Lecture 7 - Vertebrate Immune System Flashcards
What is Innate Immunity?
-In all animals
- Recognition of traits shared by broad ranges of pathogens, using a small set of receptors
- Rapid response
What is Adaptive Immunity?
- Vertebrates only
- Recognition of traits specific to particular pathogens, using a vast array of receptors
- Slower response
What is Barrier defense?
-Innate Immunity
- Skin, Mucous membranes, Secretions
Internal defense?
- Innate Immunity
- Phagocytic cells
- Natural killer cells
-Antimicrobial proteins
-Inflammatory response
Humoral response
-Adaptive Immunity
- Antibodies defend against infection in body fluids
Cell-mediated response
- Adaptive Immunity
- Cytotoxic cells defend against infection in body cells
How does skin/shells/cuticles prevent pathogens?
- Innate immunity
-Barrier defense
Thickened outer surface inhibits entry by pathogens
How does the mucous membranes prevent pathogens entering the body?
- Innate immunity
- Barrier defense
Mucus secreted by internalized external surfaces trap microbes and other particles
How does Secretion prevent pathogens entering the body?
-Innate Immunity
- Barrier defense
-Saliva, tears
Washing action prevents microbial colonization
Hostile chemical environment - Lysozyme, acidic pH
How do Phagocytotic cells work?
- Internal defense
- Recognizes molecules characteristic of a set of pathogens
- That recognized molecule is absent from vertebrates and is an essential component of certain groups of pathogens
What do Phagocytotic cells do?
Destroy pathogens using phagocytosis
Where are Phagocytic cells located?
Blood, Skin, Mucous membranes, Lymph
What is in the Lymphatic system?
- Thymus
- Spleen
- Lymph nodes
- Appendix
- Peyer’s patches
- Lymphatic vessels
- Adenoid
- Tonsils
How do Natural Killer Cells work?
Recognize surface proteins of virus-infected or cancerous cells
- Internal Defense
What do Natural Killer Cells do?
Release chemicals that cause apoptosis (cell death) in infected or cancerous cells
- Internal defense
What do Antimicrobial Proteins do?
- Attack pathogens or impede their reproduction
- Eg Interfons or Complement Proteins
- Internal defense
Interferons
-Are secreted by virus-infected cells
-Trigger surrounding cells to produce chemicals that inhabit viral reproduction
- Internal defense
Complement Proteins
- Are plasma proteins activated by substances on the surface of many microbes
-Lead to lysis of invading cells - Also involved in inflammation and in adaptive immunity
- internal defense
Inflammatory response
-Signaling molecules released by injured or infected tissue causes local inflammation
-E.g. Histamine, Cytokines
- Internal Defense
Cytokines
- further increases blood flow to the affected area
Histamine
- Triggers vasodilation and increased blood vessel permeability in affected areas
-More white blood cells and proteins can enter interstitular fluid - Internal Defense
Systemic inflammatory response
- Release more white blood cells from the bone marrow
- Reset body’s thermostat to cause fever
What is pathogen-specific recognition?
Specificity is achieved through interaction between antigens and antigen receptors
Antigen definition
Large molecules found on the surface of specific pathogens or secreted by those pathogens
Antigen receptors defintion
Protein receptors are protein produced by B cells or T cells
What are epitopes?
A small, accessible portion of an antigen that binds to an antigen receptor
- Multiple are contained in each antigen
What are lymphocytes?
White blood cells produced in the bone marrow
- B cell and T cells are lymphocytes
What are B-cells?
-Matures in the bone marrow
- Is a lymphocyte
- Produces a single type of antigen receptor
- Each antigen receptor binds to a single epitope of a single antigen
What is a T cell?
- Migrates to the thymus for maturation
- Is a lymphocyte
- Produces a single type of antigen receptor
- Each antigen receptor binds to a single epitope of a single antigen
What do Variable regions do?
They are parts of antigen receptors, and produce the specificity of the antigen-binding site
