Y12 Immune System T1 Flashcards Preview

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Flashcards in Y12 Immune System T1 Deck (96):

What are communicable or infectious diseases? (transmissible diseases)

Diseases caused by foreign organisms invading the body and multiplying there


What is a pathogen?

A disease causing organism often referred to as a pathogenic organism


What does it mean if a disease is contagious?

If they are passed on by direct contact with a person suffering from a disease, or by contact with something touched by the person


What are vectors ( in relation to the spread of pathogens)?

An agent such as an insect capable of transferring a disease causing organism from one person to another


Infectious diseases are caused caused by invasion of pathogens in the form of?

Bacteria and viruses mainly but also fungi and animal parasites


Ways that transmission of pathogens can occur?

direct and indirect contact, transfer of body fluids, disease-specific vectors, contaminated food and water


What are bacteriophages?

Viruses which multiply in bacterial cells causing death to the bacterium


5 diseases caused by bacteria?

Dental caries (tooth decay),


5 diseases caused by viruses?

Bird flu,


A diseases caused by fungi?



Some diseases caused by animal parasites?

Malaria, roundworms, lice


How can diseases be transferred?

Transmission by touch
Transmission by bodily fluids
Waterborne transmission
Airborne transmission
Transmission of vectors


2 forms of transmission by contact?

(Touching an Infected person) or indirect (touching an object that has been touched by an infected individual)also known as finite transmission


How is disease spread by Transmission of bodily fluids?

through blood or other mucus membranes ( from nose, mouth, throat, genitals) eg. HIV, hepatitis b & c


How can spread of disease occur from Infection by droplets? Water Bourne.

droplets of moisture w/ pathogenic organisms are emitted when breathing, talking, sneezing or coughing eg. Influenza


How can disease be transferred via ingestion?

food or drink contaminated eg. Salmonella


How can airborne transmission cause spread of disease?

Airborne transmission- moisture in exhaled droplets carry viruses and some bacteria


How can disease be transferred by transmission by vectors?

transfer of pathogens by other animals such as insects, ticks or mites. Some transfer directly others ( house flys) via food and water.


Difference between specific defences and non specific?

Non specific- (first line) prevent entry, (second line) destroy pathogens if they enter

Specific-( third line) specialised lymphocytes target specific pathogens to destroy and remove from the body)


What is immunity?

Resistance to infection from invading microorganism


What is the immune system?

Different types of cells that occur in most organs of the body and that protect against foreign organisms, alien chemicals and abnormalities


What is an immune response?

A response triggered by foreign substances or microorganisms entering the body


What is a self antigen?

Any large molecule produced in a persons own body; does not cause an immune response in that person


What is a non self antigen?

Any compound foreign to the body that triggers an immune response


What are the physical characteristics of bacteria?

-Single cell, only seen with a microscope
- cell shape is used to classify into 4 catergories
(cocci- circular, bacilli- rods, spirilla - loose coils, vibrio (curved rods)


Modes of action for bacteria?

1. Releasing toxins which inhibit/ alter cell activity or poisons which alter metabolism, they may also cause allergic reactions
Endotoxins- released when bacteria die
Exotoxins- released by living bacteria


Physical characteristics of viruses?

Molecules of DNA or RNA wrapped in proteins


Mode of action for viruses?

DNA or RNA induces cell to manufacture more virus particles, attaching to the outside of a host cell allowing the nucleic acid to enter the cell, new virus genes are then produced by the host cells so hundreds of new virus particles are formed


Physical characteristics of fungi?

Multicellular, Eukaryotic


Mode of action for fungi?

Reproduce by spreading microscopic spores, spores often found in air and soil where they can be inhaled or come in contact with body surfaces


Physical characteristics of parasites?

Multicellular, ecto and endo


Mode of action for parasites?

Parasites cause infection by living and multiplying in another organism. This can cause fever, inflammation and other physical problems


Physical characteristics of prions?

Folded protein structure


Mode of action for prions?

Prions are a type of protein that can trigger normal proteins in the brain to fold abnormally


Diseases caused by prions?

Mad cow disease


Physical characteristics of Protozoa?

Moves independently, single cellular


Modes of action for Protozoa?

Produce toxin and multiply inside other cells


Examples of diseases caused by Protozoa?



What are some direct transmission types?

Touch, sexual,


What are some indirect transmission types

Faecal oral route ( cholera)


What kind of barriers are the first line of defence?

- physical + chemical barriers/ protective reflexes ( prevent entry into the body


What type of defences are the second line of defence

-fever, inflammation, roaming macrophages ( destroy and remove pathogens if enter)


What type of defences are the thrid line of defence?

- antibody and cell mediated defences ( specialised lymphocytes target specific pathogens to destroy and remove from the body)


What are some parts of the first line of defence?

Mucous, mucous membranes
Skin, sebum and sweat


What do lysozymes do?

They are found in eyes, sweat, saliva and secretions of the nose. They kill bacteria


What do cilia do?

Found in the tranchea and bronchi. They beat and line the walls moving mucous, trapping particles and microorganisms towards the throat to be coughed up or swallowed


What is acids role in the first line of defence?

- stomatch juries are strongly acidic. Killing many of the bacteria taken with food,
- the vagina also has acid secretions that reduce growth or microorganisms
- sweat on skin is also slightly acidic


What does skin, sweat and sebum do in the first line of defence?

Skin- covers outside of body, stops entry. + huge number of bacteria live on skin all the time.
Sebum- produced by oil glands in skin, contains substances that kill some pathogenic bacteria.
Sweat- contains salts and fatty acid which prevents the growth of many microorganisms


What are the 4 protective reflexes?

1. Sneezing
2. Coughing
3. Vomiting
4. Diarrhoea


What is cerumen and how does it contribute to the first line of defence?

Cerumen is earwax, it protects the outer ear against infection by some bacteria. It is slightly acidic and contains lysoszymes


What are protective reflexes?

Automatic, involuntary response to a stimulus that help to protect the body from injury or from opinfection


How is sneezing a protective reflex?

Dust particles and noxious fumes which are likely to carrying microorganisms cause irritation. Stimulus is irritation of the walls of the nasal cavity, response is a forceful expulsion of air from the lungs which carry mucus, foreign particles and irritating gases through the nose and mouth


How is a coughing a protective reflex?

Stimulus for coughing is irritation of respiratory tract (bronchi and bronchioles) resulting in air being forced from lungs to remove irritant.
- air drives mucus and foreign matter up the trachea towards the throat and mouth.


How is a vomiting a protective reflex?

Vomiting has a psychological stimuli. Excessive stretching of the stomach and bacterial toxins can induce vomiting, Which is the contraction of muscles of the abdomen and diaphragm in order to expel the stomach contents.


How is a diarrhoea a protective reflex?

Irritation of small and large intestines by bacteria, viruses or Protozoans can cause diarrhoea. The irritation causes increased concentrations of the muscles of the walls of the intestines so that the irritant can be removed as quickly as possible.
-Diarrhoea happens when material does not stay in large intestines long enough for water to be absorbed to the faeces are very watery


What are the functions of the lymphatic system and roaming macrophages?

1. Collect fluid lost by capillaries and returns it to the bloodstream
2. Absorb fatty acids and glycerol in the small intestines
3. Contains leukocytes which destroy and remove pathogens


Characteristics of lymph nodes?

- numerous in neck, armpit and groin
- bean shaped
- 1-25 mm diameters
- encapsulated in connective tissue
- contain macrophages


Characteristics of macrophages?

- large phagocytes
- roam in lymph targeting foreign bodies (non cell antigens)
- phagocytosis takes pathogen into the cell and digests


What is pyrexia?

A fever


Define pyrexia

Body temperature above the normal range ( 37°c) with no known cause ( exercise/ menstral cycle heat not regarded as fever)


What part of the brain controls body temperature?

The hypothalamus, above the pituitary gland, has a thermostat which controls body temperature


What are some things that happen to your body physically when you are too cold?

Goosebumps, conscious changes, vasoconstriction, shivering


What are some things that happen to your body physically when you are too hot?

Sweat, vasodilation, conscious changes


What happens during a fever?

1. Pathogens enter body or cancer cells, autoimmune disease, heatstroke develop or medications cause response

2. Pathogens are destroyed by leukocytes which then send a chemical message to the hypothalamus

3. Thermostat is reset higher, body activity heats up to reach new temp initially person feels cold ( shivering and vasoconstriction) when body reaches temp person feels hot ( sweating and vasodilation)

4. If pathogen removed thermostat resets to normal and body cools down

5. Of pathogen not removed, thermostat resets higher and process repeats itself


What happens if the thermostat gets too high?

Temperature around 41 is too hot body tissues and enzymes start to denature possibly causing convulsions and organ failure


What does increasing body temperature do?

1. Denature and inactive pathogens

2. Increase leukocyte activity meaning after destruction and phagocytosis of pathogens

3. Increases rates of repair of damaged tissues


What does the third line of defence do?

Guard against SPECIFIC types of antigens by initiating a response by specific leukocytes. B and T lymphocytes are programmed to recognise antigens on pathogens and are activated to initiate an immune response


Where do B and T lymphocytes originate

Bcells : originate and mature in bone marrow

Tcells: orgininate in bone marrow and mature in thymus gland


Where are b and T cells found

B: confined in lymph tissue

T: through tissues, organs, lymph


Mode of action for b and T cells?

B: chemical -> produce antibodies

T: cellular-> types of T cells with various roles


What cells are involved in antibody mediated response? ( humoral)

B plasma cell- produce antibodies
B memory cell


What cells are involved in cell mediated response?

Cytotoxic ( killer) T cells
Helper t cell
Suppressor t cell
Memory t cell


What is the target of antibody mediated response?

Extra cellular bacteria/ virus
Try to remove before cell in affected


What is the target of cell mediated response?

Intracellular phase of infections to destroy affected cell , cancer, foreign tissues ( eg. Transplants) and larger particles


Longevity of b she T cells

B: relatively short lived ( b plasma cells)

T: relatively long lived


In humoral response, how do SPECIFIC B cells know what antigens on pathogens to target?

There are receptors on the B cells


What happens in the humoral response when a B cell is activated?

Growth and proliferation ( cloning)


What group of proteins are antibodies a part of



What happens when antibodies meet with antigens?

- they inactivate the pathogen
- immobilise
- dissolve pathogen
- agglutination
- coat pathogen-> attract phagocytes
- neutralisation


Review diagram of lymphatic system

Review diagram of lymphatic system


What are the 7 stages of the inflammatory responses?

1. Damaged mast cells in connective tissue cause release of histamine and heparin
2. Histamine increases blood flow to site of injury. Vessel becomes leaky, bringing necessary components to site.
3.heparin prevents blood clot to immediate area. (Clot forms around actual damaged vessels to prevent spread of infection)
4. Mast cells initiate release chemicals which attract phagocytes (chemotaxis) causing phagocytosis of debris and invading pathogens
5. Abnormal conditions: pain
6. Phagocytes-> die ( filled with dead cell debris) becomes pus
7. Mitosis-> new cells repair damage


What are T cells

Lymphocytes that mature in the thymus gland containing receptors for specific antigens. They work against intracellular phase of infection to destroy affected cells, cancer cells and foreign tissue transplants.


Types of antigen presenting cells involved in cell mediated response?

Macrophages, B cells, helper T cells etc. come in contact with a specific T cell which is activated and then divides


What types of cells do T cells divide into?

Cytotoxic T cells, helper T cells, suppressor T cells and memory T cells


What do cytotoxic T cells do?

Killer T cells that secrete a chemical which dissolves the pathogen or cause it to burst (lose)


What do helper T cells do?

Release chemicals to sensitise and attract b and T cells. Chemicals released attract phagocytes which enhance the response


What do suppressor T cells do?

They release chemicals which reduce b and T cell activity. Reducing also excessive activity when antigen has been removed


What do memory T cells do?

Recognise antigen in further exposures; initiate secondary response


Difference between primary and secondary immune response?

The primary response is the response to the initial exposure to the antigen. It takes more time for antibodies to be developed because of this and there symptoms are worse.

The secondary response is the response to the second or any subsequent responses after the initial. It takes less time for antibodies to develop as the body already contains memory cells. Because of this the symptoms are often less severe or they are no symptoms


What are the four types of immunity + examples?

Natural passive: immediate, temporary immunity with no human intervention. When pathogens are passed from 1 person to another
( mother to foetus across placenta and amniotic fluid)

Natural active: takes time and is prolonged immunity with nohuman intervention. When Natural exposure to antigens occurs. ( chicken pox, flu virus)

Artificial passive:immediate, temporary immunity with human intervention. When antibodies are injected into the blood stream. ( serious illness where immediate action is required eg, tetanus, diphtheria or if someone has a poor immune system )

Artificial active:takes time and is prolonged immunity with human intervention. Occurs when antigen injected into the body initiates an immune response to produce antibodies. ( vaccines, eg. Measles, mumps) it is preventative


Define immunisation?

Programming the immune system so that the body can respond rapidly to infecting microorganisms


Define vaccination?

The introducing of antigens to a person so that they Aquire immunity without suffering from the illness


What is a vaccine?

An antigen preparation used in immunisation


What are the 4 types of vaccines + examples of each type?

- living attenuated microorganisms eg. Measles, mumps and rubella ( reduce ability to produce disease symptoms)

- dead microorganisms eg. Cholera, bubonic plague ( immunity not as prolonged as first type)

- toxoids eg. Diphtheria, tetanus. ( made from filaments of bacterial cultures containing toxins- toxins are inactivated)

- subunit eg. Human papilloma virus, hepatitis b. ( fragment of organism is used to provoke immune response )


What is herd immunity?

Type of group immunity that occurs when a high proportion of people in a population are immunised that those who are not immunised are protected


Antibiotics vs antivirals