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There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.
Hyperthyroidism leads to an increased rate of metabolism and affects about 1% of women but only 0.1% of men. For most people, this increased metabolic rate causes the thyroid gland to become enlarged (known as a goiter).
Women are two-thirds more likely than men to develop irritable bowel syndrome. This may be attributable to hormonal changes related to their menstrual cycles.
Fewer than 10% of babies are born on their exact due dates, 50% are born within 1 week of the due date, and 90% are born within 2 weeks of the date.
![Internal structures of main sequence stars, convection zones with arrowed cycles and radiative zones](https://biology-forums.com/gallery/47/medium_12359_26_01_13_3_56_03.png)
![The proportion of men and women with elevated blood pressure or taking hypertension medication incre](https://biology-forums.com/gallery/47/medium_102911_16_06_15_7_18_43_220301505.jpeg)