Friction between membranes of the heart is reduced by:
a. serous fluid in the pericardial cavity
b. the epicardium.
c. a blood-filled sinus called the pericardium.
d. a cushion of air that surrounds the heart.
e. fluid between the epicardium and the myocardium

The correct option is : a. serous fluid in the pericardial cavity

Explanation:

The heart is enclosed in a sac containing the heart, known as the  pericardium. The pericardium has two layers- fibrous and serous layer.

The serous layer of the pericardium produces and secretes the pericardial fluid into the pericardial cavity.

The pericardial fluid is a lubricating serous fluid present in the pericardial cavity. It reduces the friction caused between the pericardial membranes by lubricating the epicardial surface.

answer:

a licensed practical nurse (lpn), in much of the united states and canada, is a nurse who cares for people who are sick, injured, convalescent, or disabled. in the united states, lpns work under the direction of physicians.

explanation:

answer: every other day

explanation: because you don't want to over work your body and especially if your just starting to work out.