Chronic Diseases: Hypertension, Diabetes, Cholesterol & Cardiovascular Diseases
Etiology: In medicine, etiology refers to the study of disease causes. Hypertension, or high blood pressure, is incredibly common. But what exactly is hypertension? How does it relate to physical inactivity, obesity, and poor diet? This section will explore these questions. Let’s start by understanding blood pressure mechanisms. Blood pumped by the heart travels through arteries, veins, and capillaries to all body tissues and organs. This involves two phases: systole (heart contraction, pumping blood) and diastole (heart relaxation, chamber refilling). During systole, blood pressure in arteries is measured (systolic blood pressure). During diastole, diastolic pressure is measured. Normal blood pressure is around 120/80 mmHg (millimeters of mercury), or 12/8. Hypertension often has no early warning signs, making it a “silent killer.” It significantly increases cardiovascular disease risk. Combined with risk factors like smoking, high cholesterol, high-salt diets, stress, and family history, it becomes even more dangerous. Hypertension’s asymptomatic nature is why it’s called the “silent killer.” It dramatically increases cardiovascular disease risk, significantly impacting morbidity and mortality. The Brazilian Society of Cardiology (2004) highlighted hypertension as a major health problem in Brazil, increasing medical and social costs. They advocated a multiprofessional approach due to the disease’s multifactorial nature, emphasizing non-drug treatments such as:
- Weight reduction and maintenance of ideal weight (BMI between 20 and 25 kg/m2).
- Reduced sodium intake (ideally up to 6 g/day of salt).
- Increased potassium intake (diet rich in fruits and vegetables).
- Reduced alcohol consumption (30g alcohol/day).
- Regular physical activity (at least 30 minutes of moderate activity most days).
These measures are linked to a positive lifestyle, crucial in combating chronic disease morbidity and mortality. According to Nieman (1999), obesity triples hypertension risk. Sedentary lifestyles increase this risk by 50%. Weight loss lowers blood pressure, but combining a healthy diet with regular aerobic exercise is best.
Diabetes Mellitus Diabetes mellitus (diabetes) has a complex etiology. Two types exist: insulin-dependent (type 1) and non-insulin-dependent (type 2). This metabolic disorder impairs the body’s ability to metabolize glucose.
In type 1 diabetes, the pancreas doesn’t produce enough insulin (which allows glucose to enter cells). Glucose accumulates in the blood and is excreted in urine. Beta cells (insulin-producing pancreatic cells) are attacked by the immune system, halting insulin production. Type 1 diabetics require insulin. Previously called juvenile diabetes, it can occur at any age. Symptoms include frequent urination, excessive hunger, thirst, weight loss, blurred vision, nausea, vomiting, weakness, dizziness, irritability, fatigue, and slow-healing wounds.
Type 2 diabetes has different etiological mechanisms. The pancreas produces insulin, but cells become desensitized to it. Insulin and glucose accumulate in the blood, and the kidneys excrete them in urine. Type 2 diabetics sometimes need insulin. Symptoms are more subtle and often appear after age 30. Weight gain accelerates type 2 diabetes onset. In America, 85% of type 2 diabetes diagnoses are in overweight individuals. About 90% of diabetes cases are type 2, largely due to sedentary lifestyles, poor diets, and obesity. High blood glucose levels damage blood vessels, nerves, and tissues, increasing vulnerability to other diseases. Diabetics are four times more likely to die from cardiovascular disease (75% of diabetes-related deaths). Recommended blood glucose levels shouldn’t exceed 110 mg/dl after 12 hours of fasting. Regular aerobic exercise, good nutrition, and a positive lifestyle can manage type 2 diabetes (90% of cases are manageable with lifestyle changes). This positive lifestyle also combats obesity, hypertension, and high cholesterol, reducing cardiovascular disease risk. Exercise stimulates metabolism, increasing muscle glucose uptake and insulin sensitivity, lowering blood glucose levels. Regular exercise provides long-term benefits, but diabetics should monitor blood glucose levels to avoid hypoglycemia. Insulin-dependent diabetics should take extra care with their feet due to potential loss of feeling.
High Cholesterol High cholesterol is a major cardiovascular disease risk factor, but normal levels are essential. The body produces cholesterol and absorbs it from food (especially animal products). Excess cholesterol deposits on artery walls, increasing cardiovascular disease risk. Lifestyle changes can reduce this risk. Is cholesterol good or bad? Cholesterol, triglycerides, and other lipids are carried in the bloodstream by lipoproteins: low-density lipoprotein (LDL) and high-density lipoprotein (HDL). LDL (“bad” cholesterol) contributes to fat accumulation on artery walls. Acceptable LDL levels are below 130 mg/dl; optimal levels are 100 mg/dl. HDL (“good” cholesterol) carries cholesterol to the liver for processing or elimination. High HDL levels (above 60 mg/dl) reduce cardiovascular disease risk. The ideal cholesterol ratio is 100 mg/dl LDL to 60 mg/dl HDL, or total cholesterol of 160 mg/dl. Regular aerobic exercise increases HDL and lowers LDL. Weight reduction, smoking cessation, and reduced alcohol consumption also help. Nutritional education, especially reducing saturated fat intake, is crucial for lowering LDL. Total cholesterol above 200 mg/dl warrants attention.
Cardiovascular Diseases Cardiovascular diseases are leading causes of death. Eliminating them would add 10 years to life expectancy. Over 20 heart and blood vessel diseases exist. Cardiovascular diseases, particularly ischemic heart disease and stroke, are major causes of death and disability. Ischemic cardiomyopathy occurs when interrupted blood supply causes ischemia (tissue death from lack of blood supply).
Atherosclerosis, the formation of fatty plaques in blood vessels, underlies about 85% of cardiovascular diseases. It can cause heart disease, stroke, and peripheral arterial disease. Atherosclerosis begins with vessel wall injury (high cholesterol, oxidized lipoproteins, high blood pressure, smoking, poor diet). Monocytes (white blood cells) accumulate, becoming macrophages (cells that engulf and destroy particles). Macrophages release proteins stimulating collagen production, forming atherosclerotic plaque. This narrows blood vessels, potentially causing heart attacks, strokes, or peripheral arterial disease. Risk factors for coronary artery disease are divided into primary and secondary factors. Primary factors (modifiable): high blood pressure, high LDL-C and low HDL-C, high triglycerides, smoking. Secondary factors are divided into alterable and unalterable. Alterable: diabetes, stress, sedentary lifestyle, obesity. Unalterable: age, male gender, heredity. Hypertension is a major predictor of coronary artery disease, especially when combined with other factors.
Cerebrovascular Accident (CVA) Stroke (CVA) is another dangerous disease. The brain needs about 25% of the body’s blood and 75% of its glucose. Unlike muscles, the brain doesn’t store energy. Brief blood deprivation causes irreversible damage or death. Ischemic stroke involves disrupted blood supply and necrosis (tissue death). Hemorrhagic stroke involves brain bleeding. Atherosclerosis and hypertension are underlying factors. Modifiable risk factors (hypertension, obesity, poor diet, smoking, stress) can be countered by lifestyle changes. This unit covered major chronic diseases and how negative lifestyle factors (obesity, poor diet, smoking, stress) increase premature death, disability, and reduced quality of life. Positive lifestyle choices (regular physical activity, good nutrition, no smoking) prevent and treat these diseases, improving quality of life and longevity.