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Questions to ponder

1. Mom is type A, Dad is type O. What are possible blood

types of baby?

2. Mom is Rh+, Dad is Rh-. What will/could the baby be,

and is there any concern for erythroblastosis faetalis?

Assume this is second baby.

3. List three components of your innate, non-specific

immune system.

4. Describe how one of the three components works to

defend you against pathogens/ tumors etc.

5. List one organ of the immune or lymphatic system.

Body Defenses

Lymphatic and Immune Systems

Points to ponder

What are the parts of the lymphatic system

and what are their functions?

What are the first and second lines of

defense in nonspecific immunity?

What is the third line of defense - cell-

mediated and antibody-mediated

immunity?

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Points to ponder

What are the different types of B cells in these

processes?

Distinguish between active and passive

immunity? Describe how they are different and

giveexamples of each.

Understand allergic reactions, tissue rejection,

and immune system disorders as problems that

the immune system faces.

Microbes and You

Microorganisms are widely distributed in the

environment and carry out many beneficial

functions.

Decomposition

Nitrogen fixation

Breakdown environmental toxins

Normal flora protect you against some pathogens

Skin, vagina, mouth, gut

E. coli in your gut produce vitamin K - you cannot

make this substance yourself and without it your

blood won’t clot properly

Pathogens

Bacteria

Viruses

Fungi

Protozoans

Parasites

Prions

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Pathogens

Bacteria

See previous notes on prokaryotic cell structure

Damage host by

Exotoxins – toxins produced by bacteria

Shigella toxin, Staphylococcus aureus toxin

Endotoxins and non-specific immunity

From cell wall of E coli and related bacteria

Effects of the body’s specific humoral and cell

mediated immunity

Eukaryotic Pathogens

Fungi: examples

Althlete’s foot

Nail fungus

Histoplasmosis

Protozoans: examples

PCP: Pneumocystis carinii pneumonia

Amoebic dysentery

Parasites: examples

Tapeworms

Roundworms, pinworms

Viruses

Acellular – not quite a living organism

Obligate parasites

Virus always has two parts:

Some viruses have an outer envelope – HIV,

Influenza

Outer capsid composed of protein units

Inner core of nucleic acid, which can be either

DNA or RNA

Virus relies on the host’s enzymes and

ribosomes for its own reproduction.

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Prions

Proteinaceous infectious particles

Proteins of unknown function in the brains of

healthy individuals

Disease occurs when certain prion proteins

change their shape into a “rogue” form that

converts other normal prion proteins into the

rogue configuration.

Cause a group of degenerative diseases of

the nervous system

Bovine and human Spongiform Encephalopathy

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transmissible spongiform encephalopathies

The Lymphatic System

Consists of lymphatic vessels and the

lymphatic organs

Four main functions;

Lymphatic capillaries absorb excess tissue fluid

and return it to the bloodstream;

Lacteals absorb fats in the form of lipoproteins

from the small intestines and transport them to the

bloodstream;

Lymphatic system produces, maintains, and

distributes lymphocytes in the body;

Defends the body against pathogens.

Components of the lymphatic system

Tonsil: patches of lymphatic tissue; help to prevent entrance of

pathogens by way of the nose and mouth

Red bone marrow: site for the origin of all types of blood cells

Thymus: lymphatic tissue where T lymphocytes mature and

learn to tell “self” from “nonself”

Spleen: cleanses the blood of cellular debris and bacteria, while

resident lymphocytes respond to the presence of antigens

tissue

fluid

lymphatic

capillary

tissue cell

blood

capillary

Inguinal lymph nodes:

located in the groin region;

cleanse lymph and alert

the immune system to

pathogens

Thoracic duct: empties

lymph in to the left

subclavian vein

Axillary lymph nodes:

located in the underarm region

Right lymphatic duct:

empties lymph into the

right subclavian vein

Figure 7.1 Functions of the lymphatic system components.

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Lymphatic vessels

One-way system that carries fluid called lymph

Made of capillaries, vessels, and ducts

Function to return tissue fluid (which includes water, solutes, and cell products) to the bloodstream

Larger vessels are similar in structure to veins and even have valves

Classifying lymphatic organs

Primary

Red bone marrow

Thymus

Figure 7.2 Tissue samples from primary lymphatic organs.

Classifying lymphatic organs

Secondary

Lymph nodes

Spleen

Figure 7.2 Tissue samples from secondary lymphatic organs.

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Primary Lymphatic Organs

Red bone marrow is

Site of stem cells that divide and produce blood

cells.

More bones in children have red marrow and it

decreases as we age.

B lymphocytes mature in the bone marrow

Primary Lymphatic Organs

Red Bone Marrow

Primary Lymphatic Organs

The thymus

is a bilobed gland found in the thoracic cavity

superior to the heart.

is largest in children and shrinks as we age.

Site of T lymphocyte maturation

cells move from the marrow to the thymus

where they mature and 95% will stay.

also produces thymic hormones, and is absolutely

critical to immunity.

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Thymus

Classifying lymphatic organs

Secondary

Lymph nodes

Spleen

7.1 The Lymphatic System

Figure 7.2 Tissue samples from secondary lymphatic organs.

Secondary Lymphatic Organs

The spleen contains white pulp and red pulp.

In the upper left region of the abdominal cavity

White pulp contains a concentration of lymphocytes

Red pulp is involved in filtering the blood.

Removes damaged, dying red blood cells

In the case of infection or a blow, the spleen can burst.

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Spleen

Secondary Lymphatic Organs

Lymph nodes

Small, oval-shaped structures found along the

lymphatic vessels

Filled with B cells, T cells, and macrophages

Common in the neck, armpit, and groin

regions

Lymph is filtered through the lymph nodes.

Lymphocytes react with pathogens present in

the filtered blood and lymph. They fight

infections and attack cancer cells.

Lymph nodes

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Tonsils

The tonsils are patches of

lymphatic tissue located

around the pharynx.

Immune Defenses

Immunity involves innate and acquired

defenses.

Innate defenses protect against any pathogen,

Acquired defenses are effective against a

particular infectious agent.

What are the innate immune

defenses?

7.2 Innate Immune Defenses

Figure 7.3 Overview of innate immune defenses.

Innate defenses

Barriers to entry

Inflammatory response

Protective proteins

Phagocytes and natural killer cells

skin and mucous

membranes dendritic cell

antimicrobial molecules

pathogens

macrophage cytokines

neutrophil

natural killer ells

complement proteins and interferons

in plasma

monocyte

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The first line of defense

Physical barriers

The skin is an effective physical barrier.

Tears, saliva, and urine physically flush out

microbes.

Mucous membranes line the respiratory, digestive,

reproductive, and urinary tracts.

Resident bacteria/normal flora that inhabit the body

use available nutrients and space thus preventing

pathogens from taking up residence.

The first line of defense

Chemical barriers

Secretions of the oil glands

Lysozyme found in saliva, tears, and sweat

Acidic pH of the stomach and vagina

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The second line of defense:

Phagocytic white blood cells

Includes neutrophils and macrophages

Both leave circulation and move into tissue

Are important in the inflammatory response

7.2 Innate Immune Defenses

The second line of defense:

Inflammatory response

Four hallmark symptoms are redness, heat, swelling, and pain.

Histamine, released by mast cells, causes the capillaries to dilate and become more permeable to phagocytic white blood cells.

Increased blood flow to an area increases warmth, inhibiting some pathogens. Rise in temperature increases phagocytosis by neutrophils and macrophages.

Increased blood flow also brings more white blood cells to an injured area, with neutrophils being the first scouts to kill pathogens.

This response can be short-lived, but if the neutrophils cannot control the damage, cytokines (chemicals) will call in more white blood cells including macrophages. Monocytes become macrophages - attract lymphocytes, that are part of the specific arm of the immune system.

The second line of defense:

Inflammatory response

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Summary of the inflammatory

response

2. Macrophages phagocytize pathogens

and release cytokines, which stimulate

the inflammatory response.

Capillary

1. Injured tissue cells and mast cells

release histamine, which causes

capillaries to dilate and increases

blood flow.

mast cell

Tissue

Skin

4. Blood clotting walls off

capillary and prevents

blood loss.

3. Neutrophils and monocytes (become

macrophages) squeeze through the

capillary wall and phagocytize pathogens.

cytokines

monocyte neutrophil

macrophage histamine

injured tissue

blood clot

pathogen

Figure 7.4 Steps of the inflammatory response.

The second line of defense:

Protective proteins

Complement Group of blood plasma proteins

Involved in the inflammatory response by binding to mast cells, causing them to release histamine

Attract phagocytes to pathogens by binding them

Form a membrane attack complex that makes holes in some bacteria and viruses, causing them to burst

Interferons Proteins produced by virus-infected cells sent out to

warn neighboring healthy cells

7.2 Innate Immune Defenses

Fig. 7.9