The Lymphatic System & Immunity

4 Components that make up the lymphatic system

• lymph

• Lymphatic vessels

• lymphoid tissues and organs

• lymphocytes and other immune cells

lymphatic capillaries v. blood cappilaries

• more permeable

• closed at one end

• one way → into lymphatic system

Large lymphatic trunks empty into 2 large collecting vessels

• R lymphatic duct → empties to the R subclavian vein

• Thoracic duct → empties to the L subclavian vein

sepsis

When an infection gets into the bloodstream, causing it to spread

MALT

mucosa-associated lymphoid tissue

• A specialized immune tissue containing lymphocytes (B cells, T cells), macrophages, and other immune cells that actively respond to pathogens that breach the mucus layer.

• Gastrointestinal tract

• Respiratory tract

• Salivary glands

• Eyes

Lymph nodes

• filter fluid in your body (lymph) for harmful substances or cells.

• Immune cells in lymph nodes remove germs, damaged cells and cancer cells.

Thymus

• located in the mediastinum → above the heart

• T Cell Maturation

• secrets thymosins

• prevents autoimmune diseases

Spleen

• encased in fibrous capsule → inward expansion called trabeculae

• 2 regions

  • red pulp → RBS and macrophages

  • white pulp → rich in lymphocytes

immunity types

innate and adaptive

Innate immunity

• born with these defenses

• non specific

• 1st line defense

  • barriers

• 2nd line defense

  • phagocytes

  • inflammation

• Granulocytes

Adaptive immunity

• acquired

• developed throughout life (exposure) →specific

• 3rd line defense (Humoral Response)

  • lymphocytes (B and T cells)

  • antibodies

  • immunological memory

• Agranulocytes

pathogen v. antigen

antigen is anything foreign and a pathogen is anything that is foreign that causes disease

1st Line Defense

Barriers

• skin

• hair

• mucous

• stomach acid

2nd Line Defense

Phagocytotic Cells

• microphages → neutrophils, Eosinophils

• macrophages → come from monocytes

Neutrophils

• first on sight

• most abundant

• Contain granules filled with enzymes and proteins

• last a few hours to a few days

• produced in bone marrow

Eosinophils

• respond to parasites and allergic reactions

• secrete cytokines

• produced in bone marrow

• last days to weeks

Macrophages

• large, specialized immune cells derived from monocytes

• Engulf and digest pathogens, dead cells, and foreign particles.

  • scavengers

• Process and present antigens to T cells, linking innate and adaptive immunity.

• 2 types

  • fixed → brain and alveoli

  • free → blood stream

diapedisis

ability to squeeze through tight openings

Natural Killer Cells

• only lymphocyte in 2nd line defense

• less selective then B & T cells

  • can go after multiple things

• good at recognizing abnormal antigens

Lymphocytes

Cells that are responsible for antibody production, direct cell-mediated killing of virus-infected and tumor cells, and regulation of the immune response

• B cells

• T cells

• natural killer (NK) cell

NK cell killing steps

1. recognition and adherence to abnormal cell-presenting antigens

2. Realignment of golgi apparatus to faces abnormal cell

3. Secreation of perforin

4. lysis of abdnomal cell

Perforin

creates pores in cell membrane

Protectin

inactivated perforin if it rebounds towards the NK cell

interferons

a cytokine released by infected cells to warn neighboring cells to prepare defenses.

it will also call over NK cells

Complement system

a system of plasma proteins that can be activated directly by pathogens or indirectly by pathogen-bound antibody

• links 2nd and 3rd line

routes of complement activation

• the classical pathway

  • initiated by antibodies

• the lectin pathway

  • activated by pathogen-associated molecule

• the alternative pathway

  • activated by pathogen surfaces

inflammation symptoms

• Hot

• swollen

• painful

• red

• tender

signal that triggers inflamation - relased by mast cells

histamine

mast cells release

• histamine

• heparin

  • prevents hemostasis (blood clots)

fever temperature

37.2 C, 99F

pyrogens

signal to hypothalamus to increase body temperature

SEPSIS

• S: shiver

• E: extreme pain

• P: pale skin

• S: sleepy

• I: i feel like I might die

• S: short of breath

R naught

how many people on average can be infected

3rd line

• delayed → works togehter with 2nd line

• adaptive - unique to vertebrates

• common traits

  • specificity

  • versatility

  • memory

  • tolerance

epitope

protein portion of the antigen that sticks off and are binding sites for antibodies

Specificity

lymphocytes (B and T) have receptors on the surface, antigens must fit on the receptors

Versatility

Each B cell has different receptors for different antigens

Memory

both B and T are able to create memory

• lifelong

• shortens immune response if the same pathogen returns

Tolerance

have the ability to distinguish self from non-self

• Failure will lead to autoimmune disorders

B cells

Stay in the bone marrow until fully mature

• 10 - 15%

• Humoral response

  • produce plasma cells

    • make antibodies

  • produce memory B cells

• Antibodies are Y-shaped

• All receptors are the same on the same B cell

T cells

• migrate to the thymus to complete maturation

• Cell-mediated response

  • targets

    • virus-infected self-cells

    • cancerous cells

clonal selection

process where upon encountering a specific antigen, B cells that recognize it proliferate, forming clones of plasma cells and memory cells

Plasma cells

differentiated B cells that produce antibodies or immunoglobulins (Igs)

• can produce 2000 per second

Antibodies

tags that mark something for destruction

5 classes of antibodies

MADGE

IgM

pentomer

• recognizes the wrong blood type

IgA

Dimer

found in exocrine secretions

• sweat

• tears

• colostrum (premilk)

• semen

IgD

monomer

• found on B cells

IgG

• monomer

• most common

• very diverse

• go after viruses, bacteria, and toxins

• can cross the placenta

IgE

• monomer

• attach to mastcells and basophils

• induce inflamatory and allergy response by telling them to release histamine

oponsization

process where antibodies coat pathogens making them easily recognizable for phagocytosis

immunocompetence

The ability to demonstrate an immune response after exposure to an antigen

glucocorticoids

reduce inflamation

APC

Antigen presentation

• macrophages

• microglia

• dentritic cells

antigen presentation

When infected somatic cells or leukocytes present a piece of the antigen on their surface

MHC

Major histocompatibility complex

• extracellular glycoproteins that are identifies for the type of cell you are

• Human leukocyte antigens (HLC)

Class I MHC

• All nucleated cells

  • somatic cells

• leukocytes

Class II MHC

• APC

  • B Cells

  • Monocytes

  • dendrtic cells

• lymphocytes

macrophage

CD

cluster of differentiation

• determines whether a T Cell responds to antigens that are bound to MHC I or MHC II cells.

CD3

found on every T Cell

CD4

Call Helper T cells

• only respond to Class II MHC

• leukocytes

CD8

Cytotoxic T or Killer T

• only respond to class I MHC

  • infected somatic cells

Helper T Cell

Leader

• activates other immune cells and produces cytokines that stimulate B cells for antibody production and cytotoxic T cells for eliminating infected cells

Cytoxic T Cells

recognize a specific antigen on a pathogen and can kill it

Active immunity

• long lived

• vacination (artificial)

• getting sick (natural)

• memory cells

involves the body's own immune system producing antibodies after exposure to a pathogen or vaccine,

Passive immunity

• short lived

• receiving antibodies from an external source, like a mother to a fetus, or through an injection

• Natural

  • In utero/gestation → receives IgG

  • Breastfeeding → receives IgA

• Articial

  • monoclonal antibody → mimics the natural antibody of the body