Introduction to Immunology Flashcards
What is immunology?
The study of an organisms defence system (immune system) in health and disease
The immune system is composed of:
- Organs
- Cells
- Molecules
What is the immune system?
An organised system of organs, cells and molecules that interact together to defend the body against disease
Why is immunology important?
Helps us understand and protect against: Infectious diseases, Inflammatory Diseases, Cancer
What are microbes (that the immune system is protecting us against)?
Viruses, bacteria, fungi, protozoa.
Some microbes are pathogens (disease-causing)
What are the organs of the immune system?
Organs of the immune system: Tonsils, Thymus, Spleen, Bone marrow, Lymph nodes
What the organs of the immune system can be divided into - Primary and secondary lymphoid organs:
- Primary: production of white blood cells (lymphocytes)
- Secondary: sites where immune responses are initiated
Describe the primary lymphoid organs
Bone marrow:
- Source of stem cells that develop into cells of the ‘innate’ and ‘adaptive’ immune responses
Thymus:
- ‘school’ for white blood cells called T cells
- developing T cells learn not to react to self
Describe the secondary lymphoid organs
Spleen:
- site of initiation for immune responses against blood-borne pathogens
Lymph nodes:
- Located along lymphatic vessels
- Lymph fluid from blood and tissue is filtered
- Site of initiation of immune responses
Describe the layers of immune defence
3 layers:
1. chemical and physical barriers
2. innate ‘arm’
3. adaptive ‘arm’
Analagy to a medieval castle
Describe the physical barrier: the skin (structure, and chemical defences)
Structure:
- Epidermis: dead cells, keratin and phagocytic immune cells
- Dendritic cell: immune cells
- Dermis: thick layer of connective tissue, collagen and blood vessels and phagocytic immune cells
Constant renewal of outer layer
Chemical Defences:
- Antimicrobial peptides eg. skin ‘defensins’ - forms pores in microbial cell membranes
- Lysozyme: breaks own bacterial cell walls
- Sebum: low pH
- Salt: hypertonic
Describe mucous membranes (formation, location and chemical defenses)
- 1-2 layers
- Epithelium: tightly packed live cells, constantly renewed, mucus-producing goblet cells
- Mucus layer: traps things. Produced by mucus producing goblet cells
Location:
- Ocular
- Respiratory
- Oral
- Rectal
Chemical defences:
- Stomach - low pH
- Gall bladder - bile
- Intestine - digestive enzymes
- Mucus
- Defensins
- Lysozome (tears, urine)
Describe the mucocilary ecillator
Cilia move mucus up to the pharynx. They beat in time together to push mucus up the respiratory tract so we either cough or swallow it.
Parts of the cell: Dust particle, mucus, cilia, goblet cell, columnar cell, mucous gland, basement membrane
Summarise skin vs mucus membranes
Skin:
- Many cell layers
- Tightly packed cells
- Outer layers dead; inner layers alive
- No mucus present
- Lysosomes and defensins present
- Sebum present
- No cilia
Mucus membranes:
- 1 to a few cell layers
- Tightly packed cells
- Alive
- Mucus is present
- Lysosomes and defensins are present in some cases
- No sebum
- Cilia present in trachea and uterine tubes
Describe the two intertwined ‘arms’ of the immune system
Innate defenses:
- Surface barriers: skin, mucous membranes
- Internal defenses: phagocytes, natural killer cells, inflammation, antimicrobial proteins, fever
Adaptive defenses:
- Humoral immunity: B cells
- Cellular immunity: T cells
Innate immunity vs Adaptive immunity
Innate immunity:
- Already in place
- Rapid (mins-hours)
- Fixed
- Limited specificities
- Has no specific memory
Adaptive immunity:
- Improves during the response
- Slow (days to weeks)
- Variable
- Highly specific
- Has long-term specific memory
