14 - Lymphatic System and Immunity Flashcards Preview

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Define a pathogen.

Any substance or microorganism that causes disease or damage to the tissues of the body is considered a pathogen.


What are the three functions of the lymphatic system?

1. Fluid balance
2. Lipid absorption
3. Defence.


How is fluid balance a part of the lymphatic system functions?

About 30 liters of fluid pass from the blood capillaries into the interstitial spaces each day, whereas only 27L pass from the interstitial spaces back into the blood capillaries. The remaining fluid enters the lymphatic capillaries, and it passes through the lymphatic vessels to return to the blood.


How is lipid absorption a part of the lymphatic system functions?

The lymphatic system absorbs lipids and other substances from the digestive tract through lymphatic vessels called lacteals located in the lining of the small intestine. Lipids enter the lacteals and pass through the lymphatic vessels to the venous circulation. The lymph passing through these lymphatic vessels appears white because of its lipid content and is called chyle.


How is defence a part of the lymphatic system functions?

Pathogens, such as microorganisms and other foreign substances, are filtered from lymph by lymph nodes and from blood by the spleen. In addition, lymphocytes and other cells are capable of destroying pathogens. Because the lymphatic system is involved with fighting infections, as well as filtering blood and lymph to remove pathogens, many infectious diseases produce symptoms associated with the lymphatic system.


What is the structure of lymphatic capillaries?

The lymphatic capillaries are tiny, close-ended vessels consisting of simple squamous epithelium. They are more permeable than blood capillaries because they lack a basement membrane.


How is backflow of fluid in the lymph prevented?

By overlapping squamous cells in the capillary walls. They act as valves.


Lymphatic capillaries are present in most tissues of the body. Exceptions are ...

The CNS, bone marrow, and tissues lacking blood vessels, such as the epidermis and cartilage.


The lymphatic vessels converge and eventually empty into the what

The blood.


The lymphatic vessels converge and eventually empty into the blood at two locations in the body. Where?

Lymphatic vessels from the right upper limb and the right half of the head, neck and chest form the right lymphatic duct, which empties into the right subclavian vein. Lymphatic vessels from the rest of the body enter the thoracic duct, which empties into the left subclavian vein.


What are the lymphatic organs?

The lymphatic organs include:
1. The tonsils
2. The spleen
3. The thymus


What is spleen in norwegian?



What is thymus in norwegian?



The tonsils are plural. Why?

There are three groups of tonsils!


What are the three groups of tonsils?

1. The palatine tonsils
2. The pharyngeal tonsil
3. The lingual tonsil


What is the adenoid, or the adenoids?

This is a common name for the pharyngeal tonsil when it is enlarged.


Where are the palatine tonsils?

The palatine tonsils are located on each side of the posterior opening of the oral cavity.


Which tonsils are normally referred to as "the tonsils"?

The palatine tonsils.


Where is the pharyngeal tonsil?

The pharyngeal tonsil is located near the internal opening of the nasal cavity. When the pharyngeal tonsil is enlarged, it is commonly called the adenoid, or adenoids.


Where is the lingual tonsil?

The lingual tonsil is on the posterior surface of the tongue.


What is lymphatic tissue?

Lymphatic tissue is a tissue type that consists of many lymphocytes and other cells, such as macrophages, and is found within lymphatic organs.


What are lymph nodes?

Lymph nodes are rounded structures, varying from the size of a small seed to that of a shelled almond. Lymph nodes are distributed along the lymphatic vessels, and most lymph passes through at least one lymph node before entering the blood.


Although lymph nodes are found throughout the body, there are three superficial aggregations of lymph nodes on each side of the body. Where are these three? (six)

1. The groin
2. The armpit
3. The neck


As lymph moves through the lymph nodes, two functions are performed. Which?

1. Activate the immune system
2. Remove pathogens from the lymph.


How can the lymph nodes "activate the immune system?"

Pathogens in the lymph can stimulate lymphocytes in the lymphatic tissue to divide. The lymphatic nodules containing the rapidly dividing lymphocytes are called germinal centres. These newly produced lymphocytes are released into the lymph and eventually reach the blood.


How large, and where is the spleen located?

The spleen is roughly the size of a clenched fist and is located in the left superior corner of the abdominal cavity.


How is the spleen structured?

The spleen has an outer capsule of dense connective tissue and a small amount of smooth muscle. Trabeculae from the capsule divide the spleen into small, interconnected compartments containing two specialised types of lymphatic tissue. White and red pulp.


What is the difference between the two types of lymphatic tissue in the spleen?

White pulp is lymphatic tissue surrounding the arteries within the spleen. Red pulp is associated with the veins.


What is the function of the spleen?

The spleen filters blood. Cells within the spleen detect and respond to foreign substances in the blood and destroy worn-out red blood cells. The spleen also functions as a blood reservoir, holding a small volume of blood.


What is the function of the white pulp?

The lymphocytes in the white pulp can be stimulated in the same manner as in lymph nodes.


What is the function of the red pulp?

Macrophages in the red pulp remove foreign substances and worn-out red blood through phagocytosis.


What is the size and location of the thymus?

The thymus is a bilobed gland roughly triangular in shape. It is located in the superior mediastinum, the partition dividing the thoracic cavity into left and right parts.


What is the function of the thymus?

The thymus is the site for the maturation of a class of lymphocytes called T cells. Large numbers of T cells are produced in the thymus, but most degenerate. The T cells that survive the maturation process are capable of reacting to foreign substances.


Where do the pre-B cells mature?

In the red bone marrow.


Where do the pre-T cells mature?

In the thymus.


Where do the pre-B and pre-T cells originate?

In the red bone marrow.


What is immunity?

Immunity is the ability to resist damage from pathogens, such as microorganisms; harmful chemicals, such as toxins released by microorganisms; and internal threats, such as cancer cells.


Immunity is categorised how?

1. Innate immunity
2. Adaptive immunity.


Adaptive immunity has two characteristics that innate immunity does not have. Which?

1. Specificity and memory.


Innate immunity is accomplished by ... (4)

1. Physical barriers
2. Chemical mediators
3. White blood cells
4. Inflammatory response.


Innate immunity is accomplished by physical barriers. Explain.

The skin and mucous membranes form barriers that prevent their entry. Pathogens cannot cause a disease if they cannot get into the body.


Innate immunity is accomplished by chemical mediators. Explain.

Lysozyme in tears and saliva kills certain bacteria, and mucus on the mucous membranes prevents the entry of some pathogens. Other chemical mediators, such as histamine, complement, prostaglandins, and leukotrienes promote inflammation by causing vasodilation and stimulating phagocytosis.


What is complement?

Complement is a group of more than 20 proteins found in plasma. The operation of complement proteins is similar of that of clotting proteins. Once activations begins, a series of reactions result, in which each complement protein activates the next. Once activated, certain complement proteins promote inflammation and phagocytosis and can directly rupture bacterial cells.


What is interferons?

Interferons are proteins that protect the body against viral infections. Infected cells often produce interferons. These bind to the surface of neighbouring cells, and stimulate those cells to produce antiviral proteins. "Save yourselves"-proteins.


Name the different white blood cells you need to know (6)

1. Neutrophils
2. Macrophages
3. Basophils
4. Mast cells
5. Eosinophils
6. Natural killer (NK) cells.


What are neutrophils?

A type of white blood cell. Neutrophils are small phagocytic cells that are usually the first cells to enter infected tissues fromt the blood in large numbers. They release chemical singlas that increase the inflammatory response by recruiting and activating other immune cells. Neutrophils often die after phagocytizing a single microorganism. Pus is an accumulation of fluid, dead neutrophils, and other cells at a site of infection.


What are macrophages?

A type of white blood cell. Macrophages are monocytes that leave the blood, enter tissues, and enlarge about fivefold. Macrophages can ingest more and larger items than neutrophils. They are responsible for most of the phagocytic activity in the later stages of an infection, including cleaning up dead neutrophils and other cellular debris.


What are basophils?

A type of white blood cell. Basophils, which are derived from red bone marrow, are motile white blood cells that can leave the blood and enter infected tissues. When activated, they release chemicals such as histamine and leukotrienes, that produce an inflammatory response or activate other mechanisms, such as smooth muscle contraction in the lungs.


What are Mast cells?

Mast cells are nonmotile cells in connective tissue, especially near capillaries. Like macrophages, mast cells are located at points where pathogens may enter the body, such as the skin, gastrointestinal tract, and urogenital tract. When activated, they release chemicals such as histamine and leukotrienes, that produce an inflammatory response or activate other mechanisms, such as smooth muscle contraction in the lungs.


What are natural killed (NK) cells?

NK cells recognise classes of cells, such as tumor cells or virus-infected cells, in general, rather than specific tumor cells or cells infected by a specific virus. NK cells use a variety of methods to kill their target cells, including releasing chemicals that damage cell membranes and cause the cells to lyse.


What are antigens?

Antigens are substances that stimulate adaptive immune responses.


Antigens can be divided into two groups. Which?

Foreign antigens and self-antigens.


What are foreign antigens?

Foreign antigens are introduced from the outside of the body.


What are self-antigens?

Self-antigens are molecules the body produces to stimulate an immune system response.


There are two types of immunity. Which?

1. Antibody-mediated immunity
2. Cell-mediated immunity


What is antibody-mediated immunity?

... involves a group of lymphocytes called B cells and proteins called antibodies. Antibodies are derived from plasma cells, which are derived fromt the B cells.


What is cell-mediated immunity?

... involves the actions of a second type of lymphocyte, called T cells. Several subpopulations of T cells exist. Cytotoxic T cells produce the effects of cell-mediated immunity, and helper T cells can promote or inhibit the activities of both antibody-mediated immunity and cell-mediated immunity.


For the adaptive immune response to be effective, two events must occur. Which?

1. Antigen recognition by lymphocytes
2. Proliferation of the lymphocytes recognising the antigen.


What are MHC molecules?

Major histocompatilibity complex molecules (MHC) are glycoproteins that have binding sites for antigens. It is important not to confuse the MHC molecules with the antigen receptors on lymphocytes. MHC molecules are found on the membrane of many types of cells. The MHC molecules function as "serving trays" that hold and present a processed antigen on the other surface of the cell membrane.


After the antigen is processed and presented to a ...... cell by a macrophage.

helper T cell


After the antigen is processed and presented to a helper T cell cell by a macrophage, the helper T cell responds by producing ...

Interleukin-2 and interleukin-2 receptors.


After the antigen is processed and presented to a helper T cell cell by a macrophage, the helper T cell responds by producing Interleukin-2 and interleukin-2 receptors. Interleukin-2 binds to the receptors and stimulates the helper T cell to ...



After the antigen is processed and presented to a helper T cell cell by a macrophage, the helper T cell responds by producing Interleukin-2 and interleukin-2 receptors. Interleukin-2 binds to the receptors and stimulates the helper T cell to divide. The "daughter" helper T cells produced by this division can again be presented with the antigen by macrophages and again be stimulated to divide. Thus the number of helper T cells is greatly increased. Why is it important for the number of helper T cells to increase?

It is important for the number of helper T cells to increase because helper T cells are necessary for the activation of most B cells or T cells.


What causes B-cell proliferation?

B-cell proliferation begins when a B cell takes in the same kind of antigen that stimulated the helper T cell. The antigen is processed by the B cell and presented on the B-cell surface by an MHC class II molecule.


As a result of stimulation by the antigen on the MHC class II molecules, the B cells divides into two "daughter" cells. These daughter cells may differentiate into ... that do...

Plasma cells which can produce antibodies.


What are antibodies?

Antibodies are proteins produced in response to an antigen.


Where in the body will you find antibodies?

In the blood plasma.


Mention alternative names for antibodies.

Antibodies are sometimes called gamma globulins, because they are found mostly int he gamma globulin part of plasma, or immunoglobulins (Ig), because they are globulin proteins involved in immunity.


What are the effects of antibodies on antigens?

1. They are able to inactivate the antigen.
2. They are able to bind antigens together
3. The constant region of antibodies can activate complement and release of inflammatory chemicals from mast cells and basophils.


Production of antibodies is different from the first exposure to subsequent exposure. How is the second exposure different?

1. The time required to start producing antibodies is less
2. More plasma cells and antibodies are produced.

This response is so fast that no disease symptoms develop.


What is a monoclonal antibody?

A monoclonal antibody is a pure antibody preparation that is specific for only one antigen. Monoclonal antibodies are grown in laboratories and have many clinical uses. They are used for determining pregnancy and for diagnosing diseases.


Why is antibody-mediated immunity insufficient against viral infections?

While inside the cell, viruses have a safe haven from antibody-mediated immunity because antibodies cannot cross the cell membrane.


How does cell-mediated immunity work?

When viruses infect cells, some viral proteins are broken down and become processed antigens that are combined with MHC class I molecules and displayed on the surface of the infected cell. Cytotoxic T cells can distinguish between virally infected cells and noninflected cells because the T-cell receptor can bind to the MHC class I/antigen complex, which is not present on uninfected cells.


What is immunotherapy?

Immunotherapy treats disease by altering immune system function or by directly attacking harmful cells. Some approaches attempt to boost immune system function in general.


Give an example of immunotherapy.

Monoclonal antibodies.


What is lymphadenitis?

Inflammation of the lymph nodes; nodes become enlarged and tender as pathogens are trapped and destroyed.


What is lymphangitis?

Inflammation of the lymphatic vessels; often results in visible red streaks in the skin that extend from the site of infection.


What is bubonic plague?

Enlarged lymph nodes caused by bacterial infection (transferred by flee bites from rats); without treatment, bacteria enter the blood and death occurs rapidly due to septicaemia; known as the black death in the middle ages.


What is lymphedema?

Abnormal accumulation of lymph in tissues, often the limbs; 70%-90% cases in women; can be caused by developmental defects, disease, or damage to the lymphatic system.


What is lymphoma?

Cancer of lymphocytes that often begins in lymph nodes; immune system becomes depressed, with increased susceptibility to infections.


What is Asthma?

Antigen combines with antibodies on mast cells or basophils in the lungs, which then release inflammatory chemicals that cause constriction of the air tubes, so the the patient has trouble breathing.


What is Anaphylaxis?

Systemic allergic reaction, often resulting from inect stings or drugs such as penicillin; chemicals released from mast cells and basophils cause systemic vasodilation, increased vascular permeability, drop in blood pressure, and possible death.


What is prevalence?

Prevalence in epidemiology is the proportion of a population found to have a condition (typically a disease or a risk factor such as smoking or seat-belt use). It is arrived at by comparing the number of people found to have the condition with the total number of people studied, and is usually expressed as a fraction, as a percentage or as the number of cases per 10,000 or 100,000 people.


What is point prevalence?

Point prevalence is the proportion of a population that has the condition at a specific point in time.


What is lifetime prevalence?

Lifetime prevalence (LTP) is the proportion of a population that at some point in their life (up to the time of assessment) have experienced the condition.[1]


What is incidence?

Incidence is a measure of the probability of occurrence of a given medical condition in a population within a specified period of time.