Lymphatic and Immune SystemNatalie Sanchez, Elizabeth Garcia, Briana Pelayo

● The lymphatic system is a component of the immune system and the cardiovascular system

● Structures of the lymphatic system extend throughout the whole body but exceptions include the central nervous system

● Some major structures in the lymphatic system are the lymphatic capillaries, lymphatic vessels, lymphatic trunks and ducts, lymph nodes, thymus, spleen, and tonsils.

About the Lymphatic System

Lymphatic System

● Main functions of the lymphatic system iso Drainage of fluid, that surrounds tissues and organs and returns it to

bloodo The lymphatic system also helps with the development of immune

cells so it helps the body attack pathogens and protects from diseaseso Excessive amounts of fatty acids and fat molecules in the circulatory

system is absorbed by lymphatic system accumulated in the form of chyle (happens in the small intestine)

Functions of the Lymphatic System

Location●Parallel to networks of blood capillaries●Also found in the small intestine

Function●Drainage of any lymph that has not been absorbed into bloodstream

Special lymphatic capillaries●in the small intestine●absorbs fats and transports them to the venous circulation

Lymphatic Capillaries

Location●Located all over body exceptions are central nervous system, bone marrow, teeth, and avascular tissue

3 Layers1.endothelial lining2.smooth muscle and elastic fiber3.connective tissue

Function●helps prevent the backflow of lymph

Lymphatic Vessels

Location●located all over the body

Function●Trunks drain into ducts which bring lymph back into blood by emptying into the respected veins

About●Lymphatic trunks named after regions where they get lymph from●Major Lymphatic Trunks

o lumbaro bronchomediastinalo subclaviano jugular o intestinal

Lymphatic Trunks

About●Two ducts

o Right lymphatic ducto Thoracic duct

●The intestinal and lumbar trunks merge to the thoracic duct●Lymph empties into venous circulation at junctions of jugular vein and subclavian vein

Lymphatic Ducts

Overall Function●functions differ by where they are located●filters harmful particles before lymph reaches the bloodstream

Location●along large lymphatic vessels, major lymph nodes are:

o cervical region: which is located in the deep necko axillary region: located in underarm receives lymph from upper limbso supratrochlear region: located on the side of the elbowo inguinal region: located in the lower limbso pelvic cavity: located within the pelvic cavity lymph from pelvic viscerao abdominal cavity: located within abdominal cavity lymph from abdominal viscerao thoracic cavity: located along the trachea and bronchi lymph from thoracic viscera

Lymph Nodes

Location●upper part of the sternumFunction●maturation of T lymphocytes

Thymus

Location●left portion of abdominal cavity3 Functions1.stores products of RBC degradation2.Erythrocyte production in fetus3.Stores thrombocytes About●largest organ in the lymphatic system●Structure includes:

o fibrous capsuleo trabeculaeo Red pulpo white pulp

Spleen

Location●Found in the pharynxFunction●Helps fight infections but if you have them removed it will not cause infections.

Tonsils

● Interstitial fluid● filtration from the plasma leads to the formation which increases the

hydrostatic pressure● capillary blood pressure purifies water and other molecules from plasma● plasma colloid osmotic pressure helps draw fluid back into the capillaries● fluid returns to its venules● the rest enter the lymph capillaries as lymph● fluid contains nutrients, gases, & hormones

Tissue Fluid Formation

● formed from the movement of tissue fluid

● clear, colorless fluid● contains white blood cells● returns proteins from & excess

fluid to the bloodstream ● transports bacteria and fats

Lymph Formation & Function

● only flows in one direction slowly toward the neck within the lymphatic system

● flows into the venous bloodstream ● enters lymphatic system through the lymphatic capillaries

o flaplike valves created o tissue fluid enters capillaries through the valves

● valves prevent it from flowing backwards● through lymph vessels to lymph nodes● through the subclavian veins where it empties ● flow because of:

o contracting skeletal muscles in limbso contraction of smooth muscleso pressure changes in breathing

Lymph Flow

Lymph Flow

lymphatic capillary

lymphatic vessel

lymph node

lymphatic vessel

lymphatic trunk

subclavian vein

lymph ducts

Lymph Flow (cont.)

Non-Specific Cells

Mechanical Barriers

●Skin (first line of defense)-epidermis is compacted with cells containing keratin-protects against infection and water-not penetrated by pathogens ●Mucous membranes-tears(lacrimal apparatus) wash out eye to dilute microbial growth -saliva dilutes microbes in the oral cavity-mucous prevents drying, trapping foreign items -nasal hairs trap particles in the respiratory tract, fluids exert out-respiratory cilia sweeps mucous out

Chemical Protection - reduce bacterial growth●Skin -perspiration has fatty acids, salts (NaCl), and acid pH-sebum forms oily layer●Lysozyme-enzyme breaks down bacterial cell walls●Hyaluronic Acid -gel like matrix in most connective tissues-slows down speed of infectious diseases●Gastric Juice-hydrochloric acid of stomach is a barrier to the intestine

Non-Specific Cells

● Vaginal Secretions- lactic acid provides defense- mildly acidic pH value

Phagocytes (second line of defense)● Macrophages- wander through tissues of microbes and cellular debris ● Neutrophils - become phagocytic when encountering infectious disease● Eosinophils- deploy destructive granules against parasitic worms

Non-Specific Cells

Natural Killer Cells●small population of lymphocytes ●defend against various viruses and cancer cells ●secretes “cell-cutting” substances called perforins●perforins lyse cell membrane, destroying infected cell●secrete chemicals that enhance inflammation

Non-Specific Cells

● body’s defense against foreign items

● can be caused by antibodies attacking normal tissues that are mistaken for antigens

● immune substances build up in the tissues

● result is inflammation of the skin, injury to the tissues and pain

Inflammation

● result from hypersensitivity to weak antigens

● allergens include dust, pollen, mold, etc

● mast cells can release histamine causing the inflammation process

● histamine release can cause anaphylaxis

Allergies

1. Antigens- may be proteins, polysaccharides, glycoproteins, or glycolipids1. Lymphocytes- creates antibodies to fight against bacteriaa. T Cells- T refers to thymus- derived lymphocytes- some are abundant in the lymph nodes, thoracic duct- secrete cytokines- constitute 70-80% of circulating lymphocytes in blood

Specific Cells

Specific Cells (cont.)

1. Helper T Cells● stimulates B cell to create antibodies● CD4- type of helper t cell that is the

prime target of HIV● releases cytotoxic t cells2. Cytotoxic T Cells ● kills cancer cells and infected cells● becomes activated when it combines

with an antigen that fits its receptors

3. Memory T Cells●kills pathogen before it causes the body to show signs and symptoms ●can reproduce a faster and stronger immune response

●B Cells1.constitute 20-30% of circulating lymphocytes2.B cell receptor allows it to bind to a specific antigen

●Monocytes1.helps break down bacteria 2.largest leukocytes3.change into macrophages

Specific Cells (cont.)

- collecting and distributing oxygen, nutrients, and hormones to tissues- blood flows through a continuous circuit- blood is pumped through the arteries and carried to rest of the body - blood is visible, damage to vessels is obvious due to bruising and bleeding

Cardiovascular vs. Lymphatic System ❖ collects and removes waste left behindin

tissues❖ flows through an open circuit from

tissues into lymphatic vessels❖ does not pump. flows passively to lymph

capillaries❖ invisible, damage is hard to detect until

swelling

Similarities

●both circulate fluids●work to keep the body systems healthy and supplied with nutrients●provide immune function●lymphatic system is a well known part of the cardiovascular system

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