37 Questions
What is the primary function of tears?
To protect the eyes
Which of the following is NOT considered a chemical barrier in the body's first line of defense?
Normal microbiota
What is the primary function of lysozymes in the body's defenses?
To break down the cell wall of bacteria
What is the primary role of blood transferrins in the body's defenses?
To remove available iron, which bacteria need for growth
What is the main reason the skin's pH is slightly acidic?
To produce the chemical factor of sebum, a waxy lipid
Which of the following is considered a biological barrier in the body's first line of defense?
Normal microbiota
What is the primary function of gastric juices in the body's defenses?
To destroy most bacteria, except for those that can tolerate acidity
What is the main function of T cells and B cells?
Play a role in adaptive immunity
Which type of white blood cell is a first responder in the innate immune system?
Neutrophils
What is the first phase of phagocytosis?
Chemotaxis
Which cell type is responsible for engulfing pathogens through phagocytosis?
Phagocytes
What is a phagosome?
Endocytosed vesicle containing the pathogen
Which phase of phagocytosis involves the formation of a phagolysosome?
Digestion
What is the role of opsonization in the immune response?
To coat the surface of something
What is the function of histamine release from mast cells?
To increase blood vessel permeability
What happens when complement proteins bind to mast cells?
Release of histamine
How does the membrane attack complex (MAC) affect pathogens?
It creates holes in the pathogen's cell membrane leading to bursting
What is a strategy used by some microbes to evade the complement system?
Producing capsules to prevent complement protein binding
Which process involves attracting phagocytes to the site of infection?
Inflammation
What is the main outcome of the complement system's cytolysis process?
Pathogens bursting due to holes created in their cell wall
What is the role of the first line of host defense?
To provide physical barriers to prevent pathogens from entering the body
Which of the following is NOT a component of the first line of host defense?
Antibodies
What is the primary function of the keratin protein in the top layer of intact skin?
To reinforce and protect the underlying layers of skin
How does the ciliary escalator contribute to the first line of host defense?
It moves mucus and trapped pathogens towards the throat for removal
What is the primary role of the lacrimal apparatus in the first line of host defense?
To flush away pathogens from the eye
Which of the following statements about intact skin is TRUE?
Intact skin has a continuous layering of closely packed epithelial cells
What is the purpose of the mucus secreted by the mucous membranes?
To trap pathogens and facilitate their removal from the body
What are complement proteins unable to do easily?
Bind to bacterial cells
What prevents the formation of the membrane attack complex (MAC)?
Bacterial enzymes
How do bacteria protect themselves against complement proteins?
By inactivating complement proteins
What do interferons (IFNs) interfere with?
Viral infections in animal cells
What type of cells produce interferons (IFNs)?
Animal host cells
What is the primary function of interferons (IFNs)?
To alert neighboring cells of a potential viral infection
How do interferons (IFNs) initiate an antiviral response in uninfected cells?
By binding to cell membrane receptors
What is the first step in the mechanism of action of interferons?
Virus enters animal host cell and multiplies
What do interferons (IFNs) cause uninfected neighboring cells to do?
Heighten their antiviral defenses
What is the final step in the mechanism of action of interferons?
Uninfected cell produces antiviral proteins
This quiz provides an overview of the host's defense mechanisms against pathogens. It covers the first, second, and third lines of defense of the human body, including physical barriers like intact skin, mucous membranes, and other protective mechanisms.
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