Adipose Tissue: Functions and Characteristics

Study Notes

Adipose tissue is a type of connective tissue that accounts for 10-25% of an adult's body weight, with a main function of passive storage of excess calories in the form of triglycerides.
It serves as a metabolic energy reserve, characterized by a double energy density (calories/gram) compared to carbohydrates and proteins.
Adipose tissue also produces and releases adipokines, hormones, and growth factors, making it an endocrine organ.

The distribution of adipose tissue varies by sex, age, and genetic factors, with women having a higher concentration of subcutaneous fat, particularly during pregnancy.
Triglycerides are not stationary, but are continuously mobilized and redeposited every 10-15 days.
The average lifespan of adipocytes is approximately 6 months, with a 10-60% renewal rate.

White Adipose Tissue (WAT) is composed of distinct cells, with adipocytes accumulating to form deposits classified as subcutaneous and visceral adipose tissue.
WAT has a fundamental role in regulating the balance between nutrient availability and demand, storing excess calories.

Also known as hypodermis, it accounts for 80-85% of total adipose tissue, located beneath the dermis, and has thermal and mechanical protective functions.
It is found in the plantar surface of the foot, palmar surface of the hand, abdomen, buttocks, thighs, breasts, orbits, and pericardium, contributing to sex-specific body shapes.

Accounts for 10% of total adipose tissue, with higher metabolic activity, and is concentrated in the abdominal cavity, including the omentum, mesentery, and retroperitoneal space.
Its accumulation, known as abdominal obesity, is particularly dangerous for cardiovascular diseases, as it is immunologically dynamic, hosting numerous leukocytes.

Characterized by polyhedral cells, 70-100 microns in diameter, capable of accumulating fatty acids.
Fatty acids derive from three main sources: dietary, synthesized in the liver, and synthesized in adipocytes from glucose.
The large lipid droplet formed is composed of triglycerides and beta-carotene, which can be stained with Sudan black.
The citoplasma is reduced, and the nucleus is compressed to the periphery, with a basal membrane and a cellular membrane rich in vesicles and caveolae.