Immunology Flashcards
Define immune system
an organized system of organs, cells and molecules that work together to defend the body against disease
Component of the immune system (3)
Organs
cells
molecules
Define immunology
The study of an organism’s immune (defense) system in health and disease
Diseases affected by the immune response (3)
Infectious diseases
Inflammatory disease
Cancer
2 organs of the immune system
Primary and secondary lymphoid organs
Main functions and 2 components of the Primary lymphoid organ
Function: Where lymphocytes (white blood cells) are produced and mature
Thymus and bone marrow
Thymus
school for white blood cells called T cells - develops T cells to not react with itself
Only 10% pass
Rich source of stem cells that develop into cells of the ‘innate’ and ‘adaptive’ immune responses
Bone marrow
Main functions and 2 components of the secondary lymph organ
Function: initiation of immune response
Lymph nodes and spleen
lymph node (3)
- Located along the lymphatic vessels
- Where lymph fluid from blood and tissue is filtered
- Site of initiation of immune response
Spleen (2)
- Site of initiation for immune responses against blood-borne pathogens (as blood is filtered through the spleen, these blood-borne pathogens are removed from the blood and destroyed)
- 20% of immune cells found in gut
Lines of defence
The body ha 3 lines of defence against infection. These act together to maintain the integrity of our internal environment
3 lines of defence
- Physical & chemical barrier
- Arm 1 - Innate arm (cellular defence)
- Arm 2 - Adaptive arm
Already in place Rapid (hours) Fixed Non-specific/limited specifities (detects molecular components shared by many pathogens) No memory
What are the above characteristics of?
Innate community
Characteristics of the adaptive community (5)
Improves during response Slow (days, weeks) Variable Highly - specific (detects molecular components specific to individual pathogens) Has memory
Components of the innate community (4)
Epithelial barriers
phagocytes
Complement
Natural killer cells
Components of the adaptive community (2)
B lymphocytes - produces antibodies
T lymphocytes - makes effector T cells which kill pathogens
Thucydides
First description of immunity (adaptive immunity)
First development of vaccination
Variolation in China - purposeful, controlled injection of something disease causing to protect individuals against small pox
Variolation
Injecting something disease-causing to prevent against a particular disease
Who brought variation to England
Lady Mary Wortley
Benjamin Jesty and Edward Jenner
The first vaccination of small pox
Vaccination
Inoculation (injection) with an innocuous (harmless) biological agent
Elie Metchnikoff
Discovery of phagocytes - Innate immunity
Peter Doherty and Rolf Zinkernagel
Discovery of MHC - self/non self recognition - Adaptive immunity
What part of our body acts as the chemical and physical barrier?
skin, mucous membranes - both act as our body’s first line of defense
Physical defence of skin
2 layers - Epidermis and dermis
Epidermis and its way of preventing pathogens (4)
Outer most layer of skin that forms the main physical barrier to pathogens
- uppermost, outer layer of the epidermis consists layer of dead cells that are constantly shed/replaced which removes the pathogens along with them
- cells of the epidermis are tightly packed together so pathogens cannot skip through easily
- contains dendritic cells (Langerhans cells) which survey for pathogens and alerts the adaptive immune system
- contains keratin
Dermis
Thick layer of connective tissue, collagen, blood vessels and dendritic cells
Chemical defense of the skin (4)
Antimicrobial peptides
Lysosome
Sebum
Salt
Antimicrobial peptides (4)
- short strings of peptide that act as chemical defense against bacteria
- Produced by epithelial cells lining mucosal surfaces and keratinocytes in the skin
- Has a broad spectrum activity against microbes: active against bacteria, fungi and virus
- often work by forming pore in microbial membranes causing microbes to release its nutrients and essential ions (attacks microbes by interfering with growth and reproduction
Examples of antimicrobial peptides and how they work
skin defensins - mostly work by forming pores in cell walls
Cathelicidins - can work by physically attacking microbe and act as chemoattarctants
Lysosome (3)
- enzyme that breaks down bacterial cell wall
- Sweat glands constantly produce sweat which contains lysosomes to constantly break down bacterial cell walls
Sebum
- Produced by Sebaceous glands present in dermis which associates with hair follicles
- fat - oily secretion
- maintains skin at low pH which prevents microbial colonization
Salt (major constituent of sweat)
- secreted by sweat glands in dermis layer of skin
- creates hypertonic environment which can cause water to flow out of microorganisms and dehydrate them
Why does the salty environment created by sweat not affect our own skin
Because our outermost skin layer is dead