Blood is a connective tissue with a fluid matrix called plasma. Three basic types of cells are found suspended in plasma:The Erythrocytes (red blood cells) are pink with a light center (where the cell is thinner and the light shines through).onnective tissue fibers, blood vessels, and sweat glands can be seen embedded in the adipose tissue. As the photomicrograph illustrates this tissue consists of adipocytes that contain lipid droplets. Adipose Tissue: 1  Description: Resembles a chicken-wire fence.
It is possible that hypofunctional 5-HTP cells (reflecting TPH1 dysfunction) in the periphery, leading to deficient 5-HTP, low 5-HT, and concomitant compensatory TPH2 activation in the brain, may cause endogenous depression.
However, other important physiological factors can also be involved. Depressive symptoms can be caused by a medical condition, such as a thyroid disorder, or by external chemicals including medications, illegal drugs, and alcohol.Sometimes hormonal changes, including those that occur during the week prior to menstruation or after the birth of a child, can create symptoms of depression.Additional physical contributors to feelings of depression include environmental factors such as reduced exposure to light or physical inactivity.The long-held view that depression is caused by chemical imbalances in the brain has recently come under increasing criticism.dditional physical contributors to feelings of depression include environmental factors such as reduced exposure to light or physical inactivity. The long-held view that depression is caused by chemical imbalances in the brain has recently come under increasing criticism.