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Concept Homeostasis with Reference to the Control Essay

Explain the concept homeostasis with reference to the control of heart rate, breathing rate, body temperature and blood glucose. In this assignment I will be introducing a formal report that is based on an investigation into how the body responds to exercise and which analyses the results from the investigation. The investigation involves myself and other pupils in my class. I will be doing the Harvard step test. the other pupils in my class will be monitoring my heart rate, breathing rate and temperature before and after the test.

The actual word homeostasis means “steady state”. Homeostasis describes how the body regulates its process to keep its internal conditions as stable as possible. Homeostasis is necessary because human cells are efficient but very demanding. The phrase homeostasis is a bit confusing; conditions inside our bodies are not constant but are kept within a narrow range. some factors such as temperature and blood PH change slightly while others such as blood glucose very considerably throughout a normal day without producing any harmful effects. A brief description of homeostasis is that it is maintenance of a constant internal environment in response to a change in external environment. Negative feedback as a form of regulation

Negative feed makes sure that as levels return to normal, corrective mechanisms are scaled down. it’s when the body maintains conditions within particular limits. the body will do this by opposing a change that deviates from the normal. core temperature falls.

Core temperature rises.
Drop detected by hypothalamus . brain sends signals to the body that brings out shivering and vasoconstriction.
Temperature turns to normal.
Normal body temperature: 36.9c
Rise detected by hypothalamus. Brain sends signals to body that brings out sweating and vasodilatation.

Negative feedback comes when an important variable, sometimes known as a key variable such as the pH of blood and tissue fluid, deviates from the acceptable rang r limits, and triggers responses that return the variable to within the normal range. Basically deviation produces a negative response to counteract or nullify the deviation. it is a ‘feeding back’ of the disturbance to the status quo. due to the liver being part of the digestive system, as we know when blood glucose levels fall, the liver glycogen is converted into glucose in order to top up those crucial energy levels in cells. this is an example of a negative feedback system.

The brain and nervous system play a vital role in controlling homeostatic mechanisms and they also help us to anticipate when key variables might rise or fall beyond the acceptable range. for example, if it is several hours since your last meal and you are beginning to feel tired and cold, you will try to eat a warm, energy-giving meal to counteract these feelings. this can be termed ‘feed forward’ (rather than feedback), as you are taking steps to avoid a low energy state before it has happened. Negative feedback systems require:

* receptors to detect change
* a control centre to receive the information and process the response
* Effectors to reverse the change and re-established the original state.

blood glucose levels

The amount of glucose in your blood is carefully controlled. again, this used the hormonal system. The hormones responsible for regulating blood glucose are produced in the pancreas in particular areas call islets of Langertons. Roles of pancreas and liver

The pancreas is a small gland, located close to the stomach. the pancreas has two main functions, it contains clusters of cells that secrete the pancreatic endocrine hormones- insulin and glucagon into the blood stream in order to regulate blood glucose levels.

M2- Discuss the probable homeostatic responses to changes in the internal environment during exercise. “Homeostasis” means balance or equilibrium. How your body works to maintain equilibrium is reflected in how your vital signs vary with activity. Heart rate, blood pressure and respiration are lowest during periods of rest and sleep. During exercise, blood pressure, pulse and respiration increase to meet the increased demand for oxygen and nutrients by your musculoskeletal system. The adjustment of vital signs to match your body’s level of physical activity is an example of homeostasis in action.

As a small group of the class, we were put together to test one person’s heart rate, temperate and breathing rate of the group. By this the subject (person doing the test and being monitored on) would be doing the harvard step test. The harvard step test was simple and effective to do to find out the heart rate, breathing rate and body temperature. In the small groups, we decided to do the experiment on stairs so the subject would simply step up one step and then step down again, and they would repeatively do this for 5 minutes, rest for 5 and then do it again another 2 times. The others in the group would be getting ready to take the measurements.

* Naomi was the subject
* Kerri was the taking the breathing rate
* Sam was taking the heart rate
* Sejal was taking the temperate
* Zoe was doing the timing
* Ed was writing down the measurements.

This was really good because each person in the group had one job to do and was doing it as accurately as they could. Looking at the subjects results as a whole they looked “normal” because there wasnt any major results that didn’t seem well out of place. It was really important that we got valid results else the experiment wouldn’t be valid and the investigation wouldn’t be as effective. In the experiment the same thermometer and stop clock was used throughout the step test to make sure all the results were valid.

Throughout the test the same people took the measurements each time and the same person was doing the step test. The height of the step, the length of the exercise time and the pace of the stepping were all kept monitored so they kept the same and there were no changes to the subject. For results to be valid it must be possible to replicate them and this experiment has been carried out many times before and so the results expected have been explained many times over. If the results do not replicate the expected results, then they may not be valid and effective to use in the investigation.

Breathing rate

Exercise increases the use of energy by your muscles, which activates a series of reactions to create new energy to keep exercising and maintain homeostasis. The first reaction that occurs is an increase in your breathing rate. Energy creation requires significant oxygen. The only way to provide the necessary oxygen is to increase the speed at which your respiratory system is introducing it into your bloodstream. The harder you exercise, the more energy is used, resulting in your body increasing your breathing rate even more to maintain adequate energy levels for balance.

Heart rate

Once oxygen is deposited into the bloodstream by the lungs, the body must also increase your heart rate to deliver oxygen to the cells to once again maintain homeostasis. The increase in heart rate boosts the speed at which your arteries and capillaries can deliver oxygen to needy cells. It also increases how fast these blood vessels can deliver the broken-down components of recent foods you have consumed. Both products are necessary for energy creation to occur through aerobic respiration.

Body temperature

After energy is created, exercise continues to affect homeostasis by increasing your body temperature. Energy creation produces three main products — water, carbon dioxide and heat. Typically, the heat created from aerobic respiration is used to maintain a balanced body temperature of about 98.6 degrees. However, the increased rate of energy production during exercise often creates more heat than is necessary. This means your body has to somehow release this heat to prevent your temperature from becoming dangerously high. To maintain homeostasis, your body activates the sweating process, which helps remove the heat from your body and release it into the surrounding environment

What did we expect to happen in the investigation?
Temperature- what we expected to happen?

Our bodies are averagely 37oC as a body temperature, As we are exercising our muscles are respiring, this basicly means they are releasing energy from glucose so that we can move. To increase out body temperature, some of the energy is released as heat energy, and this is what heats our bodies up when exercising. When the body temperature increases, to keep homeostasis steady the body responds with negative feedback to reduce the temperature. In the investigation, we expected the subjects’ results to be 37oC before exercise and then during the exercise it would be increasing, then in the rest period in would have increased.

What actually happened?

At rest, the subjects’ temperature was 35.3. As this shows, this is not what we expected. In the graph, it roughly shows a straight line because throughout the investigation the subject’s temperature stayed the same. This could of been because the subject was cold to start with before doing the test.

Breathing rate- what we expected to happen?

In the investigation we expected the subject’s results to be around 16 breaths per minute, then during the exercise they would be increasing, also after the exercise too. During the recovery period, we expected the results to then decrease again. The average breath rate per minute is 16 breaths, this is because the breathing rate sufficient to supply oxygen and remove carbon dioxide. When exercising the muscles respire faster, this then requires oxygen and generates carbon dioxide. So more oxygen is needed by the body and more carbon dioxide needs to be removed from the body, this then obviously makes the body breath faster.

What actually happened?

The breathing rate did increase looking at the results in the graph and table. The table and graph shows that the first set of exercise done the breathing rate shot up to an average 17 breaths per minute, then every series of exercise after was roughly 11-12 breaths per minute. This maybe because the body warmed up and got used to the exercise and then the body relaxed more.

Heart rate – what we expected?

Before the exercise, we expected the subjects results to be around 60-80 beats per minute, then during and after the exercise then would have increased. Then during the recovery period, we would expect it to turn back to normal. We expected this because it is the average heart rate to adequately circulate the blood. When exercising muscles are respiring faster, this then requires oxygen and generate carbon dioxide. So more oxygen and glucose is needed by the body and more carbon dioxide needs to be removed, to do this the body must circulate the blood faster. Once exercising stops the demand for oxygen, glucose and removal of carbon dioxide returns to normal and so the heart rate slows down and goes back to the recovery rate.

What actually happened?

The heart rate increased after exercising then returned to the resting level during recovery period. In the results, it shows that in the first series of exercise, the heart rate shot up because maybe doing that was a shock to the body. M2- discusses the probable homeostatic responses to changes in the internal environment during exercise. During exercise it is obvious to state that when someone who is exercising and out of breathe their oxygen levels decrease and their carbon dioxide levels increase and the body temperature also increases.

Maintaining body temperature

The hypothalamus is the processing centre in the brain that controls body temperature. It does this by triggering changes to effectors, such as sweat glands and muscles controlling body hair. Heat stroke can happen when the body becomes too hot; and hypothermia when the body becomes too cold. Temperature control is the process of keeping the body at a constant temperature of 37°C. Our body can only stay at a constant temperature if the heat we generate is balanced and equal to the heat we lose.

Temperature receptors in the skin detect changes in the external temperature. They pass this information to the processing centre in the brain, called the hypothalamus. The processing centre also has temperature receptors to detect changes in the temperature of the blood. The processing centre automatically triggers changes to the effectors to ensure our body temperature remains constant, at 37°C. The effectors are sweat glands and muscles.

If we are too hot or too cold, the processing centre sends nerve impulses to the skin, which has two ways to either increase or decrease heat loss from the body’s surface.

* Hairs on the skin trap more warmth if they are standing up, and less if they are lying flat. Tiny muscles in the skin can quickly pull the hairs upright to reduce heat loss, or lay them down flat to increase heat loss. * If the body is too hot, glands in the skin secrete sweat onto the surface to increase heat loss by evaporation. This cools the body. Sweat secretion slows when the body temperature returns to normal.

Maintaining the control of Carbon Dioxide and Oxygen

The respiratory centre knows how to control the breathing rate and depth by the amount (or percent) of carbon dioxide, oxygen in the blood. There are receptors, called chemoreceptor’s, in the arch of the aorta and throughout the arteries that send signals and feedback to increase or decrease the ventilator output depending on the condition of these metabolic variables. For example, when you exercise, carbon dioxide levels increase significantly which alert the chemoreceptors, which subsequently notify the brain’s respiratory centre to increase the speed and depth of breathing.

This elevated respiration rids the body of excess carbon dioxide and supplies the body with more oxygen, which are needed during aerobic exercise. Upon cessation of the exercise, breathing rate and depth gradually declines until carbon dioxide in the arterial blood returns to normal levels; the respiratory centre will no longer be activated, and breathing rate is restored to a pre-exercise pattern. This arterial pressure regulation feedback system that carbon dioxide, oxygen and blood acid levels provide is referred to as the metabolic control of breathing. Homeostasis is the maintenance of a constant internal environment within the body. This includes:

-Control of the water balance of the blood.
-Control of blood sugar levels.
-Control of body temperature.
-Control of blood urea level.

Each of these internal controls is maintained by separate mechanisms. All mechanisms for homeostasis have specific sensors which are able to detect the value of the factor which is being monitored and any differences from the norm are corrected so the norm is more or less maintained and stable at all times. When something like the temperature outside drops our body’s homeostasis mechanism makes adjustments which produces more body heat for us. Muscular activity and shivering help to generate heat which keeps our body temperature at a constant level.

Homeostasis defines as a mechanism which maintains a constant body environment for optimum body function. Take the example of a heat increase on the body. The heat receptors in the skin recognise heat increase and send a signal to the hypothalamus. The heat inhibitory centre is stimulated and heat stimulatory centre is inhibited. As a result you get vasodilatation; hair lies flat on the skin, sweating and so on. This is important to a healthy function body because heat affects proteins for example. Say some hormones have a narrow optimum temperature, if it were to stay constantly high, then the hormones wouldn’t function properly same goes for enzymes etc


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