Lecture 30: introduction to the immune system

what is the immune system and what is it made up of?

• its used to fight off pathogens

• its made up of cells, organs, proteins and tissues

• it also recognises abnormal cells like cancer cells(sometimes are not fought off as they identify as self therefore arent attacked)

what are the main components of the immune system?

• organs and cells(thymus and spleen which produce wbc to fight off infection)

• lymph system(helps immune cells travel around the body)

• circulatory system

what are the subsets of the immune system?

acquired immunity and innate immunity

• acquired is specific and occurs overtime

• innate is non-specific and from birth

what is innate immunity ?

• natural

• non-specific defense mechanism

• fast and initial response of the body to eliminate microbes

what is the function of innate immunity?

• physical barriers such as skin, tears, mucus all protect against pathogens

• sometimes bacteria can get around the barriers

• innate immunity uses phagocytosis to remove pathogens

• sometimes backup is needed so signal to adaptive immune system

what are the components of innate immunity?

• physical/structural: barriers such as mucous lining in nasal passages

• chemical barriers: stomach acid(some pathogens are ingested through food)

• protective cells: natural killer cells, white blood cells

also sneezing, coughing and vomitting

what are some of the physical and chemical barriers

• skin, hair, cilia

• mucus membranes

• mucus

• blood brain barrier

• tears

• digestive enzymes in mouth

• stomach acid

what are the cellular components of innate immunity and what do they do?

Macrophages, Neutrophils and Mast cells

• involved in the removal of pathogens via phagocytosis

Natural killer cells

• eliminate infected or abnormal host cells

Dendritic cells

• microbicidal

• secrete chemicals which activate other immune cells

what is inflammation

• when physical barriers are breached, innate immunity triggers an inflammatory response

• releases signalling molecules such as cytokines and chemokines

• they recruited immune cells to the site of infection

what are the classical signs of inflammation

associated with heat, pain, redness and swelling

what are the 2 main things inflammation does?

• helps eliminate pathogens

• helps promote tissue repair

what is the complement system?

• a cascade of plasma proteins in innate and adaptive immunity

• they are produced in the liver but circulate the blood which helps destroy pathogens

• activation of immune cells

• bridge between innate and adaptive immunity

what is adaptive/acquired immunity?

• specific and targeted defense mechanisms

• initiated when innate response doesnt clear the pathogen

• detect specific antigens(proteins) on the pathogen

• remembers pathogens and provides a longer lasting protection

• slow response

what are the 2 branches of adaptive immunity?

• cellular immunity(cells)

• humoral immunity(production of proteins)

what is the function of adaptive immunity?

• made up of T and B cells

• T helper cells help the B cells b sending chemical signals to activate B cells to target pathogen and produce antibody to identify pathogens

• T killer cells identify infected host cells and sends chemical signals to cause them to be eliminated form the body(cytotoxic)

what is cell mediated immunity?

• dendritic cells present the antigen to the T cells to produce a response

• Cytotoxic t-killer cells attack and kill infected cells

• T helper cells help B cells produce antibodies

• regulatory T cells help maintain immune balance and prevent excess responses

• Memory T cells remember the pathogen and bring about a response much faster

what is humoral immunity?

• involves B cells

• they produce antibodies in response to antigens

• they mark the pathogens to be destroyed by phagocytosis etc

overview of adaptive immunity:

what is the comparison between innate and adaptive immunity?

cells overview of the immune system:

what is immunization?

• immune system is stimulated to produce an immune response against specific pathogens

• can be through natural infection or vaccines

what is vaccination?

• produces immunity to a specific disease

• vaccines contain weakened or killed pathogens which introduce antigens which trigger an immune response

• forms memory B cells

• remembers and eliminates the pathogen when re-exposed

what are the types of vaccines?

• Live attenuated vaccine- MMR

• inactivated or killed vaccines- hepatitis A

• subunit, recombinant or conjugate vaccines- HPV

• mRNA vaccines- COVID 19

what are allergies?

• an overreaction of the immune system to normally harmless substances such as pollen

• hypersensitivity

• through inhalation, ingestion or contact with the skin

what are the symptoms of allergies

• itching

• sneezing

• rash

anaphylactic shock- constriction of airways, leads to death sometimes

what is autoimmunity?

• when the immune system mistakenly attacks the bodys own cells and tissues

• genetic predisposition

• environmental factors may trigger an autoimmune response

what are examples of autoimmune diseases?

• Rheumatoid arthritis

• ulcerative colitis

• psoriasis

• diabetes

• multiple sclerosis