Causes and Effects

define Non-infectious diseases

• Not caused by pathogens

• Cannot be transmitted between organisms

• caused by

  • genetic factors

  • lifestyle factors → carcinogens

  • nutritional factors

genetic diseases

Inherited disorders – altered/incorrect expression of a gene that causes disease is passed on

• Results in the faulty production of a protein →alters the production of the protein the gene codes for (e.g. too much, not enough, misshapen)

• Depends on the nature of the mutation and which genes/chromosomes are affected

  • E.g. recessive sex-linked diseases more commonly affect males

• mutations can also cause cancer → translocation of BCR-ABL causing lukeumia

Example: Cystic Fibrosis

• Mutation in the CFTR gene

• CFTR channel in the outer membrane is faulty = cannot regulate the movement of salt and water ions = sticky mucus and sweat

• Mucus builds up in respiratory and digestive tract

• Causes respiratory infections, breathing problems, digestive issues and liver failure → diabetes, coughing, shortness of breath, osteoporosis

• No cure, but there are treatments to alleviate symptoms (e.g. mucus thinners)

• Can use gene therapy (crispr-cas9 → administered using an AAV virus) by replacing the faulty gene with the functional one = edited genes can develop working CFTR protein = minimises symptoms

diseases caused by environmental exposure overview

Environmental exposure – factors that trigger a disease in the organism’s lifetime

• Hypersensitivity reaction / Allergies: The overreaction of immune system in response to antigens in the environment

• Genetic disorders: the risk of spontaneous mutations in genes increases with exposure to mutagens

  • carcinogens are a specific type of mutagens linked to cancer

nutritional diseases overview

Malnutrition – a deficiency, imbalance, or excess of nutrients

• Nutrients include carbs, fats, proteins, vitamins, minerals, water

• Body cannot create these nutrients by itself ∴ must obtain it through a food

• Lack of nutrients causes disease

Undernutrition

• Stunting (low height)

• Wasting (low weight for height)

• Underweight (low weight for age)

• Micronutrient deficiencies

Overnutrition

• Obesity

• Diet-related non-infectious diseases (e.g. diabetes, stroke, cancer, cardiovascular disease)

how cancer forms

diseases involving abnormal and unregulated cell division

Carcinogen – a cancer-causing agent

Can happen spontaneously or be triggered by mutagens (carcinogens) in the environment

How it forms

1. Happens when there are mutations in:

   1. Proto-oncogenes (normal genes that become cancerous when mutated)

      1. Allows cells to grow and divide

      2. Become oncogenes (cancer causing genes) when mutated

   2. Tumour-suppressor genes (genes that prevent tumours)

      1. Regulate speed of cell division, apoptosis

   3. DNA repair genes

      1. Fix mutations during DNA replication so they don’t cause cancer

2. Leads to creation of cancerous cells

   1. Divide out of control

   2. Are undifferentiated/unspecialised (don’t have a specific role in body)

      1. Avoids the immune system

      2. Can metastasizemetastasise (break away from tumour to spread to other parts of the body) = by travelling through blood/lymphatic system

3. When cancer cells grow in clusters, they form tumours

   1. Require more nutrients and oxygen to keep growing = deprive healthy cells from it

   2. Grow into nearby tissue = prevents organs from functioning

nutritional disease example + stats

Example: Scurvy

Statistics

• More prevalent in countries with lower socioeconomic status

  • Rarely seen in Australia

  • 73.9% in Northern India

  • Most risk is babies, children and older people

• 50% mortality rate in the 19th century

• Now has low mortality rates

Cause

• Caused by a severe deficiency of vitamin C = not enough fruits/veges in diet

  • mostly due to malnutrition

  • poor access to fresh produce common in lower socioeconomic status places

• Nutrient needed to form blood vessels, cartilage, muscle and collagen in bones

  • Without sufficient vitamin C, the body cannot properly repair tissues, heal wounds, or fight infections

Symptoms

• bruising, bleeding gums, weakness, fatigue and rash

Treatment

• Treatment involves taking vitamin C supplements and eating citrus fruits, potatoes, broccoli and strawberries

cancer example 1

UV light causing melanoma

Statistics in AUS

• 11th most deadly cancer in AUS

  • 0.7% in 2020

• Third most common diagnosis rate in 2024

• Prevalence and incidence rates increasing

• More common in men than women

How it forms

• UV forms thymine dimers = forms a bond between two adjacent T/As

• Results in a kink in the DNA strand

• Disrupts the normal base pairing leading to mutations that can cause cancer

How it Kills

• Cancer cells metastasise and spread to important organs (e.g. liver, lungs, brain)

• Grow rapidly that they prevent organ function

Symptoms

• A change in an existing mole = different shape, colour, size

• Bleeding from moles

• New pigmentation or growth on the skin

Treatment

• Surgery to remove the tumour on skin so it doesn’t spread

cancer example 2

Tobacco smoke causing lung cancer

Statistics in AUS

• Most common cause of cancer-related death

  • 18.5% of all cancer-related deaths in 2023

• Leading cause is cigarette smoking

• Most common above age of 60

• Incidence and mortality rates are decreasing in men but increasing in women

How it forms

• Smoking / breathing in smoke exposes lung cells to chemical carcinogens

• They alter cell DNA and cause mutations = build up over time

• Nicotine also prevents apoptosis

• Causes cancerous cells to form in lung cells and create tumours

• Cannot be killed since apoptosis is prevented by nicotine

How it kills

• Tumour could block off part of the lung and cause it to collapse = leads to infection and death if immune system is weakened

• Prevent healthy cells from respirating by taking nutrients required, thus preventing them from functioning = e.g. killing epithelial cells in alveoli can cause inflammation and respiratory distress

Symptoms

• Chest pain

• Coughing up blood

• Persistent cough

Treatment

• Radiotherapy/chemotherapy to kill rapidly multiplying cells