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Pathology & Physiology (Subject) / Thermoregulation (Lesson)
- Negative feedback loop (in general) Sensor (affarent neuron) --> Integrator (efferent neuron) --> Effector
- Thermoregulation cascade (Temperature increase) 1. Skin temperature/Core temperature --> Peripheral thermoreceptors (10%) + Central thermoreceptors (90%) 2. Hypothalamus (Integrator) 3. Sympathetic cholinergic neurons 4. Sweat glands --> Sweat secretion --> Heat lost through evaporation AND Cutaneous blood vessels --> Vasodilation --> Heat loss to environment
- Thermoregulation cascade (Temperature decrease) 1. Skin temperature/Core temperature --> Peripheral thermoreceptors (10%) + Central thermoreceptors (90%) 2. Hypothalamus (Integrator) 3. Sympathetic adrenergic neurons + Somatic motor neurons 4.a. Cutaneous blood vessels --> Vasoconstriction --> Heat conserved AND Brown fat --> Nonshivering thermogenesis --> Metabolic heat production 4.b. Skeletal muscle --> Shivering thermogenesis --> Metabolic heat production
- Thermoreceptors - convert changes in temperature in activity of neurons 1. Type a) Warm receptors (>38°C) b) Cold receptors (<34°C) 2. Location a) Central receptors b) Peripheral receptors
- Cutaneous circulation and heat loss - External heat input + internal heat production = Heat loss 1. External heat input - Radiation - Conduction 2. Internal heat production a) Metabolism - "Waste heat" + Nonshivering thermogenesis --> Basal metabolic rate b) Muscle contraction - Shivering thermogenesis + "Waste heat" --> Muscle activity/exercise 3. Heat loss - Radiation (65%) - Evaporation (20%) - Convection (5%) - Conduction (10%)
- Limits of thermoregulation Hypothermia or Hyperthermia can lead to the dysfunction of the hypothalamus, which can't regulate the temperature anymore
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