Adipose Tissue Flashcards
Adipocytes
the characteristic cells of adipose tissue (fat), These very large cells are derived from mesenchyme (a loose connective tissue).
Reticular fibers
support adipose tissue
Subcutaneous fat
A majority of fat that is found under the skin, for thermoregulation
Visceral fat
Fat found around certain organs, in bone marrow, between muscles, and in breast tissue. For cushioning organs such as the heart, gonads, kidneys, and intestines.
Two types of adipose tissue
Brown fat and white fat
Develop from preadipocytes
White Adipose
Produce the hormone leptin which helps inhibit hunger
Single huge lipid droplet
Fewer mitochondria
Subcutaneous and visceral
locations
Stores energy
Fewer capillaries
Fibroblasts and macrophages
Brown Adipose
Brown fat is localized to kidneys, adrenal glands, and a few other places.
Newborns have 2–5% of body weight in brown
fat, but this decreases through childhood.
The cells are brown because of the large
number of mitochondria and small lipid droplets.
Produces heat by “nonshivering thermogenesis.”
Many smaller lipid droplets
More mitochondria
Kidneys, adrenal glands, and a few other
places
More capillaries
Fibroblasts and macrophages
What three sources do white adipocytes store lipid from?
Dietary fats (including triglyerides and cholesterol) packaged as chylomicrons (a type of lipoprotein).
• Other triglycerides produced in the liver and
circulating as very-low-density lipoproteins
(VLDLs).
• Fatty acids produced locally by breakdown of the
dietary fats and triglycerides by lipoprotein lipase.
How are lipids mobilized from adipocytes?
by the enzyme lipase that is activated primarily by the
hormone norepinephrine released from the
adrenal gland.
Lipids
- Triglycerides (with fatty acids)
- Cholesterol
- Phospholipids
• These are transported through the body in
packages or particles called lipoproteins.
Triglyceride
glycerol + three fatty acid chains
Lipoprotein function
a biochemical assembly whose primary function is to transport fat molecules in water, as in blood plasma or other extracellular fluids, where they are taken into cells by endocytosis.
Lipoprotein composition
They are composed of
phospholipids, triglycerides,
proteins, and cholesterol.
Lipoprotein classification
They are classified by their density.
• ULDL (ultralow-density, largest (= chylomicrons)
• VLDL (very-low density)
• IDL (Intermediate density)
• LDL (Low density)*
• HDL (High density, smallest)*
Chylomicrons (ULDLs)
transport dietary lipids from the intestines to
other locations in the body, where the triglycerides are broken down by the enzyme lipase.
one of the five major
groups of lipoproteins (sorted by density) that enable fats and cholesterol to move within the water
-based solution of the bloodstream
Obesity
excessive adipose tissue accumulation. More fat is accumulated in the cells; the number of fat cells does not increase.
Lipid storage
Free fatty acids + glycerol -> Triglyceride droplet
Lipid mobilization
Norepinephrine + Lipase -> Fatty acids + glycerol
