BIO 205 Dr. Raymond Non-Specific Immunity

immunity

the body's ability to resist infectious disease through innate or acquired mechanisms

non-specific (innate) immunity

an inborn set of pre-existing defenses against pathogens and pathogen products

what are the members of the first line of defense?

skin and mucous membranes

what are the members of the second line of defense

phagocytosis, compliment, inflammation, extracellular killing, interferons, fever

what is the role of intact skin in non-specific immunity?

it has many layers, the cells are tightly packed, it is dry so it inhibits growth, it has keratin which makes it strong, it has collagen which makes it stretchy, the outer layer is repeatedly sloughed off, it has sweat (which is salty and shrivels microbes), it has phagocytic dendritic cells, it has dermcidin (that helps eliminate bacteria), it has normal flora that outcompetes bacteria

what is the role of mucous membranes in non-specific immunity

It lines all body cavities open to the exterior, the cells are tightly packed and continually shed, mucous traps pathogens, cilia helps propel mucous and pathogens, lysozyme destroys peptidoglycan, it has phagocytic dendritic cells

blood

plasma + formed elelments

plasma

liquid portion of blood

formed elements

blood cells and blood fragments

what is the function of erythrocytes (red blood cells)

they carry oxygen and carbon dioxide

what is the function of platelets

they are cell fragments that clot blood

what is the function of leukocytes (white blood cells)

they are involved in the immune response

What are the 5 types of leukocytes?

neutrophils, eosinophils, basophils, monocytes, lymphocytes

what is the function of basophils

they are involved in allergy and inflammation

what is the function of eosinophils

they fight worm and fungal infections and are involved in allergy and inflammation

what is the function of neutrophils

they are involved in phagocytosis

what is the function of monocytes

they mature into macrophages and are involved in phagocytosis

what is the function of lymphocytes

they are T and B cells involved in specific (acquired) immunity

Phagocytosis

cellular eating by surrounding and ingesting

phagocyte

leukocyte capable of phagoctyosis

what increases phagocytosis

activating compliment, antibody binding to an antigen, fever

what decreases phagocyosis

having a capsule

what are the steps of phagocytosis

chemotaxis, adherence, ingestion, killing, elimination

What happens is phagocytic chemotaxis

the phagocyte is attracted to the site where it is needed

what happens in phagocytic adherence

the phagocyte attaches to the object

what happens in phagocytic ingestion

pseudopodia (false feet) surround the object and bring it into the phagocyte

what happens in phagocytic killing

the object is sent to lysosomes on the inside of the phagocyte where it is broken down by enzymes

what happens in phagocytic elimination

the remnants of the object exit via exocytosis

extracellular killing

using toxic chemicals secreted by an eosinophil or natural killer cell to kill things like helminths and cancer cells

what kind of cells are capable of extracellular killing

eosinophils and natural killer cells

how do eosinophils complete extracellular killing

they attach to the surface of helminths and produce an extracellular toxin that weakens or kills the helminth

how do natural killer cells complete extracellular killing

they secrete toxins that kill virus infected cells and tumor cells

compliment

30+ proteins circulating in the blood in an inactive form that when activated, work in concert to destroy bacteria and some viruses

true

Once one compliment is activated, all compliment proteins are activated (true or false)

how is compliment activated classically

it is activated by the antibody bound to the antigen

how is compliment activated via the alternate pathway

it is activated by the presence of a pathogen or pathogen product

what are the 4 things that can happen when compliment is activated

cell lysis, other immune cells are called for backup, increase in phagocytosis, increase in inflammation

interferons

antiviral proteins produced by some animal cells after viral infections

what is the function of interferons

they inhibit viral replication in neighboring cells by blocking synthesis of the virus

what are the purposes of inflammation

localizing infection, preventing the spread of pathogens, neutralizing toxins, repairing damage to tissue

what are the triggers of inflammation

heat, chemicals, UV light, cuts/abrasions/pathogens

what are the signs and symptoms of inflammation

redness, increased vasodilation (diameter of blood vessels), swelling, pain

What are the steps in the inflammation process

1. an organism gets in the body through a portal of entry

2. chemicals are released (ex. prostaglandins)

3. permeability of blood vessels increases

4. fluid accumulates in the tissues of the injured area

5. antimicrobial chemicals (and clotting factors if needed) are released

6. histamine is released

7. Vasodilation of blood vessels occurs

8. blood flow increases

9. phagocytes enter and go to work

10. (sometimes pus forms)

11. tissue repair happens

what triggers a host to develop a fever

presence of pyrogens acting on the hypothalamus

What are the 5 purposes of fever

slow growth of pathogens, increased effect of interferons, increased phagocytosis, increased specific immunity, increased tissue repair

why do we worry about a prolonged high fever

it increases heart rate, it increases caloric demand, it causes dehydration, it can cause hallucinations/coma/death