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GMED2000 > Module 4- Immune dysfucntion and infection > Flashcards

Module 4- Immune dysfucntion and infection Flashcards

1
Q

What body system is responsible for specific immune responses

A

The lymphatic system

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2
Q

Describe the role of the thymus gland

A

Stores lymphoid cells. Thymic hormone, Thymosin are thought to aid in maturation of prothymocytes which develop into T lymphocytes

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3
Q

Describe the role of the spleen

A

Acts as a storage for blood and processes expired red blood cells and platelets

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4
Q

Describe the role of the tonsils

A

Accumulation of lymphoid tissue, intercepts foreign substances that enter through respiratory means

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5
Q

Describe the role of the lymph nodes

A

Filter lymph following through them – foreign substances are engulfed by macrophages or lymphocytes to activate an immune response

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6
Q

Describe the role of bone marrow

A

Produces and stores stem cells from which all components of blood are derived from

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7
Q

Describe the cells of the immune system -granulocytes

A

Include:
Neutrophils - found in circulation for phagocytosis

Basophils - found in circulation, respiratory tract and GI tract for phagocytosis, involved in allergic response

Oesinophils - found in circulation, for release of chemo-tactic substances

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8
Q

Describe the cells of the immune system - monocytes and macrophages

A

Found in circulation, tissues, liver (Kupffers cells), alveoli, spleen, tonsils, lymph nodes, bone marrow and brain
Trap and phagocytose foreign substances and cellular debris
Secrete interleukin-1 to stimulate lymphocyte growth

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9
Q

Describe the cells of the immune system - lymphocytes, T cells

A

Mature in the thymus
Found in circulation, lymph and tissue
For activation of T and B cells, control of viral infection and destruction of cancer cells, involved in hypersensitivity reactions.
Subsets include- Regulatory T cells, cytotoxic/killer T cells and Helper T cells

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10
Q

Describe the cells of the immune system -lymphocytes, B cells

A

Mature in bone marrow
Found in circulation and the spleen
Produce antibodies to specific antigens. Can differentiate into plasma cells or memory cells

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11
Q

Describe natural killer cells

A

Found in circualtion

Cytotoxic, killing of tumour cells, fungi, viral infected cells and foreign tissue

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12
Q

What two responses does the body have to resist disease

A

Both non-specific (innate immunity) and specific (adaptive immunity)

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13
Q

Describe the non-specific inflammatory response

A

Also called INNATE response
Generalised response to a foreign substance
Body does not need to recognise the foreign substance to be activated
Consists of 2 levels of protection:
First line defence physically stops foreign substance penetrating the skin e.g. skin
Second line of defence is the activation of cells and chemical processes which is activated by the foreign substance
When first line is breached INFLAMMATION occurs
It is called non-specific because the same event occur regardless of the cause of inflammation

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14
Q

Define inflammation

A

A response to injury that brings fluid, dissolved substances and blood cells into the interstitial fluid, it has 3 stages

  1. Vascular
  2. Cellular response and phagocytosis
  3. Healing phase
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15
Q

What is the purpose of exudate

A
  1. Provide protection to the injured tissue bringing certain nutrients needed for tissue healing
  2. Dilutes bacterial toxin
  3. Transports cells for phagocytosis
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16
Q

What is specific immune response

A

Also called adaptive immunity
Able to recognise and remember specific foreign substances
Is much slower to respond, however, is more powerful and targeted
Immunity is generalised, therefore, not restricted to the initial site of infection
Immune system recognises “non-self-cells” via an antigen
This immune response can be either Humoral or Cell-mediated

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17
Q

Describe humoral (anti-bdoy mediated) immune response

A

Produced by B-lymphocytes
B cells are activated by contact with an antigen and by T cells
Each B cell has a receptor for specific antigen or antigens
The antigen activates the B cell to proliferate and differentiate into plasma cells and memory cells
Plasma cells have a life of about 1 day but can produce thousands of antibody molecules per second
Memory cells retain antibody producing information, allowing a rapid response if the antigen is re-encountered
An antibody is an immunoglobulin (Ig) which are plasma glycoproteins and bind to and inactivate specific antigens
Antibodies fall into 5 classes: Ig, IgG, IgA, IgM, IgD and IgE

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18
Q

Describe cell-mediated immune response

A

Produced by T-cells which includes Regulatory and Cytotoxic/killer T-cells
T cells are antigen specific and each subset is activated by a particular antigen
Cytotoxic T cells bind with cell surface antigens on virus-infected or foreign cells and either destroy the cell or release cytotoxic substances into the cell
Regulatory T cells control the immune response by either recognising the antigen or supressing the proliferative steps that follow antigen recognition

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19
Q

What is active and acquired immunity

A

Occurs when the body produces antibodies or develops immune lymphocytes against specific antigens. Memory cells produce immediate response on re-exposure to the antigen
Can be natural (i.e. from chickenpox) or artificial (i.e. vaccines)

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20
Q

What are vaccines

A

Typically contains an agent that resembles a disease-causing microorganism (often made from weakened or killed forms of microbes, its toxins or one of its surface proteins)
Prepare body to fight disease without exposing it to disease symptoms
• There are 4 main types:
1. Attenuated (live virus vaccines) e.g. varicella (chicken pox), measles, mumps, rubella
2. Inactivated (killed vaccines) e.g. whooping cough (Pertussis)
3. Toxoid (contain toxin or chemical made by bacteria/virus) e.g. diphtheria and tetanus
4. Biosynthetic (manmade substances) e.g. Hep B

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21
Q

Describe passive immunity

A

Provides temporary protection against disease producing antigens
Can be natural (mother to infant via breast milk) or artificial (gamma globulin infection following hepatitis A exposure)

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22
Q

What are the four main cellular components of inflammation

A

Mast cells
Neutrophils and macrophages
Eosinophils
Platelets

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23
Q

Describe mast cells

A

The most important activator of inflammatory response – responsible for the release or synthesis of inflammatory mediators such as histamine and prostaglandin

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24
Q

Describe neutorphils and macrophages

A

Engulf and destroy microorganisms

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25
Q

Describe eosinophils

A

Produced by mast cells – they kill parasitic organisms and help regulate inflammatory response

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26
Q

Describe platelets

A

Interact with proteins of the clotting systems bleeding and release a number of mediators that promote and control inflammation

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27
Q

Describe inflammation and fever

A

Fever may result from either an infectious disease or inflammation
Normal body temp is 36.2-37.5
Temperature is regulated by the hypothalamus through peripheral thermoreceptors in the skin and central thermoreceptors in the hypothalamus, spinal cord and abdominal organs
The release of inflammatory cells during the inflammation process induce the synthesis of prostaglandins in the hypothalamus which then increases the level of the hypothalamic temperature

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28
Q

What are the benefits of fever

A

Raised body temperature kills many microorganisms affecting growth and replication
Decreases serum iron, zinc and copper which are needed for bacterial replication
Causes lysosomal breakdown and auto destruction of cells preventing viral replication
Facilitates immune response as lymphocytes transform into B cells and T cells and increase neutrophils
Increases phagocytosis and production of antiviral interferons

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29
Q

What are immunocompetent people

A

People who have an immune system that identifies antigens, destroys and then removes it

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30
Q

What are inappropriate immune responses

A
  1. Exaggerate against environmental antigens (known as an allergy or hypersensitivity)
  2. Directed against transplanted foreign tissue (such as organ transplant or blood transfusion)
  3. Misdirected against body’s own cell (known as autoimmune)
  4. Insufficient to protect the host (such as acquired immunodeficiency)
31
Q

What are hypersensitivity reactions

A

Is an exaggerated immune response that results in harm to the individual

32
Q

What is an allergy

A

The hypersensitive reaction caused by an environmental antigen called an allergen
Reactions can be immediate or delayed

33
Q

What are the different ways allergens can be exposed to people

A

Direct contact: direct consumption or exposure to the skin
Cross-contact: exposure through processing and handling
Inhalation: dust or aerosols i.e. peanut flour or peanut oil cooking spray

34
Q

How do allergies work

A

Requires initial exposure to specific antigen (may only be a mild response)
Sensitisation to antigen and trigger of immune response occurs following re-exposure (can be mild or very severe)
Main causes are dairy, eggs, peanuts, tree nuts, insect stings and medications
Peanut allergies often occur following re-exposure

35
Q

What are the common signs and symptoms of allergies

A 
Hay fever (allergic rhinitis)
Runny nose
Postnasal drip
Eczema 
Itchy, red, swelling skin including hives and rashes
Swelling of lips and tongue
Difficulty breathing 
Wheezing
Stridor
Asthma
Shortness of breath
Diarrhoea
Stomach cramps
Nausea and vomiting
36
Q

What are the four types of allergy reactions

A

Type one: IGE-mediated hypersensitivity reaction
Type two: tissue-specific hypersensitivity reaction
Type three: immune complex-mediated hypersensitivity reaction
Type four: cell-mediated hypersensitivity reaction

37
Q

Describe type one IGE-mediated hypersensitivity reaction

A

Occurs after the antigen reacts with the IgE (antibodies) bound to mast cells
Leads to mast cell degranulation and the release of histamine and other inflammatory responses into extracellular space
These travel to different body parts binding and then activating H1 and H2 receptors
H1 causes pruritis (need to scratch), rhinorrhoea (increases amount of mucus fluid in nasal cavity- runny nose), tachycardia, bronchospasm (constriction in walls of bronchioles causing breathing difficulties)
H2 causes headache, flushing and hypotension

38
Q

Describe type two tissue-specific hypersensitivty reaction

A

Reactions against specific cells or tissue and caused by 4 possible mechanisms:

  1. Complement-mediate lysis
  2. Opsonisation and phagocytosis
  3. Antibody-depleted cell mediated cytotoxicity
  4. Modulation of cellular function (i.e. Graves’ disease)
39
Q

Describe type 3 immune complex-mediated hypersensitivity reaction

A

Caused by formulation of immune complexes that are deposited in target tissues and destroy healthy tissue

40
Q

Describe cell-mediated hypersensitivity reaction

A

Caused by specifically sensitised T cells, which either kill target cells directly or cause tissue destruction

41
Q

Are the different types of hypersensitivity reactions immediate or delayed

A

Type 1, 2 and 3 are immediate responses

Type 4 is a delayed response

42
Q

What is anaphylaxis

A

Occurs when person comes in to contact with allergen their body is sensitised to
Can be life-threatening (peanut allergies are most common food allergy cause) – requires immediate treatment via EpiPen (adrenaline)
Has genetic predisposition

43
Q

What inflammatory mediators are present during anaphylaxis

A

Histamine (main mediator) – vasodilation, vascular permeability
Leukotrienes – muscle contraction
Prostaglandins- vascular permeability, smooth muscle contraction
Bradykinin- vasodilator
Platelet Activating Factor (PAF)- activates platelets to release histamine and increases vascular permeability

44
Q

What can massive vasodilation during anaphylaxis cause

A

Low BP which can result in loss of consciousness, younger children may also go pale, decreased vital organ profusion and tachycardia

45
Q

How is anaphylaxis treated

A

DR CALL ABC:

  • Support airway, breathing, circulation
  • Resuscitation

Adrenaline reverses symptoms by acting on Beta- and Alpha-Adrenergic receptors (relaxes smooth muscle (bronchodilation) and increases cardiac output (contraction and HR)), achieved via EpiPen - rapid onset (5 mins S/C, 1 min inhalation), action lasts 4 hrs

Oxygen – high flow

Anti-inflammatory agents such as anti-histamines and corticosteroids

46
Q

Describe antihistamines

A 
Example: Benadryl
Works against cutaneous effects (skin) and can help antagonise respiratory and cardiac effects 
Histamine H1 receptor antagonist 
Takes 15-30 minutes to act (oral dose) 
Duration of action: 4-6 hrs
Available in tablet and liquid form
47
Q

Describe corticosteroids

A

Example: Prednisolene
Powerful anti-inflammatory effects
Influences biochemical behaviour of most tissues through protein synthesis
Absorbed from the GI tract and converted in liver to active metabolites
Takes 30-60minutes to act, peaks at 1-2 hours (oral)
Often prescribed 3 days following an allergic reaction

48
Q

How can transplantation initiate an immune response

A

Can result in organ rejections which can be hyper acute (immediate), acute (between days to months), chronic (months to years)

49
Q

How can different blood groups initiate an immune reaction

A

Occurs when individuals are transfused with non-compatible blood groups
Refers to blood (ABO) and Rhesus (Rh) groups

50
Q

Describe different blood groups

A

A & B are different antigens on the surface of red blood cells. The A antigen means blood group A, the B antigen means blood group B
O blood group have no antigens, therefore, considered universal donors
AB blood group have both sets of antigens and can receive blood from all blood groups (universal recipient)

51
Q

What are Rhesus groups

A

Rh is a group of antigens (the most important being the D antigen) on the RBC only
The present of the D antigen means the individual is Rh positive and can receive both positive and negative blood

52
Q

What are auto immune diseases

A

Autoimmunity is when self-recognition is impaired and immune defenses destroy normal host tissue
Can affect any tissue or organ in the body
Exact cause is unknown
Common example is SLE (Systemic Lupus Erythematosus) which may produce Type 2 or Type 3 hypersensitivity reaction
Also includes Type 1 diabetes, multiple sclerosis, arthritis, celiac disease

53
Q

What is immunodeficiency

A

Occurs when the immune system or inflammatory response fails to function normally
Primary are congenital which disrupts lymphocyte development and are characterised by the recurrent presence of infection
Acquired immune deficiencies are the complications of other physiological conditions

Examples: AIDS, cancers such as leukemia, viral hepatitis, can be seen in people with down syndrome

54
Q

What is infection by a pathogen influenced by

A

Mechanism of action- causes cell dysfunction
Infectivity- ability to invade and multiple
Pathogenicity- ability to produce disease
Virulence- potency of pathogen
Immunogenicity- ability to produce an immune response
Toxigenicity- pathogens that produce soluble toxins or endotoxin, determines the virulency of pathogen

55
Q

What are bacteria

A

Are prokaryocytes (no nucleus) and are small
Can be anaerobic or aerobic
Can be motile or non-motile
3 main shapes: spherical (cocci), rod-shape (bacilli) and spiral (spirochete)
Can be gram + or gram –
May survive by producing toxins

56
Q

What are exotoxins

A

Proteins released by bacterial growth that can damage cell membrane and inhibit protein synthesis. Vaccines are available for many exotoxins

57
Q

What are endotoxins

A

Are in the walls of the gram- negative bacteria and are released during destruction of bacteria which activates an inflammatory response

58
Q

What are viruses

A

Simple – consist of nucleic acid protected by layer of protein called capsid
Genetic information in form of RNA or DNA
Cannot survive long outside a host cell
Virus binds to a receptor on the plasma membrane of a host cell and then changes the activity of the host cell and viral replication occurs
Some viruses have a latent period in which time the host cell is transformed

59
Q

What are fungi

A

Large microorganism that are either single celled called yeast or multi-celled called moulds
Yeasts are facultative anaerobes (produce ATP using aerobic respiration if available)
Moulds are aerobic
Diseases caused by fungi are mycoses, which can be superficial, deep or opportunistic
Deep fungal infections involving internal organs can be life threatening

60
Q

What are parasites

A

Originally from animal kingdom and can infect and cause disease in other animals
Protozoa, helminths and arthropods are parasites
Protozoa is single celled and can be passed directly or indirectly
Helminths are wormlike parasites- gain entry through ingestion or penetration through skin & mucous membranes
Arthropod (scabies, lice) infest external body surfaces causing localised tissue damage and inflammation

61
Q

Describe antibiotics

A

Can be gram specific or broad spectrum

62
Q

What is antibiotic resistance

A

Occurs when bacteria develop the ability to defeat drugs designed to kill them
Bacteria survive and continue to multiply

63
Q

What factors lead to antibiotics resistance

A

Overuse of antibiotics
Patients not finishing antibiotic course
Poor infection control in health settings (including hygiene and sanitisation)
Using antibiotics to treat viral infections like influenzas
Using when not prescribed

64
Q

Describe penicillins

A

Antibiotic - example: amoxicillin

Usually oral dosage

65
Q

Describe antivirals

A

Relatively new to market and need to be selective in differentiating between normal cell activity and viral activity

Example: Neuraminidase inhibitors e.g. zanamivir (inhaled)

66
Q

Describe antifungals

A

Topical and systemic

Example: fluconazole (APO-Fluconazole One)

67
Q

Describe anti-parasitic medication

A

Viral depending on organism

Example: mebendazole (Combantrin-1) - chocolate squares

68
Q

List examples of NSAIDs

A 
Used to treat pain and inflammation
Aspirin 
Ibuprofen
Naproxen
Celecoxib (Celebrex) 
Diclofenac (Voltaren)
69
Q

Define colonisation

A

When bacteria grow on body sites (i.e. skin, mouth, intestines, airways) without causing an infection. Usually does not harm patient and does not need antibiotic treatment

70
Q

Define bacteraemia

A

Presence of bacteria in the blood (usually no symptoms) but can accumulate in tissues or organs and cause serious infections

71
Q

Define septicemia

A 
Blood poisoning (serious blood infection) caused by bacteria or their toxins 
Bacteria move from elsewhere in body to the blood where they can then be transported around entire body
72
Q

Define sepsis

A

(also known as bacteraemia or septicaemia)
Chemicals usually released in response to microorganisms in the blood or other tissues, are out of balance leading to a response that further damages its own tissues and organs (can lead to death)

73
Q

Aging and the immune system

A

Reduced function of B and T cells
Diminished function of mature lymphocytes
Causes immune system to weaken - more susceptible to disease or infection

74
Q

What is the complement system

A

Part of the immune system
Enhances the action of antibodies and phagocytes to clear microbes and damaged cells from an organism, promotes inflammation and assist in phagocytosis

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