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204 Cards in this Set

  • Front
  • Back
The organs of the lymphatic system also
defend the body against infx by disease causing agents
Lymphatic capillaries
are microscopic, closed end tubes that extend into interstitial space, The walls of lymphatic capillaries are similar to blood capillaries, The thin walls of capillaries make it possible for tissue fluid from interstitial space to enter the lymphatic capillaries
Lymph is fluid
inside a lymphatic capillary
The lymphatic system
is a vast collection of cells that travel in lymphatic vessels & the organs & glands that produce them.
The lymphatic system includes a network of
vessels that assist in circulating body fluids
Lymphatic vessels transport
excess fluid away from interstitial spaces & return it to the bloodstream
The organs of the lymphatic system also
defend the body against infx by disease causing agents
Lymphatic capillaries
are microscopic, closed end tubes that extend into interstitial space, The walls of lymphatic capillaries are similar to blood capillaries, The thin walls of capillaries make it possible for tissue fluid from interstitial space to enter the lymphatic capillaries
Lymph is fluid
inside a lymphatic capillary
Lacteals are
lymphatic capillaries in the lining of the small intestine
fx to transport fats to the venous system.
Lymphatic Vessel walls
similar to those of veins, Lymphatic vessels have valves that prevent backflow of lymph
Larger lymphatic vessels
lead to lymph nodes
After leaving nodes, lymphatic vessels merge
in larger lymphatic trunks
Lymphatic trunks drain
lymph from lymphtic vessels & are named for the regions they serve Examples of lymphatic trunks are lumbar, intestinal, intercostal, bronchomediastinal, subclavian, & jugular trunks
Lymphatic trunks join
one of two collecting ducts
The two collecting ducts are
the thoracic duct & right lymphatic duct
The thoracic duct is located
along side the aorta in the abdominal & thoracic cavity & empties into the left subclavian vein
The thoracic duct drains
lymph from the intestinal, lumbar, & intercostal trunks, as well as from the left subclavian, left jugular, & left bronchomediastinal trunks
The right lymphatic duct is located
on the right side of the thorax & empties into the right subclavian vein
The R lymphatic duct drains
right jugular, right subclavian, & R bronchomediastinal trunks
After leaving the 2 collecting ducts, lymph enters
venous sys & becomes part of the plasma
Lymph is
tissue fluid that has entered a lymphatic capillary, Lymph formation depends on tissue fluid formation
Tissue Fluid Formation

Capillary blood pressure filters water & small molecules from plasma & the resulting fluid consists of water, nutrients, gases, & hormones (a similar composition to plasma)Water is drawn back into capillaries because of plasma colloid osmotic pressure
Lymph Formation
Filtration from plasma normally exceeds reabsorption, leading to the formation of tissue fluid. Tissue fluid moves into lymphatic capillaries because of interstitial fluid hydrostatic pressure. 3. Lymph formation prevents edema.
Lymph fx
1. Lymphatic vessels in the small intestine play a major role in the absorption of dietary fats.
2. Lymph returns small proteins that most of the blood capillaries filtered to the bloodstream.
3. Lymph transports foreign particles to lymph nodes.
Lymphatic capillaries
can receive proteins & foreign particles that blood capillaries cannot because the epithelial cells that form the walls of lymphatic vessels overlap each other but are not attached.
The lumen of a lymphatic capillary remains
open because their epithelial cells are attached to surrounding connective tissue cells by protein filaments.
The hydrostatic pressure of tissue fluid
drives lymph into lymphatic capillaries
Muscular activity
largely influences movement of lymph through lymphatic vessels.
Lymph is under relatively
low hydrostatic pressure
Contracting skeletal muscles
compress lymphatic vessels.
Lymph does not flow back because
of valves
Breathing aids lymph circulation by
creating a relatively low pressure in the thorax & a relatively high pressure in the abdomen during inhalation
Conditions that interfere w/lymph mvmnt causes fluid to
accumulate within interstitial spaces
The continuous movement of lymph from interstitial spaces into blood capillaries & lymphatic capillaries
stabilizes the volume of fluid in interstitial spaces.
Lymph nodes are located
along lymphatic pathways
Lymph nodes contain
lymphocytes & macrophages which fight invading microorganisms
The hilum of a lymph node is
the indented region
Afferent lymphatic vessels
are those that carry lymph to a node
Efferent lymphatic vessels
are those that carry lymph away from a node
Lymph nodules
are divisions of a lymph node
Germinal centers
contain dense masses of actively dividing lymphocytes & macrophages
composed of partially encapsulated lymph nodules
Peyer’s patches
are located in the mucosal lining of the distal portion of the small intestine & are composed of M cells, macrophages, & lymphocytes
Lymph sinuses
are a network of chambers & channels through which lymph circulates.
Locations of Lymph Nodes
Lymph nodes generally occur in groups or chains along the paths of larger lymphatic vessels but are absent in the central nervous systems.
Major locations of lymph nodes are cervical region, axillary region, supratrochlear region, inguinal region, pelvic cavity, abdominal cavity, & thoracic cavity.

Lymph nodes of the cervical region are associated with
lymphatic vessels that drain the skin of the scalp & fact, as well as tissues of the nasal cavity & pharynx.

Lymph nodes of the axillary region are associated with
lymphatic vessels that drain the upper limbs, wall of the thorax, mammary glands, & upper abdominal wall.

Lymph nodes of the supratrochlear region are associated with
lymphatic vessels that drain the elbow region.

Lymph nodes of the inguinal region are associated with
lymphatic vessels that receive lymph from the lower limbs, external genitalia, & lower abdominal wall.

Lymph nodes of the abdominal cavity are associated with
lymphatic vessels that drain the abdominal viscera.

Lymph nodes of the thoracic cavity are associated with
lymphatic vessels that drain thoracic viscera & the internal wall of the thorax
The two primary fxs of lymph nodes are

to filter potentially harmful particles from lymph & to monitor body fluids.

Along with the red bone marrow, lymph nodes are centers for
lymphocyte production
Lymphocytes attack
viruses, bacteria, & other parasitic cells.
The fxs of macrophages are to engulf & destroy foreign substances, damaged cells, & cellular debris
is composed of lymphocytes & connective tissues & is located in the mediastinum
After puberty, the thymus
begins to shrink
Most cells of the thymus gland are
The hormones secreted by the thymus gland are called
Thymosins fx
to stimulate maturation of T lymphocytes
The largest lymphatic organ
The spleen is located
in the upper left portion of the abdominal cavity
The spleen resembles
a large lymph node
White pulp contains
many lymphocytes
Red pulp contains
red blood cells, lymphocytes, & macrophages
The fxs of the spleen
to remove foreign particles, damaged red blood cells, & cellular debris from the blood.
An infection
is the presence of pathogens
Examples of pathogens are
bacteria, protozoa, fungi & viruses
Innate defenses
are general defenses & protect against many types of pathogens & include species resistance, mechanical barriers, chemical barriers, enzyme actions, interferon, complement, natural killer cells, inflammation, phagocytosis, & fever
Adaptive defenses are
very precise defense mechanisms targeting specific pathogens & are carried out by lymphocytes
Species resistance
refers to the fact that a given kind of organism or species develops diseases that are unique to it
A species may be resistant to diseases that affect others because
its tissues somehow fail to provide the temperature of chemical environment that a particular pathogen requires
Mechanical barriers
prevent the entrance of some infectious agents
Examples of mechanical barriers are
skin, mucous membranes, & hair.
The first line of defense is
a mechanical barrier
The second line of defense is
a collection of the other nonspecific defenses.
Chemical barriers
are body fluids containing enzymes or antimicrobial substances
Examples of chemical barriers are
gastric juice, interferons, defensins, & collectins
is produced by lymphocytes & fibroblasts & its fxs include stimulation of phagocytosis, & to prevent viral infections
are produced by white blood cells, & certain epithelial cells.
The fxs of defensins are
to make holes in bacterial cells walls & to destroy certain pathogens
are proteins
Collectins fxs include
protect the body against viruses, bacteria, & yeasts.
is a group of proteins in plasma & other body fluids that interact in a series of reactions
Activation of complement
stimulates inflammation, attracts phagocytes, & enhances phagocytosis.
Natural killer cells
are a small population of lymphocytes
fxs of natural killer cells
are to protect the body against cancer & viruses
Perforins are cytolytic substances are secreted by
natural killer cells.
Inflammation produces
redness, swelling, heat & pain
Redness of inflammation is the result of
dilated blood vessels
Swelling of inflammation is the result of
increases capillary permeability
Heat of inflammation is the result of
the entry of blood from deeper body parts
Pain of inflammation is the result of
stimulation of pain receptors
Cells that commonly migrate to areas of inflammation are
neutrophils & monocytes
is the result of an accumulation of white blood cells, bacterial cells, & cellular debris
The fxs of inflammation
are to prevent the spread of infection, to clear infection, & to promote healing of damaged tissues
removes foreign particles
Examples of phagocytic cells are
neutrophils, monocytes, & macrophages.
Mononuclear phagocytic system is
monocytes, macrophages, & neutrophils that are spread throughout the body
A fever begins when a viral or bacterial infection
stimulates lymphocytes to produce interleukin
The fxs of fever
to increase phagocytosis & to prevent bacteria & other pathogens from obtaining iron
resistance to particular pathogens or to their toxins or metabolic by products
An immune response is based on
the ability to distinguish molecules that are part of the body from those that are foreign
are molecules that can elicit an immune response.
Cells that carry out immune responses
Lymphocytes & macrophages
Receptors on lymphocyte surfaces
enable cells to recognize foreign antigens
Antigens may be

proteins, polysaccharides, glycoproteins, or glycolipids

The antigens most effective in eliciting an immune response is
large & complex, with few repeating parts
a small molecule that must bind to a larger molecule to elicit an immune response
Examples of haptens
are chemicals found in drugs, household cleaners, dust, & skins of certain animals.
T cells are derived from
red bone marrow & the thymus gland
B cells are derived from
red bone marrow
The blood distributes
B cells
B cells & T cells
are abundant in lymph nodes, the spleen, bone marrow, & the intestinal lining
Lymphocyte fxs

1. The cellular immune response is cell to cell contact between a T cell & antigen cell.
2. Cytokines are produces by T cells
Examples of cytokines
are interleukins, colony stimulating factors, interferons, & tumor necrosis factors
fxs of cytokines
are to stimulate the production of lymphocytes, block viral replication, stimulate phagocytosis, stimulate production of antibodies, & to stop growth of tumor cells
T cells may also secrete
toxins that kill antigen bearing cells, growth inhibiting factors that prevent target cell growth, or interferon that prevent viral & tumor cell proliferation
B cells differentiate into
plasma cells
Plasma cells produce
The humoral immune response
is the immune response that is mediated by antibodies
A clone is
a cell that is identical to the cell from which it was derived
Different varieties of T cells & B cells have
a particular type of antigen receptor on their cell membranes that can respond only to a specific antigen
A lymphocyte must be activated before
it can respond to an antigen
T cell activation requires
the presence of processed fragments of antigen attached to the surface of another kind of cell
Antigen presenting cells
are macrophages, B cells, & other cell types.
T cell activation begins
when a macrophage phagocytizes a bacterium & moves the antigens of the bacterium to its membrane
The major histocompatibility complex
is a complex of proteins found on the surface of antigen presenting cells
MHC antigens help
T cells recognize an antigen as foreign
Class I MHC antigens are located
on cell membranes of all cells except red blood cells
Class II MHC antigens are located
on cell membranes of antigen presenting cells, thymus cells, & activated T cells
The fxs of helper T cells are
to stimulate B cells to produce antigens & to secrete cytokines
The fxs of cytotoxic T cells are
to eliminate viral infected cells & tumor cells
The fxs of memory T cells are
to respond to an antigen during a future exposure & to differentiate immediately into cytotoxic T cells
B cells may become activated when
an antigen binds to its membrane bound receptor
Upon activation, B cells
divide repeatedly
T cells help B cells by
releasing cytokines that stimulate B cell proliferation & antibody production
The fxs of memory B cells
are to respond rapidly to subsequent exposures to a specific antigen
The fxs of plasma cells are
to secrete antibodies
An immune response may include several types of antibodies manufactured against a single microbe because
pathogens often have different antigens on their surfaces
A polyclonal response
is the production of several different antibodies against one pathogen
Antibodies are
soluble, globular proteins
Each antibody composed of
four chains of amino acids that are linked together
The light chains are
identical & contain about half the number of amino acids as the heavy chains
The heavy chains are
identical & contain twice as many amino acids as the light chains
The five major types of antibodies are distinguished by
a particular kind of heavy chain
The variable region is
the part of the antibody that contains variable sequences of amino acids
Variable regions
are specialized to react to the shape of a specific antigen molecule
Antigen binding
sites are specialized ends of antibodies that bind to antigens
are the particular parts of antigen binding sites that actually bind to antigens.
Constant regions
are the parts of an antibody other than their variable regions
The five major types of immunoglobulins are
IgG, IgA, IgM, IgD, & IgE
The three types of immunoglobulins that make up the bulk of circulating antibodies are
IgG, IgA, & IgM
is found in tissue fluid & plasma
The fxs of IgG
to defend against bacterial, viruses, & toxins; it also activates complement
IgA is found
in exocrine gland secretions
The fxs of IgA
are to defend against bacteria & viruses
IgM is found
in plasma
The fxs of IgM
to react with antigens occurring on red blood cells & to activate complement
IgD is found
in the cell membranes of B cells
The fxs of IgD
to act as receptors for B cells
IgE is located
in exocrine gland secretions
The fxs of IgE
to promote inflammation & allergic reactions
The three ways antibodies react to antigens
directly attack antigens, activates complement, or stimulate localized changes (inflammation) that help prevent the spread of the pathogen
In a direct attack, antibodies combine with
antigens & cause them to clump
Phagocytic cells
can engulf antigen bearing pathogens more readily when they have clumped together
Antibodies can also
cover the toxic portions of antigens & neutralize their effects
Complement is activated by
the binding of certain antibodies to antigens
fxs of complement
opsonization, chemotaxis, cell lysis, & inflammation.
IgE antibodies are usually attached
to membranes of mast cells
Mast cells release their biochemicals when
antigens combine to antibodies on their surfaces
The primary immune response
occurs when a person is first exposed to an antigen
Following a primary immune response, some B cells produce
memory cells
The secondary immune response occurs when
a person is later exposed to an antigen & memory cells are activated
Naturally acquired active immunity
develops when a person is naturally exposed to an antigen
Artificially acquired active immunity
develops when a person is given a vaccine
A vaccine
a preparation that includes a antigen that stimulate a primary immune response
Artificially acquired passive immunity
occurs when a person is injected with antibodies or anti toxins
Naturally acquired passive immunity
occurs when antibodies are passed across the placenta or through mother’s milk
Allergic reaction
is an immune response against a nonharmful substance
Allergens are
substances that trigger allergic reactions
An immediate reaction allergy
occurs when an allergens bind to IgE antibodies & allergy mediators are released from mast cells & basophils
Anaphylactic shock
is a severe form of immediate reaction allergy that may lead to death
Antibody dependent cytotoxic reactions
occur when an antigen binds a specific cell, simulating phagocytosis & complement mediated lysis of the antigen
Immune complex reactions
occur when antigen antibody complexes cannot be cleared from the body
refers to the loss of the ability to tolerate self antigens
A delayed reaction allergy
occurs when a person is repeatedly exposed to an allergen & the allergic reaction occurs about 48 hours after exposure to the antigen
Transplanted tissues & organs include
corneas, kidneys, lungs, pancreases, bone marrow, skin, livers, & hearts
A tissue rejection reaction
is the destruction of transplanted tissue by the recipient’s immune system
Tissues are rejected because
the cell surface molecules (MHC antigens) of the donor tissue are recognized as foreign by the recipient
are grafts from an identical twin
are grafts from one’s self
are grafts from another person
are grafts from a different species
Immunosuppressive drugs
are used to reduce rejection of transplanted tissues
Autoantibodies are
antibodies that cannot distinguish self from nonself
Reasons people develop autoimmunities are
viruses may incorporate some self proteins into its coating & the body then recognizes the self proteins as foreign in all cells, T cells may never learn to differentiate between self & nonself cells, or some antigens may resemble self antigens
is a condition caused by autoimmunity that produces fatigue, swollen joints, stiff fingers, hardened blood vessels, & a mask like face
The immune system begins to decline
early in life
By age 70, the thymus
is one tenth of its original size
Elderly people have a higher risk of developing cancer & infections because
the strength of their immune systems has declined
AIDS is more difficult to diagnose in older people because
physicians do not initially suspect the condition
Elderly people may not be candidates for certain medical treatments because
of their declining immune systems.