C3 Quick immunlogy Flashcards
What are pathogens?
Microorganisms such as bacteria and viruses that cause disease in humans
What is the main structural difference between bacteria and viruses?
Bacteria are prokaryotic cells with circular DNA, while viruses are made of nucleic acid (DNA or RNA) enclosed in a protein coat
What is a prokaryotic cell?
A cell that lacks a nucleus and membrane-bound organelles; characteristic of bacteria
Why can’t viruses survive without a host?
Because they lack cellular machinery and rely entirely on the host’s cells to reproduce and carry out metabolic processes
Name some of the bacterial structures:
Cell membrane
Cell wall
Cytoplasm
Ribosomes
Plasmids
Flagella
Pili
Which is smaller, a virus or bacterium?
A virus is significantly smaller than a bacterium
What is Tuberculosis (TB)?
A bacterial disease caused by Myobacterium tuberculosis that infects lung phagocytes, often lying dormant in tubercles
Why are TB bacteria not destroyed during the initial infection?
Because they are sealed in tubercles with a thick waxy coat that protects them from the immune system
What are some symptoms of Active TB?
Breathing problems, coughing, weight loss, fever and possibly death
What causes cholera and how is it transmitted?
Cholera is caused by Vibrio Cholerae and is transmitted through contaminated food and water
What is the Cholera symptom mechanism?
A toxin binds to intestinal receptors, triggering water loss into the lumen by osmosis, leading to severe diarrhea
How is cholera treated?
With oral rehydration therapy
What is HIV?
A virus that causes AIDS by weakening the immune system over time
What are the initial symptoms of HIV?
Fever, tiredness and headaches
What is meant by HIV positive?
A person who has HIV antibodies in their blood
What is AIDS and how is it related to HIV?
AIDS is the advanced stage of HIV infection when the immune system becomes severely weakened
What is Smallpox?
A viral disease caused by Variola major leading to a rash and blistering
What is Infleunza?
A viral infection caused by the influenza virus, often leading to fever, fatigue and respiratory symptoms
What is Athlete’s Foot?
A fungal infection spread by direct contact with spores on skin or surfaces
How is malaria transmitted?
Through indirect transmission by a vector, specifically the female mosquito
What are antibiotics used for?
To kill bacteria or inhibit their growth, helping to fight infections
What are Bactericidal antibiotics?
Kill bacteria by destroying their cell wall, causing them to burst
What are Bacteriostatic antibiotics?
Inhibit bacterial growth by stopping the protein synthesis and nucleic acid production
How do penicillin work?
Blocks the formation of peptidoglycan cross-links in bacterial cell walls, preventing proper wall formation
How does antibiotic resistance develop in bacteria?
Through natural selection, resistant bacteria survive antibiotics, reproduce, and pass on the resistance allele
What is meant by the term antibiotic resistance?
When bacteria evolve the ability to survive antibiotics, often due to misuse or overuse of the drugs
What is MRSA?
A type of antibiotic-resistant bacterial infection often found in hospitals
What are some hospital strategies to control antibiotic-resistant infections?
Screening and isolating new patients
Using antibiotics only when necessary
Completing full antibiotic courses
Enforcing strict hygiene
How does HIV evade the immune system?
By constantly changing its protein coat, preventing recognition by immune cells
What is skin and how does it prevent infection?
A tough physical barrier made of keratin that prevents pathogen entry
How does stomach acid help protect the body from infection?
It contains hydrochloric acid which kills bacteria
What does Gut and Skin flora do in order to prevent pathogenic growth?
Natural bacteria that compete with pathogen for food and space, preventing their growth
What is the role of histamines during inflammation?
Cause vasodilation and increase blood vessel permeability, allowing immune cells and antibodies to reach the infected area
What is meant by inflammation?
A non-specific response where histamines cause increased blood flow and immune activity at the site of infection
What is a lysozyme?
An enzyme found in tears and mucus that destroys bacterial cell walls
What do interferons do in response to viral infections?
They prevent viruses from spreading by inhibiting protein synthesis in infected cells
What is meant by phagocytosis?
A process in which white blood cells engulf and destroy pathogens using lysosomes
What happens after a phagocyte engulfs and digests a pathogen?
It presents the pathogen’s antigens on its surface, becoming an antigen-presenting cell that activates the immune response
What makes the specific immune response different from the non-specific response?
It is antigen-specific and targets one type of pathogen only
What are lymphocytes?
White blood cells produced in the bone marrow that carry out the specific immune response
Where do B cells mature, and what are they involved in?
They mature in the bone marrow and are involved in the humoral response
Where do T cells mature and what are they involved in?
They mature in the thymus gland and are involved in the cell-mediated response
What are memory cells?
Long-lived cells that remember antigens and trigger a faster immune response upon re-exposure
What are B effector cells?
Specialised B cells that produce antibodies against pathogens
What are T helper cells?
Stimulate B cells and T killer cells to divide and respond to infection
What are T killer cells?
Attack and destroy infected cells displaying foreign antigens
Describe the Humoral response:
A B-cell is triggered when it encounters its matching antigen
The B-cell engulfs the antigen and digests it
Displays antigen fragments bound to its unique MHC molecules
This combination of antigen MHC attracts the help of a mature matching T-cell
Cytokines secreted by T-cell help the B-cell to multiply and mature into antibody producing plasma cells
What is the cell mediated response?
What is the difference between active and passive immunity?
Active immunity involves the production of antibodies by the immune system
Passive immunity involves receiving antibodies from another source
What is natural active immunity?
Immunity gained from exposure to an antigen or from getting the actual disease
What is natural passive immunity?
Immunity passed from mother to baby, either through the placenta or breast milk
What is active artificial immunity?
Gained through vaccinations which stimulate antibody production
What is passive artificial immunity?
Gained by injection of antibodies from an outside source
What is an antibody?
A globular protein produced by lymphocytes, specific to and complementary in shape to an antigen
What is neutralisation in the immune response?
When antibodies bind to antigens to block their effect, helping phagocytosis, agglutination or toxin neutralisation
What are antibodies made of?
Four polypeptide chains held together by disulfide bridges
What is the constant region of an antibody?
The part of the antibody that interacts with phagocytes to stimulate phagocytosis
What is the variable region of an antibody?
The part with a unique amino acid sequence that makes the antibody specific to one antigen
What is the Hinge region of an antibody?
Allows flexibility in the antibody’s structure so it can bind to multiple antigens
