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
- TB, Bacterial Meningitis
Virus
- HIV, AIDS, influenza
Protoctista
- Malaria
Fungi
- Athletes foot, Ringworm
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 is direct transmission?
Pathogens transferred directly between organisms
Can be transferred by:
- Direct Contact
- Airborne Droplets
What is indirect transmission?
Diseases transferred between organisms using an intermediate
Can be transferred by:
- Food and drink contamination
- Vectors
- Contaminated objects
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
inflammation
what are plant physical defences?
Waxy cuticle - physical barrier
Cell wall - physical barrier
Plant deposits callose between cell wall and plasma membrane
what are plant chemical defences?
Insect repellents
Insecticides
Antibacterial substances
Toxins
What are phagocytes?
type of white blood cell which can destroy pathogens
types of phagocytes are:
macrophages - present pathogens antigens
neutrophils
Explain the process of phagocytosis
Phagocyte recognizes that pathogen’s antigens are foreign. Phagocyte binds to pathogen
phagocyte engulfs the pathogen
Pathogen is contained in a phagosome
Lysosome, contains hydrolytic enzymes, fuses with the phagosome to form phagolysosome
Lysosome digests and destroys pathogen
Phagocyte presents pathogens antigens on surface
What are cytokines and opsonins?
Cytokines - chemicals released by phagocytes to trigger the movement of phagocyte to site of infection
Opsonins - chemicals that bind to pathogens so they can be identified by phagocytes
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, B cell divides by mitosis to produce clones
what are T helper cells
Release interleukins to activate B lymphocytes and phagocytes
can form memory cells or T killer cells
What are T killers cells?
Kills foreign cells by producing protein called perforin
What are T regulator cells?
Suppress the immune system after pathogens have been destroyed
Prevents immune system attacking body cells
What are T memory cells?
Provide long term immunity against specific pathogens
Provides rapid response if body is reinfected by same pathogen
What are the stages of cellular response?
Macrophages engulf pathogens and display their antigens on the cell surface
T helper cells with complementary receptors bind to the antigens
T helper cells are activated and divide by mitosis to form identical clones
Cloned T cells can:
Develop into memory cells
Develop into T killer cells
Stimulate phagocytosis
Stimulate division of B cells
what are B lymphocytes?
Have antibodies on cell surface that bind to complementary antigens
They engulf antigens and display them on surface
B cells divide into plasma cells and memory cells
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 - Provides rapid response if body is reinfected by same pathogen
Describe the structure of an antibody
Quaternary structure made of 4 polypeptide chains - 2 heavy, 2 light - held together by disulfide bridges
Constant region - same for all antibodies, bind to receptors on cells
Variable region - different for each antibody, complementary to specific antigen
Hinge region - flexible, can bind to multiple antigens at once
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
