lymphatic system Flashcards
lymphatic system
consists of lymphatic vessels and lymphoid organs
**closely associated with the cardiovascular system
lymphatic vessels/system
take up extra tissue fluid and return to to the blood stream
lymphatic capillaries absorb fats and transport them to the blood stream
lymphatic system helps with immunity to defend the body against disease
flow of lymphatic capillaries
the lymph flows one way
from lymphatic capillary system to the subclavian veins –
Where it joins Venous circulation to return to the heart
fluid begins in the interstitial fluid between the cells
most BUT NOT ALL of the fluid is returned to the heart via the veins of the cardiovascular system
fluid that is not returned through the veins of the cardiovascular system enters the lymphatic capillaries and flows into a lymphatic vessel
Lymphatic capillaries
lymphatic capillaries are closely connected to the capillaries of the cardiovascular system
lymph capillaries take up plasma fluid, which under great pressure, has been forced out of the capillaries of the circulatory system and has not been reabsorbed
this fluid bathes the cells assisting the capillaries with delivering oxygen, glucose, salts, amino acids, and other nutrients
excess tissue fluid entering the lymphatic capillaries is now called LYMPH
Lymph
excess tissue fluid entering the lymphatic capillaries is now called lymph
lymph flows from the lymphatic capillaries into larger lymphatic vessels until it eventually empties into venous blood of the cardiovascular system
Lymphatic vessels
extend throughout most sections of the body
have a one way flow valves similar in structure to the large veins of the cardiovascular system
the valves prevent back flow of lymph
the return of the lymph fluid into circulation is solely dependent on the squeezing action of skeletal muscles
**squeezing fluid one way through the lymphatic vessels
thoracic duct
All the lymphatic vessels merge before entering the venous circulation at either the thoracic duct (aka left lymphatic duct) or the right lymphatic duct, both located in the region on the human body
lymph then flows from the thoracic duct into the left subclavian vein (of the cardiovascular system
the right lymphatic duct drains into the right subclavian vein of the cardiovascular system.
Larger thoracic duct
the larger thoracic duct drains from both lower extremities, the abdomen, the left arm, the left side of both the head and neck
Right lymphatic duct
is smaller than the thoracic duct
the smaller right lymphatic duct is smaller and drains fluid from the right arm, the right side of both neck and head, and the right thoracic region
lymphoid organs
including the lymph nodes, spleen, thymus gland, and tonsils
the body has hundreds of lymph nodes which are found at junctions of lymphatic vessels
lymph node
is encapsulated in a fibrous connective tissue with many incoming and fewer outgoing lymphatic vessels
acts as a filtering center which rid the flowing lymph of infectious organisms and other debris as it passes through a series of sinuses (cortical, subscapular, medullary
Incoming vessels
Afferent vessels
flow through a network of sinuses that contain cells
a lymph then flows out of the lymph node through the efferent vessel
Efferent vessels
the lymph flows out of the incoming vessel and flows out of the lymph node through the efferent vessel
nodules
the anterior of the lymph node id divided into open spaces called nodules, containing lymphocytes and macrophages
Axilla (armpit) and groin
lymph nodes tend to be grouped together in regions of the body, particularly the axilla and groin regions
The spleen
in the upper left abdomen. The spleen functions to extract old or defective blood cells and platelets
the spleen also removes debris, foreign matter, bacteria, viruses, and toxins from blood that flows through it
encapsulated in a thin, fragile fibrous connective tissue with an incoming splenic artery and an outgoing splenic vein
interior divided into open spaces called lobules
lobules
the interior of the spleen is divided into open spaces called lobules containing lymphocytes and macrophages that carry out the functions of the spleen
splenic artery
blood enters the spleen via the splenic artery
splenic vein
blood leaves via the splenic vein
which flows to the hepatic portal vein (also called hepatic portal system)
hepatic portal vein
the hepatic portal system carries blood drained from the veins of the spleen, intestines, stomach, and pancreas to liver
the hepatic portal vein transports blood in to the liver where it is detoxified before returning to the general circulation
thymus gland
is located on the anterior surface of the heart
the thymus secretes thymosin and thymopoietin hormones which enable T lymphocytes to mature and function as part of the immune system
What does the thymus gland secrete
thymosin and thymopoietin - both of these enable T lymphocytes (T cells to mature) and function as part of the immune system
What do T cells do?
mature t cells attack body cells, which are cancerous or infected with pathogens
When is the thymus most prominent?
thymus is most prominent in newborns and becomes larger during childhood when it is most active. Growth of the thymus stops in adolescence and then glands withers away to a mass of fibrous fatty tissue by old age
Tonsils
a group of small lymphoid organs in the lateral, posterior portions of the throat
tonsils gather and destroy bacteria inhaled in food and air
lymphoid tissue of the tonsils have is invaginated by channels called crypts which trap bacteria and foreign matter
Crypts
lymphoid tissue of the tonsils is invaginated by channels called crypts which trap bacteria and foreign matter
The bacteria then work their way into the lymphoid tissue where most are destroyed.
non-specific immune system
innate immune system
serves as first line of defense through chemical and physical barriers to prevent pathogens from entering the body
the response is the same to ALL threats that attempt to enter the body
It is a generalized defense that rapidly destroys large numbers of pathogens
These are quick compared to specific immunity which takes several days to work
specific immune system (adaptive immune system)
takes several days to activate
the specific immune system is targeted and extremely effective against pathogens
The main lymphocytes involved in the specific immune responses are B and T cells
The skin and the lymphatic system
The skin is part of the innate (non-specific) immune system
very few pathogens can penetrate the intact human skin
tears and sweat produce an environment on which only good bacteria can grow, called normal flora
normal flora
beneficial bacteria that produce lactic acid, which inhibits pathogenic (disease causing) bacteria
how does the stomach and respiratory system deal with pathogens
microorganisms entering the stomach are destroyed by stomach acids and digestive enzymes and digestive secretions
pathogens entering the respirtory system are trapped by muscus membranes and then brought up to the throat to be spit out or swallowed and killed in stomach acid
inflammatory response
part of the non-specific immune system
inflammatory response is a localized response in the tissue. Inflammation increases blood flow to infected regions causing swelling
swelling-
tissue swelling dilates blood vessels in the infected area to help increase the number of immune cells responding to the infection
the increase of blood also causes redness and pain, helping bring a conscious awareness of the infection
cytokines
circulate within the blood, which are not cells but rather secreted proteins
cytokines help regulate and signal both the specific and non-specific immune systems.
what are the two main groups of cytokines
Interluekins and interferons
Interferons - Inhibit viral replication and assist in activating Natural killer cells
Interleukins - functions as chemical activators, sending signals throughout the body to increase the immune response
there are many subtypes of interleukins that function to activate different types of immune cells
pyrogens
a subtype of interleukin called pyrogens reset the thermostat in the hypothalamus - the temperature set-point (homeostasis) is raised to create a fever
Fevers
fevers help the body fight infection by interfering with the growth and replication of pathogens
Fevers also cause lysosomes to breakdown -the lysosomes release digestive enzymes that lyse (destroys) a cell affected by a virus
fevers can promote the activity of white blood cells
mild fevers with a short duration can assist in recovery
white blood cells
aka leukocytes are divided into two major categories - agranulocytes and granulocytes
granulocytes have granules in the cytoplasm
agranulocytes do not carry granules
ganulocytes
have granules in the cytoplasm
include neutrophils, esioinophils, basophils
all granulocytes are capable of phagocytosis
neutrophils
are the most abundant white blood cell
neutrophils are responsible for fighting infections, especially those that involve bacteria
neutrophils use phagocytosis to the ingestion of foreign materials
it can recognize a pathogen by its cell surface receptors
the neutrophil binds to the pathogen and brings it inside the cell forming a vacuole
Have a short lifespan
vacuole and neutrophils
the neutrophil binds to the pathogen and brings it inside the cell forming a vacuole
the vacuole fuses with cells lysosomes, which release digestive enzymes to destroy the pathogen
once the pathogen is destroyed the contents is released from the cell
phagocytosis
phagocytosis protects the body by engulfing and destroying pathogens
neutrophils have a short life span and die quickly after the pathogen is ingested
neutrophils life span and outcomes
neutrophils have a short life span and die quickly after the pathogen is ingested
after death neutrophils exit the body as pus (white fluid)
neutrophils under the microscope
have multi lobed nucleus and when stained have light pink granules in their cytoplasm
eosinophils
respond to allergic reactions and parasitic infections. They are similar in appearance to neutrophils, except their granules stain a darker pink to red
are less commonly seen -because we are not always fighting off a parasitic infection
as a granulocyte, eosinophils are also capable of phagocytosis
basophils
are the rarest type of granulocyte and are also capable of phagocytosis
these are involved in the release of histamines and heparin
histamines are a vasodialator, which increase blood flow through the dilation of vessels and capillaries
heparin is a blood anticoagulant which helps prevent the formation of blood clots
have a similar morphology shape to neutrophils and eosinophils, but their granules stain dark purple/blue
monocytes
monocytes are a type of agranulocytosis
monocytes- are large white blood cells with a u shaped/kidney shape nucleus
these can move into tissues and are then called macrophages -monocytes and macrophages are the greatest phagocytes of all the blood cells
these are more effective than neutrophils because they live longer and have greater phagocytic ability
Three major types of lymphocytes
T cells, B cells , and natural killer cells
the specific immune response depends on the activity of lymphocytes.
lymphocytes functions include making antibodies, attacking foreign cells, and destroying body cells that have lost normal function
have dark nucleus with little cytoplasm
main lymphocytes involved are B and T cells
B cells
millions of B cells (bone marrow derived) are produced in bone marrow daily
Each B cells is genetically programed to produce a glycoprotein receptor as part of its cell coat
each receptor binds with a specific type of antigen
an antigen is any molecule that can be specifically recognized as foreign by the immune system.
B- cells become activated when an antigen binds with its receptor -then called plasma cell
plasma cell
Once activated a B cell is called a plasma cell and begins to rapidly divide
antibodies (immunoglobulins)
each plasma cell produces antibodies (immunoglobulins) , which is a soluble form of glycoprotein receptor from B cells surface
there are 5 categories of immunoglobulins
5 types of immunoglobulins
IgG, IgE, IgD, IgM, IgA
these are the 5 major types of immunoglobulins released by B cells, each with a different purpose in the body
what happens after an antibody is released?
the antibody binds to the invading antigen to cause it to be inactive or mark it for destruction
phagocytes (cells able to carry out phagocytosis can identify the marked cell and engulf it through phagocytosis
memory B cells
some activated B cells become memory B cells, which continue to produce a small amount of antibody even after the infection is over
if the same pathogen enters the body again, the antibody immediately binds with the antigen
they can produce a specific antibody much faster and targets it for destruction at a much faster rate the second time a pathogen invades the body
anti-body mediated immunity
b-cells work in this method called anti-body mediated immunity (humoral response).
This defends the body against pathogens through the secretions of antibodies
the antibodies bind to the pathogen, making it unable to cause further damage in the body marking it for phagocytosis
T cells
thymus dependent cells
originate in bone marrow but mature in the thymus gland
T-cells work through what is called cell-mediated immunity
cell mediated immunity
Instead of using antibodies, cell mediated immunity releases contents such as cytokines or enzymes to kill a pathogen or infected cell
cell mediated immunity also includes direct cellular action, such as phagocytosis by other white blood cells
antigen receptors
T-cells contain antigen receptors that bind to a specific glycoproteins in cell membranes
Killer T-cells
aka cytotoxic T cells -recognize and destroy invading cells containing foreign antigens
killer T cells attack virus-infected cells or cells infected with cancer cells by releasing cytokines and enzymes locally to lyse the cell
helper T cells
secrete substances that activate or enhance immune responses
B cells require an interaction with helper T cells before they can begin rapid division
Natural killer cells
also originate in the bone marrow. Natural killer cells seek out abnormal body cells and destroy them
This makes NK cells highly effective against tumor cells
major histocompatabilty complex (MHC)
the glycoprotein surface receptors on all the cells of the body are called MHC
The MHC enables the immune system to determine what cells are the body’s cells and what cells are foreign.
cells of the body also have a way od displaying through MHC complex if there’s is something abnormal within the cell (such as cancer)
killer T cells (cytotoxic T cells) recognize and destroy invading cells through this self or not self recognition of the MHC complexes on each cell
T cells and antigen receptors
T cells contain antigen receptors that bind to specific glycoproteins in cell membranes.
Each person has a genetically unique surface cell receptor present on all the cells of the body in the cell membranes
Graft rejection
is the rejection of a transplanted organ by an organ donor
tissue grafts and organ transplants most often originate from another person’s body
The MHC on the surface of the graft are recognized by the host body as a foreign pathogen
an identical twin can donate to a sibling without any complications
however, most people will need immune suppressant drugs
immune surprenant drugs
these are given after a graft or organ transplant to suppress the immune system
this is necessary so that the body does not reject the organ transplant or tissue graft
while taking these drugs a person is more susceptible to disease and illnesses
Autoimmune disease
When lymphocytes launch an attack against a person’s own body it is called an autoimmune disease
this occurs when antibodies and T cells attack the body’s own tissues
ex. rhumatoid arthritis, multiple sclerosis
rheumatoid arthritis
T cells attack the synovial lining inside joints
T cells produce interleukins, which cause inflammation inside the joints systemically (body wide)
multiple sclerosis
an autoimmune disease where antibodies attack and or prevent formation of the myelin sheath around nerve cells resulting in muscular weakness
allergic reactions
in allergic reactions antibodies are produced against mild antigens called allergens
these allergens are typically common in the environment factors such as pollen, or dust mites
many people that display allergies have some type of genetic predisposition to this type of body reaction.
allergic reactions vary from person to person but generally have red/watery eyes, sneezing, runny nose, and headache
anaphylaxis
an excessive immune response to an allergen, called aniphylaxis
a severe life threatening allergic reaction against a pathogen, insect reaction, or drug
antibodies are overproduced by B cells
these circulating antibodies increase capillary permeability throughout the body
Some symptoms include hives and anaphylaxis shock, narrow respirtory pathways, causing difficulty breathing
hives
raised red bumps
anaphylactic shock
a person’s capillaries become so dilated it causes their blood pressure to drop too low, leading to collapse
A person can die from anaphylactic shock because their heart stops beating or their airway passages completely close, so the person can no longer breathe.
epinephrine auto injector
people who have severe allergic reactions should always carry an epipen
when aniphylactic shock begins to occur the epipen is injected into the thigh to release the hormone epinephrine into the bloodstream
epinephrine helps to offset the symptoms of anaphylaxis, constricting blood vessels and raising blood pressure
edema
an accumulation of too much fluid in tissues can cause localized swelling called edema
lymphedema
lymphodema is a specific form of edema where the lymphatic system is not functioning properly to return fluid back to circulation
a lymph vessel can become blocked, or lymph nodes can be removed for testing causing difficult with lymph drainage
the interstitial fluid slowly accumulates in the limb and it becomes extremely swollen and distended
lymphedema can become a serious condition if left untreated because the swollen tissues are vulnerable to infection.
if left untreated the connective tissues and vessels become permanently stretched and distended
tonsilitis
inflammation of the tonsils. The tonsils become infected and appear white or bacterial infection
