Heat, Cold, and Altitude Adaptations
Start with the big picture
Heat adaptation promotes heat loss through cutaneous vasodilation and sweating, while aldosterone helps conserve sodium. Heat-shock proteins support protein stability, and changes in plasma volume, membrane composition, and metabolic rate contribute to adjustment. Cold responses conserve and generate heat through peripheral vasoconstriction, shivering, and brown adipose tissue thermogenesis; chronic exposure also involves endocrine and membrane changes. At altitude, hypobaric hypoxia activates HIF-1α-related pathways and increases ventilation. Renal bicarbonate excretion helps compensate for respiratory alkalosis, while increased 2,3-BPG supports oxygen delivery to tissues. Hematologic, muscular, and pulmonary vascular responses are also part of the adaptation, with trade-offs such as increased blood viscosity and pulmonary vasoconstriction.
What you'll learn
- Describe how vasodilation and sweating support heat dissipation.
- Explain the roles of heat-shock proteins and membrane changes in heat adaptation.
- Compare heat conservation and heat production responses in cold conditions.
- Summarize key ventilatory, renal, hematologic, and muscular responses to altitude.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
