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M101 > W11 The immune system > Flashcards

W11 The immune system Flashcards

inc lec: the lymphatic system and the immune system Innate immune system and adaptive immune system- antigen recognition

1
Q

What are Immunogens?

A

They trigger the body’s immune response.

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2
Q

What is the definition of immunity?

A

Ability to resist damage from pathogens, toxins and internal threats

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3
Q

What does the immune system consist of?

A
  • Lymphoid tissues / Lymphatic System
  • Immune cells
  • Chemicals that coordinate and carry out immune functions
  • “self ” from “non-self” - a targeted response
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4
Q

What are the functions of the immune system?
What are the 2 types of response?

A
  • Recognize and remove abnormal “self ” cells
  • Removes dead or damaged cells
  • Protects the body from disease-causing invaders
  • Bacteria, viruses, fungi, protozoans (one cell), parasites
  • Pollens, chemicals, and foreign bodies
  • Immunogens: trigger the body’s immune response
  • Nonspecific Innate Immunity and Specific Acquired Immunity (adaptive)
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5
Q

What is the lymphatic system?

A
  • System of vessels / cells / organs that carries excess fluids to the bloodstream and
    filters pathogens from the blood
  • drain body fluids and return them to the bloodstream
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6
Q

What is lymph?

A

Interstitial fluid (fluid that fills spaces between cells) once it has entered the lymphatic system

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6
Q

What is lymph?

A

Interstitial fluid (fluid that fills spaces between cells) once it has entered the lymphatic system

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7
Q

What are the functions of the lymphatic system?

A
  • Fluid Balance
    -Lipid Absorption
  • Defence against pathogens
  • Pathogen
  • Substance or microorganism that causes disease or damage to the tissues of the body
  • use humans as a source of nutrients and as an environment to survive in
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8
Q

Lymphatic System and Drainage

A
  • Tonsils, the lymph nodes, the spleen, the thymus
  • Lymph nodes -located along lymphatic vessels
  • Groups in the cervical (neck), axillary (armpit), and inguinal (groin) areas
  • Lymph: Carries fluid from tissues to circulatory system
  • Vessels begin as open-ended capillaries,
  • Feed into larger lymphatic vessels
  • Empty into the bloodstream by ducts. –
  • Lymph travels through the lymph nodes
  • Doesn’t circulate ie not pumped by heart
  • Forced through the vessels by contraction of skeletal muscles -

Valves, (one way semi lunar valves)
* one-way flow of lymph

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9
Q

Lymphatic System: Capillaries

A
  • Where fluid enters the lymphatic system
  • In virtually all tissues
  • between arterioles and venules
  • Thinner walls than veins
  • Overlapping epithelial ‘flaps’
  • fluid moves into capillaries only
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10
Q

Lymphatic System: small intestine

A
  • Lymphatic capillaries called
    lacteals
  • Lipids and some lipid soluble
    proteins and vitamins form milky
    fluid = chyle
  • Enter lacteals
  • Enter blood stream
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11
Q

Lymphatics Circulation

A
  • Lymphatic capillaries—- Vessels—-Trunks— 2 ducts

Drainage
* Right: Right lymphatic duct drains into right subclavian vein
* right sides of the head, thorax, and right arm
* Left: Thoracic duct drains into the left subclavian vein
* remaining portions of the body

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12
Q

What are the Lymphatic Organs?

A
  • Tissue: Many lymphocytes / defence cells
  • Lymphocytes: Red bone marrow
  • Tonsils
  • Palatine tonsils
  • Pharyngeal tonsils (adenoids when enlarged)
  • Lingual tonsil
  • Protective ring of lymphatic tissue around the nasal and oral cavities and the pharynx
  • Pathogens
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13
Q

Where do you find red bone marrow cells?

A

Skull
Spongy bone at the end of compact bone

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14
Q

Lymph node

A
  • Distributed along the lymphatic vessels
  • Lymph passes through before entering blood
  • Superficial or deep
  • Superficial aggregations
  • (1) inguinal nodes in the groin, (2) the axillary nodes in the axilla (armpit), and (3) the cervical nodes in the neck.
  • Dense capsule with extensions: trabeculae
  • lymphatic tissue: Lymphocytes and lymphatic nodules
  • lymphatic sinuses: macrophages- phagocytosis (engulfing bacteria)
  • Lymph flows through nodes
  • Activates – stimulating
    lymphocytes to divide
  • Nodules: germinal centres
  • Remove pathogens: macrophages
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15
Q

What is the function of the spleen?
What are the components of it?

A

Filters blood- Respond to foreign substances, destroy old RBC

White pulp
* Composed mainly of lymphocytes
* Lymphatic tissue surrounding arteries
* Lymphocytes can be stimulated to divide

Red pulp
*Associated with extensive blood vessels and venous sinuses
* Surrounding veins
* Macrophages and red blood cells
* Macrophages remove foreign substances and worn-out red blood cells through phagocytosis
* Also functions as a blood reservoir

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16
Q

What is the thymus?

A
  • 2 lobed gland
  • Divided into lobules
  • Cortex (dark)
  • Many lymphocytes
  • Medulla (light)
  • Fewer lymphocytes
  • Maturing T-cells
  • Mature T-cells migrate to medulla, enter blood and travel to other lymphatic tissue
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17
Q

What is chyle?

A

Lipids and some lipid soluble proteins and vitamins form a milky fluid

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18
Q

Which of the lymphoid nodes us most likely to see food antigens first?
Tonsils
Bronchus-associated lymphoid tissue
Axilla
GALT

A

= Tonsils

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19
Q

How is blood returned from the lymphatic system?

A

Skeletal muscles contract and washes lymphatic vessels

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20
Q

Cells of the Immune System (6)

A
  • Leukocytes: white blood cells (WBCs): Key cells for immune response
  • Circulate in the blood but leave and function extra vascular
    (1) eosinophils
    (2) Basophils (blood); related mast cells (tissues)
    (3) neutrophils
    (4) monocytes and macrophages
    (5) lymphocytes and plasma cells
    (6) dendritic cells
    (not often found in blood)
  • Classified: morphologically and functionally
  • Phagocytes
  • Cytotoxic cells
  • APCs
  • display fragments of foreign proteins on their cell surface
  • formed in the bone marrow and
    released into the circulation* (See Prof Mohankumar’s lectures)
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21
Q

How do Basophils and Mast cells contribute to the immune response?
Where are they found?

A

They Release mediators that contribute to inflammation
* Histamine, heparin (anticoag) and other cytokines
* Allergic and immune response

Basophils- circulation
Mast cells (tissue): lungs, GI tract, skin

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22
Q

How do Eosinophils contribute to the immune response?

A
  • Allergic reactions and parasitic diseases
  • Digestive tract, lungs, urinary and genital epithelia, and connective
    tissue of the skin
  • Cytotoxic: release substances from their granules that directly
    damage or kill the parasites
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23
Q

What are Neutrophils?
What is their function?

A
  • Phagocytic cells
  • most abundant WBC
  • segmented nucleus
  • Most remain in the blood but can leave if attracted to an
    extravascular site of damage or infection
  • Kill / ingest bacteria
  • release a variety of cytokines
  • including fever-causing pyrogens
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24
Q

What are Monocytes and Macrophages

A
  • Monocytes precursors of tissue macrophages
  • Once in the tissues, monocytes enlarge and differentiate into
    phagocytic macrophages
  • Key scavengers within tissues
  • Antigen Presenting Cell (APC)
  • Antigens: Immunogens that react with B and T lymphocytes
  • APCs can insert fragments of processed antigen into its membrane -
    becomes part of surface protein complexes
  • they can bind to and activate other types of immune cells.
25
Q

What is the function of Lymphocytes
What are the 3 subtypes?

A
  • Key cells that mediate the acquired immune
    response of the body
  • Most in lymphoid tissue

3 subtypes:
* B Lymphocytes (APCs)
* T lymphocytes
* Natural Killer cells

26
Q

What are dendritic cells? What is their function
Where are they found?

A
  • Long processes
  • Antigen-presenting cells
  • Found in skin (Langerhans cells)
  • Other organs
  • Once capture antigens migrate to lymph nodes
  • Present antigens to lymphocytes which activates lymphocytes
27
Q

Phagocytosis and antigen presentation:
What are they key cells that phagocytose?
What cells present antigens?
How does phagocytosis occur?

A

Macrophages and Neutrophils key cells that phagocytose
* Some B lymphocytes and dendritic cells also present antigen

  • Some pathogens bind directly to phagocyte receptors / others precoated by antibodies
  • Stimulates internalisation
  • Digests pathogen
  • Part of it (antigen) presented on surface
27
Q

Phagocytosis and antigen presentation

A

Macrophages and Neutrophils key cells that phagocytose
* Some B lymphocytes and dendritic cells also present antigen
* Some pathogens bind directly to phagocyte receptors / others precoated by antibodies
* Stimulates internalisation
* Digests pathogen
* Part of it (antigen) presented on surface

28
Q

Which cells are phagocytic?

A

Macrophages

29
Q

Which cells degranulate and release chemical mediators?

Lymphocytes
Macrophages
Mast cells

A

Mast cells

30
Q

What is Innate immunity?

A

Response to pathogens same each time the body is exposed

31
Q

What is Adaptive immunity?
(adaptive immune response)
Characteristics?

A
  • Response to pathogens improves each time the pathogen is encountered.
  • Characteristics: Specificity and memory
32
Q

What is Adaptive immunity

A
  • Response to pathogens improves each time the pathogen is encountered.
  • Characteristics: Specificity and memory
    Specificity- Recognise a particular substance eg. specific virus or bacteria
    Memory- “remembers” previous encounters with a particular substance.
  • Future responses are faster, stronger, and longer-lasting
33
Q

What are the 2 systems of immunity?

A
  1. innate immunity / nonspecific resistance
  2. adaptive immunity / specific immunity
34
Q

A person is said to be immune if..

A

If the pathogen is destroyed before any symptoms develop

35
Q

Innate immunity is..
It consists of..
What does it enhance?

A
  • Rapid and non specific
    Consists of:
  • Physical Barriers
  • Chemical Mediators
  • Leukocytes (WBC)
  • Inflammatory Response
  • Enhances adaptive immune response
36
Q

What are physical barriers?

A
  • Skin* Epidermal Keratinized cells
  • Sweat and secretions – lower pH
  • Mouth / oral cavity* Salivary glands – lysozyme
  • Stomach/GI tract* Low pH
  • Mucosal epithelia* GI tract
  • Respiratory tract
  • Ears
  • Nose- Traps and removes
  • Tears, saliva, and urine wash these substances from body surfaces
    Pathogens cannot cause a disease if they cannot get into the body
37
Q

What do Chemical Mediators do?

A

They promote the immune response.
* Complement
* > 20 Proteins in plasma
* Normally inactive
* Once activated - series of reactions - each complement protein activates the next.
* Contribute to adaptive and innate systems
* Innate: “alternate pathway” of complement activation
* Bind to the cell membrane of the pathogen labelling it for phagocytosis (opsonization)
* Act as chemotactic agents to attract phagocytic cells to the site of inflammation
* Form damaging pores in the plasma membrane of the pathogen
* Cells swell and lyse (rupture)

38
Q

Give examples of the main chemical mediators:

A

Cytokines
Interferons (IFNs)

39
Q

What are cytokines?

A
  • Small signalling molecules released from cells to trigger immune response
  • Egs Interleukins + chemokines + interferons
40
Q

What are Interferons (IFNs)?

A
  • Viruses:
  • Induce cells to produce viral nucleic acids and proteins
  • Cells infected with viruses secrete interferons
  • Travel to adjacent cells and induce them to make antiviral proteins
  • Prevents production of new viral nucleic acids and proteins
  • Inhibit viral reproduction in these surrounding cells
  • Some IFNs also activate other immune cells (macrophages and NK cells)
41
Q

What are some other chemical mediators?

A
  • Histamine
  • Prostaglandins
  • Leukotrienes

Variously
* vasodilation,
* increasing vascular permeability
* stimulating phagocytosis
* Promote inflammation

42
Q

Innate Immunity: White Blood cells
Where are WBC produced?

A

Produced in red bone marrow / lymphatic tissue.
* Chemicals released from pathogens or damaged tissues attract WBC
* Leave blood and enter tissue
* Phagocytic cells
* Neutrophils normally first
* Release signals that increase inflammatory response
* Recruits and activates other immune cells
* Pus- dead neutrophils
* Macrophages (monocytes that leave blood)
* Larger - later stages of an infection
* cleaning up dead neutrophils and other cellular debris

43
Q

Why should you not hold urine for long periods?

A

Urination flushes out bacteria

44
Q

Inflammatory cells

A
  • Basophils* Mobile cells
  • Mast cells* Non mobile cells in connective tissue
  • Eosinophils* Allergic response
  • When activated: release histamine and leukotrienes*  Inflammatory response

Natural Killer cells
* NK cells recognize classes of cells, eg tumour cells / virus-infected cells
* Kill their target cells* releasing chemicals that damage cell membranes  causes the cells to lyse

45
Q

Inflammatory response; What is vasodilation and what hormones are involved?

A
46
Q

What does histamine increase?

A

Vascular permeability, so increases the blood supply to the area.
* Leakage of fluid into tissue - swelling /oedema
* Allows complement to enter tissue
* Enhances inflammatory response / attracts more phagocytes
* Clotting factors enter (fibringogen- fibrin) –
* Wall off/ first step in wound repair

(Boosts blood flow and H1 receptors)
histamine is a chemical organic compound that your immune system releases

47
Q

Which cells are responsible for much of the phagocytosis at an EARLY stage of an infection?

A

Neutrophils

48
Q

What do Mast cells do?

A

They are non mobile cells that sit on connective tissue
They detect a pathogen, then degranulate

49
Q

Which are the 2 main phagocytic cells?

A

Neutrophils and Macrophages

50
Q

Which cells are responsible for much of the phagocytosis at a LATER stage of an infection?

A

Macrophages

51
Q

Which cells are the most important in the release of histamine which promotes inflammation?

A

Mast cells

52
Q

Which of the following signs is not a characteristic of inflammation?

A

Redness
Pain
Cold
Swelling

53
Q

Antigen Presenting Cells have which class of MHC molecule?

A

MHC Class ll

54
Q

Antigens are…

A

Foreign substances introduced into the body
Molecules produced by the body
Stimulate an adaptive immune response

55
Q

The secondary antibody response
a. Is slower than the primary
b. Produces fewer antibodies
c. Is quicker to produce antibodies

A

C= Is quicker to produce antibodies

56
Q

What are the functions of Cytoxic T cells ? (2)

A

Release cytokines:
* Attract innate immune cells
* Macrophages
* Phagocytosis of antigen/cell
* Inflammatory response
* Activate additional cytotoxic T cells

Directly kill virus infected
cells:
* Viral antigens on surface
* T cells bind to the antigens on the surfaces and cause the cells to lyse or under go apoptosis

57
Q

Allergic response

A

*Immune response to a non-pathogenic antigen
*Allergen is an antigen that is typically not harmful to the body
*Sensitive individuals : inappropriate immune
response
* Sensitivity / hypersensitivity to the antigen
*Immediate hypersensitivity reactions are
mediated by antibodies
Sensitisation and Re-exposure Phase
*Sensitization phase
* equivalent to the primary immune response

58
Q

Aging Immune system

A

*Little effect on the lymphatic system
* remove fluid from tissues,
* absorb lipids from the digestive tract
* remove defective red blood cells
*Severe impact on the immune system
* thymus replaced with adipose tissue
* lose the ability to produce mature T cells
* May lose functionality
* Antigen exposure leads to fewer helper t cells
* Less stimulation of B and cytotoxic T cells
*Antibody and cell mediated responses decrease
*Primary and secondary antibody responses decrease

M101 (41 decks)

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