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This means the brain-to-body mass ratio is, on average, approximately the same for both sexes. [85] [86] Comparing a male and a female of the same body size, an average difference of 100 grams in brain-mass is present, the male having the bigger and heavier brain. This difference of 100 grams applies over the whole range of human sizes.
Structurally, adult male brains are on average 11–12% heavier and 10% bigger than female brains. [21] Though statistically there are sex differences in white matter and gray matter percentage, this ratio is directly related to brain size, and some [ 22 ] argue these sex differences in gray and white matter percentage are caused by the average ...
An elephant's brain weighs just over 5 kg (11 lb), a bottlenose dolphin's 1.5 to 1.7 kg (3.3 to 3.7 lb), whereas a human brain is around 1.3 to 1.5 kg (2.9 to 3.3 lb). Brain size tends to vary according to body size. The relationship is not proportional, though: the brain-to-body mass ratio varies. The largest ratio found is in the shrew. [57]
The axial skeleton (80 bones) is formed by the vertebral column (32–34 bones; the number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length), a part of the rib cage (12 pairs of ribs and the sternum), and the skull (22 bones and 7 associated bones).
A scanner used to measure bone density using dual energy X-ray absorptiometry. Bone density, or bone mineral density, is the amount of bone mineral in bone tissue.The concept is of mass of mineral per volume of bone (relating to density in the physics sense), although clinically it is measured by proxy according to optical density per square centimetre of bone surface upon imaging. [1]
The human brain is the central organ of the nervous system, and with the spinal cord, comprises the central nervous system. It consists of the cerebrum, the brainstem and the cerebellum. The brain controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sensory nervous system ...
A 2022 follow-up meta-analysis refuted these finding based on methodological flaws, and concluded that "The human brain shows highly reproducible sex differences in regional brain anatomy above and beyond sex differences in overall brain size" and that these differences were of a "small-to-moderate effect size." [35]
Bcl-2 is an antiapoptotic protein. The level of Bcl-2 in PD8 male rats is much higher than that in female rats of the same age, hence the number of apoptotic cells of MPNc in PD8 male rats is much lower than PD8 female rats. On the other hand, Bax, a proapoptotic protein, shows lower level in PD8 males than in PD8 females.