|
|
The most destructive flu epidemic of all times in recorded history occurred in 1918, with approximately 20 million deaths worldwide.
Patients who cannot swallow may receive nutrition via a parenteral route—usually, a catheter is inserted through the chest into a large vein going into the heart.
Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.
Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
The first oncogene was discovered in 1970 and was termed SRC (pronounced "SARK").
![In most ecosystems, sunlight provides the ultimate source of energy to power all biological activity](https://biology-forums.com/gallery/47/medium_33_17_02_12_6_59_59_20232401.jpeg)
![Middle adulthood can bring large-scale changes in lifestyle and interests, as illustrated by this ph](https://biology-forums.com/gallery/47/medium_6_31_05_15_8_20_40_219642025.jpeg)