Introduction
Temperature changes both daily and seasonally in the surrounding environments of organisms. Different organisms of different environments such as freshwater, marine, desert, and terrestrial have varied responses to temperature fluctuations.
The terrestrial environment has more temperature fluctuations than the aquatic environment. The response of the animal widely depends on its physiology. The organisms without any internal mechanism for temperature are ectotherms.
The animals that require maintenance mechanism are endotherms. They have strategies for thermoregulation. These regulations are for both hot and cold temperatures.
Thermoregulation helps them to keep their life processes adjusted to function at their normal temperature. In this article, you will read about strategies of thermoregulation in mammals.
Thermoregulation in Humans
Thermoregulation is the capability of an organism to keep its body temperature level within certain boundaries, even when the surrounding temperature level is different. All thermoregulation mechanisms are designed to return your body to homeostasis. This is a state of balance. A healthy internal body temperature falls within a narrow range.
Mammals including humans keep their body temperature within a narrow range of about 36-38 ° C because of their endothermic attributes. The origin of endothermy in birds and mammals has provided the chance to keep a high metabolic rate and schedule of energy round the clock, hence has gotten the higher capability to adaptations and has helped in much of their larger diversity and distribution in diversified regions of the earth.
These control the rate of metabolic heat production, balancing it with the rate at which they gain or lose heat from the environment.
Shivering Thermogenesis
The rate of heat production is increased by increased muscle contraction by movements or shivering so-called shivering thermogenesis.
Non-Shivering Thermogenesis
Hormones also activate heat production as do thyroid hormones and are described as non-shivering thermogenesis.
Some mammals possess brown fat, which is specialized for rapid heat production. An overproduction of heat, it is dissipated through exposed surface areas by increasing blood flow or evaporative cooling. In mammals, it is observed that the skin has been adjusted as the organ of thermoregulation.
Regulative Strategies
In Cold Temperature
Mammals have different systems that regulate heat exchange with their environment. Vasodilation and vasoconstriction affect heat exchange and might add to local temperature level differences within an animal. On a cool day, a human’s temperature may be several degrees lower in the limbs than in the trunk, where the most crucial organs are positioned.
The majority of terrestrial mammals react to cold by raising their furs, therefore, trapping the thicker layer of still air and it acts as a good insulator between animal skin and the surroundings. Humans mainly rely on a layer of fat just insulating below the skin as an insulating product against heat loss.
Similarly, marine mammals such as whales and seals populate much chillier water than their body temperature, and have an extremely thick layer of insulating fat called blubber just under the skin.
In Warm Temperature level
Marine mammals get rid of their excess heat into warm seas by a great deal of capillary in the external layer of the skin. This dissipates the heat from the skin’s surface. In terrestrial mammals, on the other hand, is the system of evaporative cooling. The gland activity and evaporative cooling are some of the major temperature minimizing techniques. Panting, the evaporative cooling in the breathing system is the other mechanism as represented in the dogs. Bats etc. use saliva and urine for evaporative cooling.
Thermostat in Humans
The body temperature level regulation in humans is based upon complicated homeostatic systems facilitated by feedback mechanisms. The homeostatic thermostat exists in the hypothalamus, a brain part. It responds to the changes in the temperature above and below a set point which is 37 ° C.
In case of an increase in temperature level above the setpoint, specific warm temperature-sensitive thermoreceptors in the skin, hypothalamus, and other parts of nervous systems send the signals to the system that increases the blood flow to the skin and likewise trigger gland activation and sweat is evaporated for the cooling.
At a cold temperature level, the cold receptors send impulses to the hypothalamus to prevent heat loss mechanisms and trigger the heat preservation systems. This consists of the constraint of superficial capillary and promoting shivering and non-shivering thermogenesis systems.
The temperature level in fever (Pyrexia)
In bacterial and viral infections primarily, leukocytes increase in number. These pathogens and the blood cells produce chemicals called pyrogens. Pyrogens displace the set point of the hypothalamus above the typical point of 37 ° C. Fever or heat helps in stimulating the protective systems against pathogens.
MCQs
- What is thermoregulation?
- a) The ability to regulate light exposure
- b) The ability to maintain body temperature within certain limits
- c) The ability to regulate water intake
- d) The ability to control sleep patterns
- Answer: b) The ability to maintain body temperature within certain limits
- Which organisms are considered ectotherms?
- a) Fish
- b) Mammals
- c) Birds
- d) Amphibians
- Answer: a) Fish
- What is the key characteristic of endotherms?
- a) They rely on external sources for body heat
- b) They lack internal mechanisms for temperature regulation
- c) They have strategies for thermoregulation
- d) They are cold-blooded
- Answer: c) They have strategies for thermoregulation
- Why do mammals, including humans, maintain a narrow body temperature range?
- a) To adapt to seasonal changes
- b) Due to their endothermic attributes
- c) To hibernate effectively
- d) To conserve energy
- Answer: b) Due to their endothermic attributes
- What is shivering thermogenesis?
- a) A process of muscle contraction to increase heat production
- b) A mechanism for evaporative cooling
- c) A method of heat dissipation in marine mammals
- d) A hormonal activation of heat production
- Answer: a) A process of muscle contraction to increase heat production
- What activates non-shivering thermogenesis?
- a) Increased muscle activity
- b) Hormones, including thyroid hormones
- c) Exposure to warm seas
- d) Vasodilation
- Answer: b) Hormones, including thyroid hormones
- How do most terrestrial mammals respond to cold temperatures?
- a) By sweating excessively
- b) By raising their furs to trap air
- c) By diving into cold water
- d) By increasing their metabolic rate
- Answer: b) By raising their furs to trap air
- What is the primary insulating material against heat loss in humans?
- a) Blubber
- b) Fur
- c) Feathers
- d) Layer of fat under the skin
- Answer: d) Layer of fat under the skin
- How do marine mammals dissipate excess heat into warm seas?
- a) Through shivering
- b) Through increased blood flow to the skin
- c) By panting
- d) Through evaporative cooling
- Answer: b) Through increased blood flow to the skin
- Where does the body’s thermostat for temperature regulation exist in humans?
- a) Brainstem
- b) Cerebellum
- c) Hypothalamus
- d) Medulla oblongata
- Answer: c) Hypothalamus
- What happens during a fever (Pyrexia)?
- a) The body temperature decreases
- b) The hypothalamus set point is displaced above normal
- c) Sweat production increases
- d) The body enters a state of hibernation
- Answer: b) The hypothalamus set point is displaced above normal
- What is homeostasis in the context of thermoregulation?
- a) Maintaining body temperature within a narrow range
- b) Adapting to extreme environmental conditions
- c) Hibernating during winter
- d) Allowing body temperature to fluctuate widely
- Answer: a) Maintaining body temperature within a narrow range
- What signals does the hypothalamus receive during an increase in body temperature?
- a) Signals to decrease blood flow to the skin
- b) Signals to increase sweat production
- c) Signals to decrease metabolic rate
- d) Signals to increase heat preservation mechanisms
- Answer: b) Signals to increase sweat production
- How do cold receptors respond to a decrease in temperature?
- a) Trigger heat preservation mechanisms
- b) Increase blood flow to the skin
- c) Activate sweat glands
- d) Signal the hypothalamus to increase metabolic rate
- Answer: a) Trigger heat preservation mechanisms
- What is the purpose of fever (Pyrexia) during bacterial and viral infections?
- a) To cool down the body
- b) To stimulate protective systems against pathogens
- c) To induce hibernation
- d) To increase metabolic rate
- Answer: b) To stimulate protective systems against pathogens
- Which hormone is involved in non-shivering thermogenesis?
- a) Insulin
- b) Thyroid hormones
- c) Estrogen
- d) Cortisol
- Answer: b) Thyroid hormones
- What is the primary mechanism of temperature reduction in terrestrial mammals in warm temperatures?
- a) Vasodilation
- b) Shivering
- c) Increased metabolic rate
- d) Hibernation
- Answer: a) Vasodilation
- What adaptation do marine mammals use to insulate against cold water?
- a) Increased blood flow to the skin
- b) Raising furs
- c) Layer of fat (blubber)
- d) Evaporative cooling
- Answer: c) Layer of fat (blubber)
FAQs (Frequently Asked Questions)
1. What is thermoregulation, and why is it essential for mammals like humans?
- Thermoregulation is the capability of an organism to maintain its body temperature within certain boundaries, ensuring a state of balance or homeostasis. It is crucial for mammals to regulate their temperature for optimal life processes.
2. Why do mammals, including humans, keep their body temperature within a narrow range?
- Mammals, being endothermic, keep their body temperature within a narrow range (36-38 °C) to support a high metabolic rate, energy schedule, and adaptability, contributing to their diverse distribution across different environments.
3. What are the mechanisms of thermogenesis in mammals?
- Mammals employ both shivering thermogenesis (increased muscle contraction) and non-shivering thermogenesis (activated by hormones, especially thyroid hormones) for heat production.
4. How do terrestrial mammals regulate heat exchange in cold temperatures?
- In cold temperatures, terrestrial mammals often raise their fur to trap a thicker layer of still air, acting as an insulator. Humans, for instance, rely on a layer of fat beneath the skin for insulation.
5. What is the role of brown fat in mammals, and how is excess heat dissipated?
- Brown fat, specialized for rapid heat production, is present in some mammals. Excess heat is dissipated through increased blood flow or evaporative cooling, depending on the exposed surface areas.
6. How do marine mammals regulate temperature in colder water, and what is their insulating layer called?
- Marine mammals, such as whales and seals, use an insulating layer of fat called blubber under the skin to endure colder water temperatures. They dissipate excess heat through capillaries in the skin.
7. What is the role of the hypothalamus in human thermoregulation?
- The hypothalamus, part of the brain, serves as the homeostatic thermostat for regulating body temperature. It responds to temperature changes and activates mechanisms like increased blood flow, sweat production, and gland activation.
8. How does the body respond to an increase in temperature above the setpoint, and what happens during fever?
- In case of an increase in temperature, thermoreceptors send signals to increase blood flow, activate sweat glands, and promote cooling. Fever, triggered by pyrogens during infections, helps stimulate protective systems against pathogens.
9. What are the major temperature-minimizing techniques in warm temperatures for mammals?
- In warm temperatures, marine mammals dissipate heat into warm seas through capillaries in the skin. Terrestrial mammals employ evaporative cooling, including gland activity, panting, and the use of saliva and urine in some species.
10. How do cold receptors in the hypothalamus respond to low temperatures, and what mechanisms are activated for heat preservation?
- Cold receptors send signals to the hypothalamus to activate heat preservation mechanisms. This involves the constriction of superficial capillaries and the promotion of shivering and non-shivering thermogenesis systems.