Cell recognition and the immune system - Chapter 5 Flashcards
What is immunity?
The body’s ability to identify and protect itself against disease
What is the immune system ?
The system in the body responsible for maintaining homeostasis by recognising harmful from non-harmful organsims and produces an appropriate response
What are pathogens ?
Viruses, bacteria or other living things that cause disease/ immune system
Defence mechanisms
What are the two types of defence mechanisms?
Specific + non -specific
What is a non-specific defence mechanism?
Does not distinguish between one type of pathogen and another responds to all pathogens in the same way + quickly
What is a specific defence mechanism ?
It does distinguish between different pathogens long lasting immunity and slow response
What are the 2 forms of non-specific defence mechanisms ?
- Barriers to entry to the bloodstream
- Phagocytosis
What are the barriers to entry task (body) ?
- skin : many dead cells, protective layer for the majority of the body surfaces
- saliva : antibacterial enzymes
- tears : antibacterial enzyme: lysozyme. tear ducts : flushes out things in enzymes
- mucus : linings traps dirt + microbes , nasal hair …
- stomach acid : low pH kills harmful microbes. Contains hydrochloric acid, helps to kill any pathogens in food/water
When you get a cut, how does the body respond ?
By clotting the blood to prevent/ reduce the entry of pathogens
What does blood clotting involve (and the definition )?
Involves platelets found in the bloodstream.
Platelets: tiny, short-lived fragments of cells, with no nucleus, formed in the bone marrow + released in the blood
What does tissue damage result in ?
Inflammation
When tissue is damaged, what type of cells are activated , and what do they release ?
Mast cells are activated, releasing the chemicals histamine + cytokines
What does histamine do?
~> Causes capillaries to dilute
~> this increases blood supply (to infected area)
~> causes area to feel hot + red
The increased temperature reduces the ability of pathogens to reproduce.
Histamine also makes blood vessel walls more permeable.
~> allows more blood plasma to leave blood + form tissue fluid, causes tissues to swell
What do cytokines do ?
Attract phagocytes to the damaged tissue .
~> Phagocytes invade tissue
~> Phagocytosis
What is the flow chart of response?
Tissue damage ~> inflammation ~> phagocyte ~> phagocytosis ~> pathogen destroyed
What are the steps of inflammation?
Damaged cells ~> histone ~> capillaries dilate ~> increased blood supply
~> chemokines ~> Attract phagocytes ~> Phagocytes invade tissue
~> Phagocytosis
What are inflammation side effects
Red, when touch it (your skin), it is hot
Why does your skin turn red when inflamed?
Due to increased blood flow because of phagocytes.
Chemokines attract the phagocyte
What is phagocytosis ?
Is a form of endocytosis in which a phagocyte ( type of white blood cell) engulfs + digests a pathogen
Where are phagocyte produced ?
In the bone marrow
They are distributed around the body in the blood
What are phagocytes responsible for?
Responsible for removing dead cells + invasive microorganisms.
They carry out a non-specific immune system
What are the phagocytosis stages ?
- Phagocyte (neutrophils) detects chemicals released by pathogen and moves towards it (chemotaxis)
- [There are many receptor binding points on the surface of the phagocytes]
The phagocyte attaches to the antigen on the pathogen via these receptors - Phagocyte engulfs pathogen to form a vesicle ( a phagosome)
- Lysosomes move to phagosome and fuses with it (forms phagolysosome and release their contents into it. )
- The lysozyme in the lysosome destroysthe pathogen (by hydrolysis of their cell walls)
- The breakdown products are absorbed and used by the phagocyte
- After killing and digesting the pathogens, the phagocytes (neutrophils) die
- Pus is an accumulation of a sign of dead neutrophils
what is a non - specific response ?
Phagocytosis