Endothelium The endothelium is the single-cell-thick lining of all blood vessels that is in direct contact with the blood stream. In arteries and veins, the endothelium is the inner most surface of the vessel, overlying the deeper wall components, such…
Cell-cell communication It is no surprise that cells communicate with each other. Signaling is essential for coordinating the function and differentiation of nearby cells. Cells located close to one another communicate in three main ways: If the cells are connected…
Signal transduction The cell membrane is a barrier to the free movement not only of matter (molecules, ions), but also to that of information . Just as living cells must maintain an internal environment chemically separate from but in regulated…
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Cell membrane structure and transport functions The contents of cells are sealed off from the extracellular environment by a lipid barrier called the plasma membrane that protects the cell’s interior from the changing conditions of the extracellular environment and helps…
Presentation: History and physical examination J.B is a 38 year old woman who presents to her primary care physician with a chief complaint of fatigue and weight gain. She was in her normal state of health until about 6 months…
Introduction The male reproductive system has three principal functions: 1. The differentiation and maintenance of the primary and secondary sex characteristics under the influence of the hormone testosterone, made in the testes. 2. Spermatogenesis: The creation of the male gametes…
The organs of pregnancy The placenta serves as the point of exchange between the circulatory systems of the mother and fetus; it is also a hormone-producing organ ( Fig. 35.1 A). The fully developed placenta is a round oval organ…
Introduction The menstrual cycle defines the reproductive years of a woman’s life. It begins with menarche (the onset of menstruation) at about age 8 to 13 years and ends with menopause, which begins at about age 50 years. Evolutionarily, the…
Introduction The word skeleton comes from the Greek skellein, meaning to dry up; a dried-up body (skeleton soma) is one with only the bones remaining. Thus etymologically, but also in our cultural imagination, our bones refer to death. However, the…