What is meant by the term homeostasis? Increased metabolic rate, piloerection and vasoconstriction are responses in mammals to falling external temperatures - Leaving Cert Biology - Question c - 2016

Metabolism encompasses all chemical reactions occurring within an organism, whether in the cell or across the body. These reactions are essential for converting food into energy, building cellular structures, and facilitating growth and repair.

An increase in metabolic rate generates additional heat, which helps to maintain the body's core temperature when external temperatures drop. This thermoregulatory mechanism is vital for sustaining physiological processes and overall health.

The term used for this category of animals is 'endotherms' or 'endothermic' organisms. These animals can regulate their body temperature internally, allowing significant variability in their metabolic activities.

Animals that cannot significantly adjust their metabolic rate, known as ectotherms, may respond to falling temperatures by seeking shelter, moving to warmer environments, or hibernating to reduce their metabolic needs and conserve energy.

Piloerection refers to the reflex action where body hairs stand upright, often in response to cold temperatures. This reaction traps a layer of air, providing insulation and helping to retain body heat.

Piloerection is an important thermoregulatory mechanism because it enhances insulation. By trapping air close to the body, it reduces heat loss, thereby helping to maintain the organism's core temperature during cold conditions.

Vasoconstriction is the narrowing of blood vessels, which reduces blood flow to the skin. This response minimizes heat loss from the body surface, helping to conserve core body heat when external temperatures drop.