Respiratory Gases and Strategies

Peripheral Thermoreceptors

• Detect changes in environmental temperature.
• Provide information to the central nervous system.
• Enable the animal to adjust its behavior or physiology.

Hypothermic Lesions in Ectotherms

• Hypothermic lesions impair thermoregulatory behavior in ectotherms.
• Ectotherms become less responsive to temperature changes.
• Difficulty in maintaining optimal body temperatures for metabolic activity.

Albedo and Heat Uptake

• Albedo refers to the reflectivity of a surface.
• Higher albedo surfaces reflect more solar radiation, resulting in less heat uptake.
• Lower albedo surfaces absorb more solar radiation, increasing heat uptake.

Ectotherm Heat Exchange Regulation

• Behavioral adaptations are primarily used by ectotherms.
• Seeking out microclimates with ideal temperatures.

Ectotherm Heating Rate in Similar Environments

• Body size is a significant factor.
• Larger ectotherms have greater thermal inertia, heating up more slowly.

Ectotherm Temperature Tolerance

• Eurythermal describes animals capable of surviving a wide temperature range.
• Stenothermal animals are limited to a narrow temperature range.

Ectotherm Behavioral Adaptation for Thermoregulation

• Basking in the sun to absorb heat.
• Seeking shade or cool water to reduce heat.

Poikilothermy

• Animals that have variable body temperatures.
• Temperature changes with the environment.
• Body temperature depends on external sources of heat.

LT50 - Temperature Regulation

• Refers to the Lethal Temperature 50%.
• The temperature at which 50% of a population dies.
• Indicates the thermal tolerance of a species.

Larger Terrestrial Ectotherms and Thermoregulation

• Have a more stable body temperature due to greater thermal inertia.
• Experience less rapid change in body temperature with environmental fluctuations.

Climate Change and Fish

• Warming water temperatures can lead to reduced oxygen levels.
• Impacts fish physiology and behavior.
• Can lead to fish mortality.

Stenothermal Animals

• Limited to a narrow range of temperatures.
• Are vulnerable to environmental temperature changes.
• Cannot adapt well to fluctuating temperatures.

Temperature and Protein Structure

• Temperature influences the structure of proteins.
• Extreme temperatures can disrupt protein conformation.
• Leads to loss of function or denaturation.

Terrestrial Ectotherm Heat Mitigation

• Seeking refuge in shaded areas.
• Utilizing burrows to escape high temperatures.
• Adjusting activity levels.

Q10 Value - Biological Reactions

• The Q10 value represents the temperature coefficient.
• It indicates the change in a specific biological reaction rate over a 10°C temperature increase.
• Helps predict the rate of metabolic processes at different temperatures.

Reptile Thermoregulation

• Basking in the sun.
• Seeking shade.
• Adjusting body position.

Lizard Basking

• Surface areas exposed to sunlight heat up faster.
• Tail, head, and limbs, especially dark-colored ones, are typically warmer than the core temperature.

Cryoprotectants in Freeze-Tolerant Animals

• Act as antifreeze agents.
• Prevent intracellular ice formation.
• Promote survival during freezing conditions.

Reptile Cooling Mechanisms

• Gular fluttering (rapid throat movements) to increase airflow.
• Seeking shaded areas or immersing in water.
• Reducing activity levels.

Ectotherm Survival During Cold Months

• Dormancy and hibernation.
• Freezing tolerance in some species.
• Migration to warmer regions.

Reptile Brain Temperature Maintenance

• Counter-current heat exchange in the carotid arteries.
• Warm blood from the body core heats up the blood flowing to the brain.

Freeze-Tolerant Species Freezing Location

• Freezing typically occurs in the extracellular fluid.
• Ice formation is controlled by cryoprotectants.

Convergent Evolution in Antifreeze Compounds

• Different species, such as fish and insects, have independently developed antifreeze compounds.
• Example: the antifreeze glycoproteins found in both fish and insects.

Physiological Response to High Temperatures in Reptiles

• Increased heat dissipation through physiological mechanisms.
• Panting or gular fluttering for cooling.
• Cardiac output and blood flow adjustments.

Amphibian Oxygen Acquisition During Hibernation

• Cutaneous respiration (absorbing oxygen through the skin).
• Reduced metabolic rate to minimize oxygen demand.

Metabolic Suppression in Reptiles at Low Temperatures

• Reduced oxygen consumption and heart rate.
• Slower metabolic processes.

Colligative Antifreeze

• Increases solute concentration in body fluids to lower the freezing point.
• Example: glucose or salt.

Reptile Respiratory Cooling Priority

• Cooling the brain to prevent overheating.
• Maintain optimal brain function.
• Ensure normal neurological processes.