IB Sports, exercise and health science A.1.2 Maintaining Homeostasis Key Definitions

The physiological adjustments the body makes over time in response to environmental changes such as heat, humidity, or altitude.

A structure in the heart that delays electrical impulses to allow the atria to contract before the ventricles.

The pressure exerted by the weight of the atmosphere on a given surface. At sea level it is approximately 760 mmHg, and it falls as altitude rises.

A type of fat tissue that generates heat through non-shivering thermogenesis by burning fat, especially in response to cold exposure.

A part of the heart’s conduction system that transmits impulses from the AV node to the ventricles.

The volume of blood the heart pumps per minute.

Transfer of heat through the movement of air or liquids

The dynamic process of losing body water. It is the action that produces a state of hypohydration.

A specialized cell or structure that detects changes in the internal or external environment and sends signals to the control center.

A structure (e.g., muscle or gland) that responds to signals from the control center to restore homeostasis.

Electrolytes are minerals that carry an electrical charge, essential for fluid balance, nerve signaling, and muscle contraction.

A hormone released by the kidneys that stimulates red blood cell production in response to low oxygen levels.

Cooling mechanism where sweat evaporates from the skin, absorbing heat from the body and lowering body temperature. Efficiency is affected by humidity.

Damage to skin and underlying tissue caused by prolonged exposure to freezing temperatures, commonly affecting extremities like fingers and toes.

The production of glucose from non-carbohydrate sources, such as proteins and fats.

The process of converting glucose into glycogen for storage, mainly in the liver and muscles.

The process of breaking down glycogen into glucose to be released into the blood for energy use.

The physiological adaptations the body makes over 10 to 14 days of repeated training in the heat, including earlier and greater sweating, more dilute sweat, and expanded plasma volume, which together improve heat tolerance and exercise performance.

Homeostasis is the maintenance of a stable internal environment within an organism, ensuring optimal conditions for cellular processes.

Humidity refers to the amount of moisture in the air, and its effects on the body are particularly significant because it directly influences the body’s ability to cool down through evaporation.

A condition where the body’s core temperature drops below 35°C, impairing normal physiological functions and potentially leading to severe health complications.

A condition in which the body or a tissue is exposed to insufficient oxygen, typically caused by low atmospheric oxygen at altitude or by impaired oxygen delivery.

Negative feedback is a homeostatic mechanism in which a change in a physiological condition triggers a response that counteracts the initial change, maintaining balance.

The portion of total atmospheric pressure contributed by oxygen molecules. At sea level it is about 159 mmHg, roughly 21% of the total 760 mmHg barometric pressure.