Pathology: Diseases

Pathology: Diseases

Disease Definition

• A disease is a condition affecting specific functions or structures in the human body.

• It is usually associated with signs or symptoms.

• Diseases commonly affect a specific location and are not caused by physical trauma.

• Severity ranges from mild to severe.

• Duration ranges from acute to chronic, depending on the disease type and treatment effectiveness.

Acute vs. Chronic Diseases

Acute Diseases

• Sudden onset.

• Short duration.

• Severe cases can be life-threatening.

• Often associated with infections or trauma.

• The body's immune system can fight off the infection, leading to dissipation.

Chronic Diseases

• Present for long periods, usually over three months.

• Examples: asthma, hepatitis C.

• May involve periods of exacerbation (disease affecting health) and remission (no active signs or symptoms).

• Some chronic diseases, like cancer or diabetes, are always present and can cause continuous illness.

Types of Diseases

Acquired Diseases

• A disease obtained after birth.

• Not congenital (present at birth).

• Vary in severity.

Autoimmune Diseases

• The body's immune system attacks its own cells and structures.

• The immune system cannot differentiate between pathogens and normal tissue.

• Autoantibodies: Proteins released by the body that attack normal tissue.

• Autoantibodies may target specific structures (e.g., Graves' disease affects the thyroid) or multiple structures throughout the body (e.g., lupus).

• May be hereditary; for example, multiple sclerosis.

Congenital Diseases

• Present at birth.

• May be inherited or caused by environmental factors.

• Examples: heart defects, cleft lip, Down syndrome, HIV infection, spina bifida.

• Causes can include lack of maternal nutrition, alcohol use, drug use, and inadequate nutrient supply to the fetus.

Deficiency Diseases

• Caused by inadequate intake of nutrients, vitamins, and/or minerals.

• Examples of nutrients: iron, vitamin C, zinc, calcium, and iodine.

• Lack of these nutrients can cause improper organ and structure function.

• Examples:

  • Scurvy (vitamin C deficiency).

  • Osteoporosis (calcium deficiency).

  • Anemia, goiter, and rickets.

Hereditary Diseases

• Also known as genetic diseases.

• Result from abnormalities in a person's genome.

• Abnormalities vary in severity.

• Commonly passed down from parents, but can also result from gene mutations due to environmental factors or random events.

Types of Gene Inheritance:

• Single Gene Inheritance:

  • Mutations in a single gene.

  • Most of the body operates normally, but one specific aspect is affected.

  • Example: Cystic fibrosis, where a mutated gene causes excessive mucus production in respiratory passages.

• Multifactorial Gene Inheritance:

  • Mutations in multiple genes, along with environmental factors.

  • The gene may be present but dormant unless activated by environmental factors.

  • Examples: cancers, hypertension, and cardiovascular disease.

  • Avoiding environmental factors may reduce the chance of developing the disease.

• Abnormal Chromosomes:

  • Often caused by problems during cell division (nondisjunction), which damages chromosomes.

  • Example: Down syndrome, caused by an extra copy of chromosome 21 (47 total chromosomes instead of the standard 46).

Idiopathic Diseases

• Diseases with unknown origins or causes.

• Show no obvious sign of origin and appear spontaneously.

• Theories may exist, but the exact reason is unknown.

• Examples: ankylosing spondylitis, chronic fatigue syndrome, and fibromyalgia.

Infectious Diseases

• Invasion of a microorganism inside the body.

• Can be localized or systemic and life-threatening.

• The body may not initially know how to combat the infection.

• The body develops antibodies to destroy the invading microorganism.

• Four primary types: bacterial, viral, parasitic, and fungal.

Bacterial Infections

• Bacteria are single-celled organisms visible under a microscope.

• They have a membrane and reproduce via cell mitosis.

• Caused by an invasion of certain types of bacteria (e.g., H. pylori, staphylococcus, streptococcus, and salmonella).

• Bacteria come in different shapes and sizes, such as:

  • Rods (bacillus)

  • Balls (cocci)

  • Spirals (spirilla)

• Bacteria release toxic substances in their waste, causing illness.

• Serious infections (e.g., pneumonia and strep throat) require treatment.

• Treatment involves antibiotics like penicillin, which destroy the bacteria.

• Antibiotic courses should be completed fully to prevent bacteria from becoming resistant.

• Incomplete treatment can lead to antibiotic-resistant infections like MRSA (methicillin-resistant staphylococcus aureus), which may be life-threatening.

• Different forms of cocci:

  • Diplococci (Streptococcus pneumoniae)

  • Streptococci (Streptococcus pyogenes)

  • Staphylococci(Staphylococcus aureus)

  • Sarcina (Sarcina ventriculi)

• Different forms of bacilli:

  • Chain of bacilli (Bacillus anthracis)

  • Flagellate rods (Salmonella typhi)

  • Spore-former (Clostridium botulinum)

• Other types:

  • Vibrios (Vibrio cholerae)

  • Spirilla (Helicobacter pylori)

  • Spirochaetes (Treponema pallidum)