Obesity Flashcards
(25 cards)
How many adipocytes are there and what are they?
3
white adipocyte
beige adipocyte
brown adipocyte
How does obesity develop?
When energy intake exceeds energy expenditure.
Positive (pregnancy, obesity) & negative (wasting, starvation) energy balance and a lack of physical activity
What is adipose hyperplasia?
An increase in the number of cells. In the case of obesity, an increase in the number of preadipocytes produced
What is adipose hypertrophy?
With constant energy surplus, adipose cells become hypertrophic. It is a feature of dysfunctional adipose tissue where the cell size increases due to excess lipid storage capacity
WHO obesity defenition?
An abnormal or excessive accumulation of fat that presents and risk to health due to increased disease risk
What is the crude population measure for obesity?
Body mass index (BMI)
What is the equation for BMI?
weight (kg) / height (m) ^2
What are the BMI values for overweight and obese?
> 25 kg/m^2 = overweight
>30 kg/m^2 = obese
What are the 3 mechanisms that contribute to increased fat/adipose mass?
Hyperplasia, hypertrophy & adipogenesis
What leads to adipocyte dysfunction?
A constant surplus of energy intake leads to the hyperplasia of preadipocytes. Preadipocytes are matured into adipocytes by adipogenesis increasing adipocyte cell numbers. Hypertrophy involves the increased lipid storage capacity of cells.
What is released as a result of adipocyte dysfunction?
Adipokines, free fatty acids and pro-inflammatory mediators (hence obesity is an inflammatory disease/state)
What kind of organ is adipose tissue?
endocrine organ
What types of molecules does adipose tissue secrete?
hormones and cytokines
What is the primary function of cytokines?
to regulate inflammation
Which type of fat has a greater inflammatory response?
Visceral fat
Pro-inflammatory hormones are implicated in the development of what 3 specific diseases/problems?
Insulin resistance, CVD and obesity
Which 2 cytokines are indicative of low-grade inflammation?
Tumour necrosis factor - alpha (TNFa)
interleukin-6 (IL-6)
What are the lifestyle factors that cause obesity?
- When energy intake continually overtakes energy expended resulting in an energy imbalance
- increasingly sedentary lifestyles due to transportation, urban life, sedentary jobs
- increasingly consumed energy dense foods
What are some biological systems that may influence someone’s predisposition to developing obesity?
- genetic predisposition to obesity
- level of physical activity
- release of satiety hormones
- resting metabolic rate
- degree of appetite control by the brain
- adipocyte metabolism
What are some physiological causes for obesity?
- Digestion v absorption
- Maternal nutrition (Barkers hypothesis: LBW infant = increased risk for obesity in later life)
- Resting metabolic rate (affected by disease, fitness, body composition, medications)
- Appetite control (satiety by hormone regulation - leptin and ghrelin)
- Gut signalling (gut microbiome)
What is ghrelin, where is it synthesised and when is it released?
Ghrelin is a peptide hormone produced in the stomach and increases during the fasting state to initiate hunger
What is leptin, where is it synthesised and when is it released?
Leptin is a hormone synthesised in the adipose tissue. It has the opposite effect of ghrelin and stimulates the feeling of satiety (abnormalities in leptin signalling is directly correlated with overeating and obesity)
Dysfunction of what reward pathway has associations with obesity? What neurotransmitter does this system release?
Mesolimbic system.
Dopamine
What are epigenetics? How do they relate to obesity?
Mechanisms that lead to long-term effects/changes in gene expression.
They have been implicated in obesity, appetite control and metabolism
