Topic 1-4 (Lecture 4) Flashcards
What is the human body’s first layer of defense?
Skin (epidermis, made w/ keratin) - impregnable, i.e. cannot be broken into
What properties of the skin makes it a good barrier to infection?
- Lacks moisture
- High salt concentration
- sebaceous gland secrete fatty acids and lactic acid to decrease pH (inhibits growth)
- Antimicrobial peptide secretion
What protects the upper respiratory tract (URT) from infection?
Mucous membranes - traps the bacteria
ciliated cells - cilia sweeps mucous up and out
Antimicrobial peptides in secretions (tongue, throat)
What parts of the body constitute the URT?
Nose, throat, ears
What parts of the body constitute the Lower respiratory tract? (LRT)
Trachea, bonchial tubes, alveoli in lungs
What protects the LRT from infection?
Mucociliary system (moves particles up throat where they are swallowed)
Lungs - protected by macrophages and antibodies
Antimicrobial proteins and peptides
How sterile is the LRT?
Essentially sterile (very effective defence)
How colonies is the gastro-intestinal (GI) tract?
Very (contains majority of human microbiota)
What defenses against colonization are in the GI tract?
- Stomach acidity (lower pH to inhibit/kill microorganisms)
- Peristaltic movement (muscle relax/contract cycle to -propegade material through GI)
- Microbial antagonism (the pre-existing microbiota out-compete bacteria that is trying to colonize)
What are the two types of host immune defences?
Non-specific innate immune defence mechanisms
Specific adaptive immune responses
What are key features of the innate immune response? (Review of sorts)
Effective against a variety of pathogens - recognizes general features of bacteria
Innate; meaning it is not dependent on prior pathogen exposure
Effective rapidly/immediately
What are some examples of antimicrobial components in body fluids?
- lysozyme in tears, saliva, mucus, blood, and lymph
- phagocytic cells in blood and lymph
- complement proteins in blood
Review What are 4 key abilities of complement proteins?
- attract phagocytic cells to infection site (chemokine)
- Stimulate the release of histamine (cytokine)
- promote the binding of bacteria to phagocytes (opsonization)
- cause cell lysis in some bacteria (MAC)
What is inflammation?
“coming together of the innate immune host defences in response to infection and injury”
What are 4 signs of inflammation?
Redness
swelling
heat
pain
