Body Temperature Maintenance
Titanic is a blockbuster in 1997. In the cold ocean, when Titanic was sinking into the deep Atlantic Ocean, Jack the main character lifted Rose up from the bone-chilling water to a floating shipwreck. In the end, he became ice cold and sank into the sea. Many people were saddened by the last parting scene between Jack and Rose which is still considered as one of the best movie scenes.
The movie is based on the true story. On April 10, 1912, the Titanic, the biggest ocean liner in the world at that time started its maiden voyage from Southampton in the U.K. to New York City in the U.S. with about 2,200 passengers. Although it was called The Unsinkable Ship, it was nothing, compared with the power of the nature; it broke apart and sank in the deep ocean four days after its voyage.
Just after two hours after it sank, the Carpathia, which was passing nearby, received a radio signal and arrived, but it was after about 1,500 passengers had died except those who were on the lifeboats. Most passengers were wearing life vests. But why did such a tragedy happen?
A sudden change of the body temperature threatens life
Men are homeothermic; they are able to relatively maintain a constant body temperature, despite big changes in the surrounding environment. The normal human body temperature is around 36.5℃ [97.7℉]. If anyone’s temperature gets higher or lower than that, his life is in danger. Many people who couldn’t get on the lifeboat but jumped into the water died because their body temperature dropped rapidly in the cold ocean.
When a person’s core body temperature1 drops to 34℃ [93.2℉], he will suffer mental confusion and fall into a deep sleep. If it drops to 30℃ [86℉], his heartbeat will slow down and muscles will get stiff. Below 28℃ [82.4℉], his heartbeat will become erratic that he can go into cardiac arrest; he will lose consciousness as his blood pressure drops and die. On the contrary, when the temperature rises more than 41℃ [105.8℉], a man can go into convulsions. 43℃ [109.4℉] is known as the highest temperature that a man can sustain his life.
1) Core body temperature is the temperature of an organism inside the body, including the brain.
Like this, when the body temperature changes even a little, body function deteriorates dramatically. The cause relates to metabolism, chemical reactions in the body. Enzymes and hormones that accelerate metabolism and control its functions are mostly made of protein. When the body temperature increases, the reactions of enzymes and hormones speed up, but when it goes beyond a certain temperature, protein denatures just as meat gets cooked, and loses its function. When the temperature decreases, reaction time of enzymes and hormones slow down remarkably.
Efforts to sustain the body temperature
The temperature that enzymes and hormones function best is about 37℃ [98.6℉], and they are easily influenced by a slight change in the temperature. Our body makes constant efforts to keep the temperature appropriate for its proper function. The body temperature is controlled whether it is hot or cold. The part of our brain, which regulates our body temperature, is hypothalamus in the diencephalon.
First, let’s learn what changes are made in our body when the ambient temperature drops as in winter. When the ambient temperature is lower than the body temperature, the body temperature cools down as the heat is removed from the body. When the hypothalamus receives the signal through the sensory nerves that the temperature is dropped, it gives an order to each part of the body not to remove the heat as much as possible. Through the sensory nerves, it constricts capillaries to reduce blood flow, and constricts the arrector pili muscles2, making the hairs on your skin stand up and giving goose bumps. It also tightens pores to decrease perspiration significantly.
2) Arrector pili muscle is the muscle that is attached to the hair bulb in the skin.
The hypothalamus sends signals to the muscles to produce heat. It increases muscle tension through motor nerves and makes the body shiver, regardless of one’s will. That’s why your teeth chatter when you are cold. You sometimes shiver when you urinate to compensate for the heat loss. Sensory nerves also work in the cerebrum that it makes a person wear more clothes or move intentionally to control the body temperature. The cerebrum makes the body cringe to reduce the body surface area and prevent the heat loss. In the case of children who are not yet developed in movement, the release of the epinephrine in adrenal medulla increases, and some thyroid hormones act to increase the body heat by increasing the metabolism.
On the contrary, if it is hot like in summer, the body releases the heat so that the body temperature wouldn’t increase and suppresses the generation of heat. When hypothalamus recognizes that the temperature goes higher, it relaxes the skin capillaries through sensory nerves to increase releasing the heat as much as possible. The pores are dilated and increase perspiration to release the heat from the body. This is to release the heat from the body through the evaporative cooling of sweat. When humidity is high, it feels more difficult to endure the heat because it is more difficult for the body to release the heat through perspiration.
The importance of homeostasis
The environment is changeable. With the body temperature alone, there are various factors that can make a change. From a sudden change of the temperature to infection, we get influenced by many factors. Nevertheless, although we are not aware of it, the body temperature is controlled by numerous mechanisms and does not go out of the scope of the average as it cooperates with many organs. It is not just the body temperature. The blood glucose levels, heartbeats, and blood pressures always remain constant. That’s why our lives can be maintained.
Sometimes, when a system is out of balance, eventually it affects other parts of the body system, so that it will fail to sustain homeostasis. When our body loses its homeostasis, we say we are ill. If there were only one method of controlling a variable, and a problem occurs in managing the mechanism, he can lose his life immediately. That tells us that the body system is controlled in diverse and complicated ways that although one system of the body breaks down, it can make the same result by other methods.
Thankfully, our body is well made to maintain the constant temperature in the cold and hot weather. Even in the Antarctic Ocean where it goes lower than -40℃ [-40℉], or in the desert that is higher than 60℃ [140℉], the body maintains the appropriate temperature of 36.5℃ [97.7℉] with the little help of clothes. At the short moment that we feel cold and adjust our clothes and use hand fans under the sun, numerous actions occur in our body.
The brilliant sense of balance of an acrobat surprises us when he walks step by step on a rope. Our body is maintaining the homeostasis like tightrope walking. Even when we do not recognize it, our body that sustains life through careful and various ways amazes us.