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NUR1114 > Week 6 Bioscience > Flashcards

Week 6 Bioscience Flashcards

1
Q
  1. Lymphatic System
A

Components
- lymphatic capillaries & vessels
- lymph nodes
- lymph Functions
- circulates body fluids
- removes foreign materials from body fluids
- transports WBC

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2
Q

Lymph

A

A white-milky protein containing fluid à excess interstitial fluid (ISF).

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3
Q

Lymphatic Capillaries

A

Are remarkably permeable.
* contain flaplike minivalves that permit the entry of interstitial fluid, WBC and foreign materials into lymphatic capillaries

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4
Q

Lymphatic Vessels

A

Carry lymph from peripheral tissues → back to the blood (venous circulation).
This circulation of lymph (excess interstitial fluid)
* regulates interstitial fluid volume
* maintains blood volume & blood pressure
* transports white blood cells & foreign materials to lymph nodes

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5
Q

Lymph Nodes

A
  • Located along lymphatic vessels
  • Trap foreign materials = “filter lymph”
  • Contain white blood cells that:
  • directly destroy foreign materials
  • activate an immune response to destroy foreign materials
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6
Q
  1. Lymphoid Organs and Tissues
A

Primary Lymphoid Organs
* Contain stem cells that differentiate into the various WBC of the lymphoid system, e.g., red bone marrow & thymus

Secondary Lymphoid Organs and Tissues
* Contain WBC
* Sites where foreign materials become trapped & destroyed or an immune response generated, e.g., lymph nodes, spleen, appendix & tonsils

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7
Q
  1. White Blood Cells (WBC)
A
  • Many different types:
  • neutrophils, macrophages, mast cells, basophils, eosinophils, lymphocytes (natural killer cells, T cells & B cells)
  • Found in blood, lymph, lymphoid organs and tissues
  • Protect the body from foreign materials
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8
Q
  1. Cytokines
A
  • Produced and secreted by WBC
  • Chemical messengers that recruit and/or activate WBC, e.g., interferons, IL-1 & IL-2
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9
Q

Immune Defences

A

The body is armed with two main immune defences:
* Innate (non-specific) defences
* Adaptive (specific) defences

These defences:
* involve the lymphoid system, the body’s surface barriers and protective proteins
* prevent foreign materials from entering the body
* attack and destroy foreign materials that do enter the body

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10
Q

Innate Defences

A
  • Present at birth
  • Provide immediate protection against any type of foreign material (non-specific)
  • Always work in the same way
  • Aim to prevent foreign materials from:
  • entering the body
  • spreading throughout the body
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11
Q

First Line of Defence = Surface Barriers

A
  • Prevent foreign materials from entering the body
  • Include physical and chemical barriers that function to:
  • form a formidable barrier
  • trap & remove foreign materials
  • expel foreign materials
  • destroy foreign materials
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12
Q

Physical Barriers

A
  • Intact skin & mucous membranes that line internal passageways
  • epithelial cells form a formidable barrier
  • Accessory structures
  • hairs (skin & nose) → trap foreign materials
  • cilia of the “mucociliary escalator” → move foreign materials from the respiratory tract towards the throat
  • Normal flora
  • colonise areas of the skin, upper respiratory tract and parts of the digestive, urinary & reproductive tracts
  • prevent pathogen colonisation by consuming essential nutrients & taking up space - pathogens unable to attach to body cells/tissues
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13
Q

Chemical Barriers

A
  • Sweat, saliva and tears
  • cleanse body surfaces & contain lysozyme → destroys bacteria
  • Sebum
  • acidic skin secretion → inhibits pathogen growth & toxic to some bacteria
  • Mucus
  • traps foreign materials in respiratory and digestive tracts
  • Gastric juice
    • hydrochloric acid & pepsin → destroy ingested foreign materials
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14
Q

Second Line of Defence = Internal Defences

A
  • Prevent foreign materials from spreading throughout the body
  • Involves:
  • macrophages & neutrophils
  • natural killer (NK) cells
  • interferons
  • complement
  • pyrogens
  • inflammatory response
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15
Q

Macrophages and Neutrophils

A

Phagocytose (ingest) and destroy all types of foreign materials via lysosomal enzymes.

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16
Q

Natural Killer (NK) Cells

A
  • Destroy virus-infected cells & cancerous cells
  • Recognise, adhere to and destroy target cells via the release of perforins and granzymes
  • perforins → create pores in the target cell membrane, allowing entry of granzymes
  • granzymes → induce apoptosis (program the cell to die)
17
Q

Interferons

A
  • A group of specific cytokines produced by white blood cells and virus-infected cells
  • Inhibit viral replication
  • Activate macrophages and NK cells to destroy virus-infected cells and cancerous cells
18
Q

Complement

A

A large group of proteins that:
* recruit macrophages and neutrophils to the site of enemy invasion
* enhance phagocytosis by opsonisation → coat foreign material making it easier for phagocytes to identify & more palatable “tasty”
* directly destroy cellular targets, (e.g., bacteria & mismatched RBC) by forming a membrane attack complex (MAC) = hole → cell lysis
* enhance an inflammatory response

19
Q

Inflammation

A

The inflammatory response aims to:
1. Localise and contain foreign material at an injury site
2. Dispose of foreign materials and cellular debris → this involves macrophages, neutrophils & complement
3. Repair the damaged tissue

20
Q

Fever

A

Pyrogens → a group of proteins that reset the body’s hypothalamic thermostat & increase body temperature
e.g. IL-1 interferons bacterial toxins

Mild or moderate fevers can be beneficial
→ inhibit the growth of some bacteria & viruses
→ ↑ cell metabolism - accelerates immune defences

21
Q

Summary - Innate defences

A

The body’s innate defences provide:
* immediate protection against any type of foreign material
* prevent the entry of foreign material into the body
* quickly contain and eliminate foreign materials that do enter

22
Q

Adaptive Defences

A
  • Are acquired - develop throughout life
  • Provide protection against a specific foreign invader
  • Are systemic → not restricted to the initial infection site
  • Remember invaders = “immunological memory”
23
Q

Antigens (Ag)

A

An antigen is a molecule capable of inducing an immune response (third line of defence), e.g.
* viral and bacterial proteins or polysaccharides
* bacterial toxins
* pollen, egg white, peanut lectin
* transplanted tissues/organs
* tumour cell proteins
* transfused blood cells

24
Q

T cells and B cells

A
  • Antigen Presenting Cells (APC = macrophages or dendritic cells) phagocytose and present antigens to T cells → activates T cells
  • Activated T cells → activate B cells
  • Activated T and B cells mount an immune response towards the antigen
25
Q

Immunocompetence

A

(i.e., the ability to recognise and bind one specific antigen)
* Each T & B lymphocyte displays a unique surface receptor that recognises and binds one specific antigen.
- T cells → membrane bound T cell receptor (TcR)
- B cells → membrane bound antibody receptor

26
Q

Self-tolerance

A

(i.e., the ability to recognise “self-antigens” from “non-self-antigens”)
* During their maturation T & B cells are educated to recognise self from non-self (foreign) antigens
- B cell maturation occurs in the bone marrow
- T cell maturation occurs in the thymus
* If T & B cells fail to recognise self-antigens and attack normal body cells/tissues → autoimmune disease

27
Q

Immunological Memory

A

(i.e., the ability to remember antigens)
The first time an antigen invades the body a primary immune response, which produces a population of memory T and B cells, is generated. Memory cells:
* “remember” antigens
* launch a faster, stronger counterattack called a secondary immune response

28
Q

An immune response involves two interconnected responses:

A
  • Cellular immune response
    → mediated by cytotoxic T cells
  • Humoral immune response → mediated by B cells
29
Q

Activated TC cells proliferate to produce many antigen-specific:

A

→ effector TC cells
→ memory TC cells

30
Q

A cellular and humoral immune response begins with the activation of a Helper T cell (TH).

A
  • TcR binds to a specific antigen presented by an APC → TH activated
  • Activated TH cell proliferates to produce many antigen-specific:
    → effector TH cells
    → memory TH cells
  • Effector TH cells secrete cytokines (e.g., IL-2) à helps activate cytotoxic T cells (Tc) and B cells and thus “turn on” a cellular and a humoral immune response
31
Q

Activated B cells proliferate & differentiate to produce many:

A
  • plasma cells → secrete Ag-specific antibodies
  • memory B cells
32
Q

Primary vs Secondary Immune Response

A

First antigen exposure produces a primary immune response
* A small, slow, short-lived response that doesn’t protect from illness
→ humoral response produces a small amount of antibody → IgM is produced first, then IgG
* Produces thousands of long-lived antigen-specific memory T and B cells

Subsequent antigen encounters produce a secondary immune response.
* Activated memory T and B cells rapidly produce a powerful, long-lasting response that protects from illness
→ humoral response produces a large amount of IgG antibody
* Effectiveness is one of the basic principals behind the development of vaccines

33
Q

Vaccines

A
  • Expose an individual to an antigen → inactive or attenuated (weak) antigen
  • Provide the first antigen encounter
    → activate a primary immune response & generate memory T and B cells
    → prime the body for a secondary immune response
34
Q

Disorders of immune function

A
  • Immunodeficiency diseases
  • Autoimmune diseases
  • Hypersensitivities
35
Q

Immunodeficiency diseases

A

Occur when the body’s immune defences are compromised or absent and unable to mount an effective immune response.
* Severe combined immunodeficiency (SCID) syndromes → no T & B cells
* Acquired immunodeficiency syndrome (AIDS)
→ Human Immunodeficiency Virus (HIV) primarily infects & destroys TH cells
→ No TH cells = no cellular or humoral immune response

36
Q

Autoimmune Diseases

A

Occur when the body’s immune defences target normal cells and tissues, e.g., Rheumatoid arthritis, Type I diabetes and Multiple sclerosis.
* self-reactive cytotoxic T cells destroy normal body cells
* self-reactive B cells differentiate into plasma cells that secrete self-reactive antibodies = autoantibodies

37
Q

Hypersensitivities (allergies)

A

Occurs when the body’s immune defences respond to a harmless antigen that is perceived as a threat.

Immediate Hypersensitivity
* Acute, rapid allergic reaction
* The antigen is called an allergen
* Mediated by allergen-specific IgE antibodies
- allergen binds to IgE on mast cells & basophils → triggers the release of histamine which:
* stimulates bronchoconstriction, mucus production & vasodilation
* increases blood vessel permeability

NUR1114 (17 decks)

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