13. What causes a heartbeat?………… A. Stretching of the atrium and ventricle muscles
B. Closing and opening of AV and SV Valves
C. Oxygenated blood
per minute
D. The number of times your heart beats

Lymphatic vessels remove excess fluid from tissues. often after mammexront( the surgical procedure to remove of all or part of a breast) the lymphatic vessels draining the arm are damaged. explain a consequence of this damage. what can be done to reduce the symptoms?

When analyzing tree rings, what do scientists assume a thin ring indicates?

What must be done to breed dogs for a partical trait