Disease Flashcards
what is a pathogen?
A microorganisms that causes disease
what are communicable and non-communicable diseases?
Communicable diseases - caused by a pathogen and can be spread from person to person
Non-communicable diseases - not caused by pathogens and are influenced by genetics or lifestyle choices
What are the types of pathogens and examples?
Bacteria - mycobacterium tuberculosis causes TB
Virus - HIV, AIDS, influenza
Protoctist - malaria
Fungi - Athletes foot
What factors affect spread of communicable disease?
Social factors - higher transmission in countries with less healthcare access
Living conditions - overcrowding increases spread
Climate - tropical countries have ideal conditions for mosquitos to breed
What are our body defenses to pathogen?
Expulsive reflexes - coughing and sneezing
Blood clots - blocks wounds
Mucus in trachea - trap pathogens
Skin acts as physical barrier
Stomach contains highly
what are plant physical defences?
Waxy cuticle - physical barrier
Cell wall - physical barrier
Plant deposits callose between cell wall and plasma memebrane
what are plant chemical defences?
Plants produce antibiotic compounds - prevent growth of bacteria
Plants produce insecticides - reduces risk of infection by virus
What are the stages of an immune response?
phagocytosis of pathogen
activation of T lymphocytes
activation of B lymphocytes
production of antibodies by plasma cells
What are phagocytes?
type of white blood cell which can destroy pathogens
types of phagocytes are:
macrophages, monocytes, neutrophils
How does a phagocyte engulf and present antigens?
Detect the presence of pathogen when receptors on its surface binds to antigen on pathogen
The phagocyte engulfs the pathogen
The pathogen is contained in a phagosome
Lysosomes digest and destroy the pathogen using digestive enzymes
Digested pathogen removed but the antigens are presented on their cell surface membrane
What are T lymphocytes?
white blood cless which contain receptors on their surface
Different T cells have different shaped receptors
What is clonal expansion?
A specific T cells binds to a complementary antigen
The T cell is activated - this is called clonal selection.
Once activated, T cell divides by mitosis to produce clones
what are T helper cells
release cytokines to activate B lymphocytes
What are T killers cells?
destroys any cells which have been infected with pathogen
What are T regulator cells?
Suppress other immune cells and prevent them from attacking host cells
What are T memory cells?
Found in bloodstream at low levels. If infection occurs again, they will divide into T helper, T killer and T regulator cells
what are B lymphocytes?
Activated by cytokines released by T helper cells
Also activated when antibody molecules on their surface bind to complementary antigen
have different shaped antibodies
only B cells with correct shaped antibodies will be activated
What happens when B cells are activated?
B cells divide by mitosis and differentiate into two kinds of cell:
Plasma cells - produce antibodies with complementary shape to antigen
memory cells - remain in blood stream and divides into plasma cells if there is an infection again
Describe the structure of an antibody
Quaternary structure made of 4 polypeptide chains - 2 heavy, 2 light
Chains are joined together by disulfide bridges
Variable region which contains antigen binding site - complementary to shape of antigen
Constant region contains binding site to allow antibody to bind to immune system cell
Hinge region - provides antibody flexibility
What is agglutination?
Antigens contain 2 binding sites so can bind to 2 pathogens at the same time
Pathogens become clustered together
Phagocytes can engulf more pathogens at the same time
How do antibodies neutralise toxins?
Pathogens release toxins to makes us feel ill
Antibodies can bind to toxins to neuralise the toxins
Antibody-toxin complex formed and destroyed by phagocyte
How do antibodies block access to human cells?
Pathogens enter host cells when their antigens bind to receptors on host cell
Antibodies bind to antigens to prevent antigen form binding to host cell receptors
what is primary immune response?
infected by a pathogen for the first time
composed of non-specific and specific-immune response
Slow as it tales time for correct B cell to undergo clonal selection and clonal expansion to produce complementary antibody
Infected person will experience symptoms while T and B cells prepare immune response
Memory cells are made
What is a secondary immune response?
Person is re-infected with same pathogen again
T and B memory cells recognise the antigen and start dividing
T memory cells divide into T killer cells to destroys cells affected by pathogens
B memory cells divide into plasma cells which release complementary antibodies to the antigen
what is active immunity?
Body makes its own antibodies after being stimulated by an antigen.
Natural or artificial
What is passive immunity?
body is given ready-made antibodies that have been produced by another organism
Natural or artificial
what is an autoimmune disease?
Persons immune system cant distinguish between self antigens from foreign antigens
Immune system attacks normal body cells
what are vaccines?
contain dead or weakened pathogens which are injected into the blood
stimulates a primary immune response and production of memory T cells and memory B cell
How do antibiotics work?
interfere with bacterial cell walls and ribosomes
killing the bacteria or stopping its growth
Viruses not affected
Human cells not affected
Explain antibiotic resistance
A random mutation occurs in a singular bacteria
Mutation causes bacteria to survive against antibiotic
These bacteria survive and divide to produce more bacteria containing the antibiotic-resistance gene
How to prevent development of antibiotic resistance?
Rotate use of different antibiotics
Taking the full course of antibiotics
Avoid overuse
What is the future of medicine?
Personalised medicine - certain people respond more effectively to some drugs
Synthetic biology - tech used to make artificial versions of cellular components in nature
