Homeostasis free essay sample

Homeostasis by definition is the technical term for the process of maintaining a constant internal environment despite changes in the external environment. The internal environment comprises of blood, tissue fluid, body cell contents and all metabolic processes taking place inside the body. This process is essential to the survival of a person and to our species as a whole. The liver, the kidneys, and the brain (hypothalamus, the autonomic nervous system and the endocrine system) help maintain homeostasis. An inability to maintain homeostasis may lead to death or a disease, for example diseases that can occur due to the result of a homeostatic imbalance include diabetes, dehydration, hypoglycaemia, gout and any disease caused by the presence of a toxin in the bloodstream. Lucky though medical intervention can help restore homeostasis and possibly prevent permanent damage to the organs. How does Homeostasis Work? Homeostasis occurs due to a control mechanism in the body known as negative feedback. We will write a custom essay sample on Homeostasis or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Negative feedback occurs when a key variable, such as the PH of blood and tissue fluid, deviates from the acceptable range, and triggers responses that return the variable to a normal range. In basic terms, negative feedback triggers a response that counteracts the deviation which will allow the variable to stay in the normal range. The brain and nervous system both play a major role in controlling homeostasis mechanisms. This is due to the fact that both help the body to anticipate when key variables might rise or fall beyond the accepted range and send signals to the effectors to reverse the change and re-establish the original state. Homeostasis and heart rate Homeostasis is responsible for managing the heart rate. This is controlled by the autonomic nervous system which as two branches, namely the sympathetic nervous and the parasympathetic nervous system. Both these systems are responsible for managing the heart rate. The sympathetic nervous system is active when the body is undergoing muscular work, fear or stress. It causes each heartbeat to increase in strength as well causing an increase in heart rate. The sympathetic nervous system is boosted by the hormone adrenaline during periods of fright, flight and fight. Its nerves are the cardiac nerves. During exercise, a change in sympathetic activity is the predominant mechanism by which speeding and slowing of the heart is achieved. The parasympathetic nervous system calms the heart output and is active during resting, peace and contentment. The Parasympathetic system is the branch of the Autonomic Nervous System (ANS) responsible for the body’s ability to recuperate and return to a balanced state (homeostasis). The Parasympathetic functions in opposition to the Sympathetic nervous system. When the sympathetic system activates in response to some sort of stressor, the parasympathetic reacts in turn to bring the body back to a state of equilibrium. The main parasympathetic nerve is the vagus nerve and if this is severed the heart beats faster. During exercise the parasympathetic activity decreases as the increase in heart rate during exercise is triggered by the sympathetic nervous system. Both branches of the autonomic nervous system interrelate with each other through the pacemaker (S-A-node). This is a cluster of cells in the right atrium that regulate the heart to suite the circumstances. The cardiac Centre is found in the brain and is responsible for controlling the impulses of the SA Node; this means that the cardiac Centre essentially controls the heart and the heart rate. The Cardiac Centre controls the heart rate by detecting change in blood PH levels through the use of chemoreceptors, the Cardiac Centre also sends nerve impulses to the pace maker and vagus nerves to change the heart rate. During exercise hormones are secreted by the Adrenal gland therefore increasing the activity of the heart. Internal receptors play a role in the heart rate, chemoreceptor’s measure the amount of carbon dioxide in the body whilst baroreceptors measure the blood pressure. Both of which can have an influence on the heart rate. During exercise the body is deprived of oxygen therefore to absorb oxygen the chemoreceptors increase the rate of respiration. As a result of this the heart rate increases as well. Homeostasis and body temperature Thermoregulation is the term used to describe homeostasis and temperature regulation, which is governed by the hypothalamus gland within the brain, both the hypothalamus and receptors in the skin help monitor changes in external and internal temperature, activating the negative feedback system when temperatures exceed or fall beyond normal levels. When this occurs, the effects of homeostasis and temperature control are visible and voluntary, mainly relating to consciously choosing to take off clothing or putting more on to become cooler or warmer. In response to hotter conditions, the body may also react by producing sweat, which serves as a bodily cooling system. Thermoregulation during exercise will try to prevent heat from entering the body; this is done by the hairs on the skin lying flat, preventing heat from being trapped by the layer of still air between the hairs. This is caused by tiny muscles under the surface of the skin called arrector pili muscles relaxing so that their attached hair follicles are not erect. With homeostasis and temperature control in regards to cooler temperatures, the body may start shivering to generate heat through increased activity in the muscles. The adrenal and thyroid glands may produce chemicals and hormones, such as adrenaline and thyroxine to help generate internal heat. When you exercise, your body’s temperature increases, and in attempt to cool you off, your sweat glands the effectors are activated. Heat is generated from a variety of sources. The majority of heat we get is from metabolic processes such as catabolism where energy is transformed during the breakdown of large molecules. These reactions take place across the body and thus are a massive generator of heat. We also get heat from hot food and drinks that we consume as well as from the sun’s rays in extreme cases. However it is important to understand that excess exposure to the sun is not good for your health. When you exercise, the rate at which your body makes energy rapidly increases. This is also known as the metabolic rate. Heat is produced during metabolism, so an increase in metabolic rate also increases heat production. More heat production means a larger rise in body temperature during exercise. For example when we do vigorous exercise our body breaks down muscles fibres and catabolism causes them to rebuild again causing our body temperature to rise due to the heat being generated from the reaction. The skin also has an effect on temperature; functions of the skin include waterproofing the body, protecting the body against radiation and Protecting tissues from friction damage. The skin can help the body lose heat in a number of different ways: Conduction – this is when you body comes in to contact with an object and the heat is generated to the object through the body Convection – this is when you warm up the layer of air next to your skin and it moves upwards to be replaced by cooler air from the ground Radiation – Heat passes from your skin to warm up any colder objects around you and because of this you will warm up by radiation from any object hotter than yourself Evaporation of sweat – When liquid water is converted into water, it requires heat energy to do so. When you are hot, sweating will only cool the skin if it can take heat energy from the skin surface to convert to water vapour and evaporate. Exercise brings about an increase in internal body temperature and skin blood flow. At high environmental temperatures, when skin temperature is elevated, skin blood flow at any given internal temperature reaches higher levels than at cooler skin temperatures. Increased blood flow serves to deliver metabolic heat from the core to the skin. Homeostasis and breathing rate Respiratory rate is controlled by a part of the brain called the medulla, whose main purpose is to maintain a constant rate of respiration. The respiratory rate is defined as the number of breaths a person takes during a one-minute period of time while at rest. The rate of respiration can be influenced by the level of carbon dioxide in the blood, which makes the chemoreceptors aroused, thus leading to impulses being sent by the medulla to the intercostals nerves to increase the breathing rate. The control of the nerves, impulses and the breathing organs in order to create an equilibrium that provides a suitable internal environment is through homeostasis. Like the heart, respiration increases in line with exercise intensity in order to supply the increased O2 demands of the working muscles The internal receptors that are responsible for breathing rate are known as stretch receptors; these receptors are found in the tissues and muscles and have the function of informing the nervous system on the status of ventilation. The autonomic nervous system plays a role in the pace of our breathing; the sympathetic nervous system relaxes the muscles which slow down the breathing rate whilst the parasympathetic nervous system causes contraction. When we exercise our lungs expand, when the lung tissue is stretched by inflation, the stretch receptors respond by sending impulses to the respiratory centre, which in turn slows down the rate of inhalations. As the expiratory phase begins, the receptors are no longer stretched, impulses are no longer sent, and inhalation can begin again. This is called the Hering-Breuer deflation reflex. The respiratory Centre is located in the medulla, the respiratory Centre is known as the involuntary Centre because we can’t control it voluntarily. The respiratory sector consists of two groups of nerve cells referred to as the inspiratory and the expiratory Centre. The respiratory Centre controls the rate and depth of the respiratory movements of the diaphragm and other respiratory muscles. As the carbon dioxide levels increase, as it does during exercise, the respiratory Centre strengthens the signal stimulating the breathing. Responding to this stronger signal, the respiratory muscles increase both the speed and depth of breathing. The inspiratory Centre sends nerve impulses to the nerves of the diaphragm whilst the expiratory Centre sends impulses to the respiratory system, causing relaxation and expiration; because both systems have opposite functions when one is active the other is not. The action of breathing in and out is due to changes of pressure within the thorax, in comparison with the outside. This action is also known as external respiration, when we inhale the intercostals muscles (between the ribs) and diaphragm contract to expand the chest cavity allowing more oxygen to enter the body. Your breathing is under both voluntary and involuntary control, and involves two distinct phases: inhalation and exhalation. Inhalation typically is an active movement, and it involves muscle contraction from your diaphragm, abdominal muscles and intercostal muscles to be maximally effective. When you inhale, your diaphragm contracts and moves downward, away from your chest cavity, and the pressure in your lungs drops, when we exhale your diaphragm relaxes and shifts upward into your chest cavity. Your diaphragm also helps you vomit, expel solid and liquid waste. The abdominal muscles are the muscles help move your diaphragm during inhalation and give you more power to empty your lungs. Your intercostal muscles are important ventilatory muscles, but they should only be actively used during activitiessuch as vigorous exercisethat require significant rib cage expansion and a corresponding increase in oxygen intake. Homeostasis and glucose levels Glucose concentrations in the blood stream are primarily controlled by the action of two antagonistic pancreatic hormones, insulin and glucagon. Glucose is first detected in the bloodstream by glucose transporter receptors expressed on the surface of specialized pancreatic cells known as alpha- and beta-cells. Beta-cells respond to rising levels of blood glucose by secreting the hormone insulin. Insulin restores normal levels of glucose in the blood by signalling body tissues to take up glucose for energy, or to convert glucose to glycogen and lipids as future energy stored in the liver, muscle and fat cells. Basically if blood glucose levels are too high the pancreases will secrete insulin which will help to lower the blood glucose levels In the event of low levels of glucose, the alpha-cells of the pancreas release the hormone glucagon to stimulate skeletal muscle and the liver to breakdown glycogen into glucose and adipose tissue to digest lipids into fatty acids and glycerol. Glucagon also stimulates the liver to synthesize glucose from glycerol in the blood. All these reactions work together to raise glucose levels back to normal. Basically if blood glucose levels are too low the liver will release glycogen into the blood stream to increase the glucose levels in the body. When you exercise, your body responds to the activity by releasing hormones that cause your body to increase blood glucose levels. This occurs through a process called gluconeogenesis or glycogenesis that happens in the liver. Glucose that has been previously converted and stored in the liver as glycogen is converted back to glucose and sent to the muscles. In the muscles, the glucose is broken down to yield ATP, which is the fuel source for muscles. Changes in the body during exercise (general) During exercise your body can undergo a number of changes that have already been mentioned in the document but for the sake of summarising the information here is the effect on exercise on the body. During exercise, your heart rate will rapidly increase due to the amount of exercise you are doing but will slowly return to normal when you are at rest or you get exhausted. If you continue to exercise, your heart rate will increase right up until you near exhaustion, at which the heart rate levels off as it approaches its maximum level. The heart rate of an individual during exercise will be heavily dependent upon the current fitness level of Your body temperature will change depending on the intensity of the exercise you are doing. If the temperature goes to high, you might get overheated and get dizzy; this is why your body sweats, to cool off. This is known as a homeostatic response. If it goes to low, it means you’re not even doing exercise. During exercise especially training that requires explosive movements (sprinting) it is common for sweating to occur and for the body to be feeling tired due to the build-up of lactic acid from anaerobic respiration. Your glucose levels or sugar levels are very important and must not change dramatically during exercise or you might start to experience side effects. You might start to feel weaker and less energetic if your glucose levels get to low whereas if they are too high, you might become really hyper. This is because we rely heavily on glucose for energy in the body. Finally, your breathing rate is determined by the amount of oxygen you take in, which is also affected by the amount of exercise you do. You could get out of breath really quickly if you don’t exercise properly to allow the right build-up of oxygen in the lungs. The breathing rate of an individual is dependent upon their current fitness levels as a fit person would have to take in less breathes to receive oxygen than an unfit person would due the fit person having a lower resting heart rate. Importance of Homeostasis in maintaining healthy functions of the body Homeostasis is incredibly important in maintaining the functions of the body by identifying deviances in the norms and making sure they are taken care of as efficiently as possible. If our body is unable to maintain homeostasis, we get weaker and in the worst case scenario, we effectively die. This is called homeostatic imbalance. Homeostatic imbalance can lead to diabetes and dehydration amongst other problems. Homeostasis in the body is maintained through three of the body’s vital organs, the brain, the kidney and the liver. Together, these organs regulate body temperature, the iron content in our blood, the retention and production of energy and overall blood composition. If homeostasis did not function properly the heart rate would escalate and drop at rapid rates causing death due to the heart either pumping too much causing heart attacks and other ailments or pumping to less causing lack of oxygen to the body. This is due to the autonomic nervous system controlling the heart rate and the internal receptors picking up any deviances. If homeostasis did not function properly the body temperature would not be able to change when conditions are extreme. For example if the temperature was very hot our body would eventually experience severe problems that are associated with heat such as heat stroke and hyperthermia and at a much faster rate than normal. This is because without homeostasis our bodies would not be able to revert back to normal temperatures and mechanisms such as sweating to cool our bodies down would not come into play meaning that are temperature would stay hot which would eventually result in our deaths as are body can only function at a certain temperature otherwise our organs would fail. Likewise if we became cold and homeostasis didn’t help correct the imbalance our bodies would be more likely to contact conditions such as hypothermia which would greatly affect our bodies’ ability for metabolism and other reactions that occur in the body as well as our bodily functions. If homeostasis did not function properly we would likely die due to our chemoreceptors not picking up the amount of carbon dioxide in our blood resulting in poisoning as our bodies would not increase the breathing rate to take in more oxygen and reduce the carbon dioxide. Along with this the respiratory centre would not function properly as would the autonomic nervous system which would mean that if your breathing rate were to increase it would remain at that rate due to homeostasis being unable to correct the deviance. If homeostasis did not regulate blood glucose we would die as glucose are our primary source of energy within the body. Without homeostasis our bodies would not be able to differentiate between high or low blood sugar. If our blood sugar levels were to low the pancreas would not be able to secrete glycogen due to the fact that the Alpha cells would not pick up the deviance. This means that the glycogen would not be able to be converted into glucose because the pancreas would not know to release glycogen. Likewise if blood sugar levels were too high the body would not no to release insulin from the pancreas because the beta cells would not pick up the deviance. This is how diabetes occurs.