Chapter 12: Host Defenses-Innate (Down to before second line of defense)

What is the flowchart summarizing major components of host defenses?

1. Host defenses ~> Innate and Adaptive

2. Innate ~> First line of defense or second line of defense

First line of defense ~> Physical barriers, Microbiota, or Chemical barriers

Second line of defense ~> Gamma-Delta T cells, and natural killer T cells

Gamma-Delta T cells, and natural killer T cells ~> Phagocytosis, inflammation, fever, antimicrobial products

2. Adaptive

Third line of defense ~> Gamma-Delta T cells, and natural killer T cells

Gamma-Delta T cells, and natural killer T cells ~> B cells, T cells

What is the definition of the first line of defense? And what does it break into for the flow chart?

A surface protection composed of anatomical and physiological barriers that keep microbes from penetrating sterile body compartments

• It breaks into physical barriers, microbiota barrier, and chemical barriers

What is the definition of the second line of defense? What is it broken down into for the flow chart?

A cellular and chemical system that comes immediately into play if ifnfecrious agents make it past the surface defenses

• It’s broken down into Gamma-delta T cells, and natural killer T cells then phagocytosis, inflammation, fever, and antimicrobial products

What is the definition of the third line of defense?

Includes specific host defenses that must be developed uniquely for each microbe through the action of specialized white blood cells

• Broken down into Gamma-delta T cells, and natural killer T cells then B cells and T cells

What are B and T cells of adaptive defense? For T cells what do they produce?

Both are white blood cells

1. B cells: provide antibodies

2. T cells: produce Helper T cells or Cytotoxic T cells

• Helper T cells (Th): Help other WBCs and mechanisms

• Cytotoxic T cells (Tc): Role is to kill infected cells

For the first line of defense is it innate or adaptive? What is it and what does it block? What does it limit? Is it non-specific or specific?

• First line of defense: Innate

• Any barrier that blocks invasion at the portal of entry

• Limits access to the internal tissues of the body

• Very general in action (non-specific)

What are the differences between nonspecific and specific defenses? Prove an example and Which are improved by vaccines?

1. Non-specific: Doesn’t change depending on the nature of the pathogen and acts the same

• Ex: flu every time you get the pathogen it’s the same year to year

• Doesn’t improve with vaccines

2. Specific: Response changes per pathogen and improves response over time after you see a pathogen multiple times

• Ex: E. coli antibodies don’t protect against streptococci

• Over time you produce more, better, and quicker responses

• They maintain the memory of pathogens (Memory response)

• Does improve with vaccines

For the First line of defense are they are they innate/adaptive? Specific/nonspecific? What do the barriers do? What are the three types? Provide example of them if necessary

• Inborn or innate, nonspecific

Barriers that impede the entry of microbes and foreign agents

1. Physical or mechanical barriers: skin and mucous membrane

2. Chemical or physiological barriers

3. Microbiological barriers: Made of normal microbiome and immune system develops tolerance to normal microbiome

For the first line of defense what are the two things important from the skin? Can microbes get in if the skin isn’t broken?

1. Outermost layer: tough outer layer that is impervious and waterproof

2. Shedding of skin cells : Constant sloughing off of the outer layers of skin removes microbes (on surface)

• Microbes cannot enter through skin if it’s not broken

For the first line of defense where are the mucous membranes? What does the mucous impede?

Mucous membranes of the digestive, urinary, respiratory tracts and of the eye

• Mucous coating impedes entry and attachment of bacteria (Microbes can’t swim through mucous to attach)

For the first line of defense what are three ways the mucous membrane can flush and eliminate microbes?

• Blinking and tear production flush the eye’s surface

• Constant flow of saliva carries microbes to the harsh conditions of the stomach

• Vomiting and defecation evacuate noxious substances or microorganisms from the body

For the Built-In defenses of the mucous membrane what are the three parts of the respiratory tract? And what does they do?

1. Nasal hair traps larger particles

2. Copious flow of mucus and fluids provides flushing action

3. Ciliated epithelium conveys particles trapped in mucus toward the pharynx: ciliary escalator

What is a ciliary escalator? What reflex is used in the respiratory tract as defense? Foreign matter in what areas trigger what?

Ciliary escalator: Cilia traps microbes and pushes them upwards so they can be sneezed out

• Sneeze reflex expels a large amount of air at high velocity

• Foreign matter in the bronchi, trachea, and larynx triggers coughing to eject irritants

Where is the ciliated epithelium? What things are able to pass by the defenses? What’s the difference between the upper and lower area of the respiratory tract?

• The ciliated epithelium is in places like the nose

• Small things and viruses are able to pass by

• The upper respiratory tract is where particles are trapped and prevented from entering; the lower respiratory tract is where sterile tissues are

What are examples of chemicals or physiological barriers?

• Examples include: antimicrobial, enzymes, mechanisms, etc.

What are the first 3 chemical or physiological barriers discussed in class?

1. Sebaceous secretions exert an antimicrobial effect (Sebum oil on surface of skin)

2. Specialized glands of the eyelids lubricate the conjunctiva with an antimicrobial secretion (NOT TEARS it’s something separate)

3. Lysozyme: an enzyme found in tears, mucous, and saliva that hydrolyzes the peptidoglycan in the cell wall of bacteria (directly attacks and is similar to penicillin)

What are the Last 3 chemical or physiological barriers discussed in class?

4. High lactic acid and electrolyte concentration of sweat (some antimicrobial activity)

5. Acidic pH and fatty acid content of the skin (also b/c of secretions of skin)

6. Hydrochloric acid in the stomach, Digestive juices and bile in the intestines (around 2 pH)

Microbiological barrier is made of what? What is an example of the microbiological barriers discussed in class?

• Forms a type of structural barrier made of microbes

• Ex: pathogen enters via inhale and it’s looking for a cite that’s in gastrointestinal cites. But all the cites are taken normal microbiome so it can’t bind

What are the three things that a microbiological barriers does?

1. Can block the access of pathogens to epithelial surfaces or attachment sites

2. Creates competition for limited nutrients (Notmal microbiome takes all the nutrients)

3. Creates an unfavorable environment for pathogens by altering the local pH (they can’t grow because of products and environment)