animal homeostasis

Animal Homeostasis

Overview

  • Course: BIOL:1412

  • Instructor: Dr. Brandon Waltz

Objectives

  • Define homeostasis and provide an example.

  • Explain the importance of essential nutrients for animals.

  • Discuss Q10 and its significance.

  • Provide examples of adaptations to thermal environments (behavioral and physiological).

  • Explain the role of molecular evolution in animal diversification.

  • Differentiate between homeotherms and poikilotherms (ectotherms) regarding function and energy needs.

  • Analyze the importance of microenvironments for animal success in various environments.

  • Describe how feedback and feedforward control systems operate (both positive and negative feedback).

Homeostasis

  • Definition: The stability of an individual's internal environment, such as maintaining a constant body temperature, supported by physiological or behavioral feedback responses.

  • Importance: Organisms need to maintain a stable internal environment due to fluctuating external conditions (e.g., Arctic, desert, saltwater, rainforest).

  • Energy Requirement: Maintaining homeostasis requires energy.

Parameters of Homeostasis

  • Key Parameters:

    • Temperature

    • pH

    • Blood glucose

    • Blood pressure

    • Heart and respiratory rate

    • Behavioral feedback responses

    • Oxygen levels ([O2])

    • Carbon dioxide levels ([CO2])

    • Sodium levels ([Na+])

    • Calcium levels ([Ca+])

Importance of Thermoregulation

  • Daily and seasonal temperature variations can significantly impact ecosystems.

  • Temperature affects enzyme-catalyzed and uncatalyzed reaction rates.

  • The challenge lies in coordinating metabolism across varying temperatures.

Thermoregulation Mechanisms

  • Non-biological Response: e.g., heater turned off when room temperature decreases.

  • Biological Response:

  • Activation of the thermoregulation center in the brain.

  • Sweat glands secrete sweat for cooling.

  • Set Point: Example set at 20°C.

  • Responses to temperature changes include blood vessel dilation (heat loss) or constriction (minimizing heat loss).

Q10 Temperature Coefficient

  • Definition: Measures sensitivity of a process to temperature changes.

  • Calculation: Q10 = (Rate at given temperature) / (Rate at lower temperature).

  • Cannot be extrapolated beyond the defined temperature range.

Homeotherms vs. Poikilotherms

  • Homeotherms: Animals that maintain a constant internal body temperature (e.g., birds, mammals) - known as regulators.

  • Poikilotherms (Ectotherms): Animals with body temperatures that shift along with environmental temperatures (e.g., frogs, lizards, fish) - known as conformers.

Extreme Temperature Examples

  • Body temperature ranges from –2 to 50 °C (28.4 – 122 °F) for various species.

Homeothermic Animals

  • Examples:

  • Mammals

  • Birds

  • Insects (certain species only at specific times)

Definitions in Thermoregulation

  • Endotherm: Gets heat primarily from metabolic processes.

  • Ectotherm: Obtains heat mainly from external sources; body temperature may vary with the environment.

Thermoregulation Strategies

  • Behavioral Adaptations: More available options for smaller animals, including movement to microclimates (e.g., shade, wind avoidance).

  • Structural and Physiological Adaptations: Larger animals often develop specialized structures (e.g., fur insulation, countercurrent heat exchange).

Microenvironments and Homeostasis

  • Definition: Environments containing different conditions within a larger habitat.

  • Examples of microenvironments: Shade, sunbathing areas, thermoclines, root systems, and snow.

Ectotherm Behavioral Thermoregulation Example

  • Lizards adjust their body temperature by basking in the sun or seeking shade throughout the day, showing temperature regulation through behavior.

Countercurrent Heat Exchange

  • Mechanism: Arrangements where warm arterial blood transfers heat to cooler venous blood, minimizing heat loss to the environment.

  • Examples: Arctic fox, Grant's gazelle (which cools its brain).

Other Morphological Adaptations

  • Heat exchange occurs at the surface; larger surfaces typically lead to greater heat loss.

Hibernation in Animals

  • Some animals, like groundhogs, enter hibernation in protective environments, characterized by lower body temperatures and thermal conformity.

  • Example: Ground squirrels are heterothermic, maintaining homeothermy in summer but hibernating in winter.

Feedback Regulation

  • Negative Feedback: Stabilizes systems by correcting deviations from the set point or range.

  • Positive Feedback: Amplifies processes, usually not involved in homeostasis, but can trigger events like mammal birth or fever.