Anwser
<span>Enzymes act as catalysts that remain unmodified as they increase the rate of a chemical reaction</span>
Surgical destruction of brain tissue is called lesion. It is <span>a region in an organ or tissue that has suffered damage through injury or disease, such as a wound, ulcer, abscess, tumor, etc. Hope this answers the question. Have a nice day.</span>
Answer:
Regurgitation of acidic stomach contents into the esophagus, commonly called "heartburn"
Explanation: Esophagus is the part of the alimentary canal,which is a tube that transports food and water substance from the mouth to the stomach. Esophagus has an upper Esophagus sphincter and and the lower Esophagus sphincter. The lower Esophagus sphincter contains muscles that connects the Esophagus and the stomach. When the lower Esophagus sphincter is closed it prevents the movement of Acids and contents in the stomach from traveling backwards from the stomach. When it fails to effectively constrict it causes what is called "HEARTBURN".
To prevent the backflow of blood during systole and diastole, Artries from the heart dont need valves since their blood pressure is already high enough to not allow backflow of blood, but since veins' blood pressure is lower, they need valves just so the blood doesn't seep back in into the heart again!
