blood enters the left atrium.
It drops through the mitral valve into the left ventricle.
The left ventricle then pumps blood through the aortic valve and into the aorta. The aorta is the artery that feeds the rest of the body through a system of blood vessels.
Blood returns to the heart from the body via two large blood vessels called the superior vena cava and the inferior vena cava. This blood carries little oxygen, as it is returning from the body where oxygen was used.
The vena cavas pump blood into the right atrium and the cycle begins all over again.
Answer:
2, 6 are the one you should select
Explanation:
The scrotum reacts to temperature. When it is cold, the scrotum shrinks, pulling the testes against the body to keep them warm. When it is hot, the scrotum relaxes, lowering the testes away from the body. This contractile ability of the scrotum can either raise or lower the temperature of the testes by a few degrees, ensuring that the optimum temperature for sperm production is maintained.
