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74 Cards in this Set
- Front
- Back
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What are the 3 main things that characterize Metabolic Syndrome?
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-Insulin resistance
-Obesity -Genetic |
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What is the opposite of hunger?
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Satiety
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What controls hunger and satiety?
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The hypothalamus
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What is the immediate acute effect of food intake?
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As the stomach distends the vagus nerve sends input to the brain to tell it that its full
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What does the presence of food in the stomach/GI tract stimulate?
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Release of hormones to stimulate pancreatic secretions including Insulin
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What do bloodstream Glu/AA and insulin do after the absorption of nutrients from the GI tract?
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Inhibit the hypothalamus
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What do absorbed nutrients do to adipose mass?
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Stimulates it to release leptin
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What does leptin do?
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Inhibits the hypothalamus
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And what is the effect of the hypothalamus being inhibited by Leptin, Insulin, Glu/AA, and Gastric distention?
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Takes away the feeling of hunger so you stop eating
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Do patients with diabetes lack leptin?
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No
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Why are obese people fat if they still have leptin?
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They are leptin resistant.
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What 3 GI hormones are released by the intestines in response to food ingestion? What do they do?
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-CCK
-Insulin -PYY They inhibit further feeding |
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What is Ghrelin? Where is it from? When is it released? What does it do?
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Ghrelin is released from the stomach during fasting; it stimulates appetite
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Why is Ghrelin special?
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Because it is one of the only stimulatory things released from the GI tract - the other hormones and vagus nerve inhibit the hypothalamus
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When does Leptin release increase?
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When adipose cells get larger
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Why does leptin release increase with increase fatness?
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To try to make the body lose weight by inhibiting hunger.
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Is leptin only made in adipocytes?
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No it is made in many other tissues
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Leptin correlates with
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Fat mass
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Function of Leptin:
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To act with the hypothalamus to increase satiety and decrease hunger.
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What will happen to leptin secretion when:
-Body fat is low -Body fat is stable -Body fat is high -Obese |
Low: leptin release is low until more fat is gained
Stable: stable High: leptin release is high until fat is lost Obese: high levels of leptin released at a constant rate |
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How does obesity develop?
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Over many years, the increase in body fat is gradual, so the body fails to notice the increasing leptin levels and is resistant to leptin's effects.
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So what are 3 syndromes of endocrine resistance that we know of? What is the hormone and proper name of each?
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Vasopressin resistance (Nephrogenic Diabetes Insipidus)
Insulin resistance (Type II DM) Leptin resistance (Obesity) |
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Where leptin acts to induce satiety, Ghrelin acts to:
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Increase hunger
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What can reduce ghrelin?
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Bariatric surgeries
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What would decrease the desire to snack between meals?
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A ghrelin antagonist.. then we wouldn't eat all our little cheese snacks in class.
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What are the 3 things that control Hunger in the Short term?
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1. Gastric filling/Vagal afferents
2. Increased CCK 3. Decreased Ghrelin |
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What are the 3 things that control Hunger/Satiety in the Long term?
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1. Increase in fat deposition
2. Increased leptin 3. Alterations in NPY/POMC neurons in the hypothalamus |
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What are the 2 important nuclei in the hypothalamus that control hunger and satiety?
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1. Arcuate nucleus
2. Paraventricular nucleus |
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What 2 types of neurons are in the arcuate nucleus?
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1. POMC/CART neurons
2. AGRP/NPY neurons |
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What do POMC neurons release?
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a-MSH and CART
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What is the primary action of a-MSH and CART?
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Turn off food intake and increase energy expenditure
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What do AGRP/NPY neurons release?
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AGRP and NPY
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What are the primary actions of AGRP and NPY?
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Turn ON food intake and DECREASE energy expenditure
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Where does a-MSH released by POMC neurons go?
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To MCR-3 and MCR-4 - its receptors in the PVN
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What happens when a-MSH binds its receptors in the PVN?
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It activates neuronal pathways that project to the NTS and increase SNS activity and energy expenditure.
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What does AGRP do?
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Acts as an antagonist of MCR-4, the a-MSH receptor in the PVN
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Result of AGRP antagonizing MCR-4 receptors:
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Increased food intake and DECREASED energy expenditure
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What do Insulin, CCK, and Leptin act on? What is the result?
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-STIMULATE POMC/CART neurons to decrease food intake
-INHIBIT AGRP/NPY |
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What hormone ACTIVATES AGRP/NPY neurons? result?
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Ghrelin - stimulates food intake
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What would an MC4 agonist do?
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Stimulate the a-MSH receptor in the PVN and inhibit food intake
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What would happen if you invented an MC4 agonist?
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You'd be rich and could live for ever in Tahiti bc you'd have cured obesity
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So the peripheral hormones that control hypothalamic hunger and satiety centers are:
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-Ghrelin
-Leptin -Insulin -CCK |
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The 2 things controlled by the PVN are:
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-Hunger
-Energy expenditure |
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What is going on in an obese person?
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Their abnormally high leptin levels are failing to decrease hunger appropriately, and they are failing to increase energy expenditure.
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So what are the 2 problems in obese people due to leptin resistance?
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-Failure to stop eating
-Decreased basal metabolic rate |
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What is the cure for Type II Diabetes and Obesity?
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Diet and exercise
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What is obesity?
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A nationwide epidemic that is becoming worse in underdeveloped countries too
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What happened between 1971 and 1976?
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-Mcdonalds opened
-Cars and TVs proliferated -Child obesity skyrocketed |
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How do we cure obesity now?
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By stomach stapling - bariatric surgery
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How do you do Bariatric surgery?
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By detaching the jejunum from the duodenum and reattaching it to the top of the stomach.
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Why do you need to retain a little stomach during bariatric surgery?
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To still get intrinsic factor which is made in the stomach.
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How does stomach stapling help with weight loss?
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Because the stomach is so small, it's almost always full, so Ghrelin is always low.
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How does the WHO define Metabolic Syndrome?
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-Insulin resistance + 2:
Hypertension Dislipidemia Obesity Microalbuminuria |
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How is insulin resistance diagnosed?
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By measuring fasting blood sugar, which is elevated but not high enough to meet the diagnostic criteria for DMII
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What is visceral obesity?
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Belly fat
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Why is microalbuminuria bad?
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Because normally the glomerulus filters NO protein; small amounts of albumin indicate a decrease in renal function.
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What are 2 broad categories of causes of metabolic syndrome?
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1. Environmental factors
2. Genetic factors |
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What is the Thrifty gene?
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The gene that makes the body hold onto calories in case it's your last meal.
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What are 3 Environmental factors that contribute to metabolic syndrome?
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1. Sedentary lifestyle
2. Food intake/type 3. Early life programming |
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What are examples of early life programming?
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-Birth weight
-Stress in the postnatal period -Stress after the postnatal period |
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What is the definition of Insulin Resistance?
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An inability to increase glucose uptake by cells for the same amount of insulin.
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What results from Insulin resistance?
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Hyperinsulinemia
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Why is it so bad when people are obese?
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Because instead of staying where it belongs in adipocytes, the fat becomes deposited in spaces within the liver, muscles, and beta cells of the islets.
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What happens when fat gets deposited in the islets?
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It decreases their output of insulin
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What is Lipodystrophy?
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Low birth weight
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What is the adverse effect of lipodystrophy?
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There is a reduced capacity to store fat, so it gets deposited in ectopic places as in obesity.
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How can you tell apart obesity vs lipodystrophy?
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Lipodystrophy has a below normal total amount of fat; obesity obviously has above normal.
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What are babies with lipodystrophy programmed to get?
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Metabolic syndrome
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What distinguishes adults with diabetes due to lipodystrophy from obese diabetics?
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They are lean
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What is lipotoxicity?
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The ectopic fat deposition in the liver, muscle, and islet beta cells
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Why do we say that patients with metabolic syndrome have a "Relative Insulinopenia"?
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Because they actually have increased insulin levels, but they are below the level needed to function adequetely.
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What are 4 major longterm repercussions of metabolic syndrome?
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1. Glucose intolerance
2. Dyslipidemia 3. Hypertension 4. Thrombosis |
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What is the major adverse effect that results from the 4 chronic repercussions?
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Vascular/Heart disease
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What is the only way to deal with metabolic syndrome?
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Behavioral changes
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