What are the functions of the lymphatic system?
fluid recovery, immunity, lipid absorption
How does the lymphatic system contribute to fluid recovery?
fluid is filtered from blood capillaries to the tissues and the lymphatic system is responsible for picking this water back up ad transporting it back to blood.
What could happen if there's even partial damage to the lymphatic drainage
lymphedema
How does the lymphatic system assist with immunity?
as the lymphatic system picks up fluid it also picks up foreign cells and chemicals from the tissues and takes them to the lymph nodes where an immune response will occur
What happens in the lymph nodes?
Lymphoid tissue destroys antigens and activates T and B cells
How does the lymphatic system help with lipid absorption?
in the small intestine small lymphatic vessels called lacteals absorb dietary lipids
What are the components of the lymphatic system?
lymph, lymphatic vessels, lymphatic tissue, lymphatic organs
What is lymph?
a colorless fluid containing white blood cells, that bathes the tissues and drains through the lymphatic system into the bloodstream.
What does lymph flow through?
lymphatic vessels (lymphatics)similar to blood vessels
How are blood capillaries and lymphatic capillaries different?
the lymphatic have dead-ends at the end of them whereas the blood cap connects to either the veins or the arteries.
What is the structure of a lymph vessel?
loosely overlapping endothelial cells (think like shingles on a roof) NOT joined by tight junctions and they do not have a continuous basal lamina. gaps are so large that the bacteria, lymphocytes and other larger molecules can enter.
how does lymph work with circulatory
draws excess fluid from the cells and deposits it into blood vessels
How does the lymph vessels diffuse fluid?
the overlapping edges of the cells next to each other act as valves that can open as pressure inside the vessel becomes too high and close as it drops back down
What are the layers of the lymphatic vessels?
tunica interna: endothelium and valves tunica media: elastic fibers, smooth muscle tunica externa: thin outer layer
What is the path the fluid takes through the lymphatic system?
lymphatic capillaries- collecting vessels-11 lymphatic trunks- two collecting ducts- subclavian veins
How is a collecting vessel formed?
as the lymphatic capillaries converge
What forms when the collecting vessels come together?
lymphatic trunks
What happens when lymphatic trunks converge?
collecting ducts are formed
How is the right lymphatic duct formed?
convergence of right jugular, subclavian and bronchomediastinal trunks. receives drainage from right arm, right thorax and right head
Where does the right lymphatic drain?
subclavian vein
How is lymphatic fluid moved?
by pressure in the interstitial space and the milking action of skeletal muscle contractions and respiratory movements
Neutrophils
are aggressively antibacterial leukocytes
natural killer cells
Large lymphocytes that attack and destroy bacteria, transplanted tissue, host cells infected with viruses or have turned cancerous; Responsible for immune surveillance
T lymphocytes
form in the thymus and other lymphatic tissue and attack cancer cells, viruses, and foreign substances
B lymphocytes
form in the bone marrow and release antibodies that fight bacterial infections
Macrophages
phagocytize tissue debris, dead neutrophils, bacteria, and other foreign matter. They also process foreign matter and display antigenic fragments of it to certain T cells, thus alerting the immune system to the presence of an enemy
dendritic cells
specialized white blood cells that patrol the body searching for antigens that produce infections
reticular cells
produce reticular fiber stroma that supports other cells in lymphoid organs
What is lymphatic tissue?
aggregations of lymphocytes in the connective tissues of mucous membranes and various organs
What is lym. diffuse tissue called when in respiratory, digestive, urinary, and reproductive tracts?
Mucosa assosiated lymphatic tissue (MALT)
WHen is the diffuse tissue called aggregated lymphoid nodules?
lymph nodes,tonsils and the appendix
What are the lymphatic organs?
red bone marrow, thymus, lymph nodes, tonsils, spleen
How does the red bone marrow contribute to the lymphatic system?
site of lymphocyte formation and T lymphocytes production
WHat is the thymus's role in the lymphatic system?
T lymphocytes are matured here and later get sent to the medulla. Thymus also secrete hormones that control the t lym as paracrine and systematically
What do lymph nodes do?
two functions; activate T and B cells and cleanse the lymph. MOST ABUNDANT LYMPHATIC ORGAN
What does the cortex of the lymph node do
when LN is fighting a pathogen, b cells multiply and differentiate
What does the medulla do?
branching network of medullary cords, composed of lymphocytes, plasma cells, macrophages, reticular cells and fibers.
What is the white pulp of the spleen?
lymphocytes and macrophages
What is the first line of defense?
skin and mucous membranes
What is the second line of defense?
inflammatory response
What is the third line of defense?
adaptive immunity- leaves body with a memory of the pathogen, so it can quickly defeat it if it comes across it again
innate immunity
The immunity that is present before exposure and effective from birth. Responds to a broad range of pathogens.
adapted immunity
constitutes the third line of defense and is distinguished by its capacity for immune memory. It adapts the body to the presence of a pathogen so we become less vulnerable to the illness it could otherwise cause.
Innate immunity has three characteristics:
Local, nonspecific and lacks memory
Nonspecific effects
each mechanism of innate immunity acts against a broad spectrum of disease agents, not just one specific pathogen
Lacking memory
the innate immunity lacks memory to any previous exposure to the pathogen, so it is no easier to attack a pathogen the second time
Neutrophils defense
phagocytosis and digestion, superoxide, hydrogen peroxide, and hypochlorite
Eosinophils defense
stand guard against parasites and allergens, that things too big to phagocytize
Basophils defense
secrete chemicals that aid the mobility and action of other leukocytes: heparin, histamines and leukotrienes
Lymphocytes defense
natural killer cells, T and B cells
Inferons
when an infected cell dies from infection it secretes this to help surrounding cells to better defend from viral replication from being altered by the virus
complement system
A group of about 30 blood proteins that may amplify the innate and adaptive response, enhance phagocytosis, or directly lyse extracellular pathogens.
What causes inflammation?
histamine, that is released when stimulated
What initiates a fever?
exogenous pyrogens
What is fever reducing called?
ANTIpyrexia
How does ibuprofen work?
inhibits prostaglandin synthesis
What further raises the temperature of a fever?
endogenous pyrogens
What to endogenous pyrogens do?
As neutrophils and macrophages attack pathogens, they secrete a variety of polypeptides that act as release it. These in turn stimulate neurons of the anterior hypothalamus to raise the set point for body temperature
Three characteristics of adaptive immunity
systemic effect, specificity, memory
what is the systematic effect
When an adaptive response is mounted against a particular threat such as a bacterial infection, it acts throughout the body to defeat that pathogen wherever it may be found.
What is specificity?
immunity directed against a specific pathogen
What does memory do?
the body quickly recognizes and responds to pathogen so that you do not even notice any response happened
cellular immunity
immune response that relies on T cells to destroy infected body cells
humoral immunity
specific immunity produced by B cells that produce antibodies that circulate in body fluids
natural active immunity
production of one's own antibodies or T cells as a result of infection or natural exposure to antigen
artificial active immunity
Production of one's own antibodies or T cells as a result of vaccination against disease
natural passive immunity
acquired by a child through placenta and breast milk
artifical passive immunity
temporary immunity that results from the injection of immune serum (antibodies) from another person or animal treatment for snakebite, botulism, rabies, tetanus, and other diseases
What part of the antigen molecule reacts?
epitopes
What does the variable region do?
binds to antigen
What Antibodies are only monomers
IgD, IgE, IgG
What do epitopes do?
stimulate immune responses, each antigen only has one epitope but it can react with many
What is the structure of IGM
monomer and pentamer
Structure of IGA
monomer and Dimer, found in blood plasma, mucus, tears, milk
Development of T cells
Stem cells from bone marrow migrate to thymus gland. Second stage: T cells develop into activated T cells Occurs when, and if, antigen binds to T cell's surface proteins and a chemical signal is received from another T cell
Where does B cell maturation occur?
red bone marrow
T cells usually cant recognize and attack foreign antigens on their own they need the help of
antigen presenting cells
interlukins
Lymphocytes and APCs talk to each other through them
Cytotoxic T cells
the "effectors" of cellular immunity that carry out the attack on foreign cells
Helper T cells
promote the action of the killer T cells and play key roles in humoral immunity and nonspecific defense. All other T cells are involved in cellular immunity only
Regulatory T cells
limit immune response (when pathogen detected the concentration of these decreases)
Memory t cells
descended from Tc cells, responsible for immune systems memory
steps for cellular immunity
recognize, react, remember
recognize
two phases- antigen presentation and T cell activation.
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