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Flashcards in Immunity and Vaccination Deck (41)
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What are the physical and chemical barriers against disease in our bodies?

eyes - enzymes in tears

nose - nosal hair, mucus, sneezing refles

mouth - enzymes in saliva, coughing reflex

stomach - stomach acid, pepsin

vagina - acidic secretions

skin - waterproof, impermeable

respiratory system - mucus, ciliated epithelial cells


How does our immune system defend against disease?

platelets - blood clotting

white blood cells:

phagocytes - phagocytosis

lymphocytes - antibodies

lympochytes - antitoxins


What are platelets?

platelets are small cells in the blood, the function of which is blod clotting


How do platelets and blood clotting defend against disease?

When the skin is injured (e.g. through a cut), the most important thing is to seal the wound quickly, so the microbes cannot enter and blood loss is limited

Platelets are tiny cells in the blood which help close a wound. When a blood vessel is cut or broken, platelets stick together and activate the formation of a mesh made of a protein called fibrin

More platelets and red blood cells are trapped in this mesh. This leads to the formation of a clot/scab which seals the cut


Label this diagram of a phagocyte


Why is a lobed nucleus necessary in a phagocyte?

the lobed nucleus is necessary because cells need to change shape to squeeze through, e.g. ciliaped epithelial cells


How does phagocytosis defend against disease?

phagocytes can easily pass through blood vessel walls into the surrounding tissue and move towards pathogens

they engulf the pathogen

once the pathogen is engulfed they release enzymes to digest and destroy the pathogen


Phagocytes are specific/non-specific

Phagocytes are non-specific - they attack anything that's not meant to be there


What are antibodies?

antibodies are proteins that recognise and bind to antigens


What are antigens?

antigens are substances on the surface of a pathogen that can be recognised by an antibody


Different pathogens carry the same/different antigens (the same/different shape)

Different pathogens carry different antigens (different​ shape)


Different lymphocytes produce the same/different type of antibody which is specific/non-specific for a particular antigen (i.e. can bind to one/multiple types of antigen)

Different lymphocytes produce a different type of antibody which is specific for a particular antigen (i.e. can bind to only one types of antigen)


Explain lymphocyte and antibody action

when a lymphocyte meets a pathogen with an antigen that is recognised by its antibodies, it reproduces quickly and releases man ycopies of the antibody which bind to the pathogen

binding of antibodies to the antigens on the pathogen can directly destroy the pathogen or help phagocytes to engulf and digest pathogens more easily


What can bacteria (and some viruses) release?

bacteria (and some viruses) can release toxins that make us ill


What are antitoxins?

a chemical produced by a lymphocyte that can neutralise toxins


What is blood clotting?

the formation of a scab to prevent infection and blood loss


What are phagocytes?

a white blood cell that can engluf and digest pathogens


What is phagocytosis?

the process of engulfing and digesting pathogens


What are lymphocyte?

a white blood cell that can produce antibodies or antitoxins


What is a toxin?

a chemical produced by a pathogen which can make you ill


What happens during your first infection with a virus?

The person feels unwell

Lymphocytes are stimulated by the antigens on the surface of the virus and release antibodies

They also make memory cells which stay in the blood

Antibodies attach to the antigens - agglutination (microbes stick together so they can't reproduce)

The person recovers


What is agglutination?

microbes stick together so they can't reproduce


What happens during your second infection?

Memory cells, made by the lymphocytes in the first infection, can repridcue very quickly if the same antigen enters the body a second time

the memory cells are stimulated by the same antigens on the surface of the virus

Antibodies are released and attach to the antigens - agglutination

The person recovers


What do vaccines contain?

antigens of the pathogen


What can vaccines be?

parts of the pathogen

dead pathogens

similar but less infectious pathogen


What do vaccines trigger?

lymphocyte activation (antibody prdocution and memory cell formation)


How do vaccines work?

When you're infected with a new pathogen it can take your lymphocytes a while to produce the antibodies to deal with it. In that time you can get very ill, or maybe even die

To avoid this you can be vaccinated against some diseases, e.g. polio or measeles

Vaccination involved injecting dead or inactive pathogens into the body. These carry antigens, so even though they're harmless they still trigger an immune repsonse - your lymphocytes produce antibodies to attack them

Some of these lymphocytes will remain in the blood as memory cells so if live pathogens of the same type ever appear, the antibodies to kill them will be producd much faster and in greater numbers


What is the consequence of having too few platelets in the blood?

the blood would not clot; you would loose too much blood


Phagocytes ... antigens

Lymphocytes ... antibodies and antitoxins

Phagocytes engulf antigens

Lymphocytes produce antibodies and antitoxins


Describe the advantages to the human body by producing memory cells

antibodies produced faster

faster repsonse to the infection