lymphatic capillaries -> 

merge to form larger lymphatic vessels ->

which merge to form lymphatic trunks ->

which merge to form lymphatic ducts ->

which empty into the subclavian veins

Central Nervous System

CNS has splenic pulp and bone marrow

they have valves

walls are composed of three layers

 have more valves

walls are thinner

 contain lymph nodes

lumbar - lower limbs (legs), wall of viscera of pelvis, kidneys, liver, spleen, adrenal gland

intestinal-Intestines, abdomen, stomach, pancreas

bronchomediastinal- lung & heart

subclavian- arms

jugular - head & neck

Thoracic Duct

Right Lymphatic Duct

larger and longer duct.

Begins at the cisternae chyli at the level of the 2nd lumbar vertebra

approx 18" in length

empties into the left suclavian vein

drains the left side of the head, left neck, left thorax, left arm, and all areas below

is 1/2" in length 

drains the right side of the head, right neck, right arm, and right thorax

empties into right subclavian vein

1. carry protein to blood stream

2. carry foreign particles to lymph nodes

3. protection

4. carry fats to liver

1.  contraction of skeleton muscles

2. pressure change due to action of breathing muscles

3. contraction of smooth muscle in walls of large vessels

1. bean shaped structures less than one inch in length.

2. has indented region called hilum which allows blood vessels, nerves and efferent vessels to exit.

3. afferent vessels enter on convex side and efferent vessels exit on concave side.

4. capsule - white, fibrous, connective tissue that encloses node

Anatomy of a node (internal)

 1. capsule

2. stroma

3. parenchyma

stroma

parenchyma

is divided into two regions

a. cortex

b. medulla

cortex

composed of densely packed lymphocytes called lymph nodules. Nodule contains germinal center where lymphocytes produced.

medulla

center portion of node containing lymphocytes arranged in strands called medullary cords.

Passage of lymph through node

1. Lymph enters node through afferent vessels

2. Lymph passes to cortical sinus under capsule and travels around nodule to medulla

3. Lymph passes out efferent vessel from medulla

Lymph enters node through what?

Lymph passes to cortical sinus under where and travels where?

Lymph passes out of what vessel?

efferent vessel from medulla

Functions of lymph nodes

1.  Filtration and phagocytosis

2. Hemopoiesis

Hemopoiesis

Nodes give rise to lymphocytes

Thymus

Primary, central organ of lymphatic system. Is single organ composed of two pyramidal shaped lobes, each divided into lobules. Is largest at puberty (40 g.) but atropies with age and is replaced with connective tissue from capsule. Lobules are divided into cortex and medulla, both composed of connective tissue.

Functions of thymus

1. processes T-lymphocytes

2. produces thymosin which stimulates maturation of T-lymphocytes after they leave the thymus

Spleen

Largest mass of lymphatic tissue in the body (5 inches),

located in upper left portion of abdominal cavity beneath diaphragm and behind stomach.

Is soft, vascular structure that can be distended by blood filled sinuses

Anatomy of spleen

1. resembles large lymph node

2. has hilus for passage of splenic artery, splenic vein, and efferent lymphaatic vessel

3. enclosed in connective tissue capsule that invaginates and divides organ into lobules

4. lobules are composed of two types of pulp

1. White Pulp

2.  Red Pulp

distributed throughout spleen in tiny islands and composed of packed lymphocytes and macrophages around a central artery

 1. removal of old red blood cells and platelets

2. storage of platelets (up to one-third of platelets stored here

 3. production or red blood cells during fetal development

Spleen acts as a blood

Tonsils

multiple aggregates of lymphatic nodules embedded in mucous membrane.

Location of Tonsils

arranged in ring at junction or oral cavity and pharynx

Types of tonsils

1. pharyngeal tonsil - posterior wall of    nasopharynx

2. palatine tonsils - lateral walls

3. lingual tonsils - located at base of tongue

Tonsils produce

lymphocytes and antibodies to protect against invasion of foreign substances

Lymphatic Nodules

oval-shaped concentrations of lymphatic tissue that are not surrounded by a capsule. Scattered throughout the lamina propria of mucous

membranes lining the intestinal, urinary, and reproductive tracts and the respiratory

airways.

Infection

 condition caused by presence of some kind of disease causing agent (pathogen)

Non-specific Resistance

inherited ability of body to react to many different types of organisms in a variety of ways

Non-specific Resistance (8)

1. species resistance

2. mechanical factors

3. chemical factors

4. Antimicrobial Substances

5. Inflammation

6. Fever

7. phagocytosis

8. Natural Killer Cells

enzymes in various body fluids

a. gastric juice contains pepsin & HCl

b. lysozyme found in tears

c. acidic pH of skin

4. Antimicrobial Substances

a. Interferon

b. Complement

c. Properdin

Interferon

name given to group of proteins produced by certain cells, including lymphocytes, host cells, and fibroblast in response to presence of viruses. Causes uninfected cells to make protein which keeps virus from replicating in cell

Complement

group of 20 proteins found in serum that works against bacterial infections.

Functions of Complement

1. initiates activities leading to cell lysis

2. promotes opsonization

3. releases histamine which makes capillaries permeable and contributions to inflammation

4. chemotactic agent

Properdin

protein complex that acts with complement to destroy bacteria, enhance phagocytosis, and trigger inflammatory response

Inflammation

symptoms are redness, swelling, pain and fever

Fever

inhibits microbial growth

 phagocytosis

  most active phagocytic cells are neutrophils and monocytes

 Natural Killer Cells

 lymphocytes which lack specific receptors and attack cells that display abnormal plasma membrane proteins (MHC complex).

Specific Resistance

also called immunity - resistance to specific foreign agents such as pathogens or toxins they release. Involves immune mechanisms in which certain cells recognize presence of particular foreign substance and act to eliminate them. Both T and B lymphocytes are responsible for immunity.

Antigen

Characteristics of complete antigens

a. immunogenicity - ability to stimulate the formation of antibodies.

b. reactivity - ability of antigen to react specifically with antibody

10,000 or more

Antigens have a molecular weight of

Antigen may have several antigenic determinant sites (valence)

Antigen may have several antigenic determinant sites (valence)

 hapten

If antigen has only one determinant site

If antigen has only one determinant site it is called a hapten and

and has reactivity but not mmunogenicity.

Many allergic reactions may be caused by a

hapten that changes.

Three ways antigens enter lymphatic tissue

 a. antigens usually travel from blood stream to spleen

b. antigens that penetrate the skin travel to a lymph node

c. antigens that penetrate mucous membranes lodge in lymph nodules

Antibody

 protein produced by body in response to presence of antigen and is capable of combining with the antigen

Characteristics of an antibody

a. Most antibodies are bivalent (two determinant sites)

b. Antibodies are gamma globulins

c. Are composed of 4 chains, 2 heavy chains and 2 light chains

d. Each antibody has a constant portion that changes for each class of antibody, and a variable portion that is different for each antibody.

IgG - 80% -

Numbers increase during the secondary immune response.

Found in tissue fluid and plasma. Works against bacterial cells, viruses, toxins by enhancing phagocytosis, and neutralizing toxins. This antibody protects the newborn

IgA

secretions of exocrine glands. Found in tears, saliva, mucus, lymph, blood, and milk. Works against bacterial cells and viruses by providing localized protection of mucosal surfaces. Stress causes a decrease in numbers. Makes up approx. 13% of antibodies. Found in mothers’ milk.

 IgM

 primary immune response. Appear first and short-lived. Largest antibodies. Plasma reacts with antigen on RBC's following transfusions.

Causes agglutination and lysis

IgD

found in blood and lymph on the surface of B lymphocytes. May stimulate antibody producing cells to make antibodies.

IgE

found in secretions of exocrine glands and cause allergic reactions. Promotes inflammation reactions and may be excessive and harmful to tissues.

Types of Allergic Reactions

Delayed allergic reaction

Immediate allergic reaction

Delayed allergic reaction 

may take 48 hours and may occur in anyone. Results from repeated exposure of skin to chemical substances. T-

lymphocytes activated by non-self substances and T cells enter skin and cause certain chemicals to be released which cause inflammation.

Immediate allergic reaction

reaction occurs within minutes. Person has inherited ability to make abnormally large amounts of immunoglobulin E in response to certain antigens.

Types of Lymphocytes causing specific resistance

T-lymphocyte

B-lymphocytes

T-lymphocyte

 Lymphocytes originally processed in the thymus. After being processed they travel through the blood and congregate in lymphatic tissue. The

thymus stimulate the maturation of the T-lymphocyte by releasing thymosin. Once activated by a specific antigen, the T cell differentiates into sub-groups.

Cytotoxic T

migrate to site of invasion and secrete cytotoxic substances. These destroy the antigen directly

Helper T-cells

 Give off interleukin- 2 which is needed by the cytotoxic T cells. Helper T cells

Helper T cells

l. release transfer factor which reacts with non-sensitized lymphocytes in area and sensitize them.

2. They release chemotactic factor which attracts macrophages.

3. They release macrophage activating factor which

ncreases macrophage activity.

4. Migration inhibition factor is released to keep the WBC's in the area

Memory T

recognize antigen when person infected during secondary immune response

What cells are responsible for CELL MEDIATED IMMUNITY

T cells

CELL MEDIATED IMMUNITY

specially sensitized lymphocytes have capacity to attach to foreign agent and destroy it.

B-lymphocytes

 Activated helper T cell binds with activated B cell and releases lymphokines.

What hormone action of stimulate B cells to proliferate?

lymphokines

The hormone action of lymphokines stimulate B cells to proliferate and give rise to

Plasma cells

secrete 2000 antibodies per second per cell for the 4 to 5 days cell lives. Memory B cells may circulate for years.

What cells are responsible for HUMORAL IMMUNITY

B Memory cells

What immunity takes place in the blood and is caused by antibodies

Humoral immunity

Types of Immune Responses

Primary Immune Response 

Secondary Immune Response

Primary Immune Response

 response occurring when antigen first encountered

 Secondary Immune Response

  subsequent response of body in which antibodies respond rapidly due to memory T and memory B cells

Types of Immunity

Naturally acquired active immunity

Artificially acquired active immunity

Artificially acquired passive immunity

Naturally acquired passive immunity

Naturally acquired active immunity

 Person is exposed to live pathogen, develops

disease and becomes resistant due to primary immune response

Artificially acquired active immunity

Person is given vaccine which can stimulate primary immune response against particular disease but is unable to produce symptoms of disease.

Artificially acquired passive immunity

Injection of gamma globulins. Is passive because antibodies are not produced by recipient's cells

Naturally acquired passive immunity

 fetus immune for 6-12 months due to antibodies from mother