Adipose tissue

1. ADIPOSE Tissue A Specialty Connective Tissue Professor : Dr. Sabangan Subj / Sec : DMA 111 * DAB Prepared by : Khafi Makoo , Noorallah

2. Adipose Tissue Adipose Tissue is loose connective tissue designed to store fat. Description Closely packed adipocytes Have nucleus pushed to one side by fat droplet Function Provides reserve food fuel Insulates against heat loss Supports and protects organs Location Under skin Around kidneys Behind eyeballs, within abdomen and in breasts

3. Fat cells are “ adipocytes ” Found in aggregates Fat may be identified macroscopically or only microscopically. Adipose tissue accounts for: 20-25% of the weight of women 15-20% of the weight of men ADIPOSE TISSUE

4. Largest repository of energy in the body Triglycerides 9.3kcal/g Contributes to thermal insulation Important for temperature regulation Fills spaces between structures/protects Between organs Aids fit of valves in heart Pads of fat protect heels, palms Function of Adipose Tissue

5. BROWN ADIPOSE TISSUE WHITE ADIPOSE TISSUE Development of Fat Tissue

6. WHITE is comprised of 2 Fractions: 1) adipocytes 2) SVF which consists of: preadipocytes endothelial cells macrophages WHITE is central to energy storage in the body and the mobilization of this energy store is highly regulated. WHITE ADIPOSE TISSUE

7. Preadipocyte Mature adipocyte Basic Adipose Tissue Expansion

8. Predominant type of fat in humans Adipocytes have single large lipid inclusion WHITE ADIPOSE TISSUE

9. Evenly distributed throughout body, though with some differences due to sex and age WHITE ADIPOSE TISSUE Android Gynecoid

10. Pads and insulates organs WHITE ADIPOSE TISSUE

11. Energy reservoir providing low-weight, high calorie form of energy Endocrine organ involved in energy metabolism WHITE ADIPOSE TISSUE

12. Adipose Tissue Location: Subcutaneous

13. WHITE ADIPOSE TISSUE Adipocyte nuclei at arrow Less differentiated adipocyte at asterisk *

14. Chicken-wire appearance of mature white fat

15. Fat storage – Catalyzed by lipoprotein lipase stimulated by insulin Fat release – Catalyzed by hormone-sensitive lipase stimulated by norepinephrine , also glucagon, adrenaline

16. Uncommon in adult humans Sole purpose is heat generation , especially in hibernation, after birth, and during cold stress Main site of non-shivering heat production under cold stress (newborns can’t shiver!) Lipid accumulates in multilocular pattern Mitochondria and vascularity contribute to dark color BROWN ADIPOSE TISSUE

17. Human newborn Multilocular (brown) adipose tissue constitutes 2--5% of body weight and is distributed as shown in black; shaded areas are a mixture of multilocular and unilocular adipose tissue.

18. Adipose Tissue Multilocular (Brown Fat) Unilocular

19. In the adult human, found only around deep structures (kidney) In adult rats, brown fat cells are dormant; have lost mitochondria; can be “reawakened”; still being studied in humans Tumors known as “hibernomas” BROWN FAT TISSUE

20. Note multiple lipid droplets and increased vascularity

21. Cold stimulates sympathetic nerves to liberate norepinephrine into fat tissue. Activates hormone-sensitive lipase in adipocytes, promoting hydrolysis of triglycerides into fatty acids and glycerol. Liberated fatty acids are metabolized in the adipocyte. Oxygen consumption and heat production increases, elevating tissue temperature and warming blood coursing through it. BROWN FAT TISSUE

22. Heat production increases because MITOCHONDRIA in brown fat have a transmembrane protein THERMOGENIN in their inner membrane. THERMOGENIN permits backflow of protons from the intermembranous space, bypassing ATP-synthetase system. Energy generated by proton backflow is released as heat. BROWN FAT MITOCHONDRIA > THERMOGENIN = HEAT

23. WHITE vs BROWN ADIPOSE Ubiquitous, all ages 82% fat; 15% water; 3% protein Capillary supply Sympathetic Food storage, padding Unilocular 80-150 nm diameter Newborn 30% fat; 55% water; 15% protein Dense capillary network Sympathetic Thermogenesis Multilocular 8-60 nm diameter Increased mitochondria

24. WHITE vs. BROWN FAT

25. Types of Adipose tissue WAT BAT

26. White Brown

27. Neck Supraclavicular mediastinum Paravertebra suprarenal Where can we find BATs ?

28. HYPERTROPHIC: Excessive accumulation of fat in unilocular adipocytes , increasing size of cells HYPERPLASTIC: Increase in the number of adipocytes OBESITY

29. Hypertrophic Obesity - Hypertrophic obesity is excessive weight gain in adulthood. Hypertrophic is when the fat cells get bigger. 

30. Hypercellular Obesity - Hypercellular means GREAT NUMBER OF FAT CELLS. This is usaually present during childhood in which is the time of cellular differentiation and development.

31. Fetal fat stores exist by 30 th week of gestation Fat cells added thru postpartum period Fat cells added prior to and during puberty Adults: with long term obesity, adipocytes become filled with lipid to critical level -- and precursors are stimulated to add more cells. Once adipocytes are formed, they remain for life, and, naturally, we can only reduce cell size, not the number! FAT STORES

32. ONLY WAY TO REDUCE CELL NUMBER

33. A man tipping the scales at 560 kilograms (1,234 pounds) will be listed as the world's fattest man by the Guinness Book of Records, while a loss of 200 kilos (440 pounds) may make him the man who lost the most weight. "I'm glad to be in the Guinness Book as the fattest man. I am also happy to have lost 200 kilos”. His reward is a lifetime supply of burgers from his local burger shack (aka Adipocytes -R-US)