Pack 11 - Immune Response Flashcards
(42 cards)
Antigens
Molecules found on the surface of all cells
What does an antigen do when a pathogen invades the body?
The antigens on its cell surface are recognised as foreign or non-self by white blood cells
Innate immunity
- Involves non-specific defence mechanisms that happen in the same way, regardless of the antigens present on the pathogen
- It happens quickly
What are the 4 main innate immune response?
- Lysozyme Action
- Inflammation
- Antimicrobial proteins
- Phagocytosis
2 physical barriers to infection:
- Skin
- Mucous infection
How does the skin deal with infection
- Human skin keeps most pathogens out as long as it remains intact
- Any cuts can allow pathogens to enter the body
How do mucous membranes deal with infection
- Microscopic hairs called cilia line the respiratory system and ‘beat’ in unison to move mucus containing trapped pathogens towards the nose and mouth, where they can be expelled by coughing and sneezing, or swallowed into the stomach where acid destroys them
Roles of sebum in the skin:
- The function of sebum is to moisten and prevent the skin from becoming too dry
- Sebum also has antibacterial properties and is the body’s first defence against infection
- The sebaceous glands that make sebum are on just about every surface of the body
5 chemical barriers to infection
- Lysozyme
- Acid
- Anti bacterial proteins in semen
- Sebum
- Histamine
How do lysosomes deal with infection?
- Lysozyme degrades the polysaccharide that is found in bacterial cell walls by a process called hydrolysis
- A water molecule is added across the glycosidic bond
- This causes the bacteria to absorb water, swell and burst
How does acid deal with infecion?
The acid in sweat, vaginal secretions and in the stomach creates a low pH which kills pathogens and there are also anti-bacterial proteins in semen
How does anti-bacterial proteins in semen deal with infection?
These proteins kill bacteria
How does sebum deal with bacteria?
Sebum prevents bacterial invasion and infection
How does histamine deal with infection?
Histamine triggers inflammation response
3 biological defences to infection:
- Gut flora
- Phagocytes
- Other white blood cells
How does gut flora deal with infection?
- These non-pathogenic, ‘friendly’ bacteria compete with pathogens for space and nutrients, so reduce resources available for pathogens to multiply and cause disease
- Pathogens cannot grow.
How do phagocytes deal with infection?
- Phagocytes are white blood cells (e.g. neutrophils or macrophages) which engulf and digest pathogens
How do other white blood cells deal with infection?
These respond against invading pathogens
Adaptive immune system
Is a specific response to the specific antigens on the pathogen which has entered the body
How is the innate immune system activated?
By exposure to pathogens, and uses an immunological memory to learn about the threat and enhance the immune response accordingly
The humoral immune response role:
To destroy pathogens in body fluids e.g. blood, to try to stop pathogens entering cells
The humoral immune response process:
- Macrophage engulfs a pathogen, digests it and displays its antigens on its surface
- T helper cell is activated, it divides/multiplies and produces cytokines needed to activate B cells
- T memory cells are created
- B effector cell is activated, it divides/multiplies. The B effector cells then differentiate into plasma cells which produce antibodies
- B memory cells are created
- Antibodies bind to antigens on pathogen and cause agglutination (clumping)
- Phagocytes then engulf pathogens
The cell mediated immune response role:
To destroy infected cells
The cell mediated immune response process:
- T killer cell is activated, it divides/multiplies producing many T killer cells
- T memory cells are created
- T killer cells produce chemicals which create pores in the cell membrane of infected
cells, destroying them and releasing the pathogens so that phagocytes can engulf them
