Hypothalamic Control of Thermoregulation Quiz
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Questions and Answers

What is the primary mechanism of heat transport from the core of the body to the skin?

  • Conduction
  • Convection
  • Radiation (correct)
  • Evaporation

    • During fever and recovery, what are the primary mechanisms of heat production and heat dissipation?

  • Heat production: increased metabolic rate; Heat dissipation: vasoconstriction and decreased sweating
  • Heat production: shivering; Heat dissipation: vasodilation and sweating (correct)
  • Heat production: vasodilation; Heat dissipation: shivering and decreased sweating
  • Heat production: decreased metabolic rate; Heat dissipation: vasoconstriction and increased sweating

    • What is the primary function of the thermoregulatory center in the body?

  • To store excess heat in the body
  • To regulate the menstrual cycle and circadian rhythm
  • To maintain the body temperature within a narrow range around the hypothalamic set point (correct)
  • To increase the metabolic rate during fever

    • What is the primary mechanism by which heat is lost from the body at room temperature?

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

    At what core body temperature can hypothermia be diagnosed?

    <p>35°C</p> Signup and view all the answers

    Vasoconstriction of cutaneous blood vessels in response to changes in core body temperature is mediated by binding of a hormone/neurotransmitter to what receptor?

    <p>Alpha-1 adrenergic receptor</p> Signup and view all the answers

    What contributes to the production of body heat?

    <p>Muscular exercise, food assimilation, and vital processes contributing to Basal Metabolic Rate (BMR)</p> Signup and view all the answers

    What are the mechanisms for heat loss from the body?

    <p>Radiation, conduction, convection, and water evaporation</p> Signup and view all the answers

    What determines body temperature?

    <p>The balance between heat production and loss</p> Signup and view all the answers

    Which part of the body primarily controls the regulation of body temperature?

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

    What is the 'normal' core body temperature (Tb)?

    <p>37ᵒC (98.6ᵒF)</p> Signup and view all the answers

    How does rectal temperature compare to oral temperature?

    <p>Approximately 0.5°C higher</p> Signup and view all the answers

    What contributes to the fluctuation in body temperature?

    <p>Circadian and female monthly rhythms</p> Signup and view all the answers

    How is heat balance achieved in the body?

    <p>When heat gain equals heat loss</p> Signup and view all the answers

    What determines heat storage in the body?

    <p>Heat capacity, with water having a high heat capacity</p> Signup and view all the answers

    What percentage of the energy liberated through catabolism is released as heat?

    <p>60%</p> Signup and view all the answers

    What factors influence Basal Metabolic Rate (BMR)?

    <p>Age, sex, hormones, and digestive state</p> Signup and view all the answers

    What is the average Basal Metabolic Rate (BMR) in a 70 kg male?

    <p>Around 70 kcal/hr</p> Signup and view all the answers

    Which mechanism primarily contributes to heat production during moderate exercise?

    <p>Muscular activity</p> Signup and view all the answers

    What is the primary mechanism of heat loss during physical activity at high temperatures?

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

    Which organs are the primary heat producers in the body during cellular processes?

    <p>Brain, skeletal muscle, and visceral organs</p> Signup and view all the answers

    What is the approximate percentage of total heat produced by internal organs at rest?

    <p>56%</p> Signup and view all the answers

    What is the chief determinant of heat transfer to the skin?

    <p>Blood flow to the skin</p> Signup and view all the answers

    Which mechanism is responsible for heat dissipation at low temperatures?

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

    What is the primary mechanism of heat transfer from the body core to the skin?

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

    What is the primary mechanism of heat production after a meal?

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

    What regulates heat dissipation at high temperatures?

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

    What is the primary mechanism of heat transfer at low temperatures?

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

    What is the primary mechanism of heat transfer by conduction across subcutaneous fat?

    <p>Relatively constant</p> Signup and view all the answers

    Which mechanism contributes to heat production in brown adipose tissue?

    <p>Non-shivering thermogenesis</p> Signup and view all the answers

    What is the primary mechanism for heat loss from the skin surface for naked individuals in a 20°C room?

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

    What is the primary mechanism for heat loss from the skin surface for naked individuals in a 30°C room?

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

    How much heat does 1 L of water remove through evaporation from the skin surface?

    <p>580 kcal</p> Signup and view all the answers

    What is the primary method for heat dissipation in hot environments when evaporation becomes ineffective?

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

    At what relative humidity does evaporation become ineffective for heat dissipation?

    <p>75%</p> Signup and view all the answers

    Where is the thermoregulatory center located in the human body?

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

    What does the thermoregulatory center do when body temperature is below the set-point?

    <p>Activates heat-generating mechanisms</p> Signup and view all the answers

    What type of nerves innervate the sweat glands?

    <p>Sympathetic cholinergic nerves</p> Signup and view all the answers

    At high humidity, what happens to the effectiveness of sweating as a heat loss mechanism?

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

    What happens to the body's evaporation rate at high temperatures with high humidity?

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

    What can potentially lead to hypothermia or hyperthermia according to the heat balance equation?

    <p>Shifts in heat storage</p> Signup and view all the answers

    What does the hypothalamic thermoregulatory center do when body temperature is above the set-point?

    <p>Activates heat-dissipating mechanisms</p> Signup and view all the answers

    What are the mechanisms through which the hypothalamus controls thermoregulation?

    <p>Cholinergic and adrenergic mechanisms</p> Signup and view all the answers

    What happens to skin blood vessels to release heat?

    <p>They dilate</p> Signup and view all the answers

    What are common causes of hyperthermia?

    <p>Prolonged heat exposure, high humidity, and physical exertion</p> Signup and view all the answers

    What are symptoms of hyperthermia?

    <p>Weakness, sweating, nausea, vomiting, and collapse</p> Signup and view all the answers

    What can heat stroke lead to if untreated?

    <p>Disorientation, seizures, coma, and death</p> Signup and view all the answers

    What occurs during hypothermia?

    <p>Thermoregulatory mechanisms activated to raise body temperature</p> Signup and view all the answers

    What induces fever?

    <p>Cytokines released during infections</p> Signup and view all the answers

    How can fever be reduced?

    <p>Inhibitors of PG synthesis, like NSAIDs, can reduce fever</p> Signup and view all the answers

    What is the benefit of fever?

    <p>It slows microorganism growth and stimulates antibody production</p> Signup and view all the answers

    What stimulates PGE2 release, leading to fever?

    <p>Cytokines, such as IL1, IL6, and TNFa</p> Signup and view all the answers

    What can fever cause?

    <p>Increased heart rate, fatigue, joint aches, headache, and disturbances of consciousness</p> Signup and view all the answers

    Study Notes

    Hypothalamic Control of Thermoregulation and Temperature Disorders

    • The hypothalamus controls thermoregulation through cholinergic and adrenergic mechanisms
    • Skin blood vessels dilate to release heat, while vasoconstriction minimizes heat loss
    • Hyperthermia results from the body's inability to dissipate heat, leading to heat collapse, heat stroke, and malignant hyperthermia
    • Common causes of hyperthermia include prolonged heat exposure, high humidity, and physical exertion
    • Hyperthermia symptoms include weakness, sweating, nausea, vomiting, and collapse
    • Heat stroke can lead to disorientation, seizures, coma, and death if untreated
    • Hypothermia occurs in mild, moderate, and severe stages, with thermoregulatory mechanisms activated to raise body temperature
    • Fever is induced by cytokines released during infections, which stimulate prostaglandin E2 (PGE2) release and elevate the thermoregulatory set-point
    • Inhibitors of PG synthesis, like NSAIDs, can reduce fever
    • Fever is beneficial as it slows microorganism growth and stimulates antibody production
    • Cytokines, such as IL1, IL6, and TNFa, stimulate PGE2 release, leading to fever
    • Fever can cause increased heart rate, fatigue, joint aches, headache, and disturbances of consciousness

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    Description

    Test your knowledge of hypothalamic control of thermoregulation and temperature disorders with this quiz. Explore the mechanisms of heat regulation, hyperthermia, heat stroke, and hypothermia, as well as the role of fever in combating infections.

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