Final answer:
Chest compressions in CPR manually compress the blood within the heart to maintain blood flow to vital organs.
Step-by-step explanation:
The functions of chest compressions in CPR are to manually compress the blood within the heart in order to push some of the blood into the pulmonary and systemic circuits. This helps maintain blood flow to vital organs, especially the brain, to prevent irreversible damage and death of neurons. Chest compressions should be performed with the flat portion of one hand on the sternum between the line at T4 and T9, at a depth of at least 5 cm and a rate of 100 compressions per minute.