Unit 3: Non-infectious Diseases

Non-infectious (or non-communicable) diseases are chronic conditions that are not caused by an infectious agent and cannot be spread from person to person. They are typically caused by a combination of genetic, lifestyle, and environmental factors.

1. Diabetes (Type I and Type II)

Diabetes Mellitus is a metabolic disorder where the body either doesn't produce enough insulin or can't effectively use the insulin it produces. Insulin is a hormone from the pancreas that allows glucose (sugar) to enter cells to be used for energy. This results in high blood sugar (hyperglycaemia).

Comparison of Type I and Type II Diabetes

Symptoms, Complications, and Diagnosis

• Common Symptoms (Both Types): Increased thirst (polydipsia), frequent urination (polyuria), unexplained weight loss, extreme hunger, fatigue, and blurry vision.
• Complications: Uncontrolled diabetes damages blood vessels and nerves over time, leading to:
  • Cardiovascular disease: Heart attack and stroke.
  • Kidney damage (Diabetic Nephropathy): Can lead to kidney failure.
  • Eye damage (Diabetic Retinopathy): Can lead to blindness.
  • Nerve damage (Diabetic Neuropathy): Causes tingling, pain, and numbness, especially in the feet.
• Diagnosis:
  • Fasting Blood Glucose Test: Measures blood sugar after an overnight fast.
  • Glycated Haemoglobin (A1c) Test: Measures average blood sugar levels over the past 2-3 months.
• Prevention (Type II): Maintaining a healthy weight, eating a balanced diet, and regular physical activity can prevent or delay Type II diabetes. Type I is not preventable.

2. Hypertension (Primary and secondary)

Hypertension, or high blood pressure, is a condition where the long-term force of the blood against the artery walls is consistently too high. It is often called the "silent killer" because it usually has no symptoms.

Blood pressure is recorded as two numbers (e.g., 120/80 mm Hg):

• Systolic Pressure (Top Number): Pressure in arteries when the heart beats.
• Diastolic Pressure (Bottom Number): Pressure in arteries when the heart rests between beats.
• Stage 1 Hypertension: 130-139 systolic OR 80-89 diastolic.

Types of Hypertension

1. Primary (Essential) Hypertension: This is the most common type (90-95% of cases). There is no single, identifiable cause. It develops gradually over many years and is linked to risk factors like genetics, age, obesity, high salt intake, and lack of exercise.
2. Secondary Hypertension: This type is caused by an underlying medical condition. It appears suddenly and causes higher blood pressure than primary hypertension. Causes include:
   • Chronic kidney disease
   • Sleep apnea
   • Thyroid problems
   • Adrenal gland tumors (e.g., primary aldosteronism)

Symptoms, Complications, and Diagnosis

• Symptoms: Usually none. Very high pressure might cause headaches or shortness of breath, but this is rare.
• Complications: The constant high pressure damages arteries, leading to:
  • Heart Attack & Stroke: Hypertension is a major risk factor.
  • Aneurysm: Weakening and bulging of blood vessels.
  • Heart Failure: The heart muscle thickens and weakens from overwork.
  • Kidney Damage: Weakens and narrows blood vessels in the kidneys.
• Diagnosis: Done by measuring blood pressure with a cuff (sphygmomanometer). A high reading must be confirmed at multiple appointments.
• Prevention/Management: Lifestyle changes are key: low-salt diet, regular exercise, healthy weight, quitting smoking, and managing stress. Medications are also used.

3. Cancer

Cancer is a broad term for diseases where abnormal cells divide uncontrollably and have the ability to invade other tissues. These abnormal cells form a mass of tissue called a tumor.

Benign vs. Malignant Tumour

Metastasis

Metastasis is the defining characteristic of advanced cancer. It is the process by which malignant cells break away from the primary tumor, travel through the bloodstream or lymphatic system, and form new tumors (secondary tumors) in distant organs.

Detection (Diagnosis)

Cancer detection involves a combination of methods:

• Screening: Tests on healthy people to find cancer early (e.g., mammograms for breast cancer, colonoscopy for colon cancer).
• Medical Imaging: X-ray, CT scan, MRI (see Unit 5) to locate and measure tumors.
• Biopsy: The definitive diagnosis. A small sample of the tumor tissue is removed and examined under a microscope by a pathologist to see if it is benign or malignant.