Module 10: Non-Specific Defence Mechanisms of the Host Flashcards
3 Main Responsibilities of the Immune System
- Surveillance of the body
- Recognition of the body
- Destruction of entities deemed foreign
- carried out primality by white blood cells
PAMPs
- pathogen-associated molecular patterns
- shared by many microorganisms
PRRs
- pattern recognition receptors
- on host immune cells recognize and bind the PAMPs
Immune System
- large complex and diffuse network of cells and fluids which reach every part of the body
How is it possible of the immune system to be everywhere?
- mononuclear phagocyte systems (MPS) and extracellular fluid
- lymphatic system
- the blood vascular system
Mononuclear Phagocyte System (MPS)
- provides a passageway within and between tissues and organs
- loaded with macrophages waiting to attack foreign intruders
Extracellular Fluid
spaces surrounding cells
The Lymphatic System
- carries lymphatic fluid - transports white blood cells and other materials
Major Functions of the Lymphatic System
- to provide a route for the return of extracellular fluid to the circulatory system
- the act as a “drain off” system for inflammatory response
- to render surveillance, recognition, and protection against foreign materials through a system of lymphocytes, phagocytes, and antibodies
Lymphatic Vessels
along the lines of blood vessels
Primary Lymph Organs
sites of immune cell birth; red bone marrow and the thymus
Secondary Lymph Organs
lymph nodes, spleen & lymphoid tissues; contains large amounts of T and B cells that are ready to encounter antigen and become activated
Blood Vascular System
whole blood = blood cells suspended in plasma
White Blood Cells
leukocytes
Red Blood Cells
transport oxygen and CO2 to and from tissues
Platelets
- main function is hemostasis
- release chemicals in blood clotting and inflammation
5 Types of WBC
- neutrophils
- basophils
- eosinophils
- monocytes
- lymphocytes
Neutrophils
phagocyte in blood, engulf and kill bacteria
Basophils
function in inflammatory events
Eosinophils
active in fungal infection, allergy and inflammatory reactions
Monocytes
phagocytes in blood, matures into macrophages and dendritic cells
Lymphocytes
- primary cells involved in specific immunity
- T and B cells
First Line of Defence
- non specific, includes any barrier that blocks invasion at the portal of entry
- limits access to internal tissues of the body
- physical and chemical barriers
Second Line of Defence
- non specific, an internal system of protective cells, fluids, and processes
- phagocytosis
- inflammation
- fever
- antimicrobial proteins
Third Line of Defence
- highly specific, acquired through contact with foreign substances
- unique substances and cells are produced
- provides long-term immunity
Physical or Anatomical Barriers
- skin: keratin, sloughing (shedding layers of skin)
- mucous membrane of digestive, urinary, & respiratory tracts, eye-moisture
- ciliated epithelium on respiratory tract
Chemical Defences - Sebaceous Secretions
exert an antimicrobial affect
Chemical Defences - Specialized Glands of the Eyelids
lubricate conductive with antimicrobial secretion
Chemical Defences - Tears and Saliva
lysozyme, dissolves the peptidoglycan in bacteria
Chemical Defences - Sweat
high lactic acid and electrolyte concentration
Chemical Defences - Skin
acidic pH and high fatty acid content
Chemical Defences - Stomach
hydrochloric acid
Chemical Defences - Intestine
digestive juices and bile
Chemical Defences - Semen
anti microbic chemical that inhibits bacteria
Chemical Defences - Vagina
acidic pH
Phagocytosis - General Activities
- survey tissues compartments and discover microbes, particulate matter, and injured or dead cells
- ingest and eliminate these materials
- extract immunogenic information from foreign matter
Phagocyte
- “eating cell”, white blood cell capable of engulfing pathogens
- three main types: neutrophils, monocytes, macrophages
Steps of Phagocytosis
- Chemotaxis
- Adhesion
- Engulfment
- Phagosome Formation
- Phagolysosome Formation
- Destruction
- Elimination
Chemotaxis
- phagocyte migrates to areas where bacteria is present
- they are attracted to the site by signals sent out by bacteria and host cells
Adhesion
- phagocytes use pattern recognition to identify and stick to foreign cells
Engulfment
- bacteria is enclosed by phagocyte
Phagosome Formation
- bacteria is enclosed in a vacuole called a phagosome
Phagolysosome Formation
- lysosomes fuse with phagosome, realizing digestive enzymes
Destruction
- destruction of bacteria ensues
Elimination
- small bits of undigestible debris are released from macrophage
Inflammation
reaction to any traumatic event in the tissues
Inflammation - Signs and Symptoms
- Redness: caused by increased blood flow vasodilation
- Warmth: given off by increased blood flow
- Swelling: increased fluid escaping into tissues
- Pain: stimulation of nerve endings
Inflammation - Function
- mobilize and attract immune components to the site of injury
- set in motion mechanisms to repair tissues damage and localize and clear harmful substances
- destroy microbes and block further invasion
- mediated by cytokines
Cytokines
regulator chemicals released by immune cells that allow communication between them
Fever
- an abnormally elevated body temperature
- body temperature is normally controlled by hypothalamus region in brain
- fever is initiated when substances called pyrogens circulate and reset the hypothalamic thermostat to a higher setting
Pyrogens
exogenous (outside) or endogenous (inside body)
Benefits of Fever
- inhibits multiplication of temperature sensitive microorganisms
- impedes the nutrition of bacteria by reducing the availability of iron
- increases metabolism and stimulates immune reactions and naturally protective immune reactions
Antimicrobial Products - Interferon
- small proteins produced by certain white blood cells and tissue cells
- causes the production of proteins which inhibit viral multiplication
Antimicrobial Proteins - Complement Proteins
- end result is the lysis of the cell
Antimicrobial Proteins - Antimicrobial Peptides
- short proteins that are able to insert themselves into bacteria membranes
