Section I.
PROPERTIES OF THE ADIPOSE TISSUE.
The adipose tissue admits of a division into two parts, according as it is met with generally in the body, or as it is confined in the interior of the bones. The first portion is that which we have now to consider; the second is connected with the medullary membrane, and will be described with the osseous structure.
There are two forms under which fat is seen: the free state, when it is evident to the naked eye; and the state of combination, in which condition chemical agents are required, in order to detect its existence.
There are but few parts of the body, in which fat is not found at some time or other in its free state. In the early periods of life, it is accumulated in large quantities on the surface of the body, immediately under the skin; and it is to this circumstance that the fatness and plumpness of infants are owing. In old persons, on the contrary, this substance is met with in the cavities of the body, as around the heart, the stomach, intestines, etc.
The adipose matter is very abundant on the face, especially on the cheeks and in the orbits. It is in larger quantity on the anterior than on the posterior part of the neck. In the thorax, the fatty tissue is met with in the anterior and posterior mediastina; around the heart, especially in age, and in the intercostal spaces; on the exterior of the chest, it is principally found about the mammary gland, where, in the female, it often accumulates in large masses; also between and around the pectoral muscles. There is no part of the body which contains so much quantity of this structure as the abdomen, both without and within.
Fat is found between the fasciculi and fibres of the muscles which are submitted to the influence of the will; it is distinguished between the lobes of the lobulated glands; the sheaths of the vessels enclose a very little; the nervous cords possess small masses of it between their fibres; and the coarse fasciculi of the ligaments arc, in part, separated by the adipose tissue.
There are certain parts of the body which contain no fat in its free state; viz. the interior of the cranium, of the brain, the eye, the ear, and the nose; also the substance of the lungs, of the intestines, and of many glands, particularly the lymphatic. This substance is also wanting in the eyelids, in the penis, the scrotum, and the nympha. It is also deficient around the long and slender tendons, and in the intervals between many of the muscles which execute great movements. Lastly, it may be stated that there are organs in which adeps never is deposited, notwithstanding there is great obesity; and, on the contrary, that there are parts in which it never entirely disappears, although in other respects there may be complete marasmus.
As the quantity of the fat in its free state is liable to such great variation, no very accurate estimate can be made of its proportion to the whole of the body; but it is said that, in an adult of ordinary stoutness, the fat forms about the twentieth part of the body. In cases of obesity, it forms from a half to four-fifths of the total weight of the body; on the contrary, in great emaciation, the fat exists only in a few places, and in diminished quantity. The female body in general possesses more of this substance than that of the male. The proportion varies according to age, and other circumstances.
During the first half of the fetal existence, the fat is entirely deficient. It begins to appear at about the fifth month, in isolated grains, under the skin; at the period of birth this is the only region where it is accumulated into a mass, as the adeps in the internal organs is either altogether wanting or found in small and distinct grains. In advanced age, the body becomes very thin, in consequence of the diminution of the quantity of fat. Thus the two extremes of existence resemble each other in this respect; but the body of the old person differs from that of the infant in the situation of the fat which it contains: in the former, there is very little on the external surface, but a considerable quantity in the very substance of the organs; in the latter, on the contrary, there is comparatively a large proportion under the skin, and little or none in the interior of the body.
Many circumstances tend to increase the quantity of fat, especially rest and nutritious diet; and in the human species, the absence of all anxiety and of intellectual exertion. The loss of the venereal appetite, caused by the removal of the testicles in the male, and of the ovaries in the female, tends greatly to produce obesity.
The density of the adipose tissue is not the same in all parts of its extent. The degree of firmness depends on that of the cellular texture, by which the vesicles and masses are surrounded. The small grains of fat are plunged in a very delicate cellular substance, which it is difficult to observe; but between the larger masses the connecting medium is more evident, and at length becomes very apparent. In some places, as in the orbit, face, and axilla, the cellular tissue is soft and lax; on the cranium and back, firm cellular layers support and unite the adipose masses; while in the sole of the foot and palm of the hand, but especially in the former, there are very dense and resisting fibrous layers, which greatly increase the firmness of the fatty tissue.
<Callout type="important" title="Fat Distribution">Understanding where fat is distributed in the body can be crucial for medical diagnosis and treatment.</Callout>
<Callout type="tip" title="Anatomical Insight">Knowledge of adipose tissue distribution aids in understanding human anatomy and physiology, especially concerning obesity and aging.</Callout>
Key Takeaways
- Fat is distributed throughout the body, varying with age and health conditions.
- The distribution of fat changes from infancy to old age, affecting overall body composition.
- Certain areas of the body do not contain adipose tissue in its free state.
Practical Tips
- Recognize that fat accumulation patterns can indicate underlying health issues.
- Use knowledge of fat distribution for assessing nutritional status and potential obesity risks.
- Understanding anatomical fat distribution aids in medical diagnosis and treatment planning.
Warnings & Risks
- Fat deficiency or excess in certain areas may indicate severe malnutrition or disease.
- Overlooking the importance of adipose tissue can lead to misdiagnosis or ineffective treatments.
Modern Application
This chapter provides foundational knowledge on fat distribution, which is still relevant today for medical professionals and survivalists. Understanding how fat accumulates in different parts of the body aids in assessing nutritional status, diagnosing health conditions, and planning treatment strategies.
Frequently Asked Questions
Q: What are some areas where adipose tissue is not found?
Fat is absent from certain regions such as the interior of the cranium, brain, eye, ear, nose, lungs, intestines, lymphatic glands, eyelids, penis, scrotum, and nympha.
Q: How does fat distribution change with age?
In infants, fat is primarily found under the skin. In older individuals, it accumulates in internal cavities around organs like the heart and stomach.
Q: What factors influence the quantity of adipose tissue?
Rest, nutritious diet, absence of anxiety and intellectual exertion tend to increase fat accumulation, while mental or physical exertion, excess venery, insufficient food can decrease it.