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When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
Lower drug doses for elderly patients should be used first, with titrations of the dose as tolerated to prevent unwanted drug-related pharmacodynamic effects.
When blood is deoxygenated and flowing back to the heart through the veins, it is dark reddish-blue in color. Blood in the arteries that is oxygenated and flowing out to the body is bright red. Whereas arterial blood comes out in spurts, venous blood flows.
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.
Amoebae are the simplest type of protozoans, and are characterized by a feeding and dividing trophozoite stage that moves by temporary extensions called pseudopodia or false feet.
![Mother giraffe and calves feeding. It is mostly the females that raise young, and they may gather in](https://biology-forums.com/gallery/47/medium_27689_23_04_12_3_24_46.jpeg)
![Bronfenbrenner’s model of the ecological-systems approach to studying development. He suggested that](https://biology-forums.com/gallery/47/medium_6_31_05_15_8_20_41_219701596.jpeg)