Mini excavators comprise the smallest models available. This category includes: micro excavators that weigh as little as 800 kg or less; mini excavators that average around 3,000 kg; and midi versions that may be upwards of 6 tonnes. Mini excavators are perfect for construction jobs in small spaces and other lighter work.
The inner layer of the pericardium is attached to the heart muscle. A coating of fluid separates the two layers of membrane, letting the heart move as it beats. Your heart has 4 chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles.
The heart is divided into four chambers: the right atrium, the right ventricle, the left atrium and the left ventricle. Each chamber has a one-way valve at the exit that prevents blood from flowing backwards. When each heart chamber contracts, the valve at its exit opens.