lymphatic system Flashcards
Lymph flows from
lymphatic capillaries, –>
lymphatic vessels –>
circulatory system
via
lymphatic ducts
at junction of the jugular and subclavian veins in the neck.
how is lymph formed?
Lymphatic capillaries, aka terminal lymphatics: vessels where interstitial fluid enters lymphatic system to become lymph fluid. Located in almost every tissue in the body, interlaced among arterioles and venules of the circulatory system
where are there NO lymph vessels?
CNS central nervous system,
bone marrow,
bones,
teeth, and
the cornea of the eyes
what is bile
carbs and proteins, amino acid can be absorbed thru the walls
fats cannot be absorbed.
bile duct brings bile from liver and gb to emulsify fat, so it can go through wall of intestine.
this emulsified fat is picked up by the lymphatic system
Lymphatic vessels
The lymphatic capillaries empty into larger lymphatic vessels
similar to veins
three-tunic structure and
valves located fairly close to one another
The superficial and deep lymphatics eventually merge to form larger lymphatic vessels known as lymphatic trunks.
R Lymphatic Duct drains from..
R Lymphatic Duct - Drain lymph fluid from the upper right side of the body -
the right sides of the head,
thorax, and
right upper limb
and then into the right subclavian vein
Thoracic Duct
Thoracic Duct - larger than the R lymphatic duct -
drains the left side of the body
and the remaining portions of the body
which then drains into the left subclavian vein.
The thoracic duct begins just beneath the diaphragm
in the cisterna chyli, a sac-like chamber that receives lymph from the
lower abdomen,
pelvis, and
lower limbs
by way of the left and right lumbar trunks and the intestinal trunk.
3 phases of immune system
three phases based on the timing of their effects.
1) Barrier defenses
skin and mucous membranes,
act instantaneously to prevent pathogenic invasion into tissues
2) innate immune response
rapid but nonspecific
variety of specialized cells and soluble factors
3) adaptive immune response,
slower but more specific and effective
many cell types and soluble factors
primarily controlled by white blood cells (leukocytes) known as lymphocytes, which help control immune responses
The cells of the blood, including all those involved in the immune response, arise in the…
The cells of the blood, including all those involved in the immune response, arise in the
bone marrow
via various differentiation pathways from
hematopoietic stem cells.
immune cell types
Three classes based on function:
1) Phagocytic cells ingest pathogens to destroy them
2) Lymphocytes, coordinate adaptive immunity
3) Cells containing cytoplasmic granules mediate immune responses against parasites and intracellular pathogens such as viruses
Lymphocytes
Primary cells of the adaptive immune system
B lymphocytes
and
T lymphocytes
both have large central nucleus surrounded by a thin layer of cytoplasm.
distinguished from each other by their
surface protein markers &
the molecules they secrete.
B cells mature in red bone marrow
T cells mature in the thymus
both initially develop from bone marrow.
B cells and T cells circulate in the bloodstream and lymph
reside in secondary lymphoid organs, including the spleen, tonsils and lymph nodes,
B Cells
produce antibodies.
An antibody is any of the group of proteins that binds specifically to pathogen-associated molecules known as antigens.
An antigen is a chemical structure on the surface of a pathogen that binds to T or B lymphocyte antigen receptors.
Once activated by binding to antigen, B cells differentiate into cells that secrete a soluble form of their surface antibodies. These activated B cells are known as plasma cells.
Plasma Cells
B cell that has differentiated in response to antigen binding
& gained the ability to secrete soluble antibodies.
differ from B and T cells
contain a large amount of cytoplasm
packed with the protein-synthesizing rough endoplasmic reticulum.
T Cells
does not secrete antibody
adaptive immune response fx
Different T cell types have the ability to either
secrete soluble factors that communicate with other cells of the
adaptive immune response or
destroy cells infected with intracellular pathogens.
Takes part in cell-mediated immunity (part of adaptive immune response)
Natural Killer Cells (NK Cells)
A participant in the innate immune response.
circulating blood cell that contains cytotoxic (cell-killing) granules in its extensive cytoplasm. It shares this mechanism with the cytotoxic T cells of the adaptive immune response.
NK cells are among the body’s first lines of defense against
viruses and certain types of cancer.
The primary lymphoid organs are
bone marrow
and
thymus gland.
The lymphoid organs are where lymphocytes mature, proliferate, and are selected, which enables them to attack pathogens without harming the cells of the body.
Being able to recognize self from non-self = tolerance and “training” of immune cells takes place in the thymus early in life
Bone Marrow immune fx
Bone Marrow - In the embryo, blood cells are made in the yolk sac. As development proceeds, this function is taken over by the spleen, lymph nodes, and liver. In adults, the bone marrow takes over most hematopoietic functions, although the final stages of the differentiation of some cells may take place in other organs.
The B cell undergoes nearly all of its development in the red bone marrow, whereas the immature T cell, called a thymocyte, leaves the bone marrow and matures largely in the thymus gland.
Thymus Gland immune fx
Thymus Gland - a bilobed organ found in the space between the sternum and the aorta of the heart.
cortex contains large numbers of thymocytes with some epithelial cells, macrophages, and dendritic cells (two types of phagocytic cells that are derived from monocytes).
medulla, where thymocytes migrate before leaving the thymus, contains a less dense collection of thymocytes, epithelial cells, and dendritic cells.
Secondary Lymphoid Organs
lymph nodes, spleen, and lymphoid nodules
Lymphocytes develop and mature in the primary lymphoid organs, but they mount immune responses from the secondary lymphoid organs.
A naïve lymphocyte is one that has left the primary organ and entered a secondary lymphoid organ. They are fully functional immunologically, but have yet to encounter an antigen to respond to.
In addition to circulating in the blood and lymph, lymphocytes concentrate in secondary lymphoid organs, which include the lymph nodes, spleen, and lymphoid nodules.
Lymph nodes function
remove debris and pathogens from the lymph
“filters of the lymph”
Any bacteria that infect the interstitial fluid are taken up by the lymphatic capillaries and transported to a regional lymph node.
Dendritic cells and macrophages within this organ internalize and kill many of the pathogens that pass through, thereby removing them from the body.
site of adaptive immune responses mediated by T cells, B cells, and accessory cells of the adaptive immune system.
spleen lymphatic fx
about 12 cm (5 in) long
attached to the lateral border of the stomach via the gastrosplenic ligament.
The spleen is a fragile organ without a strong capsule
dark red due to its extensive vascularization.
“filter of the blood”
presence of macrophages and dendritic cells that remove microbes and other materials from the blood, including dying red blood cells.
The spleen also functions as the location of immune responses to blood-borne pathogens.
Within each splenic nodule is
an area of red pulp, consisting of mostly red blood cells
filtration system of the blood, using cells of the relatively nonspecific immune response,
white pulp,
which resembles the lymphoid follicles of the lymph nodes.
where adaptive T and B cell responses are mounted.
Tonsils
Lymphoid nodules located along the inner surface of the pharynx and are important in developing immunity to oral pathogens.
Histologically, tonsils do not contain a complete capsule, and the epithelial layer invaginates deeply into the interior of the tonsil to form tonsillar crypts. These structures, which accumulate all
sorts of materials taken into the body through eating and breathing, actually “encourage” pathogens to penetrate deep into the tonsillar tissues where they are acted upon by numerous lymphoid follicles and eliminated.
The lymphatic tissues located in the oropharynx are composed of a circumferential tonsillar ring, known as the Waldeyer’s ring which consists of the
palatine tonsils,
adenoid (nasopharyngeal tonsil),
lingual tonsil, and
tubal tonsils.
When patients and doctors discuss tonsils, they are often referring to the palatine tonsils located at the back of the throat between the two palatine arches (pillars).
Mucosa Associated Lymphoid Tissue (MALT)
An aggregate of lymphoid follicles directly associated with the mucous membrane epithelia. MALT makes up dome-shaped structures found underlying the mucosa of the gastrointestinal tract, breast tissue, lungs, and eyes.
BALT = bronchial associated
NALT = nasopharynx associated
GALT = gut associated
SALT = skin associated
Gut Associated Lymphoid Tissue (GALT)
The GALT is the largest and best defined part of MALT - roughly 70%!
Gut-associated lymphoid tissue is comprised of Peyer’s patches, interdigitating lymphocytes, plasma cells and lymphocytes present in the lamina propria, and mesenteric lymph nodes.
The role of GALT is to manage the immune response to the massive antigen exposure experienced by the gut while maintaining a potent adaptive immune response to protect the host from mucosal pathogens.
Innate system: barrier defenses
Prevent pathogens from entering the body, destroy them after they enter, or flush them out before they can establish themselves in the hospitable environment of the body’s soft tissues.
Barrier defenses are part of the body’s most basic defense mechanisms. continuously working to protect against a broad range of pathogens.
Skin - the primary barrier to the entrance of microorganisms into the body. Not only is the skin covered with a layer of dead, keratinized epithelium that is too dry for bacteria in which to grow, but as these cells are continuously sloughed off from the skin, they carry bacteria and other pathogens with them.
Additionally, sweat and other skin secretions may lower pH, contain toxic lipids, and physically wash microbes away.
types of barrier defenses
Saliva - is rich in lysozyme—an enzyme that destroys bacteria by digesting their cell walls.
Acidic environment of the stomach - low pH makes bacteria surviving unlikely
Mucus layer of the gastrointestinal tract, respiratory tract, reproductive tract, eyes, ears, and nose traps both microbes and debris, and facilitates their removal. In the case of the upper respiratory tract, ciliated epithelial cells move potentially contaminated mucus upwards to the mouth, where it is then swallowed into the digestive tract, ending up in the harsh acidic environment of the stomach.
phagocytes
cell that is able to surround and engulf a particle or cell, a
process called phagocytosis. The phagocytes of the immune system engulf other particles or cells, either to clean an area of debris, old cells, or to kill pathogenic organisms such as bacteria. The phagocytes are the body’s fast acting, first line of immunological defense against organisms that have breached barrier defenses and have entered the vulnerable tissues of the body.
mechanism of destroying pathogens during innate immune responses.
The phagocyte takes the organism inside itself as a phagosome, which subsequently fuses with a lysosome and its digestive enzymes, effectively killing many pathogens.
which cells are phagocytic
Macrophages,
neutrophils, and
dendritic cells
are the major phagocytes of the immune system.
macrophages
irregularly shaped phagocyte
amoeboid
most versatile of the phagocytes in the body
Macrophages move through tissues and squeeze through capillary walls using pseudopodia.
innate immune responses
and cooperate with lymphocytes
adaptive immune response as well
freely roaming through connective tissues or
fixed to reticular fibers within specific tissues such as lymph nodes.
When pathogens breach the body’s barrier defenses, macrophages are the first line of defense.
They are called different names, depending on the tissue:
Kupffer cells in the liver
histiocytes in connective tissue, and
alveolar macrophages in the lungs.
neutrophil
phagocytic cell that is attracted via chemotaxis from the bloodstream to infected tissues.
spherical
type of granulocyte: contains cytoplasmic granules, which in turn contain a variety of vasoactive mediators such as histamine.
reinforcements that are called into a battle to hasten the destruction of the enemy.
Usually thought of as the primary pathogen-killing cell of the inflammatory process of the innate immune response
- most often against bacteria.
monocyte
circulating precursor cell that differentiates into either a
macrophage or dendritic cell
can be rapidly attracted to areas of infection by signal molecules of inflammation.
soluble mediators
chemical signals that can induce cells to change various physiological characteristics, such as the expression of a particular receptor.
These soluble factors are secreted during both innate and adaptive immune responses.
Cytokine
Cytokine is signaling molecule that allows cells to communicate with each other over short distances.
Cytokines are secreted into the intercellular space
induces the receiving cell to change its physiology.
ex. inflammation
chemokine
Chemokine is a soluble chemical mediator
similar to cytokines
attract cells (chemotaxis) from longer distances.
early induced proteins
those that are not constitutively present in the body
made as needed early during the innate immune response.
ex. Interferons
Cells infected with viruses secrete interferons that travel to adjacent cells and induce them to make antiviral proteins.
Thus, even though the initial cell is sacrificed, the surrounding cells are protected.
Other early induced proteins specific for bacterial cell wall components:
mannose-binding protein and C-reactive protein (CRP), made in the liver, which bind specifically to polysaccharide components of the bacterial cell wall. Phagocytes such as macrophages have receptors for these proteins, and they are thus able to recognize them as they are bound to the bacteria. This brings the phagocyte and bacterium into close proximity and enhances the phagocytosis of bacterium by the process known as opsonization: tagging of a pathogen for phagocytosis by the binding of an antibody or an antimicrobial protein.
inc. in CRP = inflammation, because it’s induced by tissue damage
The complement system
not cells, but substances
series of proteins constitutively found in the blood plasma.
not considered part of the early induced immune response
Made in the liver,
variety of functions in the innate immune response, using what is known as the “alternate pathway” of complement activation.
The complement system consists of several proteins that enzymatically alter and fragment later proteins in a series, which is why it is termed cascade.
Once activated, is irreversible, and releases fragments that have the following actions:
- Bind to the cell membrane of the pathogen that activates it, labeling it for phagocytosis (opsonization)
- Diffuse away from the pathogen and act as chemotactic agents to attract phagocytic cells to the site of inflammation
- Form damaging pores in the plasma membrane of the pathogen
Inflammatory Response - main goals
innate immune response = inflammation.
infection and/or tissue damage -> inflammation
The inflammatory reaction brings in phagocytic cells to the damaged area to clear cellular debris and to set the stage for wound repair.
This reaction also brings in the cells of the innate immune system, allowing them to get rid of the sources of a possible infection.
brings fluid and cells into the site to destroy the pathogen and remove it and debris from the site,
helps to isolate the site, limiting the spread of the pathogen.
4 characteristics of inflammation
four characteristics: heat, redness, pain, and swelling
(and loss of function)
Acute vs. chronic
Acute inflammation
short-term inflammatory response to an insult to the body.
caused by allergic reactions, infections, trauma injury. pathogen or injured tissue
cells: neutrophils, mononuclear cells (monocytes, macrophages)
Chronic inflammation
ongoing inflammation and is associated with major tissue destruction and fibrosis.
It can be caused by persistent acute inflammation, foreign bodies, persistent pathogens, and autoimmune reactions.
cells: mononuclear cells (monocytes, macrophages, lymphocytes, plasma cells, fibroblasts)
4 phases of inflammatory response
1) Tissue Injury. The released contents of injured cells stimulate the release of mast cell granules ex histamine (vessel dilation and permeability), leukotrienes (recruit neutrophils), prostaglandins (vasodilation)
2) Vasodilation - causes increased blood flow and is responsible for the heat and redness of inflamed tissue.
3) Increased Vascular Permeability - leakage of fluid into the interstitial space, resulting in edema
4) Recruitment of Phagocytes - Leukotrienes attract neutrophils from the blood to the site of infection by chemotaxis. Following an early neutrophil infiltrate stimulated by macrophage
cytokines, more macrophages are recruited to clean up the debris left over at the site. When local infections are severe, neutrophils are attracted to the sites of infections in large numbers, and as they phagocytose the pathogens and subsequently die, their accumulated cellular remains are visible as pus at the infection site
- important to clear out the pus if it’s not dispelling naturally
adaptive immune system: Primary vs. secondary immune response
immunological memory
Self recognition
T-cell mediated responses
Antigens & Antigen presenting cells
MHC Classes - which MHC relates to which types of cells
T Cell Development and Differentiation
Cellular basis of immunological memory
T Cell types and functions - Helper T cells, Cytotoxic cells, Tregs
B-Cell Mediated responses
Antibodies defined - antibody structure and know 4 types of Abs
Class switching and importance
B Cell differentiation and activation, clonal selection of B cells
Primary vs. secondary B cells responses
Active vs. Passive immunity
