Biochemical And Physiological Underpinning Of Hypertension Assignment Sample

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Introduction

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The essay will be discussing the biochemical and physiological pathways associated with hypertension along with symptoms and prevalence of this condition. In addition, an elaborate discussion will be done on dietary management of this condition and the role of exercise in controlling high BP.

Task 1: Biochemical and Physiological Underpinning of Hypertension

1.1 Definition and Symptoms of Hypertension

Hypertension is considered to be a chronic condition where the blood pressure (BP) is higher than the normal range and that is majorly responsible for Coronary Heart Disease (CHD). It causes other vascular complications and strokes as well (Unger et al. 2020). The normal range of BP is 120 mm-hg/dl and 80 mm-hg/dl for Systolic Blood Pressure (SBP) and Diastolic Blood Pressure respectively (DBP) as recommended by WHO (World Health Organisation). Blood pressure greater than 140/90 mm-hg/dl is considered to be hypertensive. Hypertension can be classified according to different stages of hypertension.
Other than the BP range, Hypertension is classified into two types- “Primary Hypertension” and “Secondary Hypertension”. Primary Hypertension is popularly known as “Idiopathic or Essential Hypertension”. It is again classified into two types- “Benign Hypertension” and “Malignant Hypertension” (Wakerley et al. 2015). The benign one causes high BP without any specific cause and it is mostly symptomless. However, genetic predisposition can be a major cause. Some people have persistent high BP due to which the probability of developing renal or other cardiovascular complications, strokes enhance. Certain symptoms of this condition include nose bleeding, severe headache, chest pain, breathlessness, fatigue, loss of vision as well as dizziness. Secondary Hypertension occurs due to the presence of some diseases such as cardiovascular disease (CVD), renal disease, endocrine dysfunction, Pregnancy Induced Hypertension (PIH) (Gupta-Malhotra et al. 2015).

1.2 Prevalence of Hypertension

According to the latest data by WHO (2021), hypertension is one of the leading causes of premature deaths. Approximately 1.28 billion people, aged between 30-79 years old have been suffering from hypertension, worldwide. However, 46% of them are unaware of having hypertension, and only 42% get themselves treated following diagnosis. It is estimated that 1 in every 5 adults or around 21% is having controlled hypertension. Around 516,955 people in the US died due to hypertension in 2019. According to reports, men have a slightly higher tendency of developing this condition than women. Around 50% of males and 44% of females are having hypertension in the US (Cdc.gov 2021). Moreover, the prevalence is 31.5% or around 1.04 billion peoplebelonging to low and middle-income groups are suffering from hypertension than high-income groups (28.5% or around 349 Million) (Mills et al. 2020). WHO states obese people have more tendency to develop lifestyle diseases such as CVD, hypertension, diabetes, etc.

1.3 Aetiology of Hypertension

Some people have abnormally high blood pressure due to genetic causes. There is no specific reason for that but genetic predisposition leads to primary hypertension. Other than the genetic factors obesity is one of the major causes of this condition (Jiang et al 2016). Abnormal accumulation of fat in the adipose tissue, intra-abdominal as well as intra-vascular regions due to positive energy balance is the reason for obesity. People having “Body Mass Index” or BMI higher than 30 is suffering from Grade 2 obesity having more probability of developing complications (Mills et al. 2020). Consumption of excess calories than expenditure leads to complications such as CVD, diabetes, gall-bladder disorders and hypertension. However, there is no single cause associated with hypertension and obesity. Environmental factors including eating simple carbohydrates, refined grains, saturated fat, trans fat, present high-calorie beverages, snacks etc. cause obesity over time. An excess amount of fat gets accumulated in the inner walls of blood vessels slowly leading to atherosclerosis. The diameter of the blood vessels gets narrowed down and when blood flows at the normal speed it gives partial pressure and that causes hypertension (Aronow, 2017). This is the reason why obese people are more prone to developing other CVDs. Moreover, the peripheral alpha1 and the beta-adrenergic receptors get activated due to consumption of excess fat and carbohydrate leading to obesity-associated hypertension (Jiang et al. 2016). Stress, anxiety, and excessive alcohol consumption can lead to hypertension as well. Sedentary lifestyle lacking in physical activity or exercise, smoking etc. cause hypertension too. Cigarette smoking enhances endothelial damage, enhances heart rate, increases BP and over time leads to hypertension and other CVDs.
Hypertension is considered to be an independent risk factor for CHD as well as stroke. High BP leads to enhanced endothelial damage and targets specific organs. It is associated with other risk factors such as blood-lipid abnormalities or dyslipidemia, insulin resistance, leading to glucose intolerance or diabetes, and renal failure as well (Blake et al. 2016). Insulin resistance in diabetes leads to impaired insulin signalling, along with impaired fibrinolysis as well as inflammation (Manne-Goehler et al. 2017). Abnormal insulin-signalling pathways such as the overactivation of phosphatase enzymes can lead to abnormal regulation of protein kinase cascade. This can lead to enhanced activity of growth factors, cytokines, as well as peptidase and excess production of "Very Low-Density Lipoprotein (VLDL)". This enhances the probability of excess fat accumulation of fat in the inner vessels. "LDL (Low-Density Lipoprotein)” is made from VLDL which is considered to be bad cholesterol as it is responsible for the accumulation of fat to different body tissues collecting from the liver (Knop et al. 2018). Hence, the probability of hypertension enhances along and if remains untreated in worst cases lead to CHD.
Disturbances in the endocrine system cause hormonal disbalance which leads to hypertension as well. The narrowing of blood vessels prevents blood flow to the kidneys. The function of the kidney is to blood filtration and formation of urine. The nutrients and oxygen are carried to the kidney by blood; hence, narrowing of blood vessels restrict carrying of sufficient oxygen to kidneys making it unable to perform its function and in the long run develop into “Chronic Kidney Disease (CKD)” (Motedayen et al. 2019). Other than that, excessive production of “Aldosterone” hormone production leads to fluid retention as well as salt retention in the body. Aldosterone is a part of the Renin-angiotensin-aldosterone system that is activated when blood volume drops in the body (Wiesmann et al. 2017). Excess amount of aldosterone production due to endocrine dysfunction leads to higher retention of fluid and salt tension in the body and can cause hypertension.

Task 2: Diet and Exercise for the management of Hypertension

2.1 Dietary management

DASH or “Dietary Approach to Stop Hypertension” is the principle followed while making a diet for hypertensive patients. Inclusion of easily digestible carbohydrates such as fruits, low sodium-containing fruits including carrot, broccoli, eggplant, etc. is part of this diet approach (Siervo et al. 2015). In addition, low-fat milk, fish, lean meats rich in “Polyunsaturated Fatty Acid or PUFA” and “Monounsaturated Fatty Acid or MUFA” are suggested by the DASH diet.
All the dietary management described in this section is done by following suggestions by DASH. Adopting a DASH diet plan can help to reduce SBP by 8-14 mm-hg.Dietary management is very necessary to reduce BP. Weight reduction is the primary principle for dietary modifications. Consumption of a calorie-restricted diet to maintain the “Ideal Body Weight (IBW)” is the key principle for planning the diet to reduce the SBP by 5-20 mm-hg per 10kg weight reduction. Carbohydrates must contribute around 60% of the total calorie consumption. Easily digestible carbohydrate sources such as fruits and vegetables must be eaten instead of green leafy vegetables (GLVs) because GLVs contain a high amount of sodium that is responsible for elevating the BP. Hence, it is suggested to avoid this type of food group. The protein must supply around 20-25% of the total calorie. Usually, it is prescribed to eat 1g protein/kg body weight to prevent excess burden on the kidneys and at the same time to maintain the positive nitrogen balance (Dasinger et al. 2020). Poultry meat, fish, egg without the yolk, etc. belong to first-class protein sources that supply all the essential amino acids to the body. Egg yolk, red meat must be avoided especially for those who are aiming to lose weight. Some vegetarian sources of protein are legumes, low-fat milk such as skimmed or double toned milk and milk products (Geissler and Powers, 2017). Moreover, these saturated fatty acids enhance LDL, VLDL, total cholesterol levels in blood that in turn increases the complications of hypertension, such as CHD and stroke. However, for patients suffering from severe hypertension, “Kempner’s diet” is suggested to them that only supplies 20g of protein. The Kempner diet gives 2000kcal energy in which protein content is only 20g, fat is 5g or even less, low in sodium (around 150mg) and is made with rice, fruit juice, and vitamin supplements to treat hypertension.
The role of fat in a hypertensive diet is the most crucial. Saturated fat and trans fat is completely prohibited for hypertensive patients. Essential fatty acids such as “PUFA” or including “Omega-6” and “Omega-3” fatty acids as well as “MUFA” are permitted for patients suffering from hypertension (Lee et al. 2019). Vegetable oil or unsaturated fatty acids rich in PUFA and MUFA can be consumed that provide 15-20% of the total calories. Linoleic acid is present in sunflower oil, nuts, and flaxseed. Arachidonic acid is present in animal tissues such as liver, egg, poultry meat, and fish (Li et al. 2020). Both linoleic and arachidonic acid are types of omega-6 fatty acid and help in the reduction of bad cholesterol such as triglycerides, LDL, VLDL, and cholesterol from the blood. However, it reduces the “HDL or High-Density Lipoprotein" as well which is good cholesterol and scavenges excess fat from different parts of the body and transports them to the liver (Molinar-Toribio et al. 2015). Linoleic acid, Eicosapentaenoic acid (EPA), and Docosahexaenoic acid (DHA) are some of the examples of omega-3 fatty acids. These are not only responsible for reducing bad cholesterol but at the same time elevate HDL that preventing the further complication of hypertension (Kharazmi-Khorassani et al. 2021). Linseed oil, Salmon, walnut, cashew, mackerel, cod liver oil, shellfish, flax seeds, and chia seeds are some of the richest sources of omega-3 fatty acids.
A mild to moderate and even severe sodium-restricted diet is very necessary to control high BP. Several studies have proved low sodium and high potassium-rich diet improves hypertension and significantly reduces the probability of stroke. Therefore, fruits must be incorporated into the daily diet. Sodium not only elevates BP but also at a cellular level, increased intracellular sodium is exchanged for increased intracellular calcium with its potential effects of augmented vascular tone and vascular hypertrophy with resulting persistent hypertension. Sodium restricted diet reduces SBP by 2-8 mm-hg (Steinberg et al. 2017). Hence, table salt consumption must be restricted. It is ideal to avoid canned food, pickles, highly salted snacks, cheese, instant food, etc. Moreover, chips, biscuits, cakes and pastries are rich in trans-fat; hence, must be avoided.

2.2 Role of exercise

The hypertensive patients are prescribed aerobic exercises to enhance the strength of the heart and improve the blood volume as well. Regular exercise or brisk walking for at least 30 minutes each day to reduce the SBP by 4-9 mm-hg (Panagiotou et al. 2015). This helps in improving blood circulation and significantly reduces the accumulation of LDL, calcium, platelets, and other plaques in the intima of blood vessels. Severe to moderate exercise along with a calorie-restricted diet help to reduce SBP remarkably. Several studies have proven that vascular endothelial functions improve, along with an increase in parasympathetic tone, and the tolerance against reperfusion injury and other CVDs enhance with physical activities (Lopes et al. 2018). Consumption of PUFA along with exercise improves the balance between vasodilation as well as vasoconstriction that accelerates the flexibility of blood vessels and thus tendency of atherosclerosis get reduced (Wen and Wang, 2017). A very recent study showed people take regular medications for high BP, and doing a combination of cycling and walking thrice a week for at least 40 minutes the SBP reduced by 7.1 mm-hg/dl and DBP reduced by 5.1 mm-hg/dl on an average (Health.harvard.edu, 2021). Hence it can be certainly said that regular exercise with a DASH prescribed diet can significantly help to reduce weight and at the same time control the high BP in hypertensive patients.

Conclusion

The essay was divided into two broad categories to discuss the definition, symptoms, prevalence and aetiology of hypertension as well as the importance of dietary modifications and the role of exercise to control high BP.

References

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