CPPS303 XIAO Lecture 5 Adipose Tissue March_19_2025 (1) Flashcards
What are the physiological characteristics of adipose tissue?
Storage of energy in the form of TAG, highly sensitive to insulin, secretory functions that regulate distant target cells.
Disruption of these functions may lead to systemic metabolic dysfunction.
Name the different types of adipocytes.
- White adipocyte
- Brown adipocyte
- Beige adipocyte
- Pink adipocyte
Each type has distinct characteristics and functions.
What is the primary function of white adipose tissue (WAT)?
Energy storage, endocrine communication, and insulin sensitivity.
Predominant cell type is the white adipocyte.
What triggers the ‘beiging’ of white adipose tissue?
Cold exposure, diet, exercise, pre-/pro-biotics, drugs.
Beiging results in beige adipocytes that have characteristics of both brown and white adipocytes.
What is the unique feature of brown adipose tissue (BAT)?
Rich in mitochondria and contains uncoupling protein-1 (UCP1) for thermogenesis.
BAT is specialized for heat generation.
Fill in the blank: Adipose tissue stores body fat as neutral _______.
TAG
What is the role of lipolysis in adipose tissue?
Release of fatty acids to supply energy to other tissues during fasting or high energy demand.
Lipolysis is regulated by hormonal cues.
True or False: All WAT depots are equal in their metabolic effects.
False
Abdominal WAT is closely linked to insulin resistance and metabolic diseases.
How does adipose tissue respond to energy surplus?
Stores TAG and can undergo hypertrophy or hyperplasia.
Hypertrophy refers to an increase in the size of adipocytes, while hyperplasia refers to an increase in the number of adipocytes.
What is the primary function of beige adipocytes?
Similar to brown adipocytes, they are involved in thermogenesis and energy expenditure.
Beige adipocytes emerge from the transformation of white adipose tissue.
What is lipogenesis?
The process of storing TAG in conditions of energy surplus.
It is crucial for maintaining energy homeostasis.
How do adipocytes uptake glucose?
Via GLUT4 transporters.
Insulin stimulates the uptake of glucose into adipocytes.
What are the consequences of chronic activation of adipocyte expansion?
Weight gain and obesity.
Can lead to ectopic lipid accumulation and insulin resistance.
What are the constituents of adipose tissue?
- Mature adipocytes
- Precursor cells
- Non-adipocytes (stromal vascular fraction)
Non-adipocytes produce hormones and cytokines that affect adipocyte function.
What is the significance of UCP1 in brown adipocytes?
It is a major factor for the thermogenic process.
UCP1 helps in the uncoupling of oxidative phosphorylation, leading to heat production.
What is the primary energy reservoir in mammals?
Neutral TAG stored in adipose tissue.
This storage is vital for energy balance.
What is the role of nutritional and hormonal cues in adipose tissue?
They help balance lipid storage and breakdown in adipocytes.
This balance is crucial for whole-body insulin sensitivity.
Fill in the blank: Lipid uptake in adipocytes primarily occurs through dietary lipids from circulation in the form of free _______.
fatty acids
What is the impact of ectopic lipid accumulation?
Leads to insulin resistance and metabolic dysfunction.
Insufficient lipid retention in WAT forces lipids to accumulate in other tissues like the liver and muscle.
What is the process by which adipose tissue releases lipids?
Lipolysis
Lipolysis involves the sequential action of lipases including ATGL, HSL, and MGL, resulting in free fatty acids and glycerol.
What are the main products of lipolysis?
Free fatty acids, glycerol
These products are released into circulation and delivered to other tissues such as the liver and muscle.
What regulates lipolysis?
Nutrition, sympathetic nervous system, hormones
Factors such as feeding, fasting, and hormonal changes influence lipase activities.
How does insulin affect lipolysis?
Insulin inhibits lipolysis
In cases of insulin resistance at adipocytes, lipolysis increases, leading to the delivery of more fatty acids to other tissues.
What is the consequence of increased lipolysis due to insulin resistance?
Whole-body insulin resistance
Increased delivery of fatty acids leads to ectopic lipids, which contribute to systemic insulin resistance.
