Lymphatic System & Immunity

Week 1

What is a pathogen

Disease producing microbe (bacteria/virus)

What are lymphocytes

Agranular leukocytes involved in immune response (B/T cells)

What about macrophages n monocytes

Agranular leukocyte

What is different about monocytes | 2

• Monocytes performs phagocytosis in blood

• When it migrates to tissue becomes a macrophage

What is a virus

Non-living organism that infects cells n replicates

What is bacteria

Single cell living organism

What are cell-idenity markers

Membrane protein that allows cells to recognize self vs foreign

What is cytolysis

Destruction of cell caused by increased fluid in cell

What is apoptosis

Self destruction of cell

What is parenchyma

Functional tissue

What is stroma

Structural tissue

What is lymph

Interstitial fluid flowing in lymphatic vessels

What is lymphatic tissue

Connective tissue w/large quantity of lymphocytes

What dose the lymphatic system do | 3

• Drains excess interstitial fluid n returns to blood

• Transports dietary lipids n lipid soluble vitamins (ADEK) from GI tract

• Immune response

What about them lymphatic vessels | 3

• Similar to veins but w/thinner walls n more valves

• Vessels of skin follow same route as veins

• Vessels of viscera follow arteries n form plexuses around them

What about them lymphatic capillaries | 3

• Have end point

• Greater permeability than blood capillaries (absorb proteins n lipids)

• Have anchoring filaments

What are anchoring filaments

Secure lymphatic vessels to surrounding tissue (made of elastin fibres)

Explain the flow of interstitial fluid into lymphatic capilary | 4

• Pressure outside capillary

• Pushes door open n pulls on anchoring

• Pressure inside capillary

• Closes door

What are lacteals

Specialized lymphatic capillaries in small intestine that carry dietary lipids into lymphatic vessels

What are lymph trunks

Drain lymph from lymphatic vessels into venous system via lymphatic ducts

What does the right lymphatic duct drain

At junction of right internal jugular n right subclavian vein

What does the left lymphatic duct (thoracic duct) drain

At junction of left internal jugular n left subclavian vein

What is important to note about excess fluid | 3

• More fluid filters out of capillaries than gets reabsorbed

• 3L/day

• Can pick up plasma proteins

What is the respiratory “pump”

Inhaling n exhaling changes pressures within vessels while one way valves prevent backflow

What is the skeletal muscle “pump”

Muscle contractions compresses vessels n forces lymph towards heart

What are primary lymphatic organs

Sites where stem cells become immunocompetent

What does immunocompetent mean

Capable of mounting immune responses

What is included primary lymphatic organs | 2

Red bone marrow n thymus

What is the secondary lymphatic organs n tissues

Locations where immune responses actually occur

What is included in secondary lymphatic organs n tissues | 3

Lymph nodes, spleen n lymphatic nodules

What about that red bone marrow | 2

• Located in flat bones n epiphyses of long bones

• Immature stem cells become immunocompetent (b n pre-t cells)

What about pre-t cells

Migrate to thymus to become immunocompetent

What about the thymus | 4

• In mediastinum intermediate to sternum and aorta

• Each lobe contains outer cortex n inner medulla

• Pre-t cells proliferate in cortex n mature into t-cells

• Mature t-cells migrate to medulla then to bloodstream

What does proliferate mean

Divide n multiply

What do lymph nodes do | 2

• Filtering lymph

• Activating immune response

What about that lymph node | 3

• Has a dense connective tissue capsule

• Has trabeculae that divides node into compartments

• Has outer n inner cortex n medulla

What is trabeculae

Extensions off capsule (white stuff, allows time for filtration)

What does outer cortex contain in lymph nodes

Containing aggregates of b cells

What does aggregates mean

Clumps of something

What does inner cortex contain in lymph nodes

Mostly t cells

What does medulla contain in lymph nodes | 3

B cells, macrophages n antibody producing plasma cells

What does afferent lymphatic vessel mean

Lymph entering node

What dose efferent lymphatic vessel mean

Lymph exiting node carrying antibodies (created by b cells) and activated t cells

What about filtration in lymph nodes | 2

• Some pathogens destroyed by macrophages or lymphocytes

• Immune response occurs (activation of t-cells n memory b cells)

What does spleen do

Filter blood

What is spleen surrounded by

Dense connective tissue capsule w/trabeculae

What are the two types of parenchymal tissue

• White pulp - lymphatic tissue

• Red pulp - blood filled venous sinuses

What about that white pulp flow | 4

• Blood enters spleen via splenic artery

• Goes to white pulp

• B n t cells carry out immune response

• Macrophages also destroy blood-borne pathogens via phagocytosis

What about that red pulp flow | 3

• Blood diffuses into red pulp

• Removal of worn out RBCs n platelets

• Blood returns to circulation via splenic vein

What are the two other functions of the red pulp

• Storage of platelets (1/3)

• Production of blood cells in fetal life

What about lymphatic nodules aka follicles | 3

• Clumps of lymphatic tissue NOT surrounded by capsule

• Throughout mucosa (holes)

• Can be alone or in large aggregations

What are some examples of lymphatic nodules | 2

• Peyer’s patches - small intestine

• Tonsils - Pharyngeal (aka adenoid - posterior wall of the nasopharynx), Palatine (either side of the posterior oral cavity), Lingual (base of the tongue)

What innate immunity

Nonspecific defenses present at birth or develop overtime against ALL microbes

What is adaptive immunity

Specific recognition of specific microbe when breached innate immune defenses

What are the two first lines of defense in innate immunity

Skin n mucous membranes

What about the skin as first defense | 3

• Densely packed cells that push upwards (push microbes out)

• Mucous traps microbes in skin

• Mucosal tracts include hair/cilia that prevent access

What about the mucous membranes as first line of defense | 5

• Coughing/sneezing propel mucous w/pathogens out

• Swallowing mucous destroy pathogens by stomach acid

• Eyes produce tears w/enzymes to wash out pathogens (saliva also does this)

• Flow of urine cleans tract, vaginal secretions clean reproductive tract

• Defecation, vomit, sweat n skin oils also remove pathogens

What is second line of defense used

When pathogens breach first line of defense

What is included in second line of defense | 5

Antimicrobial substances, phagocytes, natural killer cells, inflammation n fever

What are the four main antimicrobial substances

Interferons, complement system, iron-binding proteins n antimicrobial proteins n peptides

What are interferons | 2

• Lymphocytes, macrophages n fibroblasts infected w/virus produce proteins called interferons (IFNs)

• Released n diffuse into uninfected cell where they aid in antiviral proteins that prevent viral replication

What is the complement system (cheerleaders) | 2

• Group of normally inactive proteins found in blood plasma n plasma membranes

• When activated, enhance immune responses (cytolysis, phagocytosis, inflammation)

What are iron-binding proteins

Binds to unbound iron n inhibits growth of certain bacteria as iron is required for bacterial growth

What are antimicrobial proteins n peptides | 2

• Range of antimicrobial activity

• Microbes exposed to AMPs usually don’t develop resistance compared to antibiotics

What are natural killer (NK) cells | 2

• Located in blood plasma, lymph nodes, red marrow n spleen

• Attack body cells that have abnormal plasma membrane proteins

What are the two ways NK cells remove body cells | 2

• Binds to target cell, releases toxic substances, makes holes in cell membrane, inflow of extracellular fluid — cytolysis

• Binds to target cell, releases toxic substances that induces apoptosis (does NOT kill microbes)

What are the two types of phagocytes

Neutrophils n macrophages

What is a wandering macrophage also known as

Monocyte that migrated to tissue

What do fixed macrophages do

Stand guard in specific tissues

What is the process of phagocytosis | 5

Chemotaxis, adherence, ingestion, digestion n killing

What happens in chemotaxis (flares)

Chemical stimulation of phagocyte to move to site of damage/foreign substance

What happens in adherence

Attached of phagocyte to foreign substance

What happens in ingestion (kirby)

Plasma membrane engulfs foreign substance n encloses it in a phagosome

What happens in digestion | 2

• Phagosome merges w/lysosomes in cytoplasm to form phagolysosome

• Enzymes are released within

What happens in killing

Enzymes break down what it can of foreign substance

What are residual bodies

Remains of broken down foreign substance

What causes inflammation

Tissue damage = fucking anything

What is inflammation tryna do | 3

Dispose of microbes at site of injury, prevent spread to other tissues n prepares site for tissue repair

What are the signs n symptoms of inflammation | 5

• P - pain - release of certain chemicals

• R - redness - increased blood flow to affected area

• I - immobility - loss of function

• S - swelling - accumulation of fluids

• H - heat - increased blood flow to affected area

What are the three stages of inflammation

• Vasodilation n increased blood vessel permeability

• Emigration of phagocytes from blood to interstitial fluid

• Tissue repair

What does acute mean

Rapid onset of symptoms, resolve in days or weeks

What does chronic mean

Slower onset, resolves in months or years (if ever)

What about them fever | 3

• Abnormal high body temp (>38C) occurs during infection/inflammation

• Intensifies effects of IFNs, inhibits growth of some microbes, speeds up body reactions that aid in repair

What is an antigen

Substance recognized as foreign n provokes immune response

What are the two main differences from adaptive immunity to innate immunity

Attack specific n remember how to beat the fucker after

What is clonal selection | 2

• Process when lymphocyte proliferates n differentiates in response to specific antigen

• Forms army of clones

What are the two main types of clones

Effector cells n memory cells

What are effector cells (active cells)

Actually destroy/inactivate the fucker/antigen

What are memory cells

Proliferate n differentiate into effector n memory cells in 2nd infection

What happens in cell-mediated adaptive immunity | 2

• Cytotoxic t cells attack invading antigens

• ONLY antigens in cells (intracellular)

What happens in antibody mediated immunity | 4

• B cells transform into plasma cells

• They create n secrete proteins aka antibodies (Abs) or immunoglobulins (Igs)

• Antigens OUTSIDE cell (extracellular)

• Antibody binds to n inactivates antigen

What do helper t cells do

Help w/both cell-mediated n antibody-mediated immunity

What is major histocompatibility complex (MHC) antigens | 2

• Transmembrane glycoprotein on surface of all cells EXCEPT rbcs

• Identifying markers so t cells can recognize self vs foreign

What is MCH-I

On plasma membrane of all body cells

What is MCH-II

Plasma membrane of antigen-presenting cells

What is an antigen-presenting cell (APCs)

Present the antigen to t cells to identify as foreign

What are cytokines | 2

• Small protein hormones that stimulate/inhibit normal cell functions

• Lymphocytes, apcs, etc secrete cytokines

What are four types of cytokines

Interleukin 1-6 (IL-1, IL-2), tumour necrosis factor (TNF), IFNs, macrophage migration inhibiting factor

What are autoantibodies

Antibodies that attack ourselves

What does co-morbities mean

Multiple/other medical problems