Learning Centers

Bipolar disorder is characterized by periods of excitability (mania) alternating with periods of depression. The "mood swings" between mania and depression can be very abrupt.

Pregnancy is the condition of having a developing embryo or fetus in the body. The union of an egg (ovum) with sperm is called fertilization, or conception, and it is this union that produces the embryo.

Diabetes is a life-long disease marked by high levels of sugar in the blood.

Depression may be described as feeling sad, blue, unhappy, miserable, or down in the dumps. Most of us feel this way at one time or another for short periods. True clinical depression is a mood disorder in which feelings of sadness, loss, anger, or frustration interfere with everyday life for an extended period of time. See also: Adolescent depression; Depression in the elderly.

Hypertension is the term doctors use for high blood pressure. Blood pressure readings are measured in millimeters of mercury (mmHg) and usually given as 2 numbers. For example, 140 over 90 (written as 140/90. The top number is your systolic pressure, the pressure created when your heart beats. It is considered high if it is consistently over 140; The bottom number is your diastolic pressure, the pressure inside blood vessels when the heart is at rest. It is considered high if it is consistently over 90. Either or both of these numbers may be too high. Pre-hypertension is when your systolic blood pressure is between 120 and 139 or your diastolic blood pressure is between 80 and 89 on multiple readings. If you have pre-hypertension, you are more likely to develop high blood pressure at some point. See also: Blood pressure

Breast cancer is a cancer that starts in the tissues of the breast. There are two main types of breast cancer: Ductal carcinoma starts in the tubes (ducts) that move milk from the breast to the nipple. Most breast cancers are of this type; Lobular carcinoma starts in parts of the breast, called lobules, that produce milk. In rare cases, breast cancer can start in other areas of the breast. Many breast cancers are sensitive to the hormone estrogen. This means that estrogen causes the breast cancer tumor to grow. Such cancer is called estrogen receptor positive cancer or ER positive cancer. Some women have what's called HER2-positive breast cancer. HER2 refers to a gene that helps cells grow, divide, and repair themselves. When cells have too many copies of this gene, cells - including cancer cells - grow faster. Experts think that women with HER2-positive breast cancer have a more aggressive disease and a higher risk of recurrence than those who do not have this type.

Cholesterol is a soft, waxy substance found in all parts of the body. Your body makes some cholesterol, and some cholesterol comes from the food you eat. Your body needs a little bit of cholesterol to work properly. But too much cholesterol can clog your arteries and lead to heart disease. This article focuses on cholesterol and your diet. See also: HDL test ("good" cholesterol; LDL test ("bad" cholesterol; Lipid profile; High blood cholesterol and triglycerides.

An allergy is an exaggerated immune response or reaction to substances that are generally not harmful. See also: Allergic reactions; Allergy testing; Allergy to mold, dander, dust; Drug allergies; Food allergies; Hay fever.