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The familiar sounds of your heart are made by the heart's valves as they open and close.
Adolescents often feel clumsy during puberty because during this time of development, their hands and feet grow faster than their arms and legs do. The body is therefore out of proportion. One out of five adolescents actually experiences growing pains during this period.
The top five reasons that children stay home from school are as follows: colds, stomach flu (gastroenteritis), ear infection (otitis media), pink eye (conjunctivitis), and sore throat.
As many as 28% of hospitalized patients requiring mechanical ventilators to help them breathe (for more than 48 hours) will develop ventilator-associated pneumonia. Current therapy involves intravenous antibiotics, but new antibiotics that can be inhaled (and more directly treat the infection) are being developed.
Human neurons are so small that they require a microscope in order to be seen. However, some neurons can be up to 3 feet long, such as those that extend from the spinal cord to the toes.
![Cerebral angiography. The four angiograms each reveal the distribution of blood vessels supplying th](https://biology-forums.com/gallery/47/medium_14755_14_10_12_6_48_58_94111673.jpeg)
![Endocarditis. The human heart has been sectioned to reveal the left ventricle and origin of the aort](https://biology-forums.com/gallery/47/medium_14755_11_11_12_7_14_26_100221543.jpeg)
![Although average brain size increases gradually though time in H. erectus, individuals with small br](https://biology-forums.com/gallery/47/medium_275510_22_02_15_5_56_53_207641723.jpeg)