L4 - The innate immune system Flashcards
Define the terms
a) the immune system
b) infectious disease
a) cells and organs that contribute to immune defences against infectious and non-infectious pathogens.
b) when the pathogen succeeds in evading and/or overwhelming the hosts immune responses
_____ immunity is highly specific, acts slowly, has immunological memory and can respond to changes in disease intensity
_____ immunity is non-specific, acts immediately and can’t react to changes in disease intensity
Adaptive
Innate
Innate immunity is comprised of barriers that prevent entry and limit growth and spread of pathogens. One type of barrier is physical barriers, give two examples of physical barriers we have
Skin
Mucosal membranes - mouth, respiratory tract, GI tract, urinary tract
Bronchial cilia
Give an example of a physiological barrier in innate immunity
Diarrhoea
Vomiting
Coughing
Sneezing
Explanation - these all act to expel the pathogen
Give an example of a chemical barrier in innate immunity
Low pH Antimicrobial molecules such as IgA - explanation - immunoglobulins are antibodies, IgA exists in tears, saliva, mucous membranes Mucus Gastric acid Beta-defensins in the epithelial
Give an example of a biological barrier in innate immunity
Normal flora in cavities
Explanation - these compete with pathogens for attachment sites, synthesise vitamins and allow immune maturation
Normal flora refers to the entire bacterial life that exists normally in our bodies at specific regions. Give an example of normal flora on the
a) skin
b) nasopharynx
a) staphylococcus aureus Staphylococcus epidermidis Streptococcus pyogenes Candida albicans Clostridium perfringens
b) streptococcus pneumoniae
Neisseria meningitidis
Haemophilus species
Clinical problems often occur when normal flora is displaced from its normal location to a sterile (free from bacteria) region. One way this can happen is through breaching the skin integrity, give another way
Fecal-oral route - foodborne infection - not washing hands
UTI - explanation often happens in teen women when wiping back to front
Poor dental hygiene
An example of an immunocompromised patient is someone with AIDS. Give an example of another
Diabetics/patients undergoing chemotherapy/asplenic or hyposplenic patients
What can you get if Candida albicans is displaced from the gut flora to the vagina?
Vaginal thrush
Physical barriers are the immune systems first line of defence, the second line of innate defence includes phagocytes and chemicals, these result in inflammation. List two types of phagocyte
Macrophages
Monocytes
Neutrophils
Macrophages produce cytokines (signalling molecules for a function) and chemokines (attractants), apart from phagocytes like macrophages name two other cells let in innate immunity
Basophils Mast cells Eosinophils Natural killer cells Dendritic cells
Phagocytes have pattern recognition receptors (PRR’s) on their cell surface. These recognise structures on foreign microbes called _______. This binding signals for the immune response including phagocytosis
PAMPs
Soluble proteins called opsonins are also involved in the inflammatory response. Phagocytes have receptors for these on to so when opsonins bind the microbes they bind the receptor. What does this do?
Enchances phagocyte binding and clearance of microbes
Describe the basics of the process of phagocytosis
1) phagocyte binds microbes and ingests it forming a phagosome
2) phagosome fuses with lysosome to form phagolysosome
3) digestion of microbe by enzymes
4) discharge of waste material
