The Lymphatic System Flashcards
What are the functions of the lymphatic system?
1) recovery of excess tissue fluid
2) monitoring the body for pathogens
3) producing immune cells and activating immune responses
4) absorption of dietary lipids
What is the bodily components of the lymphatic system?
- lymphatic vessels
- lymphoid tissues
- red bone marrow
- tonsils
- thymus
- spleen
- lymph nodes
Lymphatic vessels are connected at the ____ veins in the shoulder.
subclavian
How do blood capillaries exude fluid into the tissues?
capillary filtration
How much fluid is reabsorbed by the capillaries, and much is absorbed by the lymphatic vessels?
reabsorbed - 85%
absorbed by LVs - 15%
What is the fluid called in lymphatic vessels?
lymph
____ in the lymph nodes phagocytize impurities and cleanse the lymph, and further monitor it for pathogens.
macrophages
The lynmphatic system primariliy recovers water, if this reccovery were not functioning properly, 2-3 liters of water would accumulate every single day. What is this condition called where excessive swelling occurs due to a malfunction in the lymphatic system?
edema
potentially leading to gangrene
Sometimes when when have a masectomy, the auxillary (armit) lymph node is severed to prevent metastasis. When lymph flow is chronically obstructed it can lead to overly-swollen limbs. This can be cause by mosquito-borne parasitic worms. What is this disease called?
elephantiasis
(ellie-fan-tee-aye-sis)
How does mosquito-borne parasitic worms infect the lymphatic system leading to elephantasis?
The larva of the worms are introduced via the saliva of mosquitoes, moves into the lymphatic vessels, and matures into a thread-like filaria worm, blocking lymph flow.
What is the overgrowth of fibrous scar tissue called?
fibrosis
lmost common in legs, breasts, and scrotum
Which kind of cells populate the lymphatic system which can help the immune system and combat harmful bacteria, viruses, toxins and other disease agents?
lymphocytes and macrophages
What special lymphatic vessels in the small intestine help absorb dietary fats, cholesterol, and fat-soluble vitamins?
lacteals
In the lymphatic system, which component is similar to blood vessels, but do not form a complete circuit around the body?
lymphatic vessels
Lymphatic vessels beging with ____ ____ and grow larger and larger until they lead to the subclavian veins.
lymphatic capillaries
Where do lymphatic vessels converge before they lead to the lymph nodes?
collecting vessels
Collecting vessels converge to form six lymphatic ____ which drain into a specific region of the body.
trunks
In the lymphatic system, what are aggregations of lymphocytes found within the connective tissues of various organd, especially in loose connective tissue?
lymphatic tissue
Where is lymphatic tissue the most abundant? What is this tissue called?
mucous membranes; mucosa-associated lymphatic tissue (MALT)
In some places, MALT becomes concentrated into especially dense masses of lymphocytes called what?
lymphatic nodules
Located in the ileum (small intestine) what keeps the intestinal flora at appropriate levels and the pathogens at bay, thereby preventing a large number of infections?
peyer patches
associated with food allergy in the small intestine
In what systems of the body do mucous membranes open up in to?
- digestive
- respiritory
- reproductive
- urinary
In the lymphatic system, what is a mass of lymphatic tissue that is wholly or at least partially enclosed in a fibrous capsule?
lymphatic organ
List the lymphatic organs.
- red bone marrow
- tonsils
- thymus
- lymph nodes
- spleen
What are the four primary cells that populate the lymphatic system?
- Natural killer cells (NK cells)
- B lymphocytes (B cells)
- T lymphocytes (T cells)
- Antigen-presenting cells (APCs)
Which kind of cell in the lymphatic system attacks only host cells that have either turned cancerous or have been antigenically modified by a viral infection?
Natural killer (NK cells)
10-15% of lymphocytes
Which kind of cell in the lymphatic system are small lymphocytes that originate in the bone marrow and become immunocompetent there?
B lymphocytes (B cells)
What do B cells devlop that all them to respond to foreign antigens?
antigen receptors
B cells are responsible for ____ immunity.
humoral (antibody-based)
Some B cells develop a large amounts of what organelle? What cell does this further develop?
rough endoplasmic reticulum; plasma cell
Some B cells become ____ B cells which “remember” the antigen.
memory
Which kind of lymphatic cells are small lymphocytes that achieve their immunocompetence (antigen sensitivity) in the thymus?
T lymphocytes (T cells)
65-75% of lymphocytes
T cells are responsible for ____ immunity.
cellular (cell-mediated)
Which kind of T cells recognize antigen fragments (epitopes) presented tot hem by APCs? Which kind of peptides do they secrete?
Helper T (Th) cells; lymphokines
targeted to HIV
Which kind of T cells directly attack and destroy foreign cells including bacteria and transplated tissues and organs? Which kind of enzymes do these release?
Cytotoxic T (Tc) cells; granzymes
Which kind of T cells prevent excessive responses by Th and Tc cells and normally prevents attacks against own tissues?
Regulatory T (Tr) cells
Which kind of T cells are preprogrammed to respond quickly if one is reexposed to the same antigen that triggered their initial formation?
memory T cells
Which kind of lymphocytes phagocytize anitgens, digest them, and then display antigenically active fragments of them, called epitopes?
Antigen-presenting cells (APCs)
What are the three kinds of APCs?
- B cells
- macrophages
- dendritic cells
Which kind of vessel in the lymphatic system consists of a single layer of endothelial cells forming a sac?
lymphatic capillaries
How are lymphatic capillaries attches to surrounding tissue?
anchoring filaments
Endothelial cells in lymphatic capillaries overlap one another in flaps versus having tight junctions. How are these flaps used to eradicate excess fliud in the body?
When fluid fills in surrounding tissues, the pressure from the fluid pushes open the flaps, allowing it to flow into the lymphatic capillary. Then, when fluid pressure gets high within the capillary, it pushes the flaps shut and can move along in the lymphatic capillary.
Lymphatic capillaries anastomose to form ____ ____. These pass through lymph nodes on their rought and ultimately lead to ____ ____.
collecting vessels; collecting ducts
How do lymphocytes appear in tissue sections?
as densly spaced, dark violet specks
What are unencapsulated lympoid tissues called?
MALT (mucosa-associated lymphoid tissue)
What is unencapsulated lympoid tissue in the digestive tract called?
GALT (gut-associated lymphoid tissue)
What is unencapsulated lymphoid tissue in the respiratory tract called?
BALT (bronchus-associated lymphoid tissue)
Which component in the GALT has a pale germinal center and a darker periphreal zone?
lymphoid nodules (lymphoid follicles)
Which kind of unencapsulate lymphoid tissue are Peyer patches located in?
GALT (gut-associated lymphoid tissue)
In both the bronchi and intestines, the epithelium changes from its typical form to a squamous epithelium of ____ cells which are antigen-presenting cells.
Microfold (M) cells
What form of lymphoid tissue is located near the nasal and oral entraces to the throat and respond to ingested and inhaled pathogens and antigens?
tonsils
In the tonsils, what are the narrow, slightly branching pits called? What structure lines these crypts?
tonsillar crypts; lymphatic nodules
What kind of cells are scattered about the structure of the tonsil?
lymphocytes
What is the lower boundary of the tonsil marked by with fibrous connective tissue?
a sheet called the capsule
Which kind of lymphatic tissue (organ) are the tonsils decribes as due to their lower boundary of fibrous connective tissue?
partially encapsulated lymphatic organ (tissue)
Where do blood vessel enter the tonsils from?
the basal side
What are the three kinds of tonsils?
- palatine
- lingual
- pharyngeal
Which kind of tonsils are found at the back between the palatoglossal arch and palatopharyngeal arch?
palatine tonsils
How many tonsillar crypts do palatine tonsils generally have?
10-12
What is the lighter lines found in a cross section of the palatine tonsil called whichascends from the capsule into the tissue between the crypts?
trabeculae of fibrous connective tissue
Which kind of epithelium lines the exterior of the palatine tonsils?
stratified squamous epithelium
When tonsils are inflammed, and neutrophils are abundant in samples, what kind of condition is this called?
tonsillitis
Where can lingual tonsils be found in the body?
They are located at the root of the tounge, behind the vallate papillae. They are also clustered on each side of the tounge.
What do lingual tonsils have that open into the base of each crypt?
lingual glands
Where is the singular pharyngeal tonsil located?
Medially, just behind the nasal cavity, on the dorsal wall of the nasopharnyx.
Which kind of epithelium is the pharyngeal tonsil lined with?
pseudostratified columnar epithelium (like the nasal cavity)
The pharangeal tonsil does not have deep crypts, instead it has shallow folds or ____ of tissue.
pleats
Which kind of glands within the pharyngeal tonsil open into the basse of the pleats?
seromucous gland ducts
What is inflammation of the pharyngeal tonsil called?
adenoids
Which organ is located int he mediastinum, immediately superior to the heart, just below the thyroid gland?
thymus
Which kind of sections of the thymus are divided within the parenchyma?
polygonal
Each lobe of the thymus has a darker stained ____ around the outside, and a lighter stained ____ in the middle.
cortex; medulla
What is unique about the thymus compared to the tonils?
it has no ovoid lymphatic nodules or germinal centers
What does the medulla of the thymus have which consists of concentric flattened cells with degenerating central cells?
thymic (Hassal) corpuscles
What is unique about the thymus in newborns?
It is extremely large in newborns and stays that size until about 14 years old
Why is the large size of the thymus important in newborns and young children?
It helps their immune system since when they are first born, their immune system is not very strong and need extra help fighting pathogens.
What is the shrikage of the thymus called after it reaches it’s peak maturity at age 14?
involution
The thymus is the site for which class of lymphocytes?
T cells
What are immauture T cells called in the cortex of the thymus?
thymocytes
develop surface receptors for antigens
The cortex of the thymus tests the T cells to determine if they can be produced. If they fail this antigen recognition test, what is this type of selection called? What happens if they pass?
negative; positive selection
Only 2% T cells go through positive selection
What is the most abundant lymphatic organ, numbering about 450 in a typical adult?
lymph nodes
What areas of the body are lymph nodes the most concentrated?
- neck
- armpit
- breast
- groin
- mesenteries
- small parts of the elbows and knees
Where does lymph enter into the lymph nodes?
through afferent lymphatic vessels along the convex surface of the node
Where does lymph exit the lymph nodes?
through the efferent lymphatic vessels (2 to 3) at the concave surface of the node (hilum)
The lymph nodes screens lymph and filters out ____% of impurities after exiting each node.
99%
What are all the lymphocytes and bacteria-fighting components found in the lymph nodes?
- macrophages
- APCs
- T cells
- B cells
What is located at the hilum of the lymph node?
- 2-3 efferent lymphatic vessels
- veins
- arteries
What is the unique structure in the lymph nodes which is a narrow, clear space that recieves the lymph from afferent lymphatic vessels?
subcapsular sinus
What is the section of the lymph nodes which is located between the cortex and medulla? Which kind of lymphocytes is located here?
paracortex; Helper T cells
The paracortex of the thymus has special blood venules called what? Which kind of epithelium do these venuels have?
high endothelial venules; cuboidal epithelium (porous)
What is the body’s largest lymphatic organ?
the spleen
What componets penetrate the hilum of the spleen?
- splenic artery
- splenic vein
- efferent lymphatic vessels
What is the function of the spleen in fetuses and some anemic adults?
It is the site of blood cells production (fetal hemopoiesis)
What are the 5 main functions of the spleen?
1) fetal hemopoiesis
2) lymphocyte production
3) blood filtration
4) RBC destruction and removal
5) In other species, stores and releases RBCs
In the spleen, red pulp is composed of ____, and white pulp is composed of ____.
RBCs; WBCs (lymphocytes)
In the spleen, there are central arteries that are wrapped in sleeves of lymphocytes called what?
periarterial lymphatic sheaths (PALS)
When the central artery eventually loses its PALS, it divides into a tuft of parallel arteries that look like britstles. What is this tuft called?
penicillus
When the splenic vein exits the hilum, it becomes part of what larger vein which enters the liver?
hepatic portal vein
White pulp in the spleen is surrounded by a ____ ____ which is composed of T and B cells.
marginal zone
Red pulb in the sleep is composed of ____ and splenic ____.
sinusoids; cords (Billroth’s cords)
Billroth’s cords (splenic cords) look like a ____ and have a framework of which kind of connective tissue?
sponge; reticular connective tissue
What is the path that** blood **takes from when it enters the spleen?
1) splenic artery
2) central arteries
3) penicillus
4) marginal sinuses: encounters macrophages, B & T cells
What do macrophages help RBCs do in the spleen that further degrades in the liver?
Macrophages remove iron from hemoglobin
