ERA. 1  baseball, baseball game - a ball game played with a bat and ball between two teams of nine players; teams take turns at bat trying to score runs; he played baseball in high school; there was a baseball game on every empty lot; there was a desire for National League ball in the area; play ball!.
The contraction of the heart muscle starts in the two atria, which push the blood into the ventricles. Then the walls of the ventricles squeeze together and force the blood out into the arteries: the aorta to the body and the pulmonary artery to the lungs.
Frigid winds make you shiver; dry air chaps unprotected lips and hands; and a lack of sunshine can even cause depression. Cold weather also puts immense strain on the heart. Low temperatures cause your blood vessels and arteries to narrow, restricting blood flow and reducing oxygen to the heart. Your heart must pump harder to circulate blood through the constricted blood vessels. As a result, your blood pressure increases. A sudden spike in blood pressure â especially when paired with outdoor exertion, such as shoveling a snowy sidewalk â can cause serious issues such as: 1  Unstable chest pain.