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Adipose Tissue Overview
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Adipose Tissue Overview
Adipose Tissue Overview
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1
Question
What are adipose tissues?
Answer
Adipose tissues are connective tissue in which adipocytes predominate, and they normally represent 15-20% of the body weight in men.
2
Question
What do adipose tissues serve as storage depots for?
Answer
Adipose tissues serve as storage depots for neutral fats, chiefly triglycerides.
3
Question
What are adipocytes?
Answer
Adipocytes are fat-storing cells that are very large cells derived from mesenchyme, specialized for energy storage in lipid droplets with triglycerides.
4
Question
What is the function of adipocytes?
Answer
Adipocytes function as key regulators of the body's overall energy metabolism.
5
Question
What are triglycerides?
Answer
Triglycerides are long-chain fatty acyl esters of glycerol.
6
Question
What are the two properties of triglycerides?
Answer
The two properties of triglycerides are: 1. Insolubility, 2. Density.
7
Question
What do adipocytes specialize in?
Answer
Adipocytes specialize in concentrating triglycerides as lipid droplets.
8
Question
What is the significance of adipocytes in metabolism?
Answer
Adipocytes are metabolically active cells that act as an endocrine organ, produce important substances, are poor heat conductors, and provide thermal insulation.
9
Question
What are the two types of adipose tissue?
Answer
The two types of adipose tissue are white fat and brown fat.
10
Question
What characterizes white adipose tissue?
Answer
White adipose tissue is the more common type of adipose tissue specialized for fat storage, with each cell containing one large cytoplasmic droplet of whitish-yellow fat.
11
Question
What characterizes brown adipose tissue?
Answer
Brown adipose tissue has cells with multiple lipid droplets interspersed among abundant mitochondria, has a darker appearance, and functions to release heat to warm the blood.
12
Question
What is the composition of white adipose tissue?
Answer
White adipose tissue is composed of very large cells that can be up to 50-150 micrometers in diameter, typically containing a single huge lipid droplet, and half of the tissue is fibroblasts and macrophages.
13
Question
How is the distribution of adipose tissue regulated?
Answer
The distribution of adipose tissue is partly regulated by sex hormones, particularly in the deposition of fat in the breast and thighs.
14
Question
From where do adipocytes store lipids?
Answer
Adipocytes store lipids from three sources: 1. Dietary fats packaged as chylomicrons in the intestine, 2. Triglycerides produced in the liver and circulating as very-low-density lipoproteins (VLDLs), 3. Fatty acids synthesized locally.
15
Question
What are chylomicrons?
Answer
Chylomicrons are formed from ingested lipids in epithelial cells lining the small intestine and are transported in the blood and lymph, containing mainly triglycerides.
16
Question
What are VLDLs?
Answer
VLDLs are synthesized from lipids in liver cells and are routinely measured in clinical tests for blood lipids, allowing their categorization according to density.
17
Question
How are fatty acids released from adipocytes?
Answer
Fatty acids are released from white adipocytes by lipase activity when nutrients are needed and are carried throughout the body on plasma proteins such as albumin.
18
Question
What role does lipoprotein lipase play in adipose tissue?
Answer
Lipoprotein lipase is an enzyme synthesized by adipocytes and transferred to the capillary cell membrane, facilitating the breakdown of triglycerides.
19
Question
What are the two major hormones regulating lipid synthesis and mobilization in adipocytes?
Answer
The two major hormones are Growth Hormone and Insulin.
20
Question
What is the effect of Growth Hormone on adipocytes?
Answer
Growth Hormone causes free fatty acids to diffuse from adipocytes to the capillary endothelium, with free fatty acids binding to the protein albumin in the blood for transport, while glycerol remains free in blood and is taken up by the liver.
21
Question
What is the role of Insulin in adipose tissue?
Answer
Insulin inhibits hormone-sensitive lipase, reducing fatty acid release, and stimulates enzymes for lipid synthesis.
22
Question
What is leptin?
Answer
Leptin is a 16-kDa polypeptide hormone, a byproduct of the hormonal activity of white adipocytes, that has target cells in the hypothalamus and helps regulate appetite and the formation of new adipose tissue.
23
Question
How does adipose tissue respond during starvation?
Answer
During starvation, adipocytes can lose nearly all their fat and can become polyhedral or spindle-shaped cells with only very small lipid droplets.
24
Question
What are preadipocytes?
Answer
Preadipocytes are the first product of adipose development that look like larger fibroblasts with cytoplasmic lipid droplets.
25
Question
What characterizes beige adipocytes?
Answer
Beige adipocytes develop together with white adipocytes and have metabolic features generally intermediate between white and brown adipocytes.
26
Question
What occurs in the development of adipose tissue during gestation?
Answer
White adipose tissues begin to accumulate around the 14th week of gestation, with proliferation of progenitor cells diminishing until late gestation.
27
Question
What is the difference between adult-onset obesity and childhood obesity in terms of adipose tissue?
Answer
Adult-onset obesity (hypertrophy) mainly involves increasing the size of existing adipocytes, while childhood obesity (hyperplasia) often involves increases in both adipocyte size and numbers.
28
Question
What type of adipose tissue comprises up to 5% of a newborn's body weight?
Answer
Brown adipose tissue comprises up to 5% of a newborn's body weight, with smaller amounts in adults.
29
Question
What gives brown fat its color?
Answer
The color of brown fat is due to the very abundant mitochondria and many blood capillaries in this tissue.
30
Question
What is the main function of brown adipocytes?
Answer
The main function of brown adipocytes is thermogenesis, or heat production.