8_Animal_Homeostasis

Animal Homeostasis

BIOL:1412 Dr. Brandon Waltz

Objectives

• Define Homeostasis: Stability of internal environment (example: constant body temperature).

• Essential Nutrients: Animals need to consume nutrients continuously for survival.

• Q10 Significance: Measure of sensitivity of biological reactions to temperature changes.

• Adaptations: Discuss behavioral and physiological adaptations related to thermal environments.

• Molecular Evolution: Its critical role in animal diversification.

• Homeotherms vs. Poikilotherms: Differences in functionality and energy requirements.

• Microenvironments: Importance for animal success in diverse environments.

Homeostasis Overview

• Definition:

  • Stability of internal environment, essential for survival.

  • Organisms need to adapt to external environmental differences (e.g., Arctic, Desert).

Homeostatic Parameters

• Temperature

• pH

• Blood glucose levels

• Blood pressure

• Heart and respiratory rates

• Behavioral feedback responses

• Oxygen and Carbon Dioxide levels

• Ion concentrations (Na+, Ca+)

Importance of Thermoregulation

• Temperature Variations: Significant daily and seasonal variations in ecosystems.

• Impact on Reactions: Temperature affects catalyzed and uncatalyzed reaction rates, complicating metabolic coordination.

Thermoregulation Mechanisms

• Control System:

  • Set point and control center maintain homeostasis.

  • Example: Shivering to regain body heat.

• Blood Vessel Regulation: Vessels constrict or dilate based on temperature conditions.

  • Cold: Constriction near surface vessels.

  • Warm: Dilation near surface vessels.

Q10 Temperature Coefficient

• Definition:

  • Indicates the sensitivity of reactions to temperature changes.

  • Calculated as Q10 = Rate at T+10 degrees / Rate at T.

• Limitations: Not applicable outside specific temperature ranges.

Homeotherms vs. Poikilotherms

• Homeotherms: Maintain constant body temperature (e.g., birds, mammals).

  • Defined as regulators; require energy to maintain metabolism.

• Poikilotherms: Body temperature varies with environmental conditions (e.g., frogs, lizards, fish).

  • Known as conformers; energy-efficient but reliant on surroundings.

Energy Metabolism and Temperature

• Colder temperatures may require higher metabolic rates to maintain homeostasis.

• Optimal zones allow for minimal energy expenditure to sustain life functions.

Extreme Temperature Adaptations

• Animals have adapted to thrive in extreme temperatures (e.g., Antarctic Ice Fish, desert iguanas).

• Examples of resilience in harsh conditions: wood frog and tardigrades.

Homeothermic Animals

• Include mammals and birds.

• Two types of adipose tissue: brown and white (brown is more efficient in generating heat).

• Non-shivering thermogenesis is significant in infants and certain bird species.

Heat Source Definitions

• Endotherm: Obtains heat mainly through metabolism; may vary in temperature maintenance success.

• Ectotherm: Acquires heat from external sources; temperature may considerably differ from the environment.

Thermoregulation Strategies

• Behavioral Options: Especially available for smaller animals, e.g., using microclimates, seeking shelter from wind, or utilizing clothing in humans.

• Physiological and Structural Adaptations: Larger animals develop features to aid in temperature regulation (e.g., thicker hair, countercurrent heat exchange mechanisms).

Microenvironments in Homeostasis

• Define microenvironments: Variables exist within larger habitats affecting animal adaptation.

• Examples include:

  • Shade

  • Snow

  • Root systems

  • Thermoclines.

Countercurrent Heat Exchange

• Mechanism allowing organisms to maintain temperature, especially in cold environments.

• Examples include adaptations in Grant’s Gazelle, which cools its brain through this method.

Morphological Adaptations

• Surface area impacts heat exchange; larger surface areas often result in higher heat loss but can gain heat under certain conditions.

Hibernation in Animals

• Groundhogs and other small mammals exhibit hibernation as a survival strategy.

• This condition involves lower body temperature and may lead to thermal conformity.

Feedback Mechanisms

Negative Feedback Regulation

• Involves a stressor prompting physiological changes to restore homeostasis (set point).

Positive Feedback Regulation

• Accelerates or amplifies physiological changes; typically not involved in homeostasis.

• Examples: childbirth events and fever.