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The Lymphatic / Immune SystemHonors Biology

Unit 8Powerpoint #7

+ Lymphatic System: Purpose: Transports a watery fluid called lymph.

This fluid distributes immune cells, and other factors throughout the body.

It also interacts with the circulatory system to drain fluid from cells and tissues

+ Lymphatic System: Functions: Collect and return fluids, including blood plasma, to the blood, maintaining fluid homeostasis.

Defends the body against disease by producing lymphocytes.

Absorbs lipids from the intestine, and transports them to the blood.

+ Absorbs lipids from small intstine

+Why do we need the Lymphatic System?

Every 24 hours the circulatory system slowly leaks 3 liters of blood.

Lymphatic System: Structures:

white blood cells (lymphocytes)

Bone marrow ThymusSpleenTonsilslymph nodeslymph vessels

+ Lymph / Lymph VesselsLymph: fluid and protein that has been squeezed out of the blood (blood plasma).

Vessels: A network of permeable capillaries and vessels that lymph drains into.

+ Lymph Vessels The lymph system is one-way, draining lymph from tissue, back to the blood.

Lymph movement depends on smooth muscle action, and skeletal system movement.

+ Lymph Nodes: Filters Lymph as is travels

in the lymph vessels. White blood cells are

located within the lymph nodes.

Bean-shaped, size ranges from 3mm to 2cm.

Can become enlarged due to infection.

A combination burglar alarm and West Point. They guard against intruders, but also train the ‘military’ to fight.

+ Lymph Nodes

+ White Blood CellsBone marrow produces lymphocytesNormally in blood, but can be found at any location.

Re-enter blood circulation through lymph vessels.

Fight foreign invaders (microorganisms)Some last 2-5 days, others last for years.

+ Lymphocytes attacking cancer cell

+Thymus: Location of the development of T-cell lymphocytes.

+ Spleen:Fist-sized mass of lymphatic tissue that destroys old or damaged red blood cells and platelets.

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+ Elephantitis

+ Immune System & Disease

• Disease- any change that disrupts normal body functions (other than injury)

• Causes-

Bacteria

viruses

fungi

environmental factors (smoke, lead, pesticides)

genetically inherited (hemophilia, Down's Syndrome)

+Germ Theory of Disease

Proposed by Louis Pasteur & Robert Koch

Infectious diseases are caused by microorganisms

+Agents of Disease

Virus- tiny particles that invade & replicate within living cells

Is not alive, only a piece of DNA or RNA bound in a protective coat

+Agents of Disease

Bacteria- single celled organisms (prokaryotic)

Most don’t cause disease

Those that cause disease attack cells directly or produce toxins that harm cells

Agents of Disease

Protists- tiny single celled organisms that spread via insects, blood, food, or water

Examples: Malaria, Sleeping sickness, traveler’s diarrhea

Agents of Disease

Worms-- flatworms & roundworm eggs that grow inside other organisms

Examples: Schistosoma

Ascaristapeworm

Agents of Disease

Fungi– most are harmless

Tinea attacks the skin

causes athlete’s foot &

ringworm

Spread of Disease

Coughing, sneezing, or physical contact

Contaminated food & water

Animals

+Fighting Infectious Disease1. Antibiotics– compounds that kill bacteria

without harming host cells

Many are produced naturally by organisms (like mold creates penicillin) discovered by Alexander Fleming

2. Antiviral drugs– inhibit their ability to invade cells

3. Rest & fluids so your own immune system can work well!

+The Immune System Immunity- fighting off disease before it

actually makes you ill

2 categories:

1. Specific- targeted for 1 disease

2. Nonspecific- general line of defense against anything

+Non-specific Defense

1st line of defense – Physical

-Skin

-Mucus

-Sweat

-Tears

The sweat & tears contain lysozymes (enzyme that breaks down bacteria cell walls)

+Non-specific Defense

2nd Line of defense Inflammatory response–

1. Phagocytes (white blood cells)

go to site of injury to engulf foreign agents

2. Fever can slow down growth or stop growth of some pathogens (also ‘s heart rate to get WBC’s to site faster)

3. Interferon proteins help cells resist viruses by slowing down their replication in cells

+ Specific DefenseImmune response is triggered by antigens

(any foreign agent)

Creates B & T Lymphocytes

B cells Attacks antigens in body fluids

T cells Attacks antigens within cells

+ AntibodiesProteins created by B cells

Bind to antigens to stop them from moving into cells & signals proteins (produced by liver) to destroy the antigen

B memory cells store info to create antibodies quickly against another antigen attack

+ Antibodies

Y shaped with 2 identical binding sites

Shape of binding site is specific to an antigen with a complementary shape

Most healthy adults can produce 100 million different types of antibodies

+ Cell Mediated ImmunityImportant in fighting infections

caused by fungi & protists & viruses

T-cells divide into killer, helper, suppressor, & memory cells

Killer T-cells destroy the agents

Helper T-cells produce memory T cells

Suppressor T-cells releases substances that shut down the killer T-cells

+HIV & T-cells

HIV replicates inside T-cells, and then destroys them as they burst open to release more viruses

When Immune cells are destroyed, other diseases & infections can weaken & kill AIDS patients

+Acquired Immunity

Edward Jenner created the 1st vaccine against smallpox using attenuated (heated so it won’t cause the disease) cowpox

Active Immunity is the injection of a mild form of the pathogen to stimulate our immune systems to create antibodies

+Passive Immunity

Lasts only a short time because they are not created by the body’s own immune system

Examples:

1) Mother passing antibodies through placenta or breast milk to baby

2) Vaccines with antibodies against diseases like malaria, yellow fever, rabies

+Immune System Disorders

Allergies- overreactions of immune system to antigens

Mast cells are specialized cells that initiate the inflammatory response

Histamines- chemicals released by mast cells that increase blood flow & fluids to the area

This causes sneezing, watery eyes, & runny nose

Autoimmune Diseases

Body attacks the body’s own cells

Examples: Type I diabetes, rheumatoid arthritis, myasthenia gravis, & multiple sclerosis (MS), Lupus