lymphatic system

what are the functions of the lymphatic system

• fluid recovery

• lipid absorption

• immunity

how much plasma proteins and fluid is absorpbed

10-15%

Hydrostatic pressure

fluid wants to go out of blood

osmotic pressure 

fluid wants to come into blood 

• albumins gice this arteriole end

arteriole end

• high hydrostatic pressure (40 mmHg)

• low osmotic pressure (25 mmHg)

• fluid moves out

  • Net filtration

Venule end

• Low hydrostatic pressure (10 mmHg)

• High osmotic pressure (25 mmHg)

• fluid moves in

  • Net re-absorption

the amount that is filtered out is _____ than the amount that gets reabsorbed 

more 

• 10% is not reabsorbed 

Cuases of edema

• high capillary function

• low cappilary reabsorption (most common)

  • venus end

• onstructed lymphatic drained

Does lymph flow one or two ways, and where does it go?

one way towards the heart

Lymphatic capillaries features

• very permeable

• have mini valves

Interstitial fluid pressure > lyphatic fluid pressure

mini vales open the gate but lymph cant leak back out because increased pressure keeps gates closed

When tissues are inflammed lyphatic capilaries develop

openings where larger debris and paricles can enter

• cancer

Mechanisms of lymph flow

• lymph flows at a low pressure and speed

• rhythmic contraction of lymph vessels

• sjeletal muscles pump

• valve

what significantly increases lymphatic return

exercise

Lacteals

lymphatic capilaries in small intestines

• transport lipids

Primary lymphatic organs 

red bone marrow and thymus 

• site where T and B cells become immunocompetent 

Secondary lymphatic organs

• lymphnodes

• tonsils

• slpeen

• MALT

  • sontain immunocompetent cells

Lymph nodes

large clusters near body surface in inguinal, axillary, and cervical regions

2 basic functions of lymph nodes

• act as lymph filters with macrophages destroying microorganisms and debris

  • help activate immune system

Lymph node structure 

bean shape less than 2.5cm in length

Lymph enters conves side through ____ and exits through _____

• many afferent vessels

• 2 efferent vessels

this allows timr for lymphocytes to clense fluid

Tonsils

• simplest organ

• form ring of lymphatic tissue around entrance to pharynx

typeds of tonsils 

paired 

• palatine 

• lingual 

adenoids 

• pharyngeal 

other 

• tubal 

palatine tonsils

posterior end of oral cavity

• largest

  • most infected

pharangeal tonsils

at base of tounge

pharangeal tonsil

posterior wall of nasopharynx

tubal tonsils 

tiny, surrounded openings of auditory tubes into pharynx 

tonsil functions

gather and emove many pathogens entering pharanyx in food or inhaled air

• have dead end passages where pathogend get stuck

spleen

left side of body underneath diaphragm

• remove old and defective blood cells and platelets

• macrophages remove debrid and foreign mater

• store iron (rbs products)

• erythrocyte production in infants

thymus 

endocrine gland 

• secretes hormones that activate T cells 

• huge in fetus then atrophies 

• only lymphoid organ that doesn’t fight  pathogens 

innate immunity

non specific defenses

• broadly effective

  • no prior exposure

first line of defense

• skin

  • mucose membranes

second line of defense

• phagocytic cells

• antimicrobial proteind

• inflammation

  • fever

aquired immunity 

specific defense 

• result of prior exposure 

• protects only against a particular pathogen 

  • third line of defense (immune system) 

neutrophils

phagocytize bacteria

• degranulation

  • lysosomes cause resipratory burst

    • superoxide

    • hydrogen peroxide

eosinophils

target parasites (worms) and allergens

• superoxide, hydrogen peroxide, and neurotoxins

basophils

release histamine and heparin

monocytes

• form macrophages

circulation blood contains

• 80% T cells

• 15% B cells (make antibodies)

  • 5% NK cells (innate)

antimicrobial proteins 

• interferons → viruses 

• complement system → bacteria 

interferon

• protein chemical secreted by infected cells (no benefit for dying cellls)

• these chemical diffuse to neighboring cells and make them producr antiviral proteins → activate NK cells and macrophages

complement system

• 30 or more globulins

• in all fluids

• attach to bacteria

complement system pathways 

alternate 

• c3b runs into bacteria 

• nonspecific 

Claaical 

• antibodies help c3b find bacteria

• specific 

what does c3b do

froms holes in cell wall

inflammation

• limits the spread of pethaogens, the destroys them

• removes debris

• initiates tissue repair

cytokines 

small proteins that regulate and immunity induce:

• interferons 

• interlukins 

• tumor necrosis factor

• chemotactic factors 

inflammation

itis

• redness

• swelling

• heat

• pain

fever

• accelerate metabolic rate and tissue repair

• inhibit pathogen reproduction

• a cytokine, interuleukin -1 called pryrogen secreted by macrophages

NK cells 

destroy bacteria, transplanted cells, virus infected cells, and cancer cells  

how they kill 

• perforins: puncture holes in walls 

• granzymes: induce apoptosis 

antigen-presenting cells (activate T cells)

Class II CD4

• macrophages

Class I CD8

• dendric

• reticular

Specificity and memory

• cellular immunity

• humoral immunity

Cellular immunity

cekk mediates (CD-8) T cells

• directly attack and destroy

hummoral immunity

antibody mediates (B cells → make antibody)

• Tag for destruction

Memmory 

last for 10 years 

APCs

antigen-presenting cell

• macrophages

  • eat a pathogen and displays a piece of it (epitope) to a cytotoxic cell

Class I 

presents to CD8 (cytotoxic T cell) 

• get trained to only target a specific cell

• uses perforins and simulates apoptosis

CD4

helper T cell

Class II MCH meets CD4

• macrophage englufs and displays a pathogen

• this activates T helper cell (CD4)

• CD4 stimulates cytotoxic and B cells

• makes memmory 

B cell vs antibody 

B cell 

• doesn’t make antibodies 

Plasma cell 

• makes antibodies 

How long does it take to create anitbodies

• 10 -14 days 

• once developed the antibodies work within minutes 

What varies on all antibodies

the variable (V) regions

IgG (IgGy)

• attach to bacteria and viruses

• second antibody made

• most diverse group

• cross the placenta (passive immunity) 

IgM

• attach to bacteria and viruses

• first antibody made

• biggest 

IgE 

• allergies 

• stimulate histamine release 

IgD

• on the surface of B cells

IgA

• in secretions

Functions of antibodies

• neutralization: blocks binding sites

• agglutination: easy to eat

• soluble

• complent fixation

vaccines 

• gives adaptive immunity before you get the pathogen in public 

Immuniy can occur

naturally (get in public) or artifically (vaccines)

active immunity

A person’s immune system activates and makes the antibody

• permanent

Passive immunity 

• person receives the antibodies 

• breast feeding 

• vaccines 

primary response

• first exposure

• day 7: IgM>IgG

Second response

• 2nd exposure

• IgG is always > IgM