Homeostasis and Physiological Regulation
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What happens to insulin levels when glucose absorption from the digestive tract is complete?

  • Insulin levels decrease and glucagon levels increase. (correct)
  • Insulin levels become erratic while glucagon levels stabilize.
  • Both insulin and glucagon levels rise simultaneously.
  • Insulin levels remain high and glucagon levels decrease.

    • Which statement about glucose transport in body cells is correct?

  • All body cells require insulin for glucose transport.
  • Muscle cells utilize insulin-independent mechanisms for glucose absorption.
  • Glucose transporters in the nervous system are dependent on insulin.
  • Most body cells require insulin receptors for glucose transport. (correct)

    • Which function of insulin is primarily related to energy storage?

  • Inhibiting the conversion of glucose to glycogen.
  • Encouraging the breakdown of proteins into amino acids.
  • Enhancing the release of glucose from the liver.
  • Promoting the storage of glycogen, fats, and proteins. (correct)

    • What is the basis of the glucostatic theory regarding hunger?

    <p>Hunger is triggered by specific drops in blood glucose levels.</p> Signup and view all the answers

    Which of the following best describes glucoprivic hunger?

    <p>Hunger triggered by the absence of glucose in cells.</p> Signup and view all the answers

    What primarily motivates animals to eat according to the positive-incentive perspective?

    <p>Anticipated pleasure of eating</p> Signup and view all the answers

    What is a significant criticism of set-point theories regarding hunger?

    <p>They do not account for taste and societal influences.</p> Signup and view all the answers

    What occurs when the vagus nerve is cut in relation to hunger signals?

    <p>Both lipoprivic and glucoprivic hunger cease.</p> Signup and view all the answers

    Which theory accounts for meal initiation and termination during eating?

    <p>Glucostatic theory</p> Signup and view all the answers

    How do high levels of fat deposits affect hunger at the time of eating?

    <p>They can increase hunger instead.</p> Signup and view all the answers

    What is one of the crucial factors that is claimed to be disregarded by set-point theories of hunger?

    <p>Environmental food availability</p> Signup and view all the answers

    According to lipostatic theory, what is the primary determinant of the set point for hunger?

    <p>Specific levels of body fat</p> Signup and view all the answers

    Which factor does NOT influence the positive-incentive value of eating?

    <p>The genetic predisposition to certain food allergies</p> Signup and view all the answers

    What is the primary reason humans tend to prefer sweet, fatty, and salty tastes?

    <p>These tastes are usually associated with high-energy foods</p> Signup and view all the answers

    What learning mechanism helps animals develop taste preferences?

    <p>Conditioned responses to flavors and the nutritional outcomes</p> Signup and view all the answers

    What might lead to dietary deficiencies in humans, according to the text?

    <p>Food manufacturers prioritizing taste over nutritional value</p> Signup and view all the answers

    Why might humans struggle to learn which foods are beneficial?

    <p>Keeping an extensive variety of substances in their diet</p> Signup and view all the answers

    What typically triggers a preference for sodium-rich foods in animals?

    <p>A deficiency of sodium in their diet</p> Signup and view all the answers

    Which of the following factors does NOT influence when humans eat?

    <p>The color of the food served</p> Signup and view all the answers

    Which statement accurately describes bitterness in food preferences?

    <p>Bitterness is associated with toxins, leading to aversion</p> Signup and view all the answers

    How do humans typically develop specific food preferences?

    <p>By experiencing flavors on the breath of others</p> Signup and view all the answers

    What role does ghrelin play in the regulation of appetite?

    <p>It stimulates appetite and thoughts about food.</p> Signup and view all the answers

    How does leptin function in the body regarding fat and appetite?

    <p>It decreases appetite and promotes fat metabolism.</p> Signup and view all the answers

    Why might leptin injections be ineffective in most overweight individuals?

    <p>They have a reduced ability for leptin to cross the blood-brain barrier.</p> Signup and view all the answers

    Which of the following is true about insulin's role in body fat regulation?

    <p>It acts as a negative feedback signal on fat metabolism.</p> Signup and view all the answers

    What effect does serotonin have on eating behaviors?

    <p>It causes resistance to high-calorie foods in certain conditions.</p> Signup and view all the answers

    In rodents, what is the result of ghrelin injection?

    <p>Stimulated thoughts about food and increased appetite.</p> Signup and view all the answers

    What happens to the appetite of genetically modified mice with lower levels of brain insulin?

    <p>They show increased levels of body fat.</p> Signup and view all the answers

    Which statement best describes the relationship between fat storage and leptin levels in overweight individuals?

    <p>They usually have high leptin levels despite their body weight.</p> Signup and view all the answers

    What is a common misconception about the role of fat in the body?

    <p>Fat contributes to metabolic regulation through hormone release.</p> Signup and view all the answers

    What role do osmoreceptors primarily serve in the body?

    <p>They detect changes in hydration levels.</p> Signup and view all the answers

    Which brain region is primarily associated with osmometric thirst?

    <p>Lamina terminalis</p> Signup and view all the answers

    What occurs when there is damage to the lamina terminalis?

    <p>Adipsia or a lack of drinking.</p> Signup and view all the answers

    Volumetric thirst is primarily triggered by which condition?

    <p>Reduction of blood plasma volume.</p> Signup and view all the answers

    Which substances are likely to pass easily into the organum vasculosum of the lamina terminalis?

    <p>Dissolved substances in the blood.</p> Signup and view all the answers

    How does the activity in the anterior cingulate cortex relate to thirst upon drinking?

    <p>It returns to baseline levels after drinking.</p> Signup and view all the answers

    What physiological response accompanies volumetric thirst, related to sodium levels?

    <p>Development of a salt appetite.</p> Signup and view all the answers

    Which feature of a physiological regulatory mechanism monitors the value of the system variable?

    <p>Detector</p> Signup and view all the answers

    What does osmometric thirst specifically arise from?

    <p>Loss of water from intracellular fluid</p> Signup and view all the answers

    Which mechanism is NOT considered a satiety mechanism?

    <p>Measurement of energy expenditure</p> Signup and view all the answers

    How does osmotic pressure affect intracellular fluid?

    <p>It drives water out of the cell when solutes are concentrated externally.</p> Signup and view all the answers

    Which characteristic of homeostasis is NOT a part of the physiological regulatory mechanism features?

    <p>Homeostatic balance</p> Signup and view all the answers

    Which factor is least likely to influence the positive-incentive value of eating?

    <p>Color of the food</p> Signup and view all the answers

    What is a common consequence of dietary deficiencies in humans as suggested by the content?

    <p>Increased salt consumption</p> Signup and view all the answers

    Which nutritional deficiency triggers an immediate preference for a taste?

    <p>Sodium deficiency</p> Signup and view all the answers

    How do animals typically learn to prefer certain tastes?

    <p>Based on social feedback from others</p> Signup and view all the answers

    What primarily affects the amount and timing of meals in most humans?

    <p>Culture and social norms</p> Signup and view all the answers

    Which taste is generally avoided due to its association with potential toxins?

    <p>Bitter</p> Signup and view all the answers

    What factor contributes to the difficulty in determining which foods are beneficial for people in industrialized societies?

    <p>Overwhelming food variety</p> Signup and view all the answers

    What impact does a major energy deficit have on hunger and eating behaviors?

    <p>It significantly increases hunger</p> Signup and view all the answers

    What characteristic of sweet and fatty tastes is considered adaptive?

    <p>They indicate high-energy foods</p> Signup and view all the answers

    What is the primary effect of sensory-specific satiety on food consumption?

    <p>It leads to a decrease in the positive-incentive value of specific foods.</p> Signup and view all the answers

    Which factors are primarily associated with general satiety?

    <p>Both sensory input and postingestive consequences.</p> Signup and view all the answers

    How does sensory-specific satiety support a varied diet?

    <p>By encouraging consumption of different food items after a food is abandoned.</p> Signup and view all the answers

    What is the role of blood glucose levels in the initiation of eating?

    <p>The intention to eat leads to a decline in blood glucose levels.</p> Signup and view all the answers

    Which brain structures are crucial for processing taste information relevant to hunger?

    <p>Nucleus of the solitary tract and area postrema.</p> Signup and view all the answers

    What effect do lesions in the area postrema have on feeding behaviors?

    <p>They abolish both glucoprivic and lipoprivic feeding.</p> Signup and view all the answers

    What role do melanin-concentrating hormone (MCH) and orexin play in the lateral hypothalamus?

    <p>They increase food intake and decrease metabolic rate.</p> Signup and view all the answers

    Which foods seem to be less affected by long-lasting sensory-specific satiety?

    <p>Grains and sweets.</p> Signup and view all the answers

    What can be inferred about the relationship between sensory-specific satiety and animal behavior?

    <p>Animals may consume more when exposed to a variety of foods.</p> Signup and view all the answers

    Study Notes

    Homeostasis and Physiological Regulation

    • Homeostasis is maintaining a stable internal environment, crucial for survival.
    • Physiological regulatory mechanisms ensure homeostasis in response to environmental changes.
    • These mechanisms have 4 key features: a system variable to be regulated, a set point (ideal value), a detector to monitor the variable, and a correctional mechanism to restore the variable to the set point.
    • Negative feedback is a vital process in these systems, reducing or stopping the initial action based on its effects.
    • Ingestive behaviors (eating and drinking) can be part of correctional mechanisms.
    • Satiety mechanisms reduce hunger/thirst to promote adequate nutrient/water intake. These mechanisms monitor the correctional mechanism, not the system variable.

    Thirst and Drinking

    • Intracellular fluid is the fluid inside cells, while intravascular fluid is blood plasma, and interstitial fluid surrounds cells.
    • Osmometric thirst arises from a higher solute concentration in the interstitial fluid, causing water to leave cells (osmosis).
    • Osmoreceptors, located in the lamina terminalis (OVLT/SFO), detect changes in cell volume and trigger thirst.
    • Volumetric thirst results from a reduction in blood volume (e.g., through blood loss or vomiting).
    • Angiotensin, a hormone produced in the kidneys, is crucial for volumetric thirst. Angiotensin does not cross the blood-brain barrier, and volumetric thirst is initiated in the subfornical organ.
    • The median preoptic nucleus integrates information from osmoreceptors to regulate drinking.
    • Damage to the lamina terminalis can lead to adipsia (lack of drinking).
    • Osmoreceptors in the OVLT and SFO detect changes in extracellular fluid composition.
    • The anterior cingulate cortex and hypothalamus are activated during thirst, while the lamina terminalis shows sustained activation, indicating continued thirst sensation.

    Digestion and Metabolism

    • Digestion breaks down food into lipids, amino acids, and glucose.
    • Energy is stored primarily as fat, with less stored as glycogen and proteins. A gram of fat stores more energy than a gram of glycogen.
    • Energy metabolism is divided into the cephalic, absorptive, and fasting phases, each controlled by insulin and glucagon. Insulin dominates during the absorptive phase, and glucagon during the fasting phase.
    • The cephalic phase is the preparatory phase from sensing (sight, smell) to the start of eating. The absorptive phase occurs during or after eating when nutrients are entering the bloodstream, while the fasting phase begins after absorbed nutrients are used and the body withdraws from stores.

    Theories of Hunger and Eating

    • Set-point theories suggest that eating is regulated by specific levels of body fat or blood glucose.
    • Glucostatic theory focuses on blood glucose levels.
    • Lipostatic theory focuses on body fat levels.
    • Positive-incentive theory emphasizes the anticipated pleasure of eating rather than simple energy deficits.
    • Some animals have a set point for energy expenditure rate, and changes in intake balance this.

    Factors Influencing Eating

    • Taste preferences (sweet, fatty, salty) are generally associated with high-energy foods.
    • Learning and societal influences significantly affect what and when we eat.
    • Serving sizes and eating with others can influence consumption.
    • Overeating shares some similarities to drug addiction.

    Brain Structures and Hormones

    • The hypothalamus plays a central role in regulating hunger and satiety, specifically the lateral hypothalamus and the paraventricular nucleus (PVN).
    • The arcuate nucleus is crucial for integrating signals about nutrient levels in the blood and gut, containing neurons which secrete neuropeptide Y (NPY) and agouti-related protein (AGRP).
    • Neuropeptides like MCH, orexin, NPY, AGRP, CART, and a-MSH, have key roles in appetite-regulating processes.
    • Ghrelin increases appetite when the stomach is empty, while leptin decreases appetite when fat stores are high.
    • Insulin and serotonin also play a role in satiety. Insulin acts as a negative feedback signal on appetite.
    • The lamina terminalis and the nucleus of the solitary tract detect glucose.
    • The area postrema and nucleus of the solitary tract (AP/NST) receives sensory information from the tongue and other internal organs and detects glucose.
      • Lesions of these areas abolish glucoprivic and lipoprivic feeding.
    • Melanocyte-stimulating hormone (MSH) is an anorexigenic hormone which suppresses appetite.

    Eating Disorders

    • Anorexia nervosa involves extreme underconsumption, while bulimia nervosa involves bingeing and purging.
    • Binge-eating disorder involves bingeing without purging.
    • Evolutionary, psychological and social factors can influence the development of these disorders.
    • Anorexia nervosa has been linked to reduced brain tissue (possibly reversible) and is influenced by hereditary factors.
    • Bulimia nervosa involves cycles of bingeing and purging, resulting in feelings of guilt and depression.

    Body Weight Regulation

    • Diet-induced thermogenesis adjusts energy utilization based on body fat levels.
    • The settling-point model suggests that the body adjusts to specific body weights.
    • Weight loss programs can be challenging as bodies are programmed to eventually return to a previous weight. Initial weight loss is often rapid, but the rate of loss slows as the body adapts to reduced intake.
    • Permanent weight loss often requires sustained lifestyle changes.

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    Task 7 - Hunger & Homeostasis PDF

    Description

    Explore the mechanisms of homeostasis and how physiological regulation maintains a stable internal environment crucial for survival. This quiz covers the role of negative feedback, thirst, and the different types of body fluids involved in maintaining balance and responding to environmental changes.

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