The heart is a muscular organ that pumps blood through a network of blood vessels called the circulatory system.

The skin is the largest organ in the human body, covering an area of approximately 2 square meters.

The respiratory system is responsible for breathing, exchanging oxygen and carbon dioxide, and filtering dust and particles from the air. It does not produce red blood cells, which are produced in the bone marrow.

The primary function of the digestive system is to break down food into nutrients that can be absorbed into the bloodstream.

Nausea is not a common symptom of the flu. Common symptoms include fever, cough, sore throat, runny nose, and body aches.

Adults typically need 6-8 hours of sleep per night to function optimally.

Smoking cigarettes is a major risk factor for a variety of health problems, including cancer, heart disease, and stroke.

Adults should aim to consume 4-5 servings of fruits and vegetables per day.

Heart disease is not a type of cancer. It is a group of conditions that affect the heart and blood vessels.

The primary function of the immune system is to fight infection and protect the body from harmful substances.

Cancer is not a type of infectious disease. It is a group of diseases characterized by the uncontrolled growth and spread of abnormal cells.

Adults should aim for at least 60 minutes of moderate-intensity physical activity or 30 minutes of vigorous-intensity physical activity most days of the week.

Obesity is not a type of chronic disease. It is a condition characterized by excessive body fat.

The primary function of the nervous system is to process information and control movement.

Obesity is not a type of mental health disorder. It is a condition characterized by excessive body fat.