Week 1:

• Energy in = Energy out
• Energy out
  • Physical Exercise
  • Basal Matabolic Rate
  • Diet-Induced Thermogenesis
• 5 meals a day
• Food triggers
  • People with you
  • Visual Cues
  • Time of the day
  • Comfort foods
  • Learned Cues
• Homestasis refers to biological processes that keep certain body variables within a fixed range.
  • System variable is the variable that is controlled by a regulatory mechanism.
  • Set point is the optimal value of the system variable in the regulatory system.
  • Detector monitors the value of the system variable.
  • Correctional mechanism is required to restore the system to the set point.
  • Negative feedback is a process to diminish or terminate the action set in place to return the system variable to set point once set point is achieved. This is essential to regulatory systems.
  • Satiety mechanisms are produced by adequate and available supplies of the variable in question.
• Pavlov Dog Saliva Study
• Classical or Pavlovian Conditioning
• Unconditioned and Conditioned Response and Stimulus
• Insulin increases in anticipation of food called cephalic phase insulin release

Week 2:

• Signals
  • Short Term signals tell about a meal
  • Long Term (Adiposity) arise from adipose/fat(leptin) tissue and pancreas(insulin)
  • CNS
• Blood Brain Barrier is the highly selective semi permeable membrane that protects the brain
  • Passive diffusion in fat soluble harmones, water
  • Active transport for leptin
  • Neural Transmission via vegus nerve(cranial nerve)
• Orexigenic Appetite Stimulant and antonym anorexia is an eating disorder
• Obesity depends on
  • How big is a meal
  • How much time between meals
  • How much time is spent eating a meal
• Roles of insulin
  • Involved in Short and Long term control of food intake and body weight regulation
  • Used in creating drugs for type 2 diabetes
• Hormones
  • Gut Hormones
    • Ghrelin
      • Increases food intake
      • Meal initiating hormone
      • Peripheral Hormone made in stomach
      • Acts at receptors in hypothalamus
      • Stimulates neurogenic peptides
      • Released in anticipation of eating food
    • Cholecystokinin (CCK)
      • Released in intestinal tract and found in gut and brain
      • Tells body and brain when and what food is ingested
      • Reduces food intake
      • Found in duodenum and jejunum ie upper and middle small intestine
      • Trianguar shaped and apical side is towards the inside of intestine
      • Basal Plasma CCK levels increase with a meal
      • Dietary Fat and protein are more potent stimulators of CCK than carbohydrates
      • Obesity not treated using this as it reduces the meal size but increases the frequency of the meals in a day
    • Glucagon-like Peptide 1
      • Produced in intestinal tract ie ileum and closer to the stomach
      • Also produced in hindbrain (Nucleus of solitary tract)
      • Stops food intake
      • During fast period, concentrations of GLP-1 are low
      • Incretin hormone amplify insulin secretion
      • Used to model drugs for diabetes
  • Pancreatic Hormones
    • PYY3 - 36
      • Released from intestines esp from ileum and colon
    • Pencreatic Polypeptide
      • Produced by cells in pencreas
      • Released in circulation system after food is processed
      • Released both in cephalic phase(anticipation of food) and gastric phase(food is in gut)
    • Insulin
      • Directly proportional to fat mass
      • Cephalic phase release
      • Handles glucose in negative direction
      • Act as receptor in brain including hypothalamus
      • Reduces food intake
• Stomach releases hormones that trigger hunger signals
• Intestinal tract releases hormones when we eat
• Hormones stimulate or inhibit parts of your brain to affect feeding
• Environmental and learned factors can change response to signals generated by the gut and brain to change behaviors.
• Gut
  • Stomach
  • Small intestine
    • Duodenum
    • Jejunum
    • Ileum
  • Large intestine
  • Liver
  • Pencreas
• Adiposity Signals
  • Hormones that provide information to brain about overall energy status
  • Released in proportion to fat mass
  • If Lacking then hyperphagic and obese, if excess then hypophagic and loose weight
  • Accesses and acts at the areas of brain which are involved in controlling food intake and regulating energy balance
• Adiposity Hormones
  • Leptin
  • Insulin
• Hypothalamus
  • Communicates with pitutary gland via secretion of hormones
  • Lateral Hypothalamus
    • Lesions to this area cause Aneroxic and stimulation causes hyperphagia
    • Was thought of as Hunger Center
    • Neural connections to hindbrain
      • Nucleus of the solitary tract
        • Taste processing
    • Neural connections to cerebral cortex
      • Facilitate ingestion
      • Increase cortical responses to taste, smell or sight of food
  • Ventromedial Hypothalamus
    • Lesions to this area cause hyperphagia and stimulation causes Aneroxic
    • Was thought of as Satiety Center
    • Lesions result in increased meal frequency and faster gastric emptying
      • Damage increases insulin production increasing food storage
  • Hormones from gut signal hypothalamus about energy status
    • Arculate Nucleus has two types of neurons
      • Orexigenic neuropeptides
        • Neuropeptide Y
        • Agouti related protein
        • Stimulation of these neurons stimulates food intake
        • Grehlin stimulates NPY and AgRP
      • Anorexigenic neuropeptides
        • Pro-opiomelanocortin
        • Cocaine Amphetamine Regulated Transcript
        • Stimulation of these neurons decreases food intake
        • Insulin and Leptin stimulates POMC and CART
• Associated brain areas involved in regulating energy balance
  • Learning and Memory
    • Hippocampus
  • Reward system
    • Neurotransmitter Dopamine
      • Active in Nucleus Accumbens and Ventral Tegmental
    • Neuronal projections from the hypothalamus
  • Taste
    • Nucleus of the solitary tract (NTS) in hindbrain
    • Receives input from taste buds and several cranial nerves
      • Facial, Vagus, and Glossopharyngeal cranial nerves
    • Flavor is the result of integration of taste and smell properties
    • Parabrachial nuclei (PbN) of the pons and Medullary motor nuclei in brain determine the quality and concentration of tastes
• Maintaining Weight Loss
  • With weight loss we have decreased leptin and we have increased activity in brain areas associated with emotional, cognitive and sensory control of food intake
  • Leptin treatment post weight loss is beneficial
• Sweet treats after meals for several biological, psychological and lifestyle-related reasons
  • Low serotonin levels cause us to want to eat sugar
  • Serotonin is a chemical in the brain that elevates mood
  • Sugar can help the body absorb tryptophan, which helps produce serotonin