Search results
Results from the WOW.Com Content Network
In terms of tissue type, the body may be analyzed into water, fat, connective tissue, muscle, bone, etc. In terms of cell type, the body contains hundreds of different types of cells, but notably, the largest number of cells contained in a human body (though not the largest mass of cells) are not human cells, but bacteria residing in the normal ...
The gradual growth in sex difference throughout a person's life is a product of various hormones. Testosterone is the major active hormone in male development while estrogen is the dominant female hormone. These hormones are not, however, limited to each sex. Both males and females have both testosterone and estrogen. [109]
Claude Bernard, French physician who introduced the concept of homeostasis. The human body and even its individual body fluids may be conceptually divided into various fluid compartments, which, although not literally anatomic compartments, do represent a real division in terms of how portions of the body's water, solutes, and suspended elements are segregated.
In lean healthy adult men, the total body water is about 60% (60–67%) of the total body weight; it is usually slightly lower in women (52–55%). [2] [3] The exact percentage of fluid relative to body weight is inversely proportional to the percentage of body fat. A lean 70 kg (150 lb) man, for example, has about 42 (42–47) liters of water ...
No more egg cells are produced. Hormones stimulate the beginning of menstruation, and the ongoing menstrual cycles. [39] [41] The female external sex organs are the vulva (labia, clitoris, and vestibule). [42] [39] The male external genitalia include the penis and scrotum that contains the testicles.
Chromosomal sex is determined at the time of fertilization; a chromosome from the sperm cell, either X or Y, fuses with the X chromosome in the egg cell. Gonadal sex refers to the gonads, that is the testicles or ovaries, depending on which genes are expressed. Phenotypic sex refers to the structures of the external and internal genitalia. [6]
The Human Cell Atlas project, which started in 2016, had as one of its goals to "catalog all cell types (for example, immune cells or brain cells) and sub-types in the human body". [13] By 2018, the Human Cell Atlas description based the project on the assumption that "our characterization of the hundreds of types and subtypes of cells in the ...
For example, female muscle-derived stem cells have a better muscle regeneration efficiency than male ones. [133] There are reports of several metabolic differences between male and female cells [ 134 ] and they also respond to stress differently. [ 135 ]