Lecture 30 Flashcards
What is immunology?
The study of an organism’s defense system (immune system) in health and disease.
The immune system is composed of:
Organs (eg spleen)
Cells (eg T cells)
Molecules (eg antibodies)
What is the immune system?
An organised system of organs, cells and molecules that interact together to defend the body against disease (eg pathogenic microorganisms and cancer).
Examples of diseases affected by the immune response: Infectious Diseases
- HIV/AIDS
• Tuberculosis
• Influenza
• Malaria
• SARS-CoV-2
Examples of diseases affected by the immune response: Inflammatory Diseases
- Arthritis/Rheumatism
• Allergy/Asthma
• Lupus
• Diabetes
• Crohn’s Disease/ Inflammatory Bowel Disease
• Multiple sclerosis
Is cancer an example of diseases affected by immune system
Yes
What are microbes?
Viruses
Bacteria
Fungi
Protozoa
Viruses
Bacteria
Fungi
Protozoa
Name from smallest to largest nm
Viruses
Bacteria
Fungi
Protozoa
What are pathogens
microbes
(disease-causing)
Name the Organs of the immune system
Tonsils
Thymus
Spleen
Bone marrow
Lymph nodes
Explain to me the Primary and secondary lymphoid organs
Primary: production of white blood cells (lymphocytes)
Secondary: sites where immune responses are initiated
Primary lymphoid organs in depth
Thymus
• ‘school’ for white blood cells called T cells
• developing T cells learn not to react to self
Bone marrow
• Source of stem cells that develop into cells of the ‘innate’ and ‘adaptive’ immune response
Secondary lymphoid organs
Lymph nodes
- Located along lymphatic vessels
• Lymph fluid from blood and tissue is filtered
Site of initiation of immune responses
Spleen
• site of initiation for immune responses against blood-borne pathogens
The medieval castle as a model for the immune system: 3 layers of defense
1= chemical and physical barriers
2= innate ‘arm’
3= adaptive ‘arm’
Physical and chemical barriers
Skin and mucosal surfaces
Physical Barrier: The Skin
Epidermis:
Dead cells, keratin and phagocytic immune cells
Dermis:
Thick layer of connective tissue, collagen and blood vessels and phagocytic immune cells
In between those 2 there are dendritic cell (immune cells)
Chemical defenses of the skin
- Antimicrobial peptides e.g. skin ‘defensins’ - forms pores in
microbial cell membranes
• Lysozyme: breaks down bacterial cell walls
• Sebum: low pH - Salt: hypertonic
What is the Mucous Membranes
- 1-2 layers
• Epithelium: tightly packed live cells, constantly renewed, mucus-producing goblet cells
Where are the Mucosal Membranes
Ocular
Respiratory
Oral
Urogenital/Rectal
Mucosal membranes line parts of the body that lead to the outside and are exposed to air
The mucociliary escalator
The mucociliary escalator consists of:
Dust particle
Mucus
Cilia
Goblet cell
Columnar cell
Mucous gland
Basement membrane
Cilia move mUcUs up to the pharynx
Chemical defenses of mucosal surfaces
- Stomach - low pH
• Gall bladder - bile
• Intestine - dgestive enzymes - MUCUs
• Defensins
• Lysozyme (tears, urine)
Skin: Number of cell layers
Many
Tightly packed cells? Skin
Yes
Cells dead or alive? Skin
Outer layers dead; inner layers alive
Mucus present? Skin
No
Lysozyme and defensins present? Skin
Yes
Sebum present? Skin
Yes
Cilia present? Skin
No
Number of cell layers Mucous membranes
1 to a few
Mucous membranes Tightly packed cells?
Yes
Cells dead or alive? M
Alive
Mucus present? M
Yes
Lysozyme and defensins present?
In some cases
Sebum? Mocous
No
Cilia present? M
In trachea and uterine tubes
Two intertwined ‘arms’ of the immune system
Surface barriers
• Skin
• Mucous membranes
Internal defenses
• Phagocytes
• Natural killer cells
• Inflammation
• Antimicrobial proteins
• Fever
This is the Innate defences
Humoral immunity
• B cells
Cellular immunity
• T cells
This is the Adaptive defenses
Innate immunity
• Already in place
• Rapid (hours)
• Fixed
• Limited specificities
• Has no specific memory
Adaptive immunity
• Improves during the response
• Slow (days → weeks)
• Variable
• Highly specific
• Has long-term specific memory
