Homeostasis - Increasing and Decreasing Body Temperature (GCSE Biology)
Increasing and Decreasing Body Temperature
The Skin
The skin plays a role in maintaining a constant body temperature. It has many components to do this including hairs, sweat glands, erector muscles and blood vessels. Receptors and sensory neurones are also present to detect external temperatures.
Responses to Increases in Body Temperature
If the body temperature increases too much, the body has protective mechanisms that reduce the temperature to stop enzymes from denaturing:
- Blood vessels dilate – the blood vessels near the skin tend to dilate. This is known as vasodilation. This means that more blood can pass close to the skin, and so more heat can be lost through conduction to the environment (rather than this hot blood running through deeper vessels away from the surface!).
- Sweating – sweat glands open up, causing our skin to release more sweat through pores in the epidermis. When there is more sweat, more heat is given to the environment through evaporation. This is because the liquid sweat absorbs heat, which increases the kinetic energy of molecules enough to overcome the forces of attraction between them, enabling the liquid to evaporate into a water vapour.
- Skin hair lies flat – the hair erector muscles relax, causing the hair on the skin to lie flat. Therefore hair traps less air and heat near the body so the skin is less insulated and heat can be lost more easily.
Responses to Decreases in Body Temperature
If the body temperature decreases too much, there are mechanisms in place to increase body temperature:
- Blood vessels constrict – the blood vessels near the skin constrict. This is known as vasoconstriction. This means that less blood can pass near to the skin so less heat is lost to the environment.
- Shivering – during shivering, the skeletal muscles contract and relax very quickly. This means that energy is released as heat from the muscles as more respiration takes place to provide energy for the shivering.
- Skin hairs stand up – the hair erector muscles contract, causing the hairs on the skin to stand up on their end. This causes more air to be trapped near the skin, leading to less heat loss as it provides insulation.
- Sweat less – by sweating less when you are cold, you lose less heat.
Cooling Curves
You should also be able to plot cooling curves. These sound complicated but they are effectively just graphs of temperature vs. time.
They might give you a cooling curve like below, and ask you to describe the different changes happening in the body at different stages. For example, during minute 0 the participants may be sweating a lot, whereas during minute 5 they will be shivering instead.
Temperature Experiments
You should also know different methods of measuring body temperature. Temperatures can be measured at different places of the body – the most common being the ear, mouth, nose, armpit and forehead. Forehead thermometers and skin temperature sensors are often used.
Homeostasis is the ability of the body to regulate and maintain a stable internal environment, despite changes in the external environment.
The body is responsible for maintaining a stable internal temperature, also known as core temperature. This is achieved through a delicate balance between the heat produced by the body’s metabolism and the heat lost to the environment.
The body can increase body temperature by constricting blood vessels to reduce heat loss, producing heat through shivering, or releasing hormones such as adrenaline to increase metabolic rate and produce more heat.
The body can decrease body temperature by dilating blood vessels to increase heat loss, sweating to cool the skin, or releasing hormones such as thyroxin to decrease metabolic rate and reduce heat production.
A fever is a temporary increase in body temperature that is often a response to an infection or illness. Fevers help the body fight illness by creating a less hospitable environment for harmful bacteria or viruses and by boosting the immune system.
Prolonged high body temperatures can cause dehydration, muscle weakness, and damage to the brain and other vital organs. It is important to seek medical attention if you have a fever that lasts for more than a few days or if you experience other symptoms such as severe headache, confusion, or difficulty breathing.
These questions and answers provide a comprehensive introduction to homeostasis, specifically the regulation of body temperature, making it easier for 15-16 year old students to understand this important concept as they study GCSE biology.
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