Adipose tissue is composed of adipocytes that store fat. It comes in two types - white adipose tissue and brown adipose tissue. White adipose tissue is the main fat storage tissue in humans and is found throughout the body. It stores fat in large droplets within adipocytes. Brown adipose tissue is found in humans primarily in infants, where it contains many mitochondria and helps generate heat. The document provides details on the structure, function and development of both white and brown adipose tissues.

1. 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

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

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

7. 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.

8. Basic Adipose Tissue Expansion
Preadipocyte Mature adipocyte

9.  Predominant type of fat in humans
 Adipocytes have single large lipid inclusion

10.  Evenly distributed throughout body, though with
some differences due to sex and age
Android Gynecoid

11.  Pads and insulates organs

12.  Energy reservoir providing low-weight, high
calorie form of energy
 Endocrine organ involved in energy metabolism

13. Location: Subcutaneous

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

15. Chicken-wire appearance of mature white fat

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

17.  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

18. 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.

19. Unilocular
Multilocular
(Brown Fat)

20.  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”

21. Note multiple lipid droplets and increased vascularity

22.  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.

24.  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.
MITOCHONDRIA > THERMOGENIN = HEAT

25.  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

27. WAT BAT

28. White
Brown

29. Neck
Supraclavicul
ar
mediastinum
Paraverteb
ra
suprarenal

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

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

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

33.  Fetal fat stores exist by 30th 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!

34. ONLY WAY TO REDUCE CELL NUMBER

35. 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)