Here is how the body regulate temperature through neuronal effects.

1. Thermoregulation

2. Normal Body Temperature
 Body Core Temperature: deep tissues, constant (±1°F - ±0.6°C)
 Skin Temperature: rises & falls with surroundings
 Normal core temperature:
 36.1°C (97.0°F) to 37.8°C (100.0°F)
 Orally 98.0°F (36.7°C) - 98.6°F (37°C)
 Rectally +1°F
 Strenuous exercise: 101°F (38.3°C) - 104°F (40°C)
 Extreme cold: < 96°F (35.6°C)

3. Hypothalamus
 Preoptic & anterior hypothalamic nuclei
 Heat/cold-sensitive neurons
 In skin: cold & warmth receptors
 Deep body temperature receptors:
spinal cord, abdominal viscera, in or
around great vessels in upper abdomen &
thorax.
 Concerned with preventing hypothermia.

4. Neuronal Effector Mechanisms
 Posterior hypothalamus
 Temperature-Decreasing Mechanisms:
1. Vasodilation of skin blood vessels Inh. sympathetic centers
2. Sweating 37°C (98.6°F)
3. Decrease in heat production Inh. shivering, chemical
thermogenesis

5. Neuronal Effector Mechanisms
 Temperature-increasing mechanisms:
1. Skin vasoconstriction Stim. sympathetic centers
2. Piloerection sympathetic stimulation
3. Increase in thermogenesis:
 Shivering: primary motor center for shivering
- Stretch reflex
- Inhibited by heat center
- Excited by cold signals from skin & spinal cord

6. Temperature-Increasing Mechanisms
 Chemical thermogenesis:
1. Sympathetic stimulation norepinephrine & epinephrine uncouple
oxidative phosphorylation releasing energy
2. Thyrotropin-releasing hormone thyroid-stimulating hormone
thyroxine increase rate of cellular metabolism

7.  Critical body core temperature is 37.1°C (98.8°F)
 Set-point
 Pyrogens: - liposaccharide toxins
- macrophages, lymphocytes
- IL-1 hypothalamus Prostaglandin E₂ Fever
- Aspirin
 Chills: attempt to accommodate higher set-point
 Crisis (Flush): attempt to accommodate lower set-point
 Heatstroke 105 - 108°F (40.5 - 42.2°C)
 Dizziness, abdominal distress, loss of consciousness