M7 Immune Flashcards
What is immunity?
The ability to resist infectious diseases.
What is the immune system comprised of?
Cells, organs and secreted factors
What are pathogens that can affect the body?
Virus, parasites, bacteria and fungi
What are the 2 types of defences?
Innate and adaptive defense
What are the 2 types of defence in the body’s innate defence?
Surface Barriers
- Skin + mucous membranes
Internal defenses
- Phagocytes
- Natural killer cells
- Inflammation
- antimicrobial proteins
- fever
What are the 2 types of immunity in the body’s adaptive defenses?
Humoral immunity - B cells (creates antibodies)
Cellular immunity - T cells (recognising pathogen)
What are some examples of physical barriers to pathogens?
Skin + epithelial surface has a tight junction between cells.
Mucus in the gut and the lung trap organisms.
urine sheds mucus from the gut. cilia in the lung move mucus out.
What are some examples of chemical barriers?
Acid pH in the stomach, and surface of skin is acidic
Antimicrobial peptides secreted onto epithelial surfaces
Enzymes - saliva can degrade peptidoglycan
What is biological competition in terms of barriers to pathogens?
Commensals in the gut and skin compete with pathogens, if a niche is already occupied, the pathogen cannot easily move in.
What is the complement system?
Secreted proteins directly attack bacteria by making pores in the cell membrane, leading to lysis - disintegration of the cell membrane. Or marking bacteria for phagocytosis.
What are the 3 types of cells that can do phagocytosis?
neutrophils, dendritic cells, macrophages.
(phagocytes)
What are the steps involved in phagocytosis?
- recognition of pathogens by phagocyte receptors
- Extension of membrane around the pathogen, forming a phagosome.
- a lysosome containing degrading enzymes fuse with phagosome.
- the reactive free radical molecules dissolve or acidify the pathogen (enzymes activated by low pH) then ejected.
(pathogens can evade phagocytosis by having a membrane to prevent acidification)
What are some innate immune cells?
Monocytes, Macrophages, and dendritic cells
What are neutrophils?
60-70% of white blood cells in humans. The first cell type to migrate to sites of infection or tissue damage.
What does neutrophils do?
First responders, many die at site of infection leading to the formation of pus, when they die, their DIA is released with anti-bacterial protein that traps and kills pathogens like a net.
