Homeostasis
Homeostasis is a process that helps living organisms maintain their internal conditions at equilibrium, which means keeping everything in balance. The word 'homeostasis' comes from two Greek words: 'homeo' (which means 'similar to') and 'stasis' (which means standing still, or steady). Although our body's internal conditions are never completely still, they try to maintain an state of balance. Think of it as a state of dynamic equilibrium, where the body responds differently to changes both inside and outside of it. These changes can happen in different parts of the body, like cells, tissues, organs, or the whole organism itself.
The significance of homeostasis
Homeostasis is essential for the functioning and survival of organisms. Homeostasis is important for maintaining proteins' structures, water potential in the body, and successfully adapting the body's temperature to changing external conditions.
Maintaining the protein’s structure
Proteins are super important molecules that help our cells function well. But they're also really sensitive to changes in temperature and pH. If there's any change in these factors, the proteins can lose their shape and function, which makes them not work as well.
One type of protein that's really important is called an enzyme. Enzymes have a special part called an active site, which fits perfectly with the molecule they're supposed to with. If the temperature or pH changes, it can mess up the active site and make it hard for the enzyme to do its job.
When proteins lose their shape, they can clump together and cause problems in the cell. This can even lead to the cell dying.
Maintaining the water potential
Water potential is important for both plant and animal cells. As we know, water always moves from a system of high water potential to a system of low water potential. In plants, the cells have a cellulose cell wall protecting them. Hence, the cells only become turgid when water diffuses in, and shrivel as water leaves them (Figure 1).
In contrast, animal cells have no cell wall, so there is a risk of cellular damage when too much water diffuses in or out (Figure 2). Maintaining blood glucose levels at a dynamic equilibrium is essential to ensure a constant water potential for the cells. It also ensures that the cells receive a sufficient amount of glucose to use for respiration. Plasmolysis and hemolysis is irreversable in animal cells, while plasmolysis in plant cells is reversable.
Adapting to a wider geographical range
One cool thing about animals is that they can keep their body temperature the same, no matter what's going on around them. This means they don't have to rely as much on their environment to stay comfortable. In fact, this ability to regulate their own body temperature allows animals to live in all sorts of different places, from hot deserts to freezing cold polar regions. Thanks to this adaptation, mammals have been able to make their homes in variety of habitats.
Homeostasis’ control mechanisms
For any system that can regulate itself, there are five things that need to be in place (as shown in Figure 3):
- An optimal point This is the perfect condition for the system to its best.
- A sensor: A group of receptors that can detect any changes or deviations from that perfect condition.
- A coordinator: This control center knows what the optimal point is and can compare it to the current value provided by the sensor.
- An effector: This is the organ that can change the value of the variable to match the optimal point.
- A feedback mechanism: This is how the sensor responds to the change in the variable, and it helps to bring things back to the optimal point. There are two types of feedback mechanisms: negative and positive.
Negative feedback mechanisms
Negative feedback is the most common type of feedback mechanism in living organisms. It works by detecting and correcting deviations from the optimal point. An example of this is how mammals like humans regulate their body temperature, which needs to be maintained at a relatively constant level despite changes in the environment.
The human body has sensors in the skin and hypothalamus that detect deviations from the optimal temperature range of 36°C to 38°C. When a deviation is detected, the hypothalamus activates various mechanisms to restore the core body temperature. These mechanisms include vasoconstriction of arterioles near the skin to reduce heat loss, shivering to generate metabolic heat, and activation of hair erector muscles to create an insulating layer of air. Additionally, humans and animals can use behavioral mechanisms to avoid heat loss, such as finding shelter or huddling together to reduce the volume to surface ratio.
Overall, negative feedback mechanisms help living organisms maintain stable internal conditions despite external changes, allowing them to survive and thrive in a variety of environments.
In response to hot external environments
Negative feedback is the most common type of feedback mechanism in living organisms. It works by detecting and correcting deviations from the optimal point. An example of this is how mammals like humans regulate their body temperature, which needs to be maintained at a relatively constant level despite changes in the environment. The human body has sensors in the skin and hypothalamus that detect deviations from the optimal temperature range of 36°C to 38°C. When a deviation is detected, the hypothalamus activates various mechanisms to restore the core body temperature. These mechanisms include vasoconstriction of arterioles near the skin to reduce heat loss, shivering to generate metabolic heat, and activation of hair erector muscles to create an insulating layer of air. Additionally, humans and animals can use behavioral mechanisms to avoid heat loss, such as finding shelter or huddling together to reduce the volume to surface ratio.
Overall, negative feedback mechanisms help living organisms maintain stable internal conditions despite external changes, allowing them to survive and thrive in a variety of environments.
Positive feedback Positive feedback is quite rare in biological systems. It involves causing an even further deviation from the optimum point after a small deviation is detected. One example of positive feedback is during childbirth. Uterine contraction stimulates the release of oxytocin which then stimulates more contractions. Therefore, this results in an increase in both intensity and frequency of contractions during labour (Figure 5).Figure 5. Positive feedback during childbirth. 1: When the head of fetus pushes against the cervix. 2: It stimulates nerve impulses from the cervix to the brain.3: When the brain is notified, pituitary glands are notified to release oxytocin hormone.4: Oxytocin is carried in the bloodstream to the uterus.5:
Homeostasis - Key takeaways Homeostasis is a state of dynamic equilibrium characterised by different responses to changes within the external and internal environments. It is comprised of many processes trying to maintain the internal conditions of the body despite changes in the external environment. Homeostasis is important for various reasons. these include maintaining the blood water potential, preventing proteins denaturation, and increasing the chance of survival in a wider geographical range of habitats. Homeostatic mechanisms need to have five necessary components. These include: An optimum point A sensor A coordinator or control centre An effector A feedback mechanism There are two types of feedback: Negative and positive. The negative feedback is the main feedback mechanism in homeostatic processes. It involves returning the condition back to the optimum point.
Homeostasis
What is homeostasis?
It is a state of dynamic equilibrium characterised by different responses to changes within the external and internal environments.
How does the body maintain homeostasis?
By control mechanisms that need an optimum point, a sensor, a coordinator, an effector, and a feedback loop.
What are three examples of homeostasis?
Osmoregulation, thermoregulation, and regulation of blood calcium levels.
Why is homeostasis important?
It maintains optimal conditions for enzymes to work efficiently throughout the body, as well as all cell functions.
What effect does negative feedback have on homeostasis?
It acts to stop the stimulus or cue that triggered it after the optimum point is re-established.
What are examples of negative feedback in homeostasis?
Osmoregulation, thermoregulation, regulation of blood calcium levels.
When does negative feedback stop in homeostasis?
When the condition returns to normal, and the optimum point is re-established.
