Hypothalamus I and II
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Questions and Answers

Which of the following is a function controlled by the hypothalamic nuclei?

  • Hearing
  • Balance
  • Breathing
  • Hunger (correct)

    • Which hormones are released by the supraoptic and paraventricular nuclei?

  • Oxytocin and arginine vasopressin (correct)
  • Insulin and glucagon
  • Testosterone and estrogen
  • Cortisol and adrenaline

    • What is the role of the posterior pituitary gland?

  • To release oxytocin and AVP (correct)
  • To control body temperature
  • To regulate hunger
  • To release hormones into the bloodstream

    • Which hormone is also known as anti-diuretic hormone (ADH)?

    <p>Arginine vasopressin (AVP)</p> Signup and view all the answers

    What is the effect of dopamine released from the arcuate nucleus and other nuclei?

    <p>Inhibits the release of prolactin</p> Signup and view all the answers

    What is the role of the hypothalamic nuclei?

    <p>Maintenance of body weight</p> Signup and view all the answers

    What is the function of oxytocin and arginine vasopressin (AVP)?

    <p>Release of hormones</p> Signup and view all the answers

    What is the relationship between the hypothalamus and the autonomic nervous system?

    <p>Hypothalamus can control the autonomic nervous system</p> Signup and view all the answers

    What is the blood brain barrier (BBB)?

    <p>A barrier that prevents the release of hormones into the brain</p> Signup and view all the answers

    What is the function of the releasing hormone GHRH?

    <p>Stimulate the release of growth hormone</p> Signup and view all the answers

    Which hormone is released directly into the bloodstream by axonal nerves in the posterior pituitary gland?

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

    What is the role of negative feedback pathways in hormone regulation?

    <p>To inhibit the release of hormones</p> Signup and view all the answers

    What is the effect of cortisol on PNMT mRNA?

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

    Which hormone can negatively feedback to inhibit the release of either GHRH or GH?

    <p>Insulin growth factor-1 (IGF-1)</p> Signup and view all the answers

    What is the effect of somatostatin on the release of GH?

    <p>Inhibit the release of GH</p> Signup and view all the answers

    What is the influence of a positive feedback pathway on the release of oxytocin?

    <p>Stimulate the release of oxytocin</p> Signup and view all the answers

    Which of the following is a function controlled by the hypothalamus?

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

    What is the role of the hypothalamus in the stress response?

    <p>It activates the prefrontal cortex to release cortisol</p> Signup and view all the answers

    What are the three nuclei that the hypothalamus is divided into?

    <p>Anterior, medial, and posterior</p> Signup and view all the answers

    What is the output of the hypothalamus in response to stimuli?

    <p>ANS or Endocrine output via the pituitary gland</p> Signup and view all the answers

    What is the effect of chronic stress on the prefrontal cortex?

    <p>It impairs its function</p> Signup and view all the answers

    Which of the following is NOT a physiological function of the hypothalamus?

    <p>Visual perception</p> Signup and view all the answers

    What systems does the hypothalamus coordinate to maintain homeostasis?

    <p>Multiple systems including endocrine and ANS</p> Signup and view all the answers

    What is the role of negative feedback loops in hypothalamic responses?

    <p>To inhibit the hypothalamic response</p> Signup and view all the answers

    What type of pathways to the hypothalamus are mostly unmyelinated?

    <p>Afferent and efferent pathways</p> Signup and view all the answers

    What can initiate hypothalamic responses?

    <p>Cortical centers</p> Signup and view all the answers

    What can be activated by the hypothalamus?

    <p>Cortical centers</p> Signup and view all the answers

    What is the effect of cortisol on plasma glucose levels?

    <p>It elevates plasma glucose levels</p> Signup and view all the answers

    What is the role of beta-endorphins in the stress response?

    <p>To reduce the response to pain</p> Signup and view all the answers

    Which part of the brain is responsible for enhancing state of alertness in the stress response?

    <p>Locus ceruleus</p> Signup and view all the answers

    What is the effect of extreme psychological stress on vagal activity?

    <p>It increases vagal activity</p> Signup and view all the answers

    What is the effect of insulin overdose in Type I and Type II diabetics?

    <p>It results in hypoglycemia</p> Signup and view all the answers

    What is the effect of beta-2-adrenergic receptor activation in the cardiovascular readjustments of the stress response?

    <p>It causes vasodilation</p> Signup and view all the answers

    What is the effect of parasympathetic tone on cardiac output in the stress response?

    <p>It decreases cardiac output</p> Signup and view all the answers

    What is the effect of hypnosis and meditation on stress reduction?

    <p>They decrease stress levels</p> Signup and view all the answers

    What is the effect of chronic hypoglycemia on the stress response?

    <p>It elevates plasma glucose levels</p> Signup and view all the answers

    What is the effect of overshoots and undershoots of body core temperature during a fever?

    <p>Less precise control of body core temperature</p> Signup and view all the answers

    What can cause protein denaturation?

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

    What is the effect of pro-inflammatory cytokines released during a fever?

    <p>Increased body temperature</p> Signup and view all the answers

    What is the effect of stimulation of heating mechanisms during the 'Chills' phase of a fever?

    <p>Increased core temperature</p> Signup and view all the answers

    What is the primary cooling mechanism in humans?

    <p>Eccrine sweat gland activation</p> Signup and view all the answers

    What is the effect of cooling mechanisms during the 'Fever' phase of a fever?

    <p>Decreased core temperature</p> Signup and view all the answers

    What is the state of a fever when the hypothalamic setpoint is reset back to normal?

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

    What is the effect of increased AVP levels during a fever?

    <p>Increased water conservation</p> Signup and view all the answers

    What is the set point center for proper body temperature?

    <p>The hypothalamus</p> Signup and view all the answers

    Which part of the hypothalamus controls reflex responses activated by warmth?

    <p>Anterior hypothalamus</p> Signup and view all the answers

    What can cause heat production in the body?

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

    What is the normal body temperature by oral route?

    <p>37°C or 98.6°F</p> Signup and view all the answers

    What is the process by which heat loss can occur through vaporization of water in respiratory passages and on skin called?

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

    What is the effect of increased release of thyroid hormone in response to cold?

    <p>Increased heat production</p> Signup and view all the answers

    What is the effect of beta-3-adrenergic receptor activation in response to cold?

    <p>Increased heat production</p> Signup and view all the answers

    What is the process by which heat loss can occur through direct contact with a colder object called?

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

    What is the process by which heat loss can occur through emission of heat waves from the body called?

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

    What can lead to obesity?

    <p>Increased food intake without an equal amount of energy expenditure.</p> Signup and view all the answers

    What signals influence appetite at the level of the hypothalamus?

    <p>Neural afferents, hormones, and metabolites.</p> Signup and view all the answers

    Which mouse models produce hyperphagia and obesity when leptin or the leptin receptor is knocked out?

    <p>Both ob/ob and db/db mouse models.</p> Signup and view all the answers

    What is the central integrator for appetite?

    <p>The ARC.</p> Signup and view all the answers

    Which neurons in the ARC become activated and produce POMC protein in the presence of Anorexigenic signals?

    <p>POMC neurons</p> Signup and view all the answers

    Which melanocortin receptors are most abundant in the CNS?

    <p>MC3R and MC4R.</p> Signup and view all the answers

    What does MC4R do in the body?

    <p>It is responsible for actions on body weight and blood pressure.</p> Signup and view all the answers

    What is the effect of exogenous leptin given to rodents?

    <p>It increases blood pressure.</p> Signup and view all the answers

    What is the anorexigenic effect of CRH?

    <p>Decreases appetite</p> Signup and view all the answers

    How does gastric distension affect appetite?

    <p>Decreases appetite</p> Signup and view all the answers

    What is the effect of chewing gum on snacking on high calorie foods?

    <p>Decreases snacking</p> Signup and view all the answers

    What is the anorexigenic effect of leptin on the body?

    <p>Decreases appetite</p> Signup and view all the answers

    What is the effect of increased plasma leptin on the VMN?

    <p>Activates gene (TORC1)</p> Signup and view all the answers

    What is the effect of low leptin in women?

    <p>Increase in amenorrhea</p> Signup and view all the answers

    What is the effect of low leptin in men?

    <p>Reduces rate of sperm production</p> Signup and view all the answers

    What hormone stimulates the lateral hypothalamus area (LHA) and can lead to hyperphagia?

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

    What is the effect of Neuropeptide Y (NPY) on cortisol releasing hormone (CRH)?

    <p>Inhibits release of CRH through activation of GABA-producing neurons</p> Signup and view all the answers

    What hormone can lead to the release of ACTH/Cortisol under chronic low level stress conditions, such as stress eating?

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

    Which hormone stimulates higher centers to increase fat intake and decrease insulin secretion?

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

    What is the effect of Agouti-related peptide (AgRP) on the MC4R pathway and POMC?

    <p>Inhibits MC4R pathway and POMC</p> Signup and view all the answers

    What can stimulate the HPA or increase appetite when given exogenously?

    <p>Chronic stress</p> Signup and view all the answers

    What type of foods are highly consumed in Western society to alleviate stress?

    <p>Comfort foods (high dense, palatable foods)</p> Signup and view all the answers

    What is the anorexigenic effect of CRH?

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

    Which hormone influences short- and long-term regulation of appetite?

    <p>All of the above</p> Signup and view all the answers

    What is the effect of vagotomy on ghrelin?

    <p>Inhibits ghrelin's ability to stimulate food intake</p> Signup and view all the answers

    What happens to plasma ghrelin levels after gastric bypass surgery?

    <p>They decrease significantly</p> Signup and view all the answers

    What is the mechanism behind the decrease in plasma ghrelin levels after gastric bypass surgery?

    <p>Decreased production and secretion of ghrelin</p> Signup and view all the answers

    What is the effect of higher plasma cortisol levels on eating behavior?

    <p>Increased phasic responses to eating</p> Signup and view all the answers

    What is the hypothesis behind the decrease in plasma ghrelin levels after gastric bypass surgery?

    <p>Direct contact between gastric mucosa and food is important for the production and secretion of ghrelin</p> Signup and view all the answers

    What is the effect of gastric bypass surgery on fat accumulation?

    <p>It decreases fat accumulation</p> Signup and view all the answers

    What is the effect of vagotomy on GH release?

    <p>Inhibits GH release</p> Signup and view all the answers

    What type of information can chemoreceptors in gut mucosa send to the nucleus tractus solitarius (NTS) to influence appetite?

    <p>Nutrients, motility of tract, and neuroendocrine responses</p> Signup and view all the answers

    What effect does distension of the stomach have on appetite?

    <p>Decreases appetite</p> Signup and view all the answers

    What can shrink astrocytes surrounding POMC nerves to increase feelings of satiety and decrease appetite?

    <p>Increased plasma glucose</p> Signup and view all the answers

    What protein was discovered in 2017 as an orexigenic protein?

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

    What type of drugs have been used to stimulate appetite in patients with cancer cachexia?

    <p>5-HTR3 antagonists</p> Signup and view all the answers

    What mediates the thirst response in the body?

    <p>Hypertonicity and hypovolemia</p> Signup and view all the answers

    What regulates drinking water in the body?

    <p>Plasma osmolality and extracellular fluid volume</p> Signup and view all the answers

    What can induce thirst independent of plasma osmolality?

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

    What factors can contribute to the regulation of water intake besides physiological factors?

    <p>Social factors</p> Signup and view all the answers

    Which type of receptor works through Gq to cause vasoconstriction?

    <p>V1</p> Signup and view all the answers

    What is the function of the lateral hypothalamus in thirst response?

    <p>It triggers thirst response</p> Signup and view all the answers

    What is the synthetic analog of vasopressin used to treat?

    <p>Neurogenic or central diabetes insipidus</p> Signup and view all the answers

    What triggers milk ejection during breastfeeding?

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

    What is the reflex that triggers milk ejection called?

    <p>Neuroendocrine reflex</p> Signup and view all the answers

    What type of receptors are activated by touch receptors in the nipple during breastfeeding?

    <p>Sensory afferents</p> Signup and view all the answers

    What can cause waves of uterine contraction during childbirth?

    <p>A positive feedback loop involving oxytocin release</p> Signup and view all the answers

    What is the effect of estrogen on sensitivity to oxytocin?

    <p>Increases sensitivity to oxytocin</p> Signup and view all the answers

    Which system links the neuroendocrine, autonomic, and somatic motor systems?

    <p>Limbic system</p> Signup and view all the answers

    What is the role of the amygdala in the stress response?

    <p>It stimulates the arcuate and paraventricular nuclei</p> Signup and view all the answers

    What is the role of the hypothalamus in controlling thirst?

    <p>It releases hormones to promote thirst</p> Signup and view all the answers

    Which type of receptor do most peptide hormones use to induce a specific signaling pathway?

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

    What is the mechanism of action of V2 receptors?

    <p>They work through Gs to increase cAMP</p> Signup and view all the answers

    What is the role of 5-HTR3 antagonists in appetite stimulation?

    <p>They help to stimulate appetite</p> Signup and view all the answers

    What is the purpose of anticholinergics and antihistamines in appetite stimulation?

    <p>They help to stimulate appetite</p> Signup and view all the answers

    What is anamorelin used for in cancer patients?

    <p>To stimulate appetite</p> Signup and view all the answers

    What is negative feedback in the context of hypothalamic control?

    <p>A mechanism by which a change in a variable leads to a response that counteracts the initial change</p> Signup and view all the answers

    Study Notes

    Hypothalamic Nuclei and Functions

    • Hypothalamic nuclei control diverse functions, including hormone release, appetite, thirst, and body temperature regulation.
    • Supraoptic and paraventricular nuclei release oxytocin and arginine vasopressin (AVP), also known as anti-diuretic hormone (ADH).
    • Posterior pituitary gland stores and releases hormones produced by the hypothalamus, including oxytocin and AVP.
    • Dopamine released from the arcuate nucleus and other nuclei regulates prolactin release.
    • Oxytocin and AVP play crucial roles in social bonding, milk ejection, water reabsorption, and blood pressure regulation.
    • Hypothalamus coordinates with the autonomic nervous system to regulate internal environment, including heart rate, blood pressure, and body temperature.
    • Blood brain barrier (BBB) restricts passage of certain substances from the bloodstream to the brain, protecting the central nervous system.
    • Growth hormone releasing hormone (GHRH) stimulates the release of growth hormone from the pituitary gland.
    • Oxytocin and AVP are released directly into the bloodstream via axonal nerves in the posterior pituitary gland.
    • Negative feedback pathways regulate hormone levels by inhibiting further hormone release, with cortisol negatively feeding back to inhibit GHRH and GH release.
    • Somatostatin inhibits GH release.
    • Positive feedback pathways enhance hormone release, as seen with oxytocin during childbirth and breastfeeding.

    Hypothalamic-Pituitary-Adrenal (HPA) Axis

    • Hypothalamus plays a central role in the stress response, triggering the HPA axis.
    • Hypothalamus is divided into three nuclei: anterior, middle, and posterior.
    • The hypothalamus releases corticotropin-releasing hormone (CRH) in response to stress.
    • Chronic stress can negatively impact the prefrontal cortex, affecting cognitive function.
    • Hypothalamus coordinates endocrine, nervous, and immune systems to maintain homeostasis.

    Stress Response Pathways

    • Hypothalamus receives information from various pathways, including sensory, autonomic, and neural.
    • Hypothalamus can activate sympathetic nervous system and HPA axis in response to stress.
    • Cortisol increases plasma glucose levels to provide energy for the stress response.
    • Beta-endorphins reduce pain and provide feelings of well-being during stress.
    • Amygdala enhances alertness and activates fight-or-flight response during stress.
    • Extreme psychological stress can suppress vagal activity, affecting heart rate variability.

    Insulin & Stress

    • Insulin overdose in Type I and Type II diabetics can lead to hypoglycemia.
    • Beta-2-adrenergic receptor activation in the cardiovascular system causes increased heart rate and blood pressure during stress.
    • Parasympathetic tone decreases cardiac output during stress.
    • Hypnosis and meditation can reduce stress by promoting relaxation and altering brain activity.
    • Chronic hypoglycemia triggers hormonal responses and activates the HPA axis.

    Fever Response

    • Overshoots and undershoots of body core temperature during a fever are part of thermoregulation.
    • Protein denaturation can be caused by extreme temperatures and pH fluctuations.
    • Pro-inflammatory cytokines released during a fever reset the hypothalamic set point for temperature.
    • Stimulation of heating mechanisms during the 'Chills' phase of a fever causes shivering.
    • Sweating is the primary cooling mechanism in humans.
    • Cooling mechanisms during the 'Fever' phase of a fever are suppressed to maintain elevated temperature.
    • Hypothalamic setpoint returns to normal when the fever resolves.
    • AVP levels increase during a fever, contributing to vasoconstriction and heat retention.
    • Hypothalamus acts as the set point center for proper body temperature.
    • Anterior hypothalamus controls reflex responses to warmth.
    • Heat production can be increased by shivering, muscle contraction, and metabolic processes.
    • Normal body temperature measured by oral route is approximately 98.6 degrees Fahrenheit.
    • Evaporation is the process of heat loss through vaporization of water from respiratory passages and skin.
    • Increased thyroid hormone release in response to cold enhances metabolism and heat production.
    • Beta-3-adrenergic receptor activation contributes to thermogenesis in response to cold.
    • Conduction is the process of heat loss by direct contact with a colder object.
    • Radiation is the process of heat loss by emission of heat waves from the body.

    Appetite Regulation and Obesity

    • Obesity can be caused by a combination of genetic predisposition, environmental factors, and lifestyle choices.
    • Hypothalamus integrates signals influencing appetite, including leptin, ghrelin, insulin, and CRH.
    • Leptin and leptin receptor knockout mouse models exhibit hyperphagia and obesity.
    • Arcuate nucleus (ARC) is the central integrator for appetite.
    • POMC neurons in the ARC become activated in the presence of anorexigenic signals, leading to POMC protein production.
    • Melanocortin receptors (MC4Rs) are most abundant in the CNS and suppress appetite.
    • MC4R activation reduces food intake and promotes energy expenditure.
    • Exogenous leptin administration in rodents decreases food intake.
    • CRH has an anorexigenic effect by suppressing appetite.
    • Gastric distension triggers signals leading to satiety.
    • Chewing gum can reduce snacking on high-calorie foods by stimulating signals of satiety.
    • Leptin has an anorexigenic effect by inhibiting appetite and increasing energy expenditure.
    • Increased plasma leptin activates the ventromedial nucleus (VMN), leading to reduced appetite.
    • Low leptin levels in women can disrupt menstrual cycles and fertility.
    • Low leptin levels in men can contribute to decreased testosterone production.
    • Ghrelin stimulates the lateral hypothalamus area (LHA), increasing appetite.
    • Neuropeptide Y (NPY) increases CRH release, potentially contributing to stress eating.
    • CRH can lead to the release of ACTH/Cortisol under chronic low-level stress conditions.
    • Ghrelin stimulates higher centers to increase fat intake and decrease insulin secretion.
    • Agouti-related peptide (AgRP) inhibits MC4R pathway and POMC production, promoting appetite.
    • Ghrelin and NPY stimulate the HPA axis and increase appetite when given exogenously.
    • Highly processed foods and comfort foods are often consumed in Western society to alleviate stress.
    • CRH has an anorexigenic effect by suppressing appetite and promoting satiety.
    • Leptin influences short- and long-term regulation of appetite.
    • Vagotomy can disrupt ghrelin signaling and reduce appetite.
    • Gastric bypass surgery significantly reduces plasma ghrelin levels.
    • Gastric bypass surgery alters gastric emptying and nutrient absorption, leading to reduced ghrelin levels.
    • Higher plasma cortisol levels can increase food intake and promote fat storage.
    • Gastric bypass surgery can improve metabolic health and reduce obesity.
    • Vagotomy can reduce GH release.

    Appetite Regulation: Other Players

    • Chemoreceptors in gut mucosa send signals about nutrient content to the nucleus tractus solitarius (NTS) to influence appetite.
    • Distension of the stomach sends signals of satiety.
    • 瘦素 (瘦素) can decrease appetite by shrinking astrocytes surrounding POMC nerves.
    • Orexigenic protein, discovered in 2017, stimulates appetite.
    • Appetite stimulating drugs have been used to treat cancer cachexia by activating NPY pathway or ghrelin receptors.

    Thirst Regulation

    • Hypothalamus mediates the thirst response.
    • Hypothalamus regulates drinking water in response to plasma osmolality.
    • Angiotensin II, hypovolemia, and dry mouth can induce thirst independent of plasma osmolality.
    • Psychological factors and habit can also contribute to water intake regulation.
    • Vasoconstriction is mediated by AVP receptors working through Gq.
    • Lateral hypothalamus plays a crucial role in the thirst response.
    • Desmopressin, a synthetic analog of vasopressin, treats diabetes insipidus.

    Milk Ejection and Childbirth

    • Oxytocin triggers milk ejection during breastfeeding.
    • Milk ejection reflex is initiated by touch receptors in the nipple.
    • Mechanoreceptors in the nipple are activated by tactile stimulation during breastfeeding.
    • Oxytocin also causes waves of uterine contraction during childbirth.

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    Test your knowledge of the hypothalamus and its role in controlling the autonomic nervous system with this quiz. Learn about the various nuclei involved in basic functions such as hunger, body weight maintenance, and body temperature regulation, as well as their link to behavior through the limbic system.

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