Week 3 Adipose Tissue Dysfunction Flashcards
how does adipose tissue appear under a microscope?
thin walled empty vacuole with nucleus pushed to periphery of cell (appear empty becuase stain is hydrophobic and dissolved the fat)
what is brown fat?
fat that is important in heat production thermogenesis
where/in who do we see brown fat?
newborns have quite a bit of brown fat, amount decreases with age and remains only around kidney, large vessels, neck and back at older age
how does brown adipose tissue appear under a micrsocope?
smaller, more numerous fat vacuoles within each adipocyte (than white adipose tissue)
describe the vascularity and innervation of brown adipose tissue?
highly vascular and innervated
what is metabolic syndrome?
A cluster of conditions (high BP, high cholesterol, hyperglycemia, high visceral fat) that occur together, increasing your risk of heart disease, diabetes, and stroke
what is visceral obesity?
fat surrounding organs
what does adpiose tissue consist of?
macrophages, adipocytes, fibroblasts, pre-adipocytes
what is role of fibroblasts?
make ECM and collagen
what is role of pre-adipocytes?
stemm cell-like that generate new adipose cells
what is role of macrophages?
seen mostly in visceral adipose, recruited to adipocytes as they grow larger, increase inflammation and decrease adiponectin
what is the role of white adipose tissue?3
insulate body, store and release FFAs, protect organs
what is role of lipoproteins such as chylomicrons?
transport triglycerides from intestines to adipose tissue
what is role of lipoprotein lipase?
separates TGs from lipoproteins so they can be stored in adipocytes
what is role of hormone sensitive lipase?
liberates FFAs from adipocytes to increase FFAs in bloods
what effect does insulin have on LPL and HSL
promotes LPL and inhibits HSL (promotes TG sotrage)
why do individuals with type II diabetes get fatter?
increased insulin levels increases the amount of TG stored in adipocytes (LPL increases and HSL decreases)
what are adipokines?
the endocrine hormones of adipocytes
in general, as adipose volume increases, what occurs to adipokine levels?
increase as well (except for adiponectin!)
Leptin: main site of production, role 2, stimulated by
mainly produced in SubQ adipocytes, increases lipid oxidation in liver and lipolysis in muscle and adipose tissue (fat burner)
stim by FFAs and insulin
Adiponectin: role 3
anti-atherosclerotic, enhances insulin sensitivity, increases glucose uptake
when is adiponectin synthesis/activity reduced?3
obesity, insulin resistance, metabolic syndrome
what is the role of IL-6? where is it produced
recruits macrophages to adipose tissue, visceral adipocytes
which hormones are primarily produced in visceral adipose 2
angiotensinogen, IL-6
where is leptin primarily produced
SubQ adipose
are macrophages more prevelant in visceral or SubQ adipose?
visceral
what is the signaling between adipocytes and macrophages
large adipocytes release FFAs–>macrophages releases TNF-alpha–>adipocytes induce lipolysis and express IL-6–>more macrophages are recruited–>inflamation seen in obesity occurs (adipose tissue dysfunction)
obesity is associated with what form of inflammation? attributed to?
a chronic low grade inflammatory state. attributed to increased macrophages
what is meant by adipose tissue dysfunciton?
this denotes a state of hypersecretion of pro-atherogenic, pro-inflammatory, and pro-diabetic adipocytokines
who has more macrophages in their adipose tissue skinny or fat people?
fat
macrophage number in adipose tissue correlates with…
insulin resistance
how does insulin resistance occur in obese people?
the viscous cycle of inflamation and hyper-secretion seen in adipose of fat people releases FFAs. chronically high levels of FFA inhibits insulin signaling TNF-alpha also confers insulin resistance
how does adiponectin increase insulin sensitivity?
trigger break down (oxidation) of FFAs in liver, inhibits glucose production
what causes type II diabets (2)?
insulin resistance and a decreased insulin secretoty fxn of pancreatic beta-cells
why is there increased insulin in fat people?
more insulin is made due to hyper-nutrition and insulin resistance…if this compensatory mechanism is exceeded type II diabetes occurs
low adiponectin, and high IL-6, TNF-a, and leptin are associated with an increased risk of…
type II diabetes
increased angioteninogen leads to what in obese people? (produced by dysfunctional adipocytes)
high blood pressure
what is one explanation for the atherosclerosis seen in obese people?
a decrease in adiponectin
low levels of which hormone is an independent predictor of future vascular disease?
adiponectin
which hormone is a good measure of adipocyte dysfunction? why
adiponectin because it is only produced by adipocytes
define independent risk factor
something is a significant contributor to a disease state
what are the benefits of exercise in obese people?
reduce adipocyte size and modify adipocyte dysfunciton (decrease IL-6, TNF-alpha, leptin and increase adiponectin levles)
