Introduction to the Immune System Flashcards
What is immunology?
The study of an organisms defence system(immune system) in health and disease
What is the immune system composed of?
Organs, cells and molecules
What is the immune system?
An organised system of organs, cells and molecules that interact together to defend the body against disease (pathogenic micro-organisms and cancer)
what diseases are affected by the immune response?
Infectious diseases, inflammatory diseases and cancer
What are examples of infectious diseases?
HIV/AIDS, tuberculosis, influenza, malaria, SARS-CoV-2
What are examples of inflammatory diseases?
Arthritis/rheumatism, allergy/asthma, lupus, diabetes, chyrons’s disease/inflammatory bowel disease, multiple sclerosis
what are microbes?
Viruses, bacteria, fungi and protozoa
What are the small microbes?
Viruses and bacteria (prokaryotes)
What are the larger microbes?
Fungi and protozoa (eukaryotes)
what are some microbes?
Pathogens
What are pathogens?
Disease causing microbes
What are the organs of the lymphatic system?
Tonsils, thymus, spleen, bone marrow, lymph nodes
What are the two types of lymphoid organs?
Primary and secondary
What happens at primary lymphoid organs?
Production of white blood cells (lymphocytes)
What happens at secondary lymphoid glands?
Sites where immune responses are initiated
What are the primary lymphoid organs?
Bone marrow and thymus
What is the bone marrow?
A rich source of stem cells (pluripotent) that develop into cells of the ‘innate’ and ‘adaptive’ immune responses
What happens at the thymus?
Where white blood cells become T cells and learn not to react to themselves
What are the secondary lymphoid organs?
Spleen and lymph nodes
What is the spleen?
The site of initiation for immune responses against blood-borne pathogens (disease causing microbes)
Where are lymph nodes located?
Along lymphatic vessels
What happens at lymph nodes?
Lymph fluid from blood and tissue is filtered and it is the site of the initiation of immune response
What are the 3 layers of defence?
Chemical and physical barriers, innate arm, adaptive arm
What are the layers of the skin?
Epidermis and dermis
What is the epidermis?
The outer layer of the skin composed of densely packed dead cells, keratin and phagocytic immune cells
What constantly renews?
The outer layer of the dermis
What is the dermis?
Thick layer of connective tissue, collagen and blood vessels and phagocytic immune cells beneath the epidermis
What is also in the skin?
Dendritic cells (immune cells)
What are the chemical defences of the skin?
Antimicrobial peptides (skin defensins), lysozyme, sebum and salt
What do antimicrobial peptides (skin defensins) do?
Form pores in microbial cell membranes causing them to leak nutrients and die
What does lysozyme do?
Breaks down bacterial cell walls
What is sebum?
Produced by the sebaceous glands and has a low pH which microbes don’t like the acidic environment
What is salt?
Produced in sea by the sweat glands and causes the microbes to desiccate (dry out) and die
What is the mucous membranes composed of?
Epithelium
What is the epithelium?
Tightly packed live cells which are constantly renewed, mucus producing goblet cells
How many layers in a mucous membrane?
1-2
Where are mucous membranes found?
Lining parts of the body that lead to the outside and are exposed to air (ocular, respiratory, oral, urogenital/rectal)
What happens in the mucociliary escalator?
Cilia move mucus which contains trapped microbes and dust particles up to the pharynx to be removed from the respiratory tract
What are the chemical defences of mucosal surfaces?
Stomach-low pH, gall bladder- bile, intestine- digestive enzymes, mucus, defensins, lysozyme (tears, urine)
What action do the chemical defences of mucosal surfaces have?
A flushing action to get rid of things
How do skin and mucous membranes compare in the number of cell layers?
Skin=many and mucous membrane=1 to a few
How do skin and mucous membranes compare in the packing of cells?
Both have tightly packed cells
How do skin and mucous membranes compare in cells being dead or alive?
In skin outer cells are dead and inner cells are alive while in mucous membranes all are alive
How do skin and mucous membranes compare in mucus being present?
Only present in mucous membranes
How do skin and mucous membranes compare in lysozyme and defensins being present?
Present in skin but only in some cases the mucous membrane
How do skin and mucous membranes compare in sebum being present?
Present in skin but not mucous membranes
How do skin and mucous membranes compare in cilia being present?
Not present in skin but present in trachea and uterine tubes which are mucous membranes
What is the two arms of the immune system?
Innate and adaptive defenses
What is included in innate defences?
Surface barriers and internal defences
What is included in surface barriers?
Skin and mucous membranes
What is included in internal defences?
Phagocytes, natural killer cells, inflammation, antimicrobial proteins and fever
What is included in adaptive defences?
Humoral and cellular immunity
What is included in humeral immunity?
B cells
What is included in cellular immunity?
T cells
How is innate immunity described?
Already in place, rapid (hours), fixed (not much variation in cells), limited specificities (detects molecular components shared by many pathogens), has no specific memory
How is adaptive immunity described?
Improves during the response, slow (days to weeks), variable, highly specific (detects molecular components specific to individual pathogens, has memory
