Block III: video 5 Flashcards
WHat is adipose tissue?
A specialized form of connective tissue in
which have large accumulations of fat cells
(adipocytes)
What are the types of adipose tissue and how do they differ?
White fat and brown fat that differentiate from different cell origins under influence of different
transcription factors
What is white fat and its functions?
(unilocular)
1. typical type of fat in adults.
2. Acts as a major energy store for the body.
3. Large cells
4. single large drop of fat -signet ring shape
What is brown fat and its functions?
(multilocular)
1. present in some areas of fetus & neonate, and isolated areas in adult.
2. Multiple droplets of fat in cytoplasm.
3. Can generate heat, rather than acting as an energy store
WHat does brown fat involve?
Involves inner mitochondrial membrane uncoupling
protein UCP-1 (thermogenin) which uncouples oxidation of lipids from ATP synthesis
identify
low magnification of white adipose tissue
identify
high magnification of white adipose tissue
identify
brown fat at low magnification
identify
brown fat at high magnification
What other things does adipose tissue secrete?
white fat is considered an endocrine organ that secretes adipokines including hormones, growth factors, and cytokines that are important for energy
storage, metabolism, and weight control
WHat hormone is important in adipose tissue?
sex hormone metabolism
What is the brain-gut-adipose axis?
adipose tissue: regulates appetite, hunger, satiety, and energy homeostasis
What is lipoprotein lipase?
for the storage of lipids: is an enzyme, sythesized by adipose cells, that breaks down lipids and is transferred to the luminal surface of the associated capillaries.
What type of molecules does lipoprotein lipase breaks down?
very-low-density lipoproteins (VLDLs) into
triglycerides and fatty acids in the capillary endothelium
What happens after the low density lipoproteins break into lipids in the capillaries?
The free fatty acids and triglycerides from the capillaries then enter the adipose cells and become re-esterified and stored as triglycerides in the
large fat droplet. Fatty acids may also be synthesized from glucose
what molecule promotes fat storage
insulin
By what is the release of stored lipids affected?
by neural impulses and/or adrenaline.
Also affected by glucagon & growth hormone (acts in opposite direction of insulin)
Explain the process of release of lipids
During release, stored triglycerides are hydrolyzed by hormone-sensitive lipase which is activated by cAMP, and the released free fatty acids enter back into the capillaries
What does short term weight regulation on daily basis involves?
- Ghrelin – an appetite stimulant (stomach gastric cells)
- Peptide YY (PYY) an appetite suppressant (small intestinal epithelial cells)
they both act through receptors in the hypothalamus
what does long term weight regulation involve?
- insulin
- leptin
How does insulin work?
increases the accumulation of lipid by increasing synthesis of lipoprotein lipase and increasing the uptake of glucose which can be converted
to lipid. [store fat for future use]
May also suppress or inhibit hormone-sensitive lipase breakdown of fat
how does leptin work?
a hormone made in adipocytes as well as other tissues that acts to reduce food intake. Morbidly obese individuals are often resistant to it because
of defective leptin receptors in the hypothalamus or other factors. (supresses appetite)
how does both insulin and leptin work?
For regulation of weight both can act through receptors in the hypothalamus.
Although insulin’s main action may be at the level of cellular glucose uptake there is evidence that it may be regulated in part through receptors in the
hypothalmus
Explain obesity
Obesity has been recently classified as a disease by the Centers for Disease Control and the World Health Organization. Individuals are considered to be
obese if their adipose tissue buildup results in a body mass index (BMI) greater than 30 kg/m2 where m is the height in meters.
Research suggests that obesity is almost always accompanied by chronic inflammation in the adipose tissue, and can be associated with a number of
health related problems.
What are the types of obesity?
Hypertrophic obesity
Hypercellular obesity (hyperplastic or hyperplasia)
Explain hypercellular obesity
Increase in number of adipocytes
It is a frequent cause of childhood obesity involving both genetic factors and environmental factors
Explain hypertrophic obesity
Increase in amount of fat stored in each cell (adult onset)
How does obesity impact molecules?
obesity can involve major changes in hormones such as leptin and insulin, and resistance to the effects of these hormones, as well as increased inflammation due to factors such as IL-6.
It has a high correlation with the development of type II diabetes and cardiovascular disease in overweight
individuals
does adipose tissue have stem cells?
Recent studies have shown that white adipose tissue has a 100-fold richer supply of stem cells than does bone marrow
What are the stem cell from adipose tissue called and what do they do?
adipose-derived stem cells have the capacity
to be transformed into cartilage cells (chondrocytes), muscle cells (myoblasts), bone cells (osteoblasts) as well as adipocytes
