Thermoregulation and Metabolism lec

Flashcards covering key vocabulary related to thermoregulation and metabolism.

Thermoregulation

The ability to keep internal body temperature within strict values characteristic to the species. This process involves complex physiological mechanisms to maintain optimal enzymatic activity and cellular function.

Optimal Temperature

Range of environmental temperatures ideal for growth and development, characteristic for the species, individual, or population. Deviations from this range can lead to stress, reduced performance, or death.

Endotherms

Animals that maintain a body temperature largely independent of the environment. They use metabolic processes to generate heat and maintain a stable internal temperature.

Poikilotherms

Animals whose body temperatures fluctuate with the external temperature. Their metabolic rate and activity levels are heavily influenced by environmental conditions.

Effectors of Thermoregulation

Organ systems involved in heat creation, saving, or elimination, including the circulatory system, sweat glands, skeletal muscles, liver, and adipose tissue. These effectors respond to signals from the hypothalamus to maintain temperature homeostasis.

Postprandial Thermogenesis

Energy dissipated during digestion, absorption, and disposal of ingested nutrients. This process contributes to heat production and can vary depending on the type and amount of food consumed.

Thermic effect of food

The energy dissipated during digestion, absorption, and disposal of ingested nutrients, also known as postprandial thermogenesis. It represents the increase in metabolic rate after eating.

Heterothermy

A property of homeotherms to change internal temperature by modifying metabolism intensity. This adaptation allows them to cope with varying environmental conditions and energy demands.

Hibernation/Aestivation

A state of metabolic depression and inactivity in endotherms, typically during winter (hibernation) or summer (aestivation). It involves reduced heart rate, breathing, and body temperature to conserve energy.

Torpor

A period of decreased physiological activity, usually by reduced metabolic rate and body temperature; short-term hibernation often used by smaller animals to conserve energy during periods of inactivity or food scarcity.

Fever (Pyrexia)

Increase in body temperature above the normal range due to an increase in the temperature set point. It is a common symptom of infection or inflammation and is regulated by the hypothalamus.

Pyrogenic Factors

Internal (endogenous) - cytokines produced by activated immune cells. External (exogenous) - factors released by/from infectious agents. These factors trigger the release of prostaglandins, which act on the hypothalamus to raise the body's temperature set point.

Heat Balance Equation

Total Heat = Metabolic Heat + Conduction + Radiation + Convection/Evaporation + Stored Heat. This equation describes how body heat is influenced by various factors, including metabolic rate, environmental exchanges, and energy storage.

Thermogenesis

Heat production in the body through metabolic processes. It can occur through shivering or non-shivering mechanisms and is essential for maintaining body temperature.

Shivering Thermogenesis

Heat generation as a by-product of energy release in skeletal muscles. Rapid muscle contractions produce heat, which helps to raise body temperature.

Non-Shivering Thermogenesis

Metabolic heat production involving unnecessary ATPase cycles, sympathetic stimulation, lipolysis, and UCP1 induction. It primarily occurs in brown adipose tissue and is important for maintaining body temperature in infants and hibernating animals.

Thermogenin (UCP1)

Uncoupling protein 1; mitochondrial protein that generates heat by uncoupling oxidative phosphorylation. It is found in brown adipose tissue and allows protons to flow across the inner mitochondrial membrane without producing ATP, generating heat instead.

Luke-Warm Blooded Animals

Animals that generate heat (liver and muscles) and have heat exchangers with modified RYR1 channels; this mechanism enhances heat production and conservation.

Malignant Hyperthermia

A hypercatabolic state triggered by stress or anesthesia, leading to high temperature, increased heart rate, rapid breathing, and muscle rigidity. It is often caused by genetic mutations affecting calcium regulation in muscle cells.

Porcine Stress Syndrome (PSS)

Mutation in ryanodine receptor RYR1 that can lead to malignant hyperthermia-like symptoms in pigs. The mutation causes uncontrolled calcium release in muscle cells, leading to rapid metabolism and heat production.

Homeothermy

Maintenance of relatively stable core body temperature regardless of environmental pressure through internal regulatory mechanisms. Mechanisms like shivering, sweating, and adjusting blood flow to the skin maintain stable temperatures.

Poikilothermy

Core body temperature highly dependent on ambient temperature, regulated mainly through behavioral strategies.