Innate Immunity
What is the first line of defence in the immune system?
Physical and chemical barriers like skin, mucous, stomach acid
What type of cells are responsible for the adaptive immune response?
B cells and T cells
What is the difference between active and passive immunity?
Active = body produces antibodies; Passive = antibodies are given
What is the role of helper T cells in immunity?
They activate B cells and cytotoxic T cells
What is the primary purpose of vaccines in controlling the spread of disease?
To stimulate the immune system to produce memory cells, providing long-term protection against specific pathogens.
Name two types of phagocytes involved in innate immunity.
Macrophages/neutrophils/Dendritic Cells
What is the difference between humoral and cell-mediated immunity?
Humoral = B cells and antibodies; Cell-mediated = T cytotoxic cells
Give an example of natural passive immunity.
Antibodies passed from mother to baby via placenta or breast milk
Which immune cells produce antibodies?
Plasma B cells
How does herd immunity reduce the spread of infectious diseases?
When a high proportion of the population is immune, either through vaccination or previous infection, the spread of the pathogen is limited, protecting vulnerable individuals.
What is the role of inflammation in innate immunity?
Inflammation isolates pathogens and recruits immune cells, vasodilation
What is clonal selection and where does it occur?
Selection and expansion of specific B or T cells in lymph nodes
Why does natural active immunity typically result in long-term protection, while passive immunity does not?
Natural active immunity involves the activation of the adaptive immune system and the production of memory cells, which remain in the body and respond quickly upon re-exposure.
What type of immune cell matures in the thymus?
T cells
Why do some pathogens, such as influenza, require new vaccines each year?
Pathogens like influenza mutate rapidly, leading to antigenic variation. This allows them to evade immune memory from previous vaccinations or infections.
How do natural killer (NK) cells target infected cells?
They induce apoptosis in virus-infected or abnormal cells by detecting abnormal MHC I markers
What do cytotoxic T cells do during an immune response?
They destroy infected or abnormal host cells
Contrast artificial and natural active immunity.
Artificial = via vaccines; Natural = via infection
How do dendritic cells link the innate and adaptive systems?
Phagocytose and they present antigens to helper T cells
Explain how antibiotic resistance in bacteria can undermine public health strategies.
Overuse or misuse of antibiotics can select for resistant bacteria. This makes infections harder to treat and increases the spread of resistant strains, challenging disease control efforts.
Explain how the complement system enhances innate immunity.
It tags pathogens (opsonisation), recruits immune cells, and forms membrane attack complexes
Describe how memory cells contribute to long-term immunity.
They respond rapidly to a previously encountered antigen, preventing reinfection
Explain why passive immunity offers immediate but short-term protection.
No memory cells are produced; antibodies degrade over time
Describe the process of antigen presentation by MHC class I molecules.
Infected cells present intracellular antigens via MHC I to cytotoxic T cells
During a pandemic, governments may implement measures like quarantine and travel restrictions. Explain how these strategies help control disease spread and why they may be challenging to implement effectively.
Quarantine and travel restrictions reduce the movement of infected individuals, limiting exposure and slowing transmission. However, these measures are challenging due to social, economic, and compliance issues, and may not fully contain highly transmissible diseases.