Sports, Exercise and Health Science · A.1 Communication

SEA.1.2 — Maintaining homeostasis

Sports, Exercise and Health Science · SL / HL · syllabus-mapped notes

1. SEA.1.2.1

   Homeostasis and negative feedback

   Homeostasis is any self-regulating biological process aiming to produce a relatively stable, constant internal environment for optimal functioning of the body. In response to changing internal and external conditions, various mechanisms work constantly towards homeostasis.

2. SEA.1.2.1.1

   Negative feedback

   Homeostasis generally occurs via negative feedback mechanisms that reverse a change back to a controlled condition.

3. SEA.1.2.1.2

   Blood pH

   Blood pH (hydrogen ion concentration) is influenced by carbon dioxide concentration. pH is monitored through the respiratory control centre of the brain and chemoreceptors throughout the body.

4. SEA.1.2.1.3

   Regulation of the heart

   Regulation of the heart is dependent on intrinsic and extrinsic excitation. A diagram of the heart’s structure is found in the SEHS data booklet.

5. SEA.1.2.1.4

   Thermoregulation and the four systems

   Regulation of temperature (thermoregulation) relies on the cardiovascular, muscular, nervous and integumentary systems working together to maintain a core body temperature of 37 ± 1°C.

6. SEA.1.2.1.5

   The five thermoregulatory mechanisms

   Thermoregulation occurs via the sweat response, vasodilation, vasoconstriction, shivering and non- shivering thermogenesis.

7. SEA.1.2.1.6

   Factors affecting thermoregulation

   Factors that affect thermoregulation are training status, body composition, environment and sex differences (including hormonal phases).

8. SEA.1.2.1.7

   Regulation of blood glucose

   Regulation of blood glucose relies on insulin and glucagon. Exercise limits the release of insulin and facilitates the uptake of glucose to regulate blood sugar levels.

9. SEA.1.2.2

   Responses to the environment

   The body has acute and possible long-term responses to the environment in which it functions.

10. SEA.1.2.2.1

    Temperature, humidity and altitude

    Short-term responses and long-term adaptations in the body can vary in response to the external environment (temperature, humidity, altitude).

11. SEA.1.2.2.2

    The activity determines the impact

    The extent to which the environment impacts performance of an activity depends on the nature of the activity.

12. SEA.1.2.2.3

    Acclimatization strategies

    Different strategies can be used to support performance of an activity and acclimatize the body to variations in the immediate environment.