B1 Infection Defence (Innate Immunity) Flashcards
What is innate immunity?
Innate immunity is present from birth and includes first line and second line defences.
Examples of physical defences
Skin, scabs, goblet and ciliated cells, nasal hairs and eyelashes
How does skin act as a physical barrier?
Skin blocks pathogens from entering the rest of the body and bacteria protects the body from colonisation from harmful bacteria.
How do scabs act as a physical barrier?
Scabs form using the body’s blood clotting pathway and stops pathogens from getting in.
How do goblet and ciliated cells act as a physical barrier?
Goblet and ciliated cells trap and sweep out bacteria in the airways.
How do nasal hairs act as a physical barrier?
Nasal hairs act as filters to dust and pathogens out of the air we inhale during respiration before they can enter the lungs.
How do eyelashes act as physical barriers?
They trap dirt and pathogens
Examples of chemical defences
Sweat, sebum, mucus, stomach acid (HCI), lysozyme, vaginal acidity, saliva, tears
How does mucus act as a chemical barrier?
Muscus, which is made by goblet cells, prevents bacteria from infecting the walls of the trachea and digestive tract
How does stomach acid act as a chemical barrier?
Stomach acid has a low pH to kill pathogens
How does lysozyme act as a chemical barrier?
Lysozyme is able to hydrolyse bacteria cells walls and destroy microorganisms
How do tears act as a chemical barrier?
Tears continuously lubricate and cleanse the eyes, they also contain lysozyme.
How do skin secretions act as a chemical barrier?
Sweat + sebum make the epidermal surface acidic which inhibits bacterial growth
How does the acidity of the vagina act as a chemical barrier?
Vaginal acidity inhibits the growth of bacteria and fungi in the reproductive tract
How does saliva act as a chemical barrier?
Saliva lubricates and cleanses the mouth, contains lysozyme
Describe the inflammation response
Inflammation is protective response by the body against something harmful. Symptoms of swelling, heat, redness and pain. Chemicals like histamines are released by mast cells and basophils as a response to an allergen. Histamines causes arterioles to dilate, and increases permeability of capillary walls which lets fluid through and makes the tissues swell. White blood cells can move in and act on antigen.
Examples of biological defences
White blood cells, also known as leukocytes act as the biological defence against pathogens if they have bypassed physical and chemical barriers in place.
What are phagocytes?
A type of white blood cell that engulfs and ingests pathogens, dead cells, and other foreign materials that have entered the body e.g neutrophils
What is a macrophage?
Another type of phagocyte. They do antigen presentation and turn into antigen presenting cells.
What are basophils?
Biological defence in the body, a white blood cell that releases histamine to an allergen, heparin to prevent unnecessary blood clotting and serotonin which makes capillary walls more leaky
What are mast cells?
Biological defence, a white blood cell that releases histamine in response to an allergen
What are eosinophils?
Biological defence, white blood cell that can carry out phagocytosis, specialises in the destruction of parasites, involved in counteracting the inflammation response
What are natural killer cells?
Biological defence, white blood cell that detects and attacks virus infected an tumour cells. They are the first to be deployed.
