Innate Host Immunity Flashcards
what 2 things mucst pathogens overcome in order to cause disease?
- must overcome surface barriers and reach underlying tissues
- must overcome resistance by host
what is the first line of defense against disease causing pathogens?
surface barriers of host
what are the 2 aspects of resistance by host?
- nonspecific resistance
2. specific immune response
what is the immune system? Define and give function
- composed of widely distributed cells, tissues, and organs
2. recognizes foreign substances or microbes and acts to neutralize or destroy them
what is immunity?
the ability of the host to resist a particular disease or infeciton
what is immunology?
the science concerned with immune responses
what is the nonspecific immune response also called? (3)
- nonspecific resistance
- innate immunity
- natural immunity
what is the first line of defense of immunity specifically
nonspecific immune response
what does the nonspecific immune response do?
offers resistance to any microbe or foreign material
does the nonspecific immune response have any immunological memory?
no
list 3 other names for the specific immune response
- acquired
- adaptive immunity
- specific immunity
to what does the specific immune response have resistance?
a particular foreign agent
discuss the memory of the specific immune response
has memory! effectiveness increases on repeated exposure to agent
what 2 things are the physical barriers in nonspecific (innate) immunity impacted by?
- direct factors
2. indirect factors
list 5 direct factors that effect the effectiveness of physical barriers in nonspecific (innate) immunity
- nutrition
- physiology
- fever
- age
- genetics
list 3 indirect factors that effect the effectiveness of physical barriers in innate (nonspecific) immunity
- personal hygiene
- socioeconomic status
- living conditions
give an example of personal hygiene as an indirect factor effecting the effectiveness of physical barriers in innate (nonspecific) immunity
feral dogs and cats are in good physical condition, so they are more susceptible to disease
what are the 2 aspects of nonspecific resistance (innate) that are the first line of defense agiant microbes?
- physical barriers
2. host secretions (flushing)
what are the 6 physical barriers in innate (nonspecific) resistance?
- skin
- mucous membranes
- respiratory system
- gastrointestinal tract
- genitourinary tract
- the eye
describe the skin
- a strong mechanical barrier to microbial invasion
2. an inhospitable environment for microbes
what is the skin made of?
keratin produced by keratinocytes in outer layer
list 4 reasons why the skin is an ihospitable environment for microbes
- attached organisms removed by shedding of outer skin cells
- pH is slightly acidic (most microbes no like)
- high NaCl concentration (most microbes no like)
- subject to periodic drying
describe mucous membranes (2)
- form protective covering that resists penetration and traps many microbes
- are often bathed in antimicrobial secretions which contain a variety of antimicrobial substances
list and describe the function of 3 antimicrobial substances found in mucous membranes
- lysozyme: hydrolyzes bonds connecting sugars in peptidoglycan
- lactoferrin: secreted by certain immune cells and sequesters iron (that microbes need for metabolic processes) from plasma and away from microbes
- lactoperoxidase: produces superoxide radicals
list the 3 physical barrier aspects of the respiratory system
- turbulent air flow deposits microbes onto mucosal surfaces
- mucociliary blanket
- alveolar macrophages
describe how the respiratory system uses a mucociliary blanket as a physical barrier against microbes (3)
- mucous secretions trap microbes
- once trapped, microbes are transported away from the lungs on the mucociliary escalator
- the microbes are then expelled by coughing or sneezing or salivation washes microbes into the stomach for death
describe how the alveolar macrophages of the respiratory tract serve as a physical barrier
phagocytic cells in alveoli of lungs eat microbes
what are the 3 aspects of the GI tract that function as physical barriers?
- stomach
- small intestines
- large intestines
how does the stomach function as a physical barrier in the GI tract?
gastric acid
in what 4 ways does the small intestine function as a physical barrier in the GI tract?
- pancreatic enzymes
- bile!!
- intestinal enzymes
- peristalsis
in what 3 ways do the large intestines function as a physical barrier in the GI tract?
- shedding of columnar epithelial cells
- secretory IgA
- normal microbiota (good gut bacteria)
in what 3 ways does the genitourinary tract function as a physical barrier?
- unfavorable environment for foreign microbes
- flushing with urine and mucus
- distance barrier of male urethra
list the 3 ways that the genitourinary tract is an unfavorable environment for foreign microbes
- low pH or urine and vagina
- vagina has lactobacilli
- urea and other toxic metabolites are end products in urine
qhat is the importance of the vagina having lactobacilli in innate immunity?
fetus 1st introduction to microbes usually, so offspring born with vaginal birth have a more robust and diverse initial immunity than C-section offspring
describe the distance barreir of the male urethra to pathogens
it is a long way for microbes to travel with no good environment or nutrients, so most die before they get inside from urethra
give the 3 ways that the eye functions as a physical barrier
- mucus-secreting epithelial membrane
- flushing action of tears
- lysozyme, lactoferrin, and secretory IgA in tears as well
describe chemical mediators in innate (nonspecific) resistance
a variety of defensive chemicals such as defensins and other polypeptides are found in blood, lymph, tears, and other body fluids
where are defensive proteins found?
in the blood
what is the complement system?
composed of over 30 defensive proteins, located in the blood, that augment or complement the antibacterial activity of antibodies
what are the 3 major activities of the complement system?
- defending against bacterial infections
- bridging innate and adaptive immunity
- disposing of wastes
what is opsonization?
the process in which microbes are coated by serum components (called opsonins) in preparation for recognition/ingestion by phagocytic cells
what do some complement proteins function as? describe this function
opsonins; bind to microbial cells, coating them for phagocyte recognition
what are the 3 ways opsonization can occur?
- coat microbe with antibodies
- coat microbe with complement proteins
- coat microbe with antibodies AND complement proteins (big red flag)
list 3 other functions of complement proteins
- function as chemotatic signals that recruit phagocytes to their activation site
- puncture cell membranes causing cell lysis
- many complement activities unite the specific and nonspecific arms of the immune system to destroy and remove invading pathogens
describe complement activation (3 aspects)
- complement proteins are produced in inactive forms
- the complement proteins are activated following enzymatic cleavage
- the complement proteins MUST be activated in a cascade fashion
what are the 3 pathways of complement protein activation?
- alternative
- lectin
- classical
what is the alternative complement pathway involved in?
nonspecific defenses against intravascular invasion by bacteria/fungi
does the alternative complement pathway happen as a result of immune memory?
no, it just happens
what is the alternative complement pathway dependent on?
dependent on interaction of complement with repetitive structures on pathogens
how does the alternative complement pathway begin?
with activation of C3 protein
what are the 2 most common complement proteins?
C3 and C5
what does the alternative complement pathway result in?
formation of the membrane attack complex
describe the membrane attack complex, and give what complement pathway it comes from
forms pores/openings in cell wall leading to a loss in pathogen cell homeostasis and destruction of the cell wall, results from the alternative complement pathway
what is the lectin complement pathway also called?
the mannose-binding lectin pathway
what does the lectin pathway begin with?
activation of C3 and lectin binding