B1 - Immune response Flashcards
What are pathogens
Organisms that can cause disease.
Name four types of pathogens.
Bacteria, viruses, fungi, and protozoa.
How do organisms cause disease
They must enter the body and damage cells.
What is the immune system’s response to pathogens?
The immune system tries to prevent disease from occurring.
- It can distinguish between self (body cells) and non-self (foreign materials).
- Pathogens are recognized as non-self and trigger an immune response
What are the two defense systems of the immune system?
The innate (non-specific) defense system.
- The adaptive (specific) defense system.
How do the innate and adaptive defense systems work?
- They work independently and cooperatively to protect the body from pathogens.
- The innate defense system provides a general defense mechanism.
- The adaptive defense system mounts a specific response tailored to the pathogen.
Transmission Route
Definition: Transfer of infecting agents through objects or substances (fomites) from one person to another.
e.g Computer keyboards, doorknobs, bedding, hair, money, hospital equipment or healthcare personnel clothing, hospital equipment or healthcare personnel clothing.
Transmission Route: Hand Shaking
Viral infections such as colds and flu can be spread through handshakes.
Transmission Route: Foodborne
Spread of infections through contaminated food or food preparation surfaces and utensils.
Transmission Route: Body Fluids
Infections can be transmitted through contact with infected body fluids.
Transmission Route: Airborne
These infections can be spread through the air.
Transmission Route: Waterborne
- Infections can be acquired by consuming contaminated water.
Transmission Route: Vector-Borne
spread by files, fleas and ticks
e.g Malaria (spread by female Anopheles mosquitoes), dengue fever (spread by female Aedes aegypti mosquitoes), Lyme disease (spread by ticks), yellow fever (spread by Aedes mosquitoes), bubonic plague (spread by fleas), sleeping sickness (spread by tsetse flies).
Transmission Route: Transplacental
These infections can be transmitted from mother to fetus during pregnancy.
Innate Immunity
Present from birth and includes first line and second line defenses.
- Activated if the first line of defense is breached.
First Line Defences
1)Intact skin forms a mechanical barrier to prevent pathogen entry.
2) Skin secretions (sweat, sebum) make the epidermal surface acidic, inhibiting bacterial growth.
3) Mucus traps microorganisms in respiratory and digestive tracts.
4) Nasal hairs filter air and trap microorganisms.
5) Cilia propel debris and mucus away from respiratory passages.
6) Lacrimal secretions (tears) lubricate and cleanse the eyes, containing lysozyme that destroys microorganisms.
7) Saliva lubricates and cleanses the mouth, containing lysozyme.
8) Gastric juice contains acid and enzymes that destroy pathogens in the stomach.
9) Urine is slightly acidic, inhibiting bacterial growth.
10) Vaginal acidity inhibits growth of bacteria and fungi.
11) Type of white blood cell that engulfs and ingests pathogens and foreign materials known as phagocytes
- Neutrophils are the most common type of phagocyte.
- Macrophages are another type of phagocyte that can also act as antigen-presenting cells.
Neutrophils
Carried out in large numbers during infections.
Carry out phagocytosis and destroy invading pathogens using lysosomes containing digestive enzymes.
Macrophages
Travel in the blood as monocytes and mature into macrophages in lymph nodes.
Carry out phagocytosis and can act as antigen-presenting cells.
Eosinophils
- Involved in combating allergies and parasitic worm infections.
- Release enzymes to kill pathogens and trap substances.
lymphocyte
Natural killer cells, B cells, and T cells are types of lymphocytes.
- B cells can become antibody cells or memory cells.
- T cells can be cytotoxic, regulatory, or memory cells.
Basophils
Coordinate immune responses and release substances like heparin and histamine.
Changes in basophil count can contribute to allergic reactions and certain conditions.
Mast cells
Found in mucosal and epithelial tissues throughout the body.
- Detect microorganisms and foreign substances, initiating local inflammatory responses.
- Play a role in parasitic infections and allergic reactions.
Passive Immunity
- Types of passive immunity:
- Natural passive immunity: Babies acquire antibodies from the mother through the placenta and breast milk.
- Artificial passive immunity: Immunity obtained through injection of antiserum containing antibodies from another person or animal.
Active Immunity
- Definition: Immunity generated by the immune system producing antibodies in response to an antigen.
- Types of active immunity:
- Natural active immunity: Body produces antibodies after exposure to a pathogenic infection.
- Artificial active immunity: Developed through the administration of a vaccine containing antigenic material.
- Process of artificial active immunity: Vaccines stimulate the adaptive immune response, producing memory B and memory T cells. These cells remain in the blood for years, providing a rapid response when the actual antigen enters the body
Functions of opsonins
Antibodies that bind to dangerous antigens, facilitating their recognition by antibodies or complement receptors on phagocytic cells. This neutralizes the pathogen and promotes phagocytosis.
Functions of agglutinins
Antibodies that bind to multiple antigens simultaneously, causing pathogens to clump together. This prevents their spread in the body and enhances phagocytosis by making it easier for phagocytes to engulf multiple pathogens at once.
