In general, the DefensePlanning Guidance tells the Army what missions and scenarios to or-ganize and train for. Internal Army processes lead to decisions aboutspecific types of units to create, whether those units should be re-serve or active, and whether those units should be resourced fully orat some lower level.
There are actually two pacemakers. The SA node is the primary; the atrioventricular node (AV node), located in a bundle of tissues on the border between the right atrium and the right ventricle, is the secondary. When the SA node sends out an electrical impulse, the first place it goes is to the AV node. While the SA node sets the rhythm of your pulse, the AV node sets the rhythm of your heart contractions. It delays the signal on its way to the ventricle, giving the atrium time to contract first.
The separate sections of the ventricular system are connected through small holes known as foramina. The lateral and third ventricles connect through the right and left interventricular foramina, while the third and fourth ventricles connect through a foramen known as the cerebral aqueduct.Other foramina that connect to specific ventricles exist but are not considered part of the ventricular system.he separate sections of the ventricular system are connected through small holes known as foramina. The lateral and third ventricles connect through the right and left interventricular foramina, while the third and fourth ventricles connect through a foramen known as the cerebral aqueduct.