Chapter 23- Lymphatic System Flashcards
functions
- produce, maintain, and distribute lymphocytes
- maintain normal blood and interstitial fluid volume
- alternate route for the transport of materials
- -nutrients
- -hormones
- -wastes
lymphatic vessels
- network of vessels
- transport fluid called lymph from tissues to the venous system
- range in size
- -small lymphatic capillaries
- -medium lymphatic vessels
- -large lymphatic trunks
- -lymphatic ducts
lymphatic vessels pt 2
- are almost always found associated with blood vessels
- location of vessels
- -most tissues
- -absent in: avascular tissue (tendons), CNS
what is lymph
- lymph is fluid connective tissue
- it occurs only in lymphatic vessels
- it is derived from:
- -interstitial fluid of tissues
- -lymphocytes
- -macrophages
origin of lymph
derived from interstitial fluid
- originates from plasma (interstitial fluid does)
- -water and dissolved materials leak out of capillaries due to diffusion and filtration (27L/day enters interstitial spaces)
- -fluid: lacks proteins, lower 02
- interstitial fluid moves into the lymphatic capillaries and is now known as lymph
- -90% of interstitial fluid is absorbed
lymphatic capillaries
- closed ended tubes
- in interstitial spaces
- form networks
- single layer of squamous cells with incomplete basal lamina
- fenestrated
lymphatic capillaries differ from blood capillaries
- larger diameter
- thinner walls
- flat and irregular
- have anchoring filaments to keep the passage open
- overlapping endothelial cells
formation of lymph
interstitial fluid enters capillaries
- overlapping cells function as one way valves
- moves through fenestrations
- large things such as viruses and debris flow in too
- lymph is filtered plasma, interstitial fluid, and stuff floating around in interstitial fluid, can be cancerous cells, pathogens
medium lymphatic vessels
- merging of lymph capillaries
- similar to veins
- -interna
- -media
- -adventitia
- -valves
- merge to form trunks
- travel with arteries of same size
lymphatic trunks: naming
named for the region they drain
-ex: lumbar, intestinal, broncomediastinal, subcalvian, jugular
lymphatic ducts: draining
- trunks drain into ducts
- two ducts
- -thoracic and right lymphatic
- deliver lymph to venous circulation at subcalvians
- -reintroduced to bloodstream
- -becomes part of plasma and is circulated
lymphatic ducts: thoracic duct
- drains lower body; left arm, head and neck
- route:
- -arises form cisterna chyli
- -through diaphragm
- -ascends in front of vertebral column
- -empties into left subclavian vein
lymphatic ducts: right lymphatic duct
drains right side of head, neck and right arm
- route:
- -starts in right thorax
- -to the right subclavian vein
lymphatic ducts: asymetry
unevenly drain fluid from the body
- thoracic does the majority
- it is much longer and drains the entire inferior half of the body
movement of lymph
contain valves
- occur at bulges
- prevent backflow
- -pressure is lower in lymphatics than veins (no heart connection)
- -lymph is moved using similar methods to veins: skeletal muscles, breathing
- if drainage does not occur= lymphedema
lymphocytes
- primary cells of the lymphoid system
- allow for specific (or adaptive) immunity
- -multi-faceted immune response to the detection of specific foreign antigens
lymphocytes: NK cells
- natural killer cells
- derived directly from bone marrow
- NON-specific immunity
- detect chemical signals other than specific antigens (like all the other leukocytes) and induce apoptosis
- the one lymphocyte that is not cell specific
lymphocytes: B-cells
- originate and develop in the bone marrow
- stimulated by an antigen to produce antibodies
- can survive for years as memory cells, and become active once exposed to a similar antigen
lymphocytes: B-cells
- originate in the bone marrow but develop in the thymus (t-cells)
- attack cells with antigens indicating viral infection or detrimental mutations
- induce apoptosis
- have memory cells similar to b-cells
- t-cells actually find the antigen themselves and kill it instead of b-cells that produce antibodies
lymphoid nodules
- reticular connective tissue dominated by lymphocytes
- MALT
- -mucosa associated lymphoid tissue
- -digestive lymph nodule
- masses of connective tissue attached to organs, not organs themselves
MALT
tonsils
- positioned around the pharynx
- remove pathogens that enter via air or food
-
three types of tonsils
pharyngeal tonsil --one nodule in nasopharynx --aka adenoids palatine tonsils --two nodules on the soft palate lingual tonsils --two nodules at the base of the tongue
aggregated lymphoid nodules
malt
-line mucosa of the small intestine
appendix
malt
- blind tube at the beginning of the intestine
- area prone to infection
- -appendicitis
- -intestinal flora enter underlying tissues
lymphatic organs
- surrounded by a fibrous connective tissue capsule
- include:
- -lymph nodes
- -thymus
- -spleen
lymph nodes
- bead shaped
- between several afferent and one efferent vessel
- hilus: indented region where BV’s, nerves, and efferent lymph vessels connect
lymph nodes
cortex on outside
-capsule has trabeculae that subdivide it
-has two regions
–outer cortex: consists of aggregated B-cells
–inner cortex: t cells enter blood here
medulla:
-b-cells leave through the efferent vessel
lymph will encounter this when traveling through lymph system and the attack on antigens begins
lymph nodes: locations
- cervical
- axillary
- inguinal
- pelvic
- abdominal
- thoracic
spleen
- found on left side of stomach
- largest lymphatic organ
- white pulp
- -resembles lymph node
- red pulp
- -large amounts of RBC
- -sinuses, macrophages, T/B cells
functions of spleen
- remove old RBCs
- store/recycle iron
- initiate immune response
- blood reservoir
- RBC production
- major place for interaction between lymph and blood
- white pulp encounters pathogens from blood and antibodies will destroy it
thymus
- in mediastium
- first lymph organ to deveolp
- -grows until puberty
- -shrinks with age: replacd by fibrous and adipose tissue
- 2 lobes with lobules
- -cortex: mostly T-cells
- -medulla: mostly epithelial cells
thymus: t-cells
- cortext produces t-cells
- mature and migrate into medulla
- enter blood vessels and go into circulation
thymus: reticular cells
- produce hormone thymosin
- promote t-cell differentiation
