Temperature Classification of Animal
According to the body temperature animals are divides into two group.
1. Poikilotherms (Cold Blooded)
2. Homeotherms (Warm Blooded)
1. Poikilotherms
Animal cannot maintain their body temperature and it can be changed accordingto the climate are called Poikilotherms.
Example
Amphibians, Reptile, Fishes.
2. Homeotherms
Animal can maintain their body temperature. It does not changed according to their environment are called Homeotherm.
Example
Birds, Mammals
Many poikilotherm can maintain their body temperature and homeotherm do not maintain their body temperature always. So there terms are changed.
Modern Classification of Animal
The modern classification of animal according to the body temperature.
1. Ectothermic
2. Endothermic
3. Heterothermic
1. Ectothermic
Ecto mean outside thermic mean heat so those animal obtained heat energy from their environment are called Ecotothermic.
Example
Invertibrate, Fish, Amphibian and Reptile.
2. Endothermic
Endo mean inside thermic mean heat so those animals use internal energy which is produced during their metabolism.
Example
Mammalia, Birds and Some Fishes.
3. Heterothermic
Those animals are able to maintain their body temperature with certain variation, so their body temperature can be changed upto certain limits are called Heterothermic.
Example
Bat, Humming birds.
Method of Thermoregulation in Animals
In animal thermoregulation occurs by two ways.
1. Behavioral Regulation
2. Physiological Regulation
1. Behavioral Regulation
When temperature is maintained by the activity of animal body, it is called behavior regulation, such as animals change their position to increase or decrease the temperature.
2. Physiological Regulation
When temperature of the body is maintained by inter-physiological process it is called physiological regulation, such as change in blood circulation etc.
Thermoregulation in Cold Temperature
In cold temperature animal regulate their body temperature by two methods.
1. Physiological Process
2. Behavioral Process
1. Physiological Regulation
This is the internal process of the body to maintain body temperature. It take place by two way
i. Non-shivering thermogenesis
ii. Shivering thermogenesis
i. Non-Shivering Thermogenesis
Hormones trigger the heat production as do thyroid hormones are called Non-shivering thermogenesis.
Mechanism
In this mechanism heat is produce by three methods.
- Erection of hairs
- Reduction of blood flow toward skin
- Sub cutaneous fat accumulation
In cold season the hair become in erect position. In furry animals air is trapped between the space of hairs and loss of body heat is stopped.
Reduction in Blood Flow toward Skin
In cold season the blood vessels of skin are reduced. It is called Vasoconstriction. Due to this process blood flow towards skin become slow and loss of heat through skin is reduced.
Sub Cutaneous Fat Accumulation
In mammals below skin fat is deposited in adipose cell. It prevent the loss of body heat. It is common in aquatic animals such as Seal, Whale.
ii. Shivering Thermogenesis
The rate of heat production is increased y increased muscle contraction by movement or shivering so called as shivering thermogenesis.
Mechanism
In very cold weather shivering occur in the muscles of the body. It produce heat Rate of Metabolism become faster. In this mechanism hormones are involved one hormone adrenaline is produce by adrenal gland. It increases the supply of glucose in blood so respiration become fast and energy is produce.
Thyroid gland also secreted thyroxin hormone in blood. This hormone also increased respiration to produce heat.
2. Behavioral Process
In this mechanism the animals produce heat by their body activities.
Movement toward Hot Place
Animals move toward hot places during cold season.
Gathering of Animals
The animals come close to each other, so energy is produced.
Use of Warm Cloths
Man used warm clothes for protection and to get heat.
Thermoregulation in Hot Temperature
In hot season the animal produce less heat and also released heat from their body. It take place by two method.
1. Physiological Mechanism
2. Behavioral Mechanism
1. Physiological Mechanism
This process take place by following method.
Less Fats Deposition
In hot season fat is not deposit in below the skin. It loss the body heat.
Increase in Blood Flow toward Skin
In hot season the blood vessels of skin are dilated and vasodialation occur to released body heat.
Softness of Hair
Hair of skin not erect in hot season not prevent the loss of heat energy.
Sweet Gland
Sweet glands become active and water is excreted out through skin. The blood becomes cold and internal temperature is maintained. It is called physiological temperature regulation.
2. Behavioral Mechanism
In this mechanism the animal released heat by their body activities.
Movement toward Cold Places
Animal move from hot to cold places. They remain in shade or moist place to reduce their body heat.
Use of Thin Clothes
Man use thin clothes during summer season.
Role of Brain in Thermoregulation
The body temperature regulation in human is based on complex homeostatic system facilitated by feedback mechanism.
The Control Center
The homeostatic thermostate is present in the hypothalamus, a brain part. It respond to the changes in the temperature above and below 37oC.
Warm Temperature
Incase of increase in temperature above 37oC certain warm temperature sensitive thermoreceptors in skin, hypothalamus and other parts of nervous system send the signals to the system that increase the blood flow to the skin and also cause sweat gland activation and sweat is evaporated for the cooling.
Cold Temperature
In cold temperature, the cold receptor send the impulse to hypothalamus to inhibit heat loss mechanism and activate the heat conservation mechanism.
Fever
When the temperature of the body is increased beyond a set point it is called Fever or Pyrexia.
Cause of Fever
The main cause of fever is the viral or bacterial infection. These germs in blood vessels produce a chemical substance called pyrogen. It increases the body temperature than normal.
Importance
- Fever helps to kill the germs
- It indicates any abnormal condition in the body or infection.
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