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203: The endocrine system > Physiology of appetite and weight > Flashcards

Physiology of appetite and weight Flashcards

1
Q

BMI

  • Calculation
  • Underweight
  • Normal
  • Overweight
  • Obese
  • Morbidly obese
A

Calculation: Kg/ m2

Underweight: <18.5

Normal: 18.5-24.9

Overweight: 25-29.9

Obese: 30-39.9

Morbidly obese: >/= 40

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2
Q

Methods of measuring weight/ body composition

A

BMI

Waist circumference

Skin fold test

Bioethical impedance analysis

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3
Q

Metabolic syndrome

A

A group of symptoms/ signs associated with high risk of cardiovascular disease.
- Insulin resistance being the underlying factor.

Visceral obesity- central body fat
Dyslipidaemia
Hyperglycaemia
Hypertension

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4
Q

Epidemiology of obesity

A

Prevalence is increasing.

- 25% in England [2010-2013]

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5
Q

Mechanism behind insulin resistance and metabolic syndrome.

A

An increase in free fatty acids causes dyslipidemia

  • Visceral fat lipolysis
  • Increase in gluconeogenesis

Increase in pro-inflammatory cytokines

  • TNF-alpha, IL-6 from white adipose tissue
  • Decreases the expression of GLUT-4 and tyrosine kinase activity of insulin receptor
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6
Q

Adipocytokines

A

White adipose tissue can release a lot of pro-inflammatory cytokines
- Such as IL-6, TNF-alpha

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7
Q

Risk factors of Type 2 DM

A

Age
Obesity
Family history
Ethnicity [i.e south asian]

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8
Q

CVD associated with obesity

A

Stroke
Coronary heart disease
Hypertension
Left ventricular hypertrophy

Effects of obesity on the CVS

  • Increased blood volume
  • Increased blood viscosity
  • Increased vascular resistance.
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9
Q

Respiratory consequences of obesity

A

Obstructive sleep apnoea

Hypoxia/ Hypercapnia

Pulmonary hypertension/ Right heart failure

Daytime somnolence—> Daytime accidents

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10
Q

GI/ Liver consequences of Obesity

A 
Progresison of:
Non-alcoholic fatty liver
Non-alcoholic steatohepatits
Cirrhosis
Portal hypertension
Heptocellular cancer

Gallstones

GORD- gastroesophageal reflux disease

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11
Q

Cancer and obesity

  • Prevalence
  • Examples
  • Mechanism
A

Increases risk of cancer significantly
- 10% of non-smoker cancer deaths related to obesity.

Common cancers included

  • Breast
  • Colon
  • Endometrial
  • Oesophageal
  • Gall bladder
  • Renal
  • Thyroid

Mechanism

  • Increase in insulin, IGF-1, oestrogen
  • Increase in adipocytokines
  • Reflux
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12
Q

Consequences of obesity on the reproductive system

A

Polycystic ovarian syndrome

Male hypogonadism

Adverse pregnancy outcomes

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13
Q

Consequences of obesity on the joints

A

Osteoarthritis

Gout

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14
Q

Consequences of obesity on mental health

A

Depression

Eating disorders

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15
Q

Genetic causes of obesity

A

Obesity associated syndromes

  • Prader Willi
  • Bardet Biedl
  • Fragile X

Can also be polygenic

  • Susceptible genes
  • Inherited almost as similarly as height.
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16
Q

Stimulation of appetite

A

Arcuate nucleus- Lateral hypothalamus contains hunger/thirst centre.
- Can be inhibited by the satiety centre.

Activation of neurones by grehlin stimulates appetite [accelerator neurones]

  • Neuropeptide Y [NPY]
  • Agouti-related protein {AgRP]

AgRP can also block melanocortin receptors

Leptin acts on NPY to promote satiety.

17
Q

Ghrelin

A

Hormone released from the stomach before meals

  • Stimulates hunger
  • Acts on hypothalamic neurones NPY, AgRP
18
Q

Hormones that reduce appetite

A

CCK

GLP-1

Peptide YY [PPY]

  • All peptide released rapidly after a meal.
19
Q

Leptin

A

Hormone released from adipose tissue.
- Slow acting on arcuate receptors [NPY neurones]

Signals to the hypothalamus body fat %.

  • Acts on satiety centre
  • Negatively regulates fat mass by inhibiting hunger.
  • Increases basal metabolic rate if fat mass rises.

Also important for puberty and reproduction.

20
Q

Leptin mutations

A

Loss of genes encoding leptin or its receptors cause severe,, early onset obesity.

  • Lack of satiety.
  • Shown in Ob/ob mouse.

If receptors are fine but there is lack of leptin
- Administering leptin can reverse obesity. [shown with ob/ob mouse]

Leptin cannot be used to reverse obesity in human adults as they already have high levels of leptin.

21
Q

Insulin and body weight

A

Acts on the cortex and limbic system

  • Regulates bod weight by signalling body fat composition.
  • Decreases food intake.
22
Q

Brake neurones

A

Located in the arcuate nucleus
- ventromedial hypothalamus

Contains neurones that inhibit appetite

  • Alpha-melanocyte stimulate hormone [MSH]
  • POMC
  • CART

These neurones can inhibit NPY and AgRP

23
Q

Diet regulation for obesity

A

Eating 500-1000 cal energy deficient

Decrease portion size and snacking.

Eating more low energy dense foods

  • More fruit and veg
  • Less food high in sat fat and sugar.
24
Q

Physical activity modification and Obesity

A

Exercising 7 days a week
- 30 min intense or 1 hr low intensity

10,000 steps a day

25
Q

Environmental factors and obesity

A

Dietary intake

  • Increase in energy intake
  • Increase in portion size
  • Cheaper cost of food.

Decease in physical activity
- Car ownership and Tv ownership show positive trend with obesity.

26
Q

Targets for lifestyle modification

A

10% of weight loss

  • Continue until ideal weight is reached
  • 1-2 lbs/ 0.5-1kg loss a week

Problems

  • 5-10% weight loss takes a year to achieve
  • Yo-yo dieting
27
Q

Orlistat

  • Mechanism of action
  • Indications
  • Adverse effects
A

Action

  • Inhibits pancreatic and and gastric lipases
  • Prevents hydrolysis of TG into FFA and glycerol.
  • Prevents absorption of dietary fat.

Indications
- Obesity

Adverse effects- associated with fat malabsorption

  • Loose/ liquid stools
  • Faecal urgency
  • Anal discharge
  • Fat-soluble vitamin deficiency [ADEK]
28
Q

Problems with using pharmacological therapy in obesity

A

Only increases 5% weight loss by 3-4 fold.

Weight gain occurs when treatment is stopped.

29
Q

Laproscopic adjustable banding [Gastric banding]

A

Restrictive surgery

  • Reduces diameter of the stomach
  • Allows reduced dietary intake and improves satiety.
30
Q

Roux-en-Y gastric bypass

A

Restrictive and malabsorptive surgery

  • Bypasses the duodenum into the jejunum and reduces stomach size
  • Alters gut hormones and bile acid flow
  • Improves satiety

Complications

  • Micronutrient deficiences
  • Dumping syndrome
31
Q

Advantages of bariatric surgery

A

Significant weight loss
- 25-30%

Resolves/ Improves co-morbities
- Cost effective in the long term.

32
Q

Disadvantages of bariatric surgery

A

Perioperative mortality/ morbidity

Long term follow-up
- Micronutrient deficiencies

Weight regain

Expensive

33
Q

Bariatric surgery guidelines

NICE

A

For T2 DM recent onset

  • Proceed if BMI > 35
  • Consider if BMI >30

For obese, after failure of other options

  • First line if BMI> 50
  • BMI> 40
  • BI> 35 with co-morbidities
34
Q

Bariatric surgery guidelines

NHS England

A

Same as NICE but

  • Obese for at least 5 years
  • Must engage with non-surgical weight loss programme for 12-24 months
35
Q

Metformin and obesity

A

Increases insulin sensitivity

  • Increases peripheral glucose uptake
  • Inhibits gluconeogenesis

Prevents hyperglycaemia

36
Q

Weight loss from lifestyle interventions

A

5-10%

203: The endocrine system (23 decks)

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