Lymphatic System

Components of lymphatic system:

• Lymph (watery fluid collected from tissues)

• Lymphocytes• Lymphatic vessels• Lymph nodes• Tonsils• Spleen• Thymus gland

Functions of the lymphatic system:

• 1. protect from invading organisms (immune system)

• 2. balance fluids in the body

• 3. absorb fats (lipids)

How lymphatic functions occur?

• 1. protect from invading organisms– The lymphatic system

does this in 3 ways:• Lymph nodes filter

microorganisms and other foreign substances from the lymph

• The spleen filters the blood

• Lymph cells attack and destroy microorganisms

Functions continued:

• 2. fluid balance

– Removes fluid (lymph) when it is in excess to prevent swelling

– Ex. Your stomach swells when you eat and drink but after a few hours the decrease occurs due to digestion and the removal of lymph by the lymph vessel

– These vessels are found all over the body

Functions continued:

• 3. fat absorption– Absorbs fat from the

digestive tract– There are special cells

that absorb fat called lacteals

– The lymph with the fat in it is called chyle

intestines

Lymph passage in the body:• Lymph- watery

substance removed from the tissues

• Lymphatic vessels- only remove lymph from the tissue- (does not take it to tissues)

• Lymphatic capillaries- tiny vessels that remove lymph form the tissue and take it to larger lymph vessel and then to the blood-found in all tissues except the CNS, bone marrow, epidermis, and cartilage

How does the body know to take lymph away from the body tissues?

• All lymphatic vessels have vessels that have a 1 way valve which keeps lymph from going backwards into the capillaries

• 3 things force the lymph from the capillaries to the larger vessels:– Contraction of surrounding

skeletal muscles– Contraction of smooth muscle

in the vessel walls– Pressure changes in the

thorax during respiration

How does lymph get from the lymphatic vessels to the blood?

• Lymphatic ducts- empties the lymph from the right upper area of the body into the blood

• Thoracic ducts- empties the rest of the body to the blood at the subclavian vein

                   

          

Lymphatic organs:

• Tonsils• Lymph nodes• Spleen

Make-up of lymphatic organs:• All are composed of cells

called lymphocytes• the lymphocytes will

divide and increase in number when foreign microorganisms contact them

Functions of lymphocytes:

1. They attack and destroy invaders and

2. form fiber networks to filter out foreign matter

TonsilsFound at the opening

of the throat

• Function: protect the openings of the oral cavity and throat from harmful materials entering

3 kinds of tonsils:• 1. Palatine- located at

the sides of the throat• 2. Pharyngeal- located

near the internal nasal opening– When it becomes enlarged,

it is called an adenoid

• 3. Lingual- on posterior surface of the tongue

Tonsil Disorders:

• Since tonsils filter out infections, they sometimes become chronically infected and inflamed

• Tonsillectomy-removal of inflamed tonsils

Lymph Nodes:

• Rounded structures found along lymphatic vessels

• 3 main areas where nodes are found:

• Groin• Armpits• neck (cervical area)

Functions of lymph nodes:• 1. activate the immune

system- when microorganisms enter the nodes the lymphocytes are triggered to start dividing and attack the foreign matter

• 2. remove microorganisms and foreign substances from the lymph by special cells called macrophages

How do the lymph nodes filter material?

• Lymph enters the nodesthrough the afferentvessels.

• Lymph is filtered and then exits the nodes through theefferent vessels(these are smaller making lymph stay in the nodes longer before it exits

Spleen

• Located on the left superior corner of the abdomen

4 functions:• 1. filters blood (not lymph)• 2. detects and destroys

foreign substances• 3. Destroys old red blood

cells• 4. blood reservoir- stores

blood which is available in an emergency

Thymus gland:

• Located at the top of the sternum

Function:• Where lymphocytes

are produced and mature. They are released into the blood to go to other lymphatic structures

Lymphatic disorders:• Elephantiasis- due to

mosquitoes injecting a parasitic worm into the body

• The worm reproduces rapidly and blocks the flow of lymph to the limbs.

• It results in the limb (where the blockage occurs) swelling enormously.

Lymphatic disorders:

• Bubonic plague- due to ingestion of rat feces and rat fleas

• Bacteria accumulates in the lymph nodes

• Swell especially in the groin area

• (called blood poisoning)

What does it mean to be immune to something?

• Immune- the body remembers a substance and it destroys it before is has an effect

• The substances the body recognizes are called antigens.

• There are 2 types of antigens:1. Foreign- introduced from

outside the body example: bacteria

2. Self-antigens- molecules produced by the body that the body must fight offExample: tumor

How does the body destroy foreign antigens?

• Uses antibodies• Antibodies- proteins

the body produces in response to being exposed to certain antigens– Have a Y-shape– It attacks and

inactivates antigens

Immunity:• Ability to resist damage from foreign substances like

microorganisms, chemicals and toxins2 types of immunity:

• 1. innate immunity- the body is born with the ability to recognize and destroy foreign substances (example: white blood cells attack infections)

• 2. acquired (adaptive) immunity- ability of the body to recognize and destroy foreign substances exposed to before– It improves each time the body encounters the

substance– Ex. vaccinations

4 ways immunity is acquired:

1. active natural immunity- results from direct exposure naturally to disease causing antigens (ex. Chicken pox)

2. active artificial immunity- deliberately introduce antigens to an individual to stimulate the immune system(ex. Tetanus, mumps)

Acquired immunity continued…3. passive artificial immunity-

begins with the vaccination of an animal (ex. Horse)-Once the animal is immune to the antigen, the antibodies are removed and injected in an individual. The persons body will immediately attack the antigens they are exposed to.Antiserum- antibodies are in a serum-it is microorganisms that are injected like rabies, hepatitis

4. passive natural immunity- transfer of antibodies from the mother to the fetus across the placenta. The mother’s antibodies go to the child and the child is protected against the same antigens. This is the benefit of breast feeding.

Inflammatory response:• When unwanted antigens enter the body, the areas

become inflamed and chemical mediators are activated to fight it

• this tells the body there is an infection

2 kinds of inflammatory responses:

1. Local inflammation- inflammatory response is confined to a specific area of the body

• Symptoms of inflammation are:– Redness– Heat– Swelling – Pain – Loss of function

• 2. systemic inflammation- inflammatory response occurs in many parts of the body

• Has symptoms like local inflammation but also has 3 other symptoms:

• Red blood cells release substances that fight the infection

• Fever

• In extreme cases, shock or death

Autoimmune disease

• Occurs when antigens produced by the body cause unwanted destruction of the body tissues

• The body attacks itself

• Ex. Rheumatoid arthritis