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immune system
cell population that inhabits all organs and defends body from agents of disease
is the immune system an organ system?
no
what is fluid recovery?
fluid continually filters from the blood capillaries into the tissue spaces
what can the lymphatic system be considered as?
a filter
immunity
excess filtered fluid picks up foreign cells and chemicals from the tissues
lipid absorption
lacteals, in small intestine absorb dietary lipids that are not absorbed by the blood capillaries
what is lymph?
the recovered fluid
What do lymphatic vessels do?
transport the lymph
What is lymphatic tissue composed of?
composed of aggregates of lymphocytes and macrophages that populate many organs in the body
What cells are concentrated in lymphatic organs? And what separates them from other organs?
- defense cells are especially concentrated in these organs
- seperated from surrounding organs by connective tissue capsules
charateristics of lymph
clear fluid, similar to plasma but no proteins.
what does lymph orginate as?
extracellular fluid drawn into lymphatic capillaries
lymphatic capilaries penetrate nearly every tissue except:
cartilage, cornea, bone, and bone marrow
what cells overlap eachother to make up the capillary wall of lymphatic capillaries?
endothelial cells
how are the cells in lymphatic capilaries tethered to surrounding tissue?
protein filaments
when do the valve like flaps that the endothelium creates when the pressure is high or low? (lymphatic caplilaries)
high- open low- close
what are the three layers of lymphatic vessels?
tunica interna tunica media tunica externa
waht does the layer tunica interna include?
endthelium and valves
waht does the layer tunica media include?
elastic fibers, smooth muscle
waht does the layer tunica externa include?
thin outer layer
what are the two collecting ducts for the lymphatic vessels?
right lymphatic duct thoracic duct
what does the right lymphatic duct do?
receives lymph from right arm, right side of head and thorax; empties into right subclavian vein
what does thoracic duct do?
larger and longer, starts as cisterna chyli in abdomen, recieves lymph from below diaphragm, left arm, left side of head, neck, thorax and empties into left subclaivain vein
What are the 3 main sets of tonsils
palatine tonsils lingual tonsils pharyngeal tonsil
spleen
the body's largest lymphatic organ
what are the two types of tissues in the spleen?
red pulp - sinuses filled with erythrocytes white pulp- lymphocytes, macrophages surrounding small branches of splenic artery
what are the spleen functions?
- spleen is erythrocyte graveyard
- it is the blood cell production in fetus
- white pulp monitors blood for foreign
- stabilizes blood vol. thru plasma transfers to lymphatic system
pathogens
capable of producing disease
three lines of defenses against pathogens
1) skin and mucous membranes 2) several innate defense mechanisms 3) adaptive immunity (leaves memory so that it can defeat faster in future)
innate defenses
guard equally against a broad range of pathogens
what does the venous retun have that lymph doesnt?
a pump
at what pressure does lymph flow at?
low pressure
how is lymph moved along in lymph flow?
rhythmic contractions of lymphatic vessels
what is lymph flow aided by?
skeletal muscle pump
what do valves fo in the flow of lymph?
prevent backward flow
what significatnly increases lumphatic return?
exercise
what are the charateristics of the natural killer cells?
large lymphocytes that attack/destroy bacteria, transplanted tissue, host cells infeceted with viruses or that have turned cancerous
where do t lymphocytes mature?
mature in thymus
what does the activation of B lymphocytes cause?
proliferation and differentiation into plasma cells that produce antibodies
what are macrophages?
large, avidly phagocytic cells of connective tissue
from what do macrophages develop from?
develop from monocytes
what do macrophages do?
phagocytize tissue debirs, dead neutrophils, bacteria and other foreign matter
how do macrophages alert the immune system to enemies?
they process foreign matter and display the antigenic fragments to certain t cells.
are macrophages antigen-presenting cells?
yes
what do dendrintic cells do?
alert immune system to pathogens that have breached the body surface
what are dendrintic cells
branched, mobile antigen-presenting cells
where can you find dendrintic cells?
epidermis, mucous membranes and lymphatic organs
what are reticular cells?
branched stationary cells that contribute to stroma of lymphatic organ
what is lymphatic tissue?
clutster of lymphocytes in onnective tissues of mucous membranes and various organs
what is the difference between lymphatic tissue and DIFFUSE lymphatic tissue?
lymphocytes are scattered not clustered
where is diffuse lymphatic tissue prevalent in the body?
body passages open to the exterior
what is the simplest form of lymphatic tissue?
diffuse lymphatic tissue
decribe lymphatic nodules (follicles]
dense masses of lymphocytes and macrophages that congregate in response to pathogens
what are lymphatic nodules a constant feature of?
lymph nodes, tonsils and appendix
what do lymphatic organs have around them to seperate them from other organs?
lymphatic tissues
what are considered PRIMARY lymphatic organs?
red bone marrow and thymus
what are considered secondary lymphatic organs?
lymph nodes, tonsils and spleen
what populate secondary lymphatic organs?
immunocompetent (having a normal immune response) cells
what are primary lymphatic organs a site for?
where t and B cells become immunocompetent
what is red bone marrow involved in?
hemopoiesis and immunity
charateristics of red bone marrow
soft, loosely organized, highly vascular material
what systems is the thymus apart of?
endocrine, lymphatic and immune
what does the thymus develop?
lymphocytes
why does the thymus secrete hormones?
to refulate their activity
what is the most numerous lymphatic organ?
lymph nodes
what are the two funcs of lymph nodes?
cleanse the lymph and act as a site of T and B cell activation
what is the interior of a lymph node divided into?
cortex and medulla
what type of lymphatic vessels lead into the node along its convex surface?
several afferent lymphatic vessels
where does lymph leave the node through
one to three efferent lymphatic vessels that leave the hilum
what is metastasis?
cancerous cells break free from original tumor, travel to other sitres in body and estabilish new tumors
what are tonsils?
patches of lymphatic tissue located at the entrance of pharynx
what do tonsils fuard the body against?
against ingested or inhaled pathogens
what are the tonsils covered by?
epithelium
what tonsil gets the most infected
palatine tonsil
what is the body's largest lymphatic organ?
spleen
what are the two types of tissue in the spleen?
red pulp and white pulp
what lymphatic organ is highly vascular and vunerable to trauma and infection?
spleen
what are pathogens?
agents capable of producing disease
what are the three lines of defense against pathogens?
- first line: skin and muscous membranes
- second line: several innate defense mechanisms (leukocytes macrophages, antimicrobial protiens, natural killer cells inflammation and fever)
- third line: adaptive immunity (leaves memory)
what line of defense against pathogens are non-specific?
first and second
what are innate defenses?
guard equally against a broad range of pathogens
what do innate defenses lack
capacity to remember pathogens
what are the three innate defenses?
protective proteins protective cells protective processes
what is adaptive immunity?
develop seperate immunity to EACH pathogen
what external barrier makes it mechanically difficult for microorganisms to enter the body?
skin
what makes skin tough?
keratin
what is the acid mantle on skin?
thin film of lactic and fatty acids from sweat and sebum that inhibits bacterial growth
what do peptides in skin do?
kill microbes
what peptides are in the skin
demicidin, defensins, and cathelicdins
what is protected by mucous membranes?
digestive, respiratory, urinary and reproductive tracts
what does mucous membranes do to microbes?
physically traps microbes
what does lysozyme do in the mucous membrane?
enzye destroys baterial cell walls
what are phagocytes?
cells that engulf foreign matter
5 types of phagocytes
neutrohils eosinophils basophils monocytes lymphocytes
where do neutrophils wander?
cibbectuve tussye jukkubg vacterua
how do neutrophils kill bacteria?
phagocytosis and digestion
what happens when lysosomes degranulate? (neutrophils)
discharge enzymes into tissue fluid causing a respiratory burst
where are eosinophils found?
in mucous membranes
what do eosinophils guard against?
guard against parasites, allergens and other pathogens
what do eosinophils promote action of?
basophils and mast cells