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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.
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
The lipid bilayer is made of phospholipids. They are arranged in a double layer because one of their ends is attracted to water while the other is repelled by water.
More than 30% of American adults, and about 12% of children utilize health care approaches that were developed outside of conventional medicine.
Vaccines prevent between 2.5 and 4 million deaths every year.