Biochemistry P6. Describe the suspected causes, diagnosis, effects (signs and symptoms) and usual treatments of either diabetes mellitus or under/overactive thyroid. Of any of the inborn errors of metabolism listed. For D2 provide the information above for both diabetes mellitus and under/overactive thyroid and all of the 4 inborn errors of metabolism listed. Provide details of the role of the relevant enzymes for all 4 of these errors.

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Our metabolism is in charge of the breakdown of foods which contain proteins, carbohydrates and fats in our bodies changing them into sugar and acid in order to create energy. Some people may experience problems which are known as metabolic disorders which disrupts this process and causing the body to lack or to produce too much of a particular substance.

Metabolic disorders can be developed when the liver or pancreases fails to function properly due to a disease. Examples of these disorders are diabetes, hypothyroidism and hyperthyroidism.

Diabetes is a lifelong condition which causes an individual’s blood glucose levels to become so high that they are unable to be controlled the homeostatic mechanisms within our body. There are two types of diabetes, ‘type 1 diabetes’ and ‘type 2 diabetes’. Type 1 diabetes is caused by the immune system destroying the cells in the pancreas that make insulin. This causes diabetes by leaving the body without enough insulin to function normally (autoimmune reaction). There is no specific cause of this but some triggers could be viral/bacterial infection, chemical toxins in food or an unidentified component causing the autoimmune reaction. Type 2 diabetes is caused by different factors such as family history, diet and obesity. Symptoms of both types of diabetes are the same however type 1 diabetes may take only weeks to develop whereas type 2 diabetes may take years to develop and diagnosis. The main symptoms are fatigue, blurred vision, cuts/wounds healing slow, weight loss, urinating more than usual etc. Type 1 diabetes and type 2 diabetes is diagnosed by a range of tests for instance, urine/blood tests, glycated haemoglobin (HbA1c) test. Type 1 diabetes can also be tested by antibody tests and type 2 diabetes can be tested by glucose tolerance test (GTT). There is no cure for diabetes but there is treatment and medication to maintain the health of those who suffer from the condition. Treatment for diabetes includes diet control, exercise, home blood glucose testing, and in some cases, oral medication and/or insulin. Approximately 40% of people with type 2 diabetes require insulin injections. Diabetes does not only cause impairment in the metabolism of sugars but is also associated with abnormal metabolism of fats and proteins. Therefore, all three key enzymes lipase, protease and amylase are vital in managing diabetes because they will help digest all three groups of nutrients: proteins, fats and sugars.
Hypothyroidism or also known as an underactive thyroid is where there isn’t enough of the hormones being produced. The main reason for an underactive thyroid is due to the immune system attacking the thyroid gland and damaging it or damage as a result of thyroids cancer or an overactive thyroid. Symptoms for an underactive thyroid may take time and the condition may not be diagnosed for many years. Some of these symptoms include fatigue, constipation, depression etc. In order to diagnose this condition, tests would be run for instance thyroid function tests. An underactive thyroid is usually treated by taking daily hormone replacement tablets called levothyroxine.
Hyperthyroidism or also known as an overactive thyroid is when there is too much of the hormones being produced in the body. There are several possible underlying causes, the most common being ‘Graves’ disease’, in which the body's immune system targets the thyroid gland and causes it to produce too much of the thyroid hormones. there are many symptoms resulting from this condition such as nervousness/anxiety, unexplained weight loss, swelling of thyroid gland (found in throat). In order to diagnose this condition, tests would be run for instance thyroid function tests. The treatment given for an overactive thyroid is called thionamides which stops the thyroid gland producing so much.

Metabolic disorders are caused by a genetic abnormality in which a specific enzyme is missing. This missing enzyme can result in serious harm and can also be harmless at the same time. This depends on the disorder however.
Galactosemia is an inherited disorder which causes babies within their first few weeks to lose their appetite. It’s possible they would suffer from vomiting, become jaundiced and have growth abnormalities. This is caused due to the high level if the monosaccharide galactose within the blood. The galactose 1-phosphate uridyl transferase is the enzyme in which are necessary for metabolising galactose and the lack of this caused the disorder to occur. The liver would also enlarge and within the urine, amino acids and proteins are now present. If a child with this condition doesn’t receive medical attention/treatment on time, this could lead to further develops such as within the cataracts galactose plays a role in the clear lens proteins. Other complications of this disease include brain damage, kidney damage and spleen damage. The diagnosis of Galactosemia is concluded when galactose and galactose 1-phosphate are identified within the urine. This is then further analysed and confirmed when the relevant enzyme is not present within the blood and the liver cells. It is vital that if there is a history of this condition within an individual’s family, that they and their family members be tested as soon as they are born. If a person does suffer from this condition, it’s important they don’t consume dairy products such as milk. This is due to galactose present within lactose which is found is dairy products. If a woman is pregnant and is aware that this condition runs in the family and as the baby could possibly have the condition, the pregnant woman cannot eat dairy products throughout the duration of her pregnancy.

Phenylketonuria (PKU) is an amino metabolism disorder and is a rare genetic condition. The body is unable to break down a substance called phenylalanine. This results in building up in the blood and brain. High levels of phenylalanine can damage the brain and could lead to brain damage. The symptoms of this condition are learning disabilities, behaviour problems and epilepsy.  There are different methods of diagnosing this condition. One is done by the heel prick test which is carried out during the first few weeks of a baby’s life. This test checks for range of conditions. If the illness is confirmed by the heel prick test, another test would be carried out which would determine the high phenylalanine levels then the individual would be referred to health professionals to specialise in treating for the disease.  To treat this disease, most people will suffer severe learning difficulties and would need care for the rest of their lives. The main treatment is to eat a low-protein diet such as potatoes and avoid high protein foods such as dairy products, meat etc. As these individuals wouldn’t be getting the nutrients from these foods, they would have to take amino acid supplements to ensure normal growth. Phenylalanine is usually broken down by the body by an enzyme known as phenylalanine hydroxylase however people who suffer from PKU are not able to do so because of an alternation in their DNA. This then causes phenylalanine levels in the blood to rise.
Glycogen storage disorders are a group of inherited diseases that result from the lack of one of the enzymes that are involved when changing glucose to glycogen or the breakdown of glycogen to glucose. There is over 12 different types of these disorders due to the number of different enzymes involved within the production of glycogen. Each of these disorders has different malfunctions which are low muscle tone, hypoglycemia (low blood sugar), heat intolerance etc.  The condition is diagnosed through a range of tests and if this condition runs through an individual’s family, they would be tested after they are born.  There would be blood tests carried out to test sugar levels and liver/kidney function and there would be scans such as an abdominal ultrasound scans. The treatment for these disorders all depends on as different types requires different treatment. With the majority of them, the treatments goal is to stablise blood sugar/energy levels. Individuals with these disorders would be put on a high protein diet. People who suffer from these diseases would be prone to having a low immune system and therefore would regularly take antibiotic medication to protect themselves from infections. If there is an enzyme lack in the production of glycogen, this can decrease the amount of normal glycogen produce. Low levels of glucose in the body (hypoglycemia) and a buildup of glycogen within the muscles and liver can be a result of problems in regards to the enzymes involved with the breakdown of glycogen into glucose.
Fructose intolerance is a disorder which is the result of the lack of protein needed for the breakdown of fructose, fructose is a sugar which is produced normally within the body. This disease can be inherited. The cause as well as inherited It may be somewhat self-imposed by our modern sugar-heavy diets. Humans have not yet evolved systems to cope with such high sugar consumption that is present within our society such as within in soft drinks, confectionery, desserts etc.  The symptoms for this condition includes fatigue, malabsorption issues (anemia), gastro-intestinal distress (bloating) etc. The diagnosis for this condition is carried out by either a H2 breath test, however this method is seen nowadays as non-reliable so a new alternative method of testing for the condition is done by using stool analysis. A Fructose-free or low-sugar diet is the best treatment. This is easy if you know which foods contain fructose - but many processed foods include fructose so foods such as this should be avoided. The enzyme responsible for this produce is known as aldolase B which is produced in the liver. This condition occurs when this enzyme is missing. Aldolase B is responsible for the second step in the metabolism of fructose, which breaks down the molecule fructose-1-phosphate into glyceraldehyde and dihydroxyacetone phosphate. To a lesser degree, aldolase B is also involved in the breakdown of the simple sugar glucose.

Reference list

NHSChoices Home Page. 2016. NHSChoices Home Page. [ONLINE] Available at: http://www.nhs.uk/pages/home.aspx.

Patient. 2016. Glycogen Storage Disorders. Inborn errors of metabolism | Patient. [ONLINE] Available at: http://patient.info/health/glycogen-storage-disorders-leaflet.

WebMD. 2016. Diagnosis of Diabetes. [ONLINE] Available at: http://www.webmd.com/diabetes/guide/diagnosis-diabetes.

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P5 M2 D2 ANATOMY AND PHYSIOLOGY !

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Explain the concept of homeostasis (P5) Discuss the probable homeostatic responses to changes in the internal environment during exercise (M2)

Homeostasis can be defined as the maintenance of a constant internal environment within the body. Sensors within our body monitor a number of things including breathing, heart rate, body temperature and also blood sugar levels. These can also be known as detectors, which send signals to the control centre when there is a change, or the value has deviated from the norm. This value will then be corrected so that the norm can be maintained (study.com, 2015). 

Negative feedback is important in homeostasis and it responds when certain conditions change. This therefore means that receptors and effectors, i.e. muscles or organs, carry out a reaction so that these conditions can remain. This may also be explained by saying that a change in variable is detected by the receptor and the information from this is sent along an afferent pathway to the control centre. The control centre then sends the information along an efferent pathway to the effector whereby it either opposes or enhances the stimulus (Bioserv, 2001).

In the medulla oblongata there are chemoreceptors which are adjacent to the respiratory centre. These chemoreceptors are sensitive to the changes of arterial PCO2, PO2 and also pH, and send information to the medulla, determining the nervous response depending on the changes of the variables (Bioserv, 2001). Nerve impulses are therefore then sent to the repiratory muscles controlling both the force and how often it contracts. Furthermore, this changes the rate and depth of breathing and also ventilation (UWE, 2015). The change in ventilation brings CO2, O2 and pH back to their norm. Nerve impulses are sent along the phrenic nerve towards the external intercostal muscles which stimulates muscle contraction for inspiration. Expiration occurs due to the elastic recoil of the lungs and chest wall. This nerve firing is what gives us our resting breathing rate of 12-15 breaths per minute. During exercise, the muscles have to metabolise faster as they require both more oxygen and nutrients. Due to this, the heart then pumps the blood harder and faster to keep up this demand, as the heart is doing more work to supply this blood. This means that more oxygen is required, meaning, the response given is breathing being increased so that oxygen is pumped to all cells quicker. Due to homeostasis, levels of oxygen in the blood are always being measured, ensuring oxygen, carbon dioxide and also pH levels return to their norm. Messages that are sent to the effectors informing them that the breathing rate has to be increased, however, will decrease again when all activity has been stopped.

Homeostasis also controls heart rate. The medulla which is located within the brain also controls heart rate. It sends information or messages normally in form of chemicals/hormones. When we are carrying out exercise the heart has to supply oxygenated blood to the rest of the body. There is information sent to the medulla from the muscles via the nervous system. This allows the release of chemicals, to travel to the sinus node. The sinus node then therefore stimulates the contractions of the heart, also increasing the force which in turn, increases heart rate. When you are at rest, or stop exercising, another message is sent to the medulla, which in turn releases acetylcholine, slowing the heart rate. When engaging in more intense exercise, epinephrine and norepinephrine is released, increasing heart rate to supply more oxygen to the body.

There are two pathways known as the autonomic nervous system and the parasympathetic nervous system. During exercise the sympathetic nervous system is activated and this increases heart rate and also the force of the contractions due to the nerve impulses being transmitted to the heart via the sympathetic nervous system (Cvphysiology, 2013). In comparison the parasympathetic nervous system decreases heart and rate and therefore it returns back to the norm and this system is activated when we are resting. The vagal nerve is what reduces heart rate.

The sinoatrial node (SA node) acts as the body’s pacemaker. The impulses initiate at the SA node moving a wave of electrical excitation across the atria, which respond by contracting. The ventricles are relaxed meaning that more blood is being pushed into them. The impulses are then passed to the atrioventricular node (AV node), however, the AV node delays the passage of impulses to the bundle of His and is then conducted to the purkinje fibres (Campton, 2010). The ventricle walls will contract from the apex working up, meaning that blood is ejected from the ventricles efficiently sending blood to the lungs and the rest of the body (Campton, 2010).

The level of glucose within the blood is also controlled by homeostasis. The maintenance of the level of glucose within the blood involves both the pancreas and the liver. Islets of Langerhans are cells located in the pancreas and these secrete two hormones known as insulin and glucagon. Blood sugar rises after we have ate a meal resulting in the stimulation of the pancreas cells, meaning b-cells of Langerhans are stimulated, releasing more insulin, enabling the sugar uptake by cells and also the storage of sugar within the liver and muscles. As a result, blood sugar levels are decreased (Tortora and Anagnostakos, 2003 recited in Nursing times, 2015). If however, blood glucose levels are low, the body will not be able to produce the sufficient amount of ATP needed for bodily functions. Alpha cells in the pancreas are then stimulated releasing glucagon into the blood. The liver then breaks this down into glucose which is then released into the blood. Glucose levels in the blood have now risen and there is no need for the release of glucagon (Bioserv, 2001). During exercise there is a demand for glucose due to the contraction of the muscles and more energy being required and so this causes an increased uptake of glucose to working skeletal muscles which is caused by an increase in the insulin. Normal blood glucose levels however, can be maintained during exercise by increased glucose production and the release through the stimulation of the breakdown of glycogen and glucose synthesis from other substances. This increase allows the maintenance of blood sugars. When we stop exercising, receptors send information to the liver telling it to slow down glucose production.

There are four different ways in which heat can be gained or lost from the body including radiation, evaporation, convection and conduction. Radiation is when heat from the body is given off into the atmosphere. Evaporation is when you sweat and the evaporation from the liquid generates heat, resulting in a cooling effect. Convection is the process of heat leaving the body via moving air flowing by the skin. Conduction is the transfer of heat from direct contact with another object (Beyondcoldwater, 2011)

The main control centre in the brain that controls body temperature is known as the thermoregulatory centre. When we exercise, body temperature will increase as the body is working hard in attempt to be able to have more oxygen in the blood which then can be delivered to the muscles providing them with energy. Change within the temperature in the blood is detected by thermoreceptors. There are also receptors which are in the skin and they detect changes in temperature within the environment. Homeostasis will occur due to the negative feedback triggering homeostatic mechanisms. The hypothalamus in the brain detects signals and sends impulses to both blood vessels and sweat glands. Firstly the hairs on the skin lie flat as the erector muscles are relaxed. This therefore increases the process of heat loss by conduction and radiation. Increased sweating also known as hyperhidrosis is due to the sweat glands releasing a salty liquid onto the skins surface, taking heat with it. Blood vessels can also dilate allowing more blood to flow through. The blood flows close to the body’s surface meaning that there is increased radiation. This is a process known as vasodilation. Also due to an increased body temperature there will also be increased sweating, and the need to drink due to thirst. When we become too cold however, the opposite of this happens and begin to shiver as a mechanism to rise body temperature. Heat loss will be reduced as the hairs on the skin stand so that they are able to trap a layer of air, acting as an insulator.

In conclusion, homeostasis is important as it maintains the appropriate levels within our body that our cells need to function properly and it allows us to adapt to environmental changes. It keeps the body at a norm, however, if conditions are at the extreme, the negative feedback mechanism will no longer work, resulting in death, if there is no medical help.

D2

Evaluate the importance of homeostasis in maintaining the healthy functioning of the body (D2).

Homeostasis is maintaining a constant internal balance within the body, which can adjust to extreme external conditions/factors. Cold blooded organisms for example are unable to maintain and regulate their internal body temperature, and so when they become too cold they are slow. Therefore, this means that ectotherms, rely on external factors such as the sun to regulate their temperature. On the other hand, warm blooded organisms are able to regulate and maintain their body temperature by carrying out exercise. Due to homeostasis, both the nervous and endocrine system will maintain a core body temperature, resulting in shivering when it is too cold at low temperatures or sweating if the temperature rises. During exercise, we can maintain body temperature as we sweat to cool down. To account for this loss in water, there will be a decrease in the production of urine. ATP is produced from the stores of glucose, therefore breathing becomes faster which will provide the body with more oxygen and also heart rate will increase meaning that blood can be pumped around the body at a faster rate.

The body is able to maintain our temperature, even if we are surrounded by extreme conditions e.g. a snow storm, or extreme heat, this is due to homeostasis. If we were in extreme heat, homeostasis would occur to ensure that we survive. The body would start to sweat and the process of vasodilation would occur, cooling down the body. The opposite would then happen if we were in a snow storm. The body would start to shiver, producing heat and also vasoconstriction would occur, rising body temperature. If however, homeostasis did not occur this would then start to cause problems as the body would be unable to recognise the changes within the environment and respond to them appropriately.

If we are in extremely hot conditions for a long period of time, the enzymes in the body will start to denature and this in turn results in the body cells dying (ABPI, 2015). This is known as hyperthermia. Due to this homeostatic mechanisms will stop working and so the hypothalamus can no longer function. If there is an excessive amount of sweating, too much salt may be lost from the body, making ions in the blood fall out of balance, leading to cramps in the muscles (ABPI, 2015). This extreme heat can also effect the messages from the brain to both the nerves and spinal cord slowing them down. Dehydration may also occur, meaning that the kidneys will hold on to urea and ammonium, however, this can be dangerous, as these toxins need to be removed (Campton, 2010). The heart may also start to beat faster as it needs to maintain blood pressure, therefore blood vessels will dilate (Bradfield, 2001)

On the other hand, if the body was exposed to extremely cold conditions, homeostasis still may not work. Hypothermia is define as when the core body temperature drops to below the norm for bodily functions to be carried out efficiently and so chances of survival would decrease. Shivering may occur however, this may not work and so when hypothermia gets more severe it will stop. Heart rate and breathing rate will decrease and there may also be an incontinence of urine due to the kidneys having a larger workload which also relates to the blood being shunted to the major organs (better health channel, 2015). If there was no action taken to support homeostasis then the body would eventually shut down, resulting in death.

A continuous supply of glucose is required by the body to carry out normal metabolism. This glucose is then converted to ATP. B-cells of Langerhans are stimulated, releasing insulin into the blood if the blood glucose levels rise, leading to a decrease in these levels. The opposite then happens if blood glucose levels fall. The a- cells of Langerhans, releases glucagon into the blood, rising blood glucose levels. In relation to blood glucose, if there was a homeostatic imbalance it could result in the development of type 1 diabetes. Type 1 diabetes is when beta cells in the pancreas are destroyed, therefore, preventing the body from producing enough insulin to regulate blood glucose levels (Diabetes.co.uk, 2015). This is also known as hyposecretion of insulin. If blood glucose levels get too low, then hypoglycaemia may occur (Diabete.co.uk, 2015). Diabetes can also lead to long term complications such as heart disease, stroke or kidney disease just to name a few. Diabetes is an example of what may happen if the homeostatic mechanism fails.

Homeostasis helps to control breathing rate. The respiratory centre and chemoreceptors regulate the breathing rate by sending information to the medulla. This in turn increases carbon dioxide levels in the blood, and nerve impulses are then sent to respiratory muscles. These muscles are then informed that they have to work harder, ensuring that there is a sufficient supply of oxygen in the blood (Campton, 2010). If the mechanism happened to fail, oxygen supplies in the blood would be insufficient, as there the blood would contain an increased amount of carbon dioxide. This may cause problems as the body needs oxygen for all body cells to work efficiently carrying out their bodily functions and without which, the body would shut down.

The medulla also controls heart rate as well as the sinus node. The sinus node receives information, responding accordingly, depending on the body’s needs. An example of this would be if the body isn’t receiving enough oxygen for the muscles to work efficiently during exercise, meaning the sinus node would then give instructions for the heart to work faster, pumping the blood around the body quicker and at a stronger force. If the homeostatic mechanism was not initiated due to problems with either the medulla or the sinus node, the body would become oxygen deprived and so would result in a heart attack, resulting in possible death if the body was to be left in this way for a period of time (Bradfield 2001

In conclusion, homeostatic mechanisms in the body are vital for survival and without such mechanism, it may result in heart failure and possibly even death, highlighting just how important it is.

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