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Did you know?

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.

Did you know?

Vampire bats have a natural anticoagulant in their saliva that permits continuous bleeding after they painlessly open a wound with their incisors. This capillary blood does not cause any significant blood loss to their victims.

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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.

Did you know?

Not getting enough sleep can greatly weaken the immune system. Lack of sleep makes you more likely to catch a cold, or more difficult to fight off an infection.

Did you know?

Though newer “smart” infusion pumps are increasingly becoming more sophisticated, they cannot prevent all programming and administration errors. Health care professionals that use smart infusion pumps must still practice the rights of medication administration and have other professionals double-check all high-risk infusions.

Negative feedback control of a regulated variable. Negative feedback control of a regulated variable.
Negative feedback control of a regulated variable. Negative feedback control of a regulated variable.
A negative feedback loop. A negative feedback loop.
Positive and negative selection during T-cell development. Positive and negative selection during T-cell development.
The cell wall of a Gram-negative bacterium, E. coli The cell wall of a Gram-negative bacterium, E. coli
Negative and positive feedback loops Negative and positive feedback loops
Video: Optic Nerve and Optic Disk Animation (Part 1 of 2)

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