The Lymphatic SystemThe Lymphatic System

The Function of the Lymphatic The Function of the Lymphatic SystemSystem

The lymphatic system is The lymphatic system is designed to fend off designed to fend off pathogenic organisms. It pathogenic organisms. It also removes excess also removes excess fluids in between cells fluids in between cells and brings it back to the and brings it back to the blood stream.blood stream.

Lymph is also responsible Lymph is also responsible for the absorption of fats for the absorption of fats in the small intestines.in the small intestines.

Lymphatic pathwaysLymphatic pathways

Patterns of vessels that transport lymph. Patterns of vessels that transport lymph. This allows the transport and relocation of This allows the transport and relocation of various components like T-cells and various components like T-cells and lymph. lymph.

Lymphatic capillariesLymphatic capillaries

Microscopic tubes Microscopic tubes that extend that extend interstitially (between interstitially (between cells) and parallel to cells) and parallel to the circulatory the circulatory system.system.

The fluids inside The fluids inside these vessels is these vessels is called lymph.called lymph.

Lymphatic vesselsLymphatic vessels

Lymph from the lymphatic capillaries is Lymph from the lymphatic capillaries is carried into the lymphatic vessels. These carried into the lymphatic vessels. These vessels have flaps on them just like in the vessels have flaps on them just like in the veins of the circulatory system to prevent veins of the circulatory system to prevent lymph from flowing backwards. lymph from flowing backwards.

Lymph nodes and Lymphatic trunksLymph nodes and Lymphatic trunks

The larger bundles of The larger bundles of lymphatic tissue are lymphatic tissue are referred to as lymph referred to as lymph nodes. nodes.

Lymph nodes then Lymph nodes then dump their lymph into dump their lymph into even larger bundles even larger bundles called lymphatic called lymphatic trunks.trunks.

Lymphatic trunksLymphatic trunks

Lymphatic trunks are aptly named for the Lymphatic trunks are aptly named for the regions in which they serve. All trunks regions in which they serve. All trunks dump into one of two specialized collecting dump into one of two specialized collecting ducts.ducts.

Collecting ductsCollecting ducts Thoracic ductThoracic duct Right lymphatic ductRight lymphatic duct

Thoracic and right lymphatic ductThoracic and right lymphatic duct

Thoracic duct- Larger Thoracic duct- Larger and longer of the two and longer of the two ducts. Gathers lymph ducts. Gathers lymph from the lower limbs, from the lower limbs, abdominal region, left abdominal region, left side of the thorax, side of the thorax, head and neck. head and neck. Empties into the left Empties into the left subclavian vein.subclavian vein.

Right lymphatic duct- Right lymphatic duct- smaller of the two, smaller of the two, gathers lymph from gathers lymph from the right side of the the right side of the head neck and head neck and thorax. Empties into thorax. Empties into the right subclavian the right subclavian vein, near the right vein, near the right jugular vein.jugular vein.

Lymphatic tissue fluid formationLymphatic tissue fluid formation

Tissue fluid originates as blood plasma. Tissue fluid originates as blood plasma. That plasma contains water and dissolved That plasma contains water and dissolved

proteins in it. Parts of this fluid can be proteins in it. Parts of this fluid can be removed by diffusion and filtration.removed by diffusion and filtration.

Some of the smaller proteins free floating Some of the smaller proteins free floating in the plasma are not reabsorbed through in the plasma are not reabsorbed through venular ends of the capillaries.venular ends of the capillaries.

This causes a change the level of osmotic This causes a change the level of osmotic pressure in the fluid.pressure in the fluid.

The higher osmotic pressure in turn causes a The higher osmotic pressure in turn causes a large increase in the hydrostatic pressure large increase in the hydrostatic pressure (pressure that water has when at equilibrium) (pressure that water has when at equilibrium) forcing some liquid into the lymph capillaries forcing some liquid into the lymph capillaries where it becomes lymph.where it becomes lymph.

The lymph returns most of the proteins lost back The lymph returns most of the proteins lost back when it enters the bloodstream. when it enters the bloodstream.

At the same time, lymph transports foreign At the same time, lymph transports foreign particles like bacteria and viruses to the lymph particles like bacteria and viruses to the lymph nodes.nodes.

Lymph NodesLymph Nodes

It is in the lymph nodes that the most It is in the lymph nodes that the most lymphocytes and macrophages do battle lymphocytes and macrophages do battle with the microorganisms that enter the with the microorganisms that enter the body everyday.body everyday.

There is an indented region in the lymph There is an indented region in the lymph node where blood vessels and nerves run node where blood vessels and nerves run to the node. This region is called the to the node. This region is called the hilium.hilium.

Locations of major lymph nodesLocations of major lymph nodes

Thoracic cavity nodes- chestThoracic cavity nodes- chest Cervical nodes- throatCervical nodes- throat Axillary nodes- armpitAxillary nodes- armpit Supratrochlear nodes- distal end of the Supratrochlear nodes- distal end of the

humeroushumerous Abdominal cavity nodes- abdomenAbdominal cavity nodes- abdomen Pelvic cavity nodes- pelvic regionPelvic cavity nodes- pelvic region Inguinal nodes- upper thigh and groin region.Inguinal nodes- upper thigh and groin region.

Major organs in the lymphatic Major organs in the lymphatic systemsystem

Thymus- located Thymus- located anterior to the heart anterior to the heart and posterior to the and posterior to the sternum. Soft and sternum. Soft and bilobed (two lobed). bilobed (two lobed). Large in children, Large in children, small and reduced in small and reduced in adults.adults.

Some T-cells can be Some T-cells can be found here.found here.

SpleenSpleen

Largest lymphatic Largest lymphatic organ, located in the organ, located in the upper left portion of upper left portion of abdominal cavity. abdominal cavity. Inferior to the Inferior to the diaphragm. Posterior diaphragm. Posterior and lateral to and lateral to stomach.stomach.

D - D -

The body fighting against infectionThe body fighting against infection

Pathogen-disease causing agentPathogen-disease causing agent Two types of defense:Two types of defense:

NonspecificNonspecific Specific (immunity)Specific (immunity)

Nonspecific defensesNonspecific defenses

Nonspecific defenses are designed to deal Nonspecific defenses are designed to deal with a variety of different pathogens. with a variety of different pathogens. Different nonspecific defenses are:Different nonspecific defenses are: Species resistanceSpecies resistance Skin and mucus membranesSkin and mucus membranes Interferons- proteins secreted by immune Interferons- proteins secreted by immune

system to fight infectionsystem to fight infection InflammationInflammation PhagocytosisPhagocytosis

Species defenseSpecies defense

When a disease only affects one species When a disease only affects one species of organism, all other species are immune of organism, all other species are immune to getting that disease.to getting that disease. Oak blight kills oak trees. Humans are not Oak blight kills oak trees. Humans are not

oak trees, thus cannot get oak blight.oak trees, thus cannot get oak blight.

Mechanical barriersMechanical barriers

Body’s first line of defense. When not Body’s first line of defense. When not damaged, they prevent most diseases damaged, they prevent most diseases from entering the body.from entering the body. SkinSkin Mucus membranesMucus membranes

Chemical barriersChemical barriers

Chemical barriers are chemicals secreted Chemical barriers are chemicals secreted by the body that due to their very nature by the body that due to their very nature can make it impossible for a bacteria to can make it impossible for a bacteria to survive.survive. Pepsin and HCl in the stomach.Pepsin and HCl in the stomach. Interferons eliminating viral coats and tumor Interferons eliminating viral coats and tumor

cells.cells.

FeverFever

The body begins to raise its overall temperature.The body begins to raise its overall temperature. Liver and spleen begin to hold on to extra iron Liver and spleen begin to hold on to extra iron

as a result.as a result. Bacteria need more iron as the temperature Bacteria need more iron as the temperature

rises, this causes a composition change in the rises, this causes a composition change in the blood and kills the bacteria in the blood.blood and kills the bacteria in the blood.

(bad news) maintaining a high fever (105(bad news) maintaining a high fever (105OO F or F or greater) over an extended period can cause greater) over an extended period can cause organ and brain damage if not brought down.organ and brain damage if not brought down.

Pus- when lymphocytes and bacteria are Pus- when lymphocytes and bacteria are all collected in one place, pus may form. all collected in one place, pus may form.

PhagocytosisPhagocytosis

When monocytes and neutrophils devour When monocytes and neutrophils devour foreign invaders, they attack foreign invaders, they attack indiscriminately, regardless of the make up indiscriminately, regardless of the make up of the bacteria or virus.of the bacteria or virus.

Specific ImmunitySpecific Immunity

Specific immunity is designed to target Specific immunity is designed to target one specific problem. When you get a flu one specific problem. When you get a flu shot each year, you receive a vaccine, you shot each year, you receive a vaccine, you receive immunity to a specific strand of the receive immunity to a specific strand of the flu virus. That strand has a unique protein flu virus. That strand has a unique protein coat that only it has. When your body runs coat that only it has. When your body runs into that protein coat again (after into that protein coat again (after vaccination) you will immediately produce vaccination) you will immediately produce the antibodies to remove the threat without the antibodies to remove the threat without getting sick again.getting sick again.

AntigensAntigens

Cell surface markers. Helps body Cell surface markers. Helps body recognize other cells as “self” or “foreign.” recognize other cells as “self” or “foreign.”

lymphocyteslymphocytes

Provide immunity by creating antibodies. Provide immunity by creating antibodies. Can differentiate into B-cells and T-cells. Can differentiate into B-cells and T-cells. Upon reaching the thymus, lymphocytes Upon reaching the thymus, lymphocytes can be given the biochemical cocktail they can be given the biochemical cocktail they need to specialize into t-cells. B-cells will need to specialize into t-cells. B-cells will specialize in the bone marrow. specialize in the bone marrow.

T-cells and B-cellsT-cells and B-cells

B-cell- 20-30% of lymphocytes in the blood. B-B-cell- 20-30% of lymphocytes in the blood. B-cells tend to settle in lymphatic organs. Produce cells tend to settle in lymphatic organs. Produce antibodies that destroy antigens and antigen antibodies that destroy antigens and antigen bearing agents. Using antibodies bearing agents. Using antibodies (immunoglobulins) to destroy a pathogen is (immunoglobulins) to destroy a pathogen is called antibody-regulated immunity.called antibody-regulated immunity.

T-cell- 70-80% of lymphocytes in the blood. T-cell- 70-80% of lymphocytes in the blood. Interact directly with antigen source with agents Interact directly with antigen source with agents to destroy that source. Binding to the pathogen to destroy that source. Binding to the pathogen directly is called cell-mediated immunity.directly is called cell-mediated immunity.

When to attackWhen to attack

T-cell activation- When a pathogen is T-cell activation- When a pathogen is phagocytized by a monocyte, some of the phagocytized by a monocyte, some of the antigens from the pathogen stick out of the antigens from the pathogen stick out of the monocyte near a monocyte near a major histocompatibility major histocompatibility complex (MHC). complex (MHC). If the T-cell recognizes If the T-cell recognizes the antigen as a foreign antigen, then the the antigen as a foreign antigen, then the T-cell will activate. This type of T-cell is T-cell will activate. This type of T-cell is called a helper T-cell because it assists called a helper T-cell because it assists another lymphocyte in non-self cell another lymphocyte in non-self cell removal.removal.

Another way this occurs is when T-cells Another way this occurs is when T-cells subdifferentiate into cytotoxic T-cells. subdifferentiate into cytotoxic T-cells. They recognize a non-self antigen as They recognize a non-self antigen as being cancerous or viral and binds to the being cancerous or viral and binds to the antigen and activates and releases a antigen and activates and releases a protein that shreds the antigen bearing protein that shreds the antigen bearing agent.agent.

B-cell activationB-cell activation B-cells will come in contact with an antigen B-cells will come in contact with an antigen

bearing source. As a result, the B-cell will bind bearing source. As a result, the B-cell will bind to it and begin to divide and create more copies to it and begin to divide and create more copies of itself. When an activated T-cell finds a B-cell of itself. When an activated T-cell finds a B-cell that is now bound to an antigen, the helper cell that is now bound to an antigen, the helper cell will release cytokines that cause the B-cell to will release cytokines that cause the B-cell to grow and increase antibody producing cells.grow and increase antibody producing cells.

Later outbreaks of that pathogen will be easily Later outbreaks of that pathogen will be easily quelled due to some B-cells becoming memory-quelled due to some B-cells becoming memory-cells and “remembering” that pathogen. When cells and “remembering” that pathogen. When that pathogen appears again, it will be quelled that pathogen appears again, it will be quelled near instantly.near instantly.

Immune ResponseImmune Response

Primary Immune Response- First Primary Immune Response- First response to an antigen. Ends with response to an antigen. Ends with creation of memory cells.creation of memory cells.

Secondary Immune Response- Secondary Immune Response- subsequent response to encountering subsequent response to encountering antigen. Memory cells know what to do antigen. Memory cells know what to do and eliminate threat to the body.and eliminate threat to the body.

Active ImmunityActive Immunity

Two ways to acquire active immunity:Two ways to acquire active immunity: First way- Get sick, produce memory cells First way- Get sick, produce memory cells

that now recognize antigen.that now recognize antigen. Second way- Vaccination. Vaccinations Second way- Vaccination. Vaccinations

introduce a dead (inactivated) or introduce a dead (inactivated) or weakened (attenuated) virus into the body. weakened (attenuated) virus into the body. The body easily fights off this virus, gains The body easily fights off this virus, gains the memory cells it needs, and now is the memory cells it needs, and now is ready to encounter the full strength virus.ready to encounter the full strength virus.

Passive immunityPassive immunity

When immunity is given by receiving When immunity is given by receiving antibodies from an outside source. Often antibodies from an outside source. Often given when we fail to produce immunity given when we fail to produce immunity fast enough or if we are not able to at all.fast enough or if we are not able to at all. i.e. Rabies vaccine.i.e. Rabies vaccine.

AllergiesAllergies

Hypersensitive response to a stimulus.Hypersensitive response to a stimulus. Eating tree nuts- not normally harmful but the Eating tree nuts- not normally harmful but the

body perceives it as a threat and attacks the body perceives it as a threat and attacks the threat in full force.threat in full force.