Case Study A: Understanding Complex Interactions Between Body Systems - An Essay.

Interpretation of Brodie's body shape and size

The goal of this assessment is to: Demonstrate understanding of complex interactions between multiple body systems.

• In this task, you will provide a written assignment response to a Case Study.

Important:

For example, you don't need to go in to details about what dietary changes are required to lose weight, or how much exercise to do. Completion guidelines and academic integrity.

Brodie is a 55 year old male, who is 185cm tall, weighs 95kg, and has a waist circumference of 100cm. Two months ago, his mean arterial blood pressure was 150/95mmHg, and he had high blood cholesterol (he has high level of LDL and total cholesterol, and low HDL). Although he has started making some lifestyle changes, including starting to exercise, he has now been diagnosed with a mild upper respiratory infection (he has "a cold").

1. Interpret Brodie's body shape and size. What would an ideal body shape and size be for him (what would he need to achieve in order to decrease his health risks?).

2. Provide an explanation of how the different types of cell respiration, aerobic and anaerobic, can be used by skeletal muscles during exercise. (include an explanation of the preferred type of respiration in skeletal muscle cells, and why it is preferred).

3. Discuss how multiple body systems normally work together for oxygen to enter the body and reach cells. (discuss the pathway of oxygen moving from outside of the body, to inside of body cells; include integration of multiple body systems).

4. Discuss how the electrolytes sodium, potassium and calcium, which are present in body fluids are important for normal neuron function. (focus on the proportions [high or low] of these electrolytes in the blood and in body cells, and how these relate to neuron signalling).

5. Discuss how exercise is important in promoting venous return. Is his venous return likely to be influenced by his mean arterial blood pressure of 150/95mmHg? (discuss how venous return is increased by exercise)

6. Discuss how Brodie's respiratory infection would be likely to influence his oxygenation, and what compensation would usually occur by the body when someone has "a cold". (compensation refers to changes that the body makes in order to compensate for a change in homeostasis).

7. Brodie's blood pressure and cholesterol are both significant risks for development of coronary artery disease, in which a blockage in a coronary blood vessel leads to insufficient blood flow reaching heart muscle cells. If Brodie were to develop severe coronary artery disease, what could that mean in terms of delivery of oxygen to his heart muscle cells? How would this effect his heart muscle cell function? (ensure that you include aerobic and/or anaerobic respiration).

Audience, tone and pitch of your assignment Write your answers using the types of language and terminology that are used within Anatomy & physiology, as though you were interpreting and discussing the case with a health professional.

1. The ideal body weight for Brodie will be 67.6 - 82.5 kg and the waist circumference will be less than 36 inches that is less than 91.44 cm (Lumb 2016, pp: 32). This from the above observation, it can be said that Brodie is over-weight.

Being over-weight is associated with several health-related risks like cardiovascular disease and type 2 diabetes mellitus and high blood cholesterol level (Mitchell et al. 2014, pp: 13-18). The case study highlights that Brodie suffers from high blood pressure and high level of blood cholesterol. In order to decrease his health related risk of Brodie due to being over-weight, needs to make certain lifestyle changes like physical exercise. Since he has been detected with upper respiratory infection, for the time being he will not be able to continue doing physical exercise but can abide by healthy yet nutritional diet, which is free from fat and cholesterol and scores less in carbohydrate. This will help to work on his escalating weight (Johns et al. 2014, pp: 1158). The diet plan of Brodie will mainly emphasize on the reduce cholesterol intake within the body as he is already suffering from hypercholestromia. The cholesterol-free diet will mainly exclude butter, fat cheese, milk, cream, coconut, palm oils and coconut cream. Moreover, Brodie is also required to reduce his overall calories intake in order to reduce the conversion of extra calorie into fat. The reduction of calorie in-take can be done via decreasing the amount of intake of carbohydrate. The carbohydrate on the other hand must be replaced with fresh fruits and vegetables in order retain the nutritional and vitamin value within the body (Evert et al. 2014, pp: 120).

2. During cellular respiration, the mitochondria present within the skeletal muscle cells converts glucose from the blood into carbon dioxide and water while producing ATP. This is known as aerobic respiration.

C6H12O6 + 6O2 → 6CO2 + 6H2O (glucose + oxygen -> carbon dioxide + water).

Anaerobic respiration occurs in cell cytoplasm. It leads to the production of energy (ATP) and lactic acid from glucose. However, it produces less energy in comparison to aerobic respiration and does not require oxygen. It mainly occurs in tissues, which have high-energy demand like working muscles. In working muscles, there is not adequate oxygen to generate all the energy needed via using aerobic respiration alone.

C6H12O6 -> 2C3H6O3 (Glucose -> Lactic acid)

The lactic acid produced is oxidised afterwards to carbon dioxide and water to prevent lactic acid build up. This process again requires oxygen thus following anaerobic respiration there is oxygen deficiency in the cell, as oxygen is used to break down the lactic acid. 

Types of cell respiration during exercise

Thus it can be said that the main preferred type of exercise for skeletal muscles is anaerobic respiration. In muscles cells there is always high oxygen demand and thus in order to preserve oxygen for the future purpose, anaerobic respiration is used. This is the reason why rigours exercise leads to the development of pain in the joints due to accumulation of lactic acid post exercise (Plowman & Smith 2013, pp: 55).

3. Oxygen transport inside and outside of the body organs mainly takes place by the body fluid, blood. Blood is made up of plasma and within the blood plasma there are EBR, WBC and platelets. The iron containing red-coloured pigment present in RBC, haemoglobin plays an important role in oxygen transport throughput the body. In lungs, the concentration of oxygen is high and here the oxygen binds reversibly with the heme ring of the haemoglobin (with the iron molecule or the prophyrin ring). While reaching at the body organs where the oxygen concentration is low, the binding of the oxygen with haemoglobin breaks leading to the transport of oxygen from the haemoglobin to the body tissue. The prophyrin ring of the haemoglobin in turn takes up the carbon-dioxide from the body cells in return on oxygen and brings to back to lungs for its excretion outside the body. The lungs then exchange carbon-dioxide with atmospheric oxygen (Hall 2015, pp: 132).

4. The main function of the neurons (nerve cells) is executed via neuro-transmission. Neuro-transmission is mainly the alteration of the electric potential across the cell members caused by the opening and the closing of the voltage gated ion channels when an particular action potential is generated. The main modulator of the voltage gated ion channels are sodium, potassium and calcium ions. The arrival of the action potential at the axon terminus leads to secretion of chemicals known as neurotransmitter leasing to neuro-transmission through one cell to another. The body of a neurone is sub-divided into four distinct regions: the cell-body, axon and axon terminals and dendrites (Hall 2015, pp: 133).

                                                                         Figure: Structure of Neuron

How multiple body systems work together to provide oxygen

                                                                         (Source: Alberts et al. 2013)

Axons are specialised for the conduction of action potentials. An action potential is defined as a series of events in the voltage or electric potential across the plasma membrane. When a neuron is resting (non-stimulated), the electrical action potential across the axonal membrane is -60mV (inside negative in comparison to outside). At the peak of the action potential, the membrane potential becomes inside positive (+50mv) with a net change in the voltage of nearly 110 mV. This is known as depolarization of the membrane followed by sharp hyper-polarization and then rapid re-polarization. It is during the membrane de-polarization that the transmission of the electrical impulses occurs (Hall 2015, pp: 133).

                                          Figure: The process of change in polarization of plasma membrane

                                                                     (Source: Alberts et al. 2013)

The depolarization of membrane occurs via opening and closing of sodium and potassium ion channels. In the resting neurons state, the nongated K+ ion channels are kept open (cytosol to the exterior) and gated Na+ ion channels are kept closed. The movement of K+ ions outward leads to the establishment of inside-negative membrane potential. The de-polarization of the membrane starts when inside becomes more negative (less than -60 mV). The depolarization is initiated via opening of the gated Na2+ ion channels from exterior to the cytosolic side of the cell creating inside less negative. Gradually the inside of the cell becomes depolarised and more Na+ channels are open leading to hyper-polarization. Hyper-polarization leads to the opening of the voltage gated K+ ion channels. This opening increase the efflux of K+ ions from the cytosol to exterior of the cell (neuron). This helps in the removal of excess positive charges from the cytosolic face (i.e., further making it more inside negative), thereby restoring the resting potential. During this process of depolarization, the neurotransmitter travel through the body of the neuron starting from the cell body through the axon terminal (Hall 2015, pp: 134).

Importance of electrolytes for neuron function

The arrival of the action potential at the axon terminal leads to the opening of the voltage gated Ca2+ ion channels and subsequent influx of Ca2+ ions. This cause localised increase in the cytosolic concentration of Ca2+ ions at the axon terminus. The rise in the Ca2+ ions triggers fusion of the small vesicle containing the neurotransmitters with the plasma membrane of the neuron leading to the release of the neurotransmitter from the presynaptic cleft to the synaptic cleft. In the synaptic cleft, the neurotransmitter are released from the small vesicles and are then attached with the receptors of the adjacent axon (postsynaptic cell) leading to transmission of the neuronal impulses from one cell to another. It mainly takes 0.5 millisecond (ms) for the neurotransmitter to diffuse across the synaptic cleft and bind to a receptor on the postsynaptic cells (Hall 2015, pp: 134).

5. The main mechanism of generating venous return during the normal locomotory activity like running and walking is conducted by muscle pump system. The peripheral veins present in the arms and legs are equipped with one-way valves that direct the flow of the blood away from the limb towards the heart. Veins are mainly situated within large muscle groups and undergo compression during the contraction of the surrounding muscles. Decompression of the veins occurs during muscle relaxation. Thus, a normal cycle of relaxation and compression leads to the alternate compression and decompression of the muscles. The contraction of the muscles propels blood flow forward through the opening of distal valves and then impedes the flow into the muscles via the closure of the proximal valves during the process of contraction. During muscle relaxation, the proximal valves open and the filling of the venous segment occurs via the flow of the blood. During the initial stages of relaxation, the distal valves close but then they open in response of the increased blood volume and blood pressure in the venous segment. The overall effect of the cycle of compression and relaxation propels the flow of the blood towards the direction of the heart. The venous valves prevent the blood from flowing backwards and thus enabling unidirectional flow that increases the process of venous return (Berlin & Bakker 2014, pp: 1565).

Physical exercise leads to an increase of the respiratory activity. This respiratory activity cast a significant impact on the venous return of the hart. Increasing and rate of respiration as occurring during the process of physical exercise, there occurs increase the venous return and thereby increasing the cardiac output. Non-typical respiratory activity like increase in the rate of respiration arising out of cold and cough like closed glottis or forced expiration reduces venous return and thereby leading to a decrease in the cardiac output (Berlin & Bakker 2014, pp: 1565). The respiratory activity affects the overall venous return via causing change in the atrial pressure. Increase in the right atrial pressure impedes the overall venous return while decreasing this pressure promotes venous return. Respiratory activity also leads to the change in the diameter of the thoracic vena cava and cardiac chambers which either directly or indirectly affect the venous return (Berlin & Bakker 2014, pp: 1565).

Importance of exercise in promoting venous return

Systemic arterial blood pressure of Brodie is 150/95mmHg. This is higher than the normal range as the normal systemic arterial blood pressure is <120/<80 mmHg. Increase in the blood pressure leads to an overall increase in the cardiac output which leads to an increase in the venous return. This is because; venous return is defined as the flow of blood from the periphery back to the right atrium (Berlin & Bakker 2014, pp: 1565). It is continues for few seconds and is equal to cardiac output.  However, it is also stated that the significance of the statement, "cardiac output is controlled by venous return" is, it is not the heart itself that is the primary controller of cardiac output. The associated peripheral circulation affect the flow of the blood into the heart from the veins and these are the primary controllers of venous return (Berlin & Bakker 2014, pp: 1565).

6. Lung is an elastic structure that collapses like a balloon and then expels all its air content through trachea. The lung mainly floats in the thoracic cavity which remains surrounded by the pleural fluid that helps to the pulmonary muscle lubricated and thereby helping the pair of lungs of contract and relax effectively via performing gas exchange.  The pleural fluid is mainly used to exert pleural pressure. Pleural pressure is defined as the pressure of the fluid present in the thin space between the pleura of the lungs and chest wall. There is a slight suction of the pleural pressure thereby leading to slight negative pressure. The normal pleural pressure during the starting of the inspiration is -5 cm of water and this is defined as the amount of suction that is required in order to hold the lungs open during the resting state of the lungs. During the initiation of the process of normal inspiration, expansion of the chest cage pulls the lungs outward with much greater force and thereby creating more negative pressure over an average of -7.5 cm of water. This change in the pleural pressure and the overall change in the volume of the lung promote the normal process of inspiration via increasing the volume of the lung via 0.5 litres. During the process of expiration the events are reversed leading to a decrease in the lung volume (Hall 2015, pp: 235).

Influence of respiratory infection on oxygenation

   Figure: Change in the lung volume in response to pleural pressure, transpulmonary pressure and alveolar pressure

                                                                            (Source: Hall 2015, pp: 235) 

Brodie is suffering from mild upper respiratory tract infection. The effect of the upper respiratory tract infection leads to the overall change in the pleural fluid due to inflammation. Change in the pleural pressure hampers the contraction and relaxation of the pulmonary muscles of the lungs. This alters the expansion and contraction of the lung muscle. As a result the oxygen transfer from the lungs does not occur adequately leading to a decrease in the overall oxygenation or the level of oxygen saturation within the body (Hall 2015, pp: 235).

The homeostasis during “cold” is usually maintained by hypothalamus of the brain. The hypothalamus of the brain senses that the body is too cold than the required body temperature. Then the hypothalamus of the brain sends signals to the muscle cells to increase the temperature of the body. The muscle cells then executes the order of the brain via increasing the shiver and creating warmth of the body. Increasing the warmth of the body leads to fever. The hypothalamus also regulates the blood pressure in order to regulate the body temperature and thereby maintaining homeostasis (Kander et al. 2015, pp: 27).

7. Coronary Heart Disease (CHD) or Coronary Artery Disease (CAD) is defined as a pathological condition which is defined as an impaired flow of the blood to the arteries which are responsible for supplying blood to the different parts of the heart. Thus it can be seen that in CHD there occurs impaired blood flow in the arteries. This lack of proper circulation of the blood inside the arteries leads to overall decrease of the supply of the blood to the heart. Decrease in the supply of the adequate blood inside the heart causes decreases in the proper supply of the blood to the different parts of the body and the heart is unable to pump adequate blood. This leads to a generation of hypoxic condition. Moreover, excessive strain over the heart increases the chance of developing heart failure or cardiac arrest (Dawber, Moore & Mann 2015, pp: 1767).

Development of coronary artery disease and effects on heart muscle function

The main role of the cardiac muscles that is the myocardium is pumping the blood to the different parts of the body. Under the condition of the severe CHR, there occurs disruption in the normal functioning of the cardiac muscles or heart muscles of myocardium. This disruption leads to the development of myocardial infarction one of the common consequences of CHD which leads to the development of heart failure. When the heart fails to pump adequate blood throughout the body, these occurs an oxygen deficiency which leads to decrease in the overall oxygen saturation of the body. Under the lack of adequate oxygen supply within the body, the mitochondrion fails to undergo normal aerobic respiration leading to a decrease in the production of ATP. The muscle cells however, conduct anaerobic respiration in the absence of oxygen and thereby helping to meet the oxygen demand. But the body is unable to salvage the lactic acid build-up, generated as the by-product of anaerobic respiration leading the development of joint pain (Swirski & Nahrendorf 2013, pp: 161).

References:

Alberts, B., Bray, D., Hopkin, K., Johnson, A., Lewis, J., Raff, M., Roberts, K. & Walter, P., 2013. Essential cell biology. Garland Science. Retrieved from: https://books.google.co.in/books?hl=en&lr=&id=Cg4WAgAAQBAJ&oi=fnd&pg=PR4&dq=Alberts,+B.,+Bray,+D.,+Hopkin,+K.,+Johnson,+A.,+Lewis,+J.,+Raff,+M.,+Roberts,+K.+%26+Walter,+P.,+2013.+Essential+cell+biology.+Garland+Science&ots=ye5P8G56M3&sig=ezqFs63F8yeOfUityXpIbRN1zZI

Berlin, D.A. & Bakker, J., 2014. Understanding venous return. Intensive care medicine, 40(10), pp.1564-1566.

Dawber, T.R., Moore, F.E. and Mann, G.V., 2015. II. Coronary heart disease in the Framingham study. International journal of epidemiology, 44(6), pp.1767-1780.

Evert, A.B., Boucher, J.L., Cypress, M., Dunbar, S.A., Franz, M.J., Mayer-Davis, E.J., Neumiller, J.J., Nwankwo, R., Verdi, C.L., Urbanski, P. & Yancy, W.S., 2014. Nutrition therapy recommendations for the management of adults with diabetes. Diabetes care, 37(Supplement 1), pp.S120-S143.

Hall, J.E., 2015. Guyton and Hall textbook of medical physiology e-Book. Elsevier Health Sciences. Retrieved from: https://books.google.co.in/books?hl=en&lr=&id=krLSCQAAQBAJ&oi=fnd&pg=PP1&dq=Guyton+and+Hall+textbook+of+medical+physiology+e-Book&ots=ZCjYntMDRW&sig=TV82wSK953xeBYzTdrZzq96sJ9M

Johns, D.J., Hartmann-Boyce, J., Jebb, S.A., Aveyard, P. & Group, B.W.M.R., 2014. Diet or exercise interventions vs combined behavioral weight management programs: a systematic review and meta-analysis of direct comparisons. Journal of the Academy of Nutrition and Dietetics, 114(10), pp.1557-1568.

Kander, T., Brokopp, J., Erlinge, D., Lood, C. & Schött, U., 2015. Temperature effects on haemostasis in whole blood from ticagrelor-and aspirin-treated patients with acute coronary syndrome. Scandinavian journal of clinical and laboratory investigation, 75(1), pp.27-35.

Lumb, A.B., 2016. Nunn's applied respiratory physiology eBook. Elsevier Health Sciences. Retrieved from: https://books.google.co.in/books?hl=en&lr=&id=aKWqDAAAQBAJ&oi=fnd&pg=PP1&dq=Nunn%27s+applied+respiratory+physiology+eBook&ots=42edD0b40V&sig=uaND3kbx-aAtVN1wwcQ129mQ9-w#v=onepage&q=Nunn's%20applied%20respiratory%20physiology%20eBook&f=false

Mitchell, R.J., Lord, S.R., Harvey, L.A. & Close, J.C., 2014. Associations between obesity and overweight and fall risk, health status and quality of life in older people. Australian and New Zealand journal of public health, 38(1), pp.13-18.

Plowman, S.A. & Smith, D.L., 2013. Exercise physiology for health fitness and performance. Lippincott Williams & Wilkins.

Swirski, F.K. & Nahrendorf, M., 2013. Leukocyte behavior in atherosclerosis, myocardial infarction, and heart failure. Science, 339(6116), pp.161-166.