Ch. 6 Adipose Flashcards
What is Adipose tissue?
-specialized connective tissue consisting of fat-storing cells (adipocytes) associated w/ a rich blood supply
Function
-to store extra calories not used immediately
Location
-loose connective tissue
what are the 2 types?
- white (unilocular): adults
- brown(mulitocular): fetal life
Where is white adipose found?
- under skin of abs, butt, axilla, thigh
- greater omentum, mesentery, retroperitoneal space, kidneys, bone marrow, palms, soles, visceral pericardium
What is the function of white adipose?
- energy storage, insulation, cushioning of vital organs
- sex differences of thickness accounts for body contour
- retains structure even after caloric intake
- synthesis and secretion of leptin, involved in regulation of energy
what is leptin?
- circulating satiety factor that controls food intake when energy is sufficient
- simulates metabolic rate
Histogenesis of Fat cells
- early lipoblasts (fr mesenchyme), commited to differentiate into an adipocyte, but is morphologically indistinguishable from a fibroblast
- develop small lipid inclusions and a thin external lamina
- have abundant ER - white adipose begins to form midway
- become ovoid as lipid accumulation changes the cell dimension
- extensive concentration of smooth vesicles and small lipid droplets around nucleus and extending toward both poles of cells - mature adipocyte- cells increased in size and become more spherical. small lipid droplets fuse to form large lipid vacuoles that occupy central portion of cytoplasm
- sER is abundant, rER isn’t (late lipoblast)
- compressing of nucleus to eccentric position
What is the structure of unilocular adipocytes?
- large cells, polyhedral or oval when crowded together in adipose tissue
- cytoplasm forms a thin rim around lipid
- nucleus is flattened and displaced to one side
- surrounded by reticular fibers, secreted by adipocytes
what is the Vimentin filament layer?
-separates hydrophobic contents of lipid droplet from hydrophilic cytoplasmic matrix
what is contained in the cytoplasm?
-Golgi ap, free ribos, rER, microfilaments, intermediate filaments, mitochondria, sER
In mature adipocytes, leptin (ob) gene:
- obese
- anorexia
the amount of adipose tissue in an individual is determined by expression of gene.
=high leptin
=low leptin
*regardless whether its caused by genetic factors hypothalamic lesions, or increased efficiency of food utilization
What is the major metabolic function of adipose tissue?
- (mobilization) uptake of fatty acids from blood and convert to triglyceride w/in adipocyte-> glycerol and fatty acids
- F.A pass through cell membrane to enter cap -> bound to carrier protein albumin and transported to other cells for metabolic fuel
what is Neural Mobilization?
- in severe cold, they continue to deposit fat (mobilize fat)
- leads to lipase activation, splitting triglycerides
**What is Hormonal mobilization?
-Norepinephrine
**insulin, inhibits action of lipase and blocks release of F.As.
-(liberated by nerve cell endings of the symp nervous system), initiates a series of metabolic steps that lead to activation of lipase
