A&P EXAM 3 Immune system and Lymphatic system

The lymphatic system functions to:

•Drain interstitial fluid

•Carry out immune responses

•Transport dietary fats

Flow of lymph photo

Hydrostatic pressure (BP) in capillary beds

Forces or pushes fluid and some plasma proteins out

Most reabsorbed at venous end

Remaining fluid becomes part of interstitial fluid between cells

Fluid and plasma proteins must be returned to keep blood volume/blood pressure maintained and to prevent

Edema which is swelling of body tissues

The lymphatic system consists of

several structures and organs that contain lymphatic tissue, bone marrow, thymus, and a fluid called lymph that flows within lymphatic vessels

Lymphatic Vessels transport

filtered fluids back to the blood

Organs & tissues house

The immune cells

•Phagocytic cells and lymphocytes

•“wastewater treatment system”

Components of the Lymphatic System

•Blind lymphatic capillaries

• Lymphatic vessels

•Lymph nodes

• Lymphatic trunks

• Lymphatic ducts

-Thoracic duct

-Right lymphatic duct

Lymphatic organ photo

Lymphatic capillaries, which are

blind; closed on one end, are located between cells of many tissues

Lymphatic capillaries merge to form lymphatic vessels, which have

thin walls and many valves to prevent backflow since there are no pumps

Lymph vessels pass through

lymph nodes and then merge into lymph trunks

Lymph trunks merge to form the

thoracic duct or the right lymphatic duct

Routes of drainage

Right lymphatic Duct

Empties at junction of right internal jugular and right subclavian veins

Routes of drainage

Thoracic Duct

Empties into the junction of left internal jugular and left subclavian veins

Most inferior part of thoracic duct

Cisterna chyli

Lymphatic duct photo

Primary lymphatic organs are organs

where immune cells become immunocompetent (Cells are able to deal immune reactions properly)

•Red bone marrow

•Thymus

Lymphoid organs photo

Thymus gland

•Peak function during childhood

•Produces thymosin and thymopoietins that functions to program lymphocytes (T cells)

•Site of T cell maturation

Secondary lymphatic organs are

the sites where most immune responses occur.

Secondary lymphatic organs and tissues include:

•Lymph nodes

•Spleen

•Lymphatic nodules

Structure of a lymph node photo

Lymph enters through

afferent lymphatic vessels--flows through node--exits at hilusby efferent lymphatic vessels

Slow flow through node

•More afferent vessels than efferent

•Allows lymphocytes and macrophages to do their job

Lymph flows through several nodes before

cleaning is complete and fluid re-enters cardiovascular system

clustered along lymphatic vessels that filter lymph

Large clusters in inguinal, axillary, and cervical regions

“Filter” lymph

Macrophages remove foreign material

Immune System Activation

Lymphocytes encounter foreign antigens and become activated

Lymph Nodes summary

• Surrounded by Connective Tissue capsule

• Contain lymphatic nodules made up of B cells

• More afferent vessels than efferent vessels –slows flow

• All lymph flows through more than one lymph node

• Contain reticular fibers that act as a filter

Swollen Lymph nodes

Buboes

Secondary cancer sites

Buboes-

overwhelmed lymph nodes, large numbers of bacteria and viruses

•Causes inflammation and tenderness

•Swelling during infection is a trapping function

Secondary cancer sites

•Some cancers use lymphatic system to spread

•Swollen glands are usually painless making them distinguishable from inflamed glands

Lymphoid Organs PHOTO

Lymphoid Organs

Spleen

•Lymphocytes check blood (not lymph) for bacteria, viruses, and debris

•Left side of abdomen

•Other functions

•Destroys and stores breakdown products of old RBCs

•Acts as blood reservoir, stores 1/3 of platelets and monocytes

•May produce RBCs in fetus

Splenectomy-

removal of spleen when hemorrhaging

•Less common today, found to heal itself and regenerate in children

Lymphatic nodules are

masses of lymphatic tissue that are not surrounded by a capsule

Lymphatic nodules are masses of lymphatic tissue that are not surrounded by a capsule. They are

scattered throughout the lamina propria of mucous membranes lining the gastrointestinal, urinary, and reproductive tracts and the respiratory airways

Lymphatic nodules in these areas are also referred to as

mucosa-associated lymphatic tissue (MALT)

Tonsils

•5 Small masses of tissue, ring the throat

•Trap foreign pathogens entering throat

•Tonsillitis - red and swollen due to excess bacteria or any foreign pathogen

•Peyer’s patches

•Wall of small intestines - ilium

•Prevent foreign substances from entering intestinal wall

Elephantiasis

Tropical disease where lymphatics are clogged with parasitic round worms resulting in edema of enormous proportions. Transmitted by mosquitos and common in India

Lymphoma

Benign or malignant tumor of lymphoid tissue

Non-Hodgkin Lymphoma

All cancers of lymphoid tissue except Hodgkins lymphoma, due to lymphocytes, 7thmost common cancer, often occurs in young people

Hodgkin Disease

•Malignant lymphoid tissue, malignant B cells, non-painful swollen lymph nodes, genetic and mononucleosis predisposing factors Mostly affects people between 15- 35 years old and 65+ cure rate of 90-95%

Sentinel node

First node that receives lymph drainage from a suspected cancerous area, biopsied to determine if cancer has metastasized into lymph tissue

Which of the following filter lymph?

lymph nodes

Filtered lymph is returned to the blood at the

subclavian veins

Immunology-

study of the immune system (specific defense)

Antigen-

protein (self or foreign) substance, recognized by immune system. On the surface of a cell, cell identity markers

Nonself-

foreign, threat

Pathogen-

disease causing microorganism helminth, virus, protozoan, bacteria

Antibody-

protein that tags a foreign substance

Self-

not seen as a threat

Functions to protect body can either be

•Direct

•Indirect

Functions to protect body can either be

Direct

Cell attack

Functions to protect body can either be

indirect

Mobilizing chemicals and antibodies

Two defense system

•Innate (nonspecific) system

First and Second line of defense, always ready, we are born with this

Two defense system

Adaptive (specific) system

•Third line of defense, must be primed

•Attacks particular foreign substances

uses specific antibodies that bind to antigens

Nonspecific Resistance (Innate Immunity)

Present at birth and includes defense mechanisms that provide general protection against invasion by a wide range of pathogens

Immunity (Adaptive Immunity)

Involves activation of specific lymphocytes that combat a particular pathogen or other foreign substance

The body system that carries out immune responses is

the lymphatic system

NON-SPECIFIC Innate Immunity

refers to a wide variety of body responses that serve to protect us against invasion by a wide variety of pathogens and their toxins

NON-SPECIFIC Innate Immunity

We are

born with this kind of immunity

Two lines of NON-SPECIFIC Innate Immunity

•Skin and mucous membranes

•Internal defenses = 5

Nonspecific Defenses

Surface Membrane barriers (external)

1st line of defense, skin and mucous membranes

Physical and chemical barriers

•Acidic pH of skin secretions and sebum inhibits bacteria growth

•Hydrochloric acid and digestion enzymes of the stomach

•Saliva and lacrimal fluid (lysozymes)

•Sticky mucus traps pathogens in respiratory and digestive tracts and cilia work to move the substance out

Nonspecific Defenses

2nd line of defense

1. Phagocytes

Phagocytes

•Engulf foreign substances

•Digest particles with enzymes in lysosomes

Types of phagocytes

Macrophages

Neutrophils

Eosinophils

Macrophages-

derived from monocytes found in tissues

Eosinophils-

weak phagocytes, defend against parasitic worms

Neutrophils-

Become phagocytic upon encountering foreign substance

Phagocyte Mobilization

Leukocytosis > Margination > Diapedesis > Chemotaxis

Chemotaxis

•Inflammatory chemicals recruit neutrophils to precise location

•Monocytes follow Neutrophils and develop into Macrophages

Stimulate cell growth and maturity

Diapedesis

Neutrophils squeeze through capillary wall

Margination

Neutrophils travel to inflamed site, stick to capillary wall

Leukocytosis

•Injured cells produce leukocytosis-inducing factors, causes neutrophil release from bone marrow

Phagocytosis 5 stages

•Chemotaxis

•Adherence

•Ingestion

•Digestion

•Killing

During ingestion of a microbe during phagocytosis, the phagocyte releases

Pseudopods Which are cell surface projections that wraps around microbe and form a vesicle containing the microbe

Nonspecific Defenses

2. Natural killer (NK) cells

•Type of lymphocyte, found in blood and lymph

•Lyse and kill a variety of cancer cells and virus-infected cells

•(not specific)

•Release chemicals called perforins that cause the target cell to disintegrate

•Secrete chemicals that enhance inflammatory response

Nonspecific Defenses

3. Inflammatory response

Response to tissue damage, includes pain, redness, immobility, swelling, and heat (PRISH)

Inflammatory response

Injured cells release these chemicals

Histamines, kinins, prostaglandins, complement, and cytokines

Inflammatory response

Chemical effects

•Blood vessels dilate causing hyperemia-redness and heat

•Exudate seeps out of capillaries-fluid with clotting factors and antibodies, swelling and pain

•Chemotaxis - attract phagocytes and WBCs

Nonspecific Defenses

3.Inflammatory response effects

a)Prevents spread of damage (clotting factors)

b)Disposes of cell debris and pathogens

•Neutrophils and Monocytes squeeze through blood vessels (diapedesis) to damaged area to clean debris

c)Sets stage for repair (fibrin mesh)

Inflammatory Responses

•Pus

•Acute inflammation

•Chronic inflammation

•Abscesses and Ulcers

Nonspecific Defenses

4. Antimicrobial Chemicals

Interferon (IFN) proteins

Proteins produced by virus-infected cells

•diffuse to nearby cells to induce synthesis of antiviral proteins –prevent replication

Genetically engineered IFNs used to combat Hepatitis C, herpes, and viral infections in organ transplants

Antimicrobial Chemicals

Interferon (IFN) proteins effects

•Cause uninfected cells to produce the enzyme PKR protein that interferes with virus replication

•Activate Macrophages and NK cells

Antimicrobial Chemicals

Complement proteins

•20-30 plasma proteins in blood

•Amplify inflammatory response, cause cell lysis, promote phagocytosis

Complement fixation-

attachment of protein to foreign body, activates the protein

Membrane Attack Complexes-

formed by complement fixation, proteins form holes in cell membrane for lysis. Non cellular means of poking holes into a cell

Opsonization

(coating of microbe)-causes membranes to become sticky, easier for adherence (phagocytosis)

Nonspecific Defenses

5. Fever

•Abnormally high body temp.

•Pyrogens-chemicals secreted by WBCs and macrophages, cause body temp. to increase

•Mild to moderate fever

•Liver and spleen gather iron and zinc, bacteria need these nutrients to multiply

•Increases metabolic rates to

High fever-

dangerous due to denaturation-proteins (enzymes) break down

Innate vs adaptive defense photo

3rd line of defense-Immune Response to Antigens - Characteristics

•Antigen specific

•Systemic-not restricted to initial infection site

•Memory-mounts stronger attacks on previously encountered pathogens

Adaptive Immunity (SPECIFIC)

refers to the body’s ability to defend itself against specific invading agents (bacteria, viruses, transplants, self-cells that have mutated)

Antigens are substances recognized as foreign that provoke immune responses (ANTIbody GENerating)

Adaptive immunity has both specificity and memory and is divided into 2 types

Cell-mediated; T cells mature in the thymus produced in bone marrow

Antibody-mediated: B cells mature in the bone marrow humorous

Self-antigens-

proteins found on our cells, don’t usually activate immune response

Self-antigens-proteins found on our cells, don’t usually activate immune response

•Major histocompatibility complex

•Human leukocyte antigens

•May be antigenic to other people (transplants)