The respiratory system works with the circulatory system to supply oxygen to the cells and expel carbon dioxide in a two-stage process. External respiration brings air into the
through the mouth
and nose. The air is warmed, moistened, and filtered by
membranes and cilia. The pharynx,
commonly known as the
is divided into three sections. The
is only intended to
carry air, while the oropharynx is a passageway for both food and air. The
keeps food and
liquids out of the larynx and trachea. The
creates sound as air passes through the vocal
cords. It sits behind the large thyroid cartilage, which moves when you swallow. Cartilage rings keep
the
open during breathing. The air travels down the left and right bronchi, leading to the
lungs. The
are smaller airways within the lungs, which end in tiny
wrapped in
capillaries to allow the exchange of oxygen and carbon dioxide. Each pressurized lung is surrounded by an
airtight
within the chest cavity. Pressure changes caused by contraction of the
intercostals, and abdominal muscles pull air into the lungs. When the muscles relax, the air is forced out.
The lungs are divided into three
on the right, but only
on the left to allow room
for the heart

b) the heart is a pump made of muscle and that is difficult to grow in the lab.

    however, coronary heart disease , or chd, is actually a result of coronary artery disease, or cad, said edward a. fisher, m.d., ph.d., m.p.h., an american heart association volunteer who is the leon h. charney professor of cardiovascular medicine and also of the marc and ruti bell vascular biology and disease program at the nyu school of medicine.

  with coronary artery disease, plaque first grows within the walls of the coronary arteries until the blood flow to the heart’s muscle is limited. view an illustration of coronary arteries. this is also called ischemia. it may be chronic, narrowing of the coronary artery over time and limiting of the blood supply to part of the muscle. or it can be acute, resulting from a sudden rupture of a plaque and formation of a thrombus or blood clot.

    the traditional risk factors for coronary artery disease are high ldl cholesterol, low hdl cholesterol, high blood pressure, family history, diabetes, smoking, being post-menopausal for women and being older than 45 for men, according to fisher. obesity may also be a risk factor.

    “coronary artery disease begins in childhood, so that by the teenage years, there is evidence that plaques that will stay with us for life are formed in most people,” said fisher, who is former editor of the american heart association journal, atvb. “preventive measures instituted early are thought to have greater lifetime benefits. healthy lifestyles will delay the progression of cad, and there is hope that cad can be regressed before it causes chd.”

  living a healthy lifestyle that incorporates good nutrition, weight management and getting plenty of physical activity can play a big role in avoiding cad.

    “coronary artery disease is preventable,” agreed johnny lee, m.d., president of new york heart associates, and an american heart association volunteer. “typical warning signs are chest pain, shortness of breath, palpitations and even fatigue.” if you feel any of these symptoms, don’t delay — call 9-1-1.