1
Q
lymphatic system
A
- helps immune system emend against infectious agents
- enlargement of lymphatic vessels is sign that organs are defending body
- transports and houses lymphocytes and immune cells
- returns excess fluid to maintain fluid balance
- lymph is fluid transported in lymph vessels
2
Q
lymphatic vessels
A
- tonsils
- lymph nodes
- spleen
- liver
3
Q
characteristics of lymph
A
- 10% of fluid entering interstitial apes not reabsorbed into blood capillaries, ~3 laters daily
- moves passively into lymphatic capillaries due to pressure gradient
- termed lymph once moved inside lymph vessels
4
Q
components of lymph
A
- water, dissolved solutes, and small amount of protein
- pathogens of metaswized cancer cells
5
Q
lymphatic capillaries
A
- overlapping endothelial cells
- one way flaps allows fluid entrance but not exit, pressure allows cells to separate to allow fluid to become lymph
- anchoring filaments
- help hold endothelial cells to each other and nearby structures
- lacteals
- lymphatic capillaries in GI tract, allow for absorption of lipid-soluble substances from GI tract
6
Q
movement of lymph into lymphatic capillaries
A
- increase in hydrostatic pressure in interstitial spaces
- rises as additional fluid is filtered from blood capillaries
- pressure pushes fluid into lymphatic capillaries called lumen
- higher pressure=great volume of fluid entering
- pressure of lymph causes endothelial cels to close
- lymph is transported through network of increasing larger vessels
7
Q
vessel sizes (smallest to largest)
A
- lymphatic capillaries
- lymphatic vessels
- lymphatic trunks
- lymphatic ducts
8
Q
lymphatic vessels
A
- formed from capillaries
- superficial vessels positioned adjacent to superficial veins
- Depp vessels next to deeps arteries and veins
- have valves in their lumen to prevent blood from pooling and prevent back flow in low-pressure system
9
Q
lymphatic system lacks a pump
A
- relies on…
- contraction of skeletal muscles
- contraction of respiratory pump
- movement of blood
- some connect directly to lymph nodes
10
Q
lymphatic trunks
A
- fed into by lymphatic vessels in left and right side of body
- jugular trunks drain lymph from head and neck
- subclavian trunks drain upper limbs, breast, and superficial thoracic wall
- bronchomedialstinal trunks drain deeps thoracic structures
- intestinal trunks drain most abdominal structures
- lumbar trunks drain lower limbs, abdominopelvic was, and pelvic organs
11
Q
lymphatic ducts
A
- largest
- drained into by lymphatic trunks
- 2 ducts: right and thoracic
- convey lymph back into venous circulation of blood
12
Q
right lymphatic duct
A
- near right clavicle
- received lymph from: right side of neck and head, right upper limb, right side of thorax
- returns lymph to venous circulation
- junction of right subclavian and right internal jugular veins
13
Q
thoracic duct
A
- larger
- from diaphragm to junction of left subclavian and left jugular veins
- drains lymph from: left side of neck and head, left upper limb, left side of thorax, abdomen and lower limbs
14
Q
thoracic duct structure
A
- has saclike structure at base, cisterna chyli
- travels superiorly from cisterna chyli
- lies directly anterior to vertebral bodies
- passes through aortic opening of diaphragm
- ascends to left of vertebral body of midline
15
Q
cisterna chyli
A
- lipid-rich lymph, chyle, from vessels draining GI tract
- left and right intestinal and lumbar trunks draining here
- where all trunk that have chyle meet
16
Q
primary lymphatic structures
A
- involved in formation and maturation of lymphocytes
- red bone marrow and thymus
17
Q
secondary lymphatic structures
A
- not involved in lymphocyte formation
- house lymphocytes and other immune cells
- provide site of immune response initiation
- lymph nodes, spleen, tonsils, and lymphatic nodules
- include MALT
18
Q
red bone marrow
A
- in spaces between trabecular in spongy bone
- responsible for hematopoiesis (produce erythrocytes, platelets, granulocytes, and agranulocytes)
- T-lymphocytes and B-lymphocytes
- T-lymphocytes migrate to thymus to complete maturation
19
Q
thymus
A
- bilobed organ in superior mediastinum
- functions in T-lymphocyte maturation
- large in infants and young in children
20
Q
why thymus is bigger in children
A
- grows until puberty
- begins to regress and is replaced by adipose tissue by process called involution
- why older adults don’t fight off infection as well due to lower amount of T-cells
21
Q
fused lobes of thymus
A
- each surrounded by connective tissue capsule
- trabeculae is fibrous extensions of capsule, dense regular connective tissue
- subdivided into lobules
22
Q
lobules of thymus
A
- each has outer cortex and inner medulla
- both with epithelial tissue
- cortex has immature T-lymphocytes
- medulla has mature T-lymphocytes
23
Q
characteristics of secondary lymphatic structures
A
- house lymphocytes and other immune cells
- lymphatic cells enmeshed in reticular connective tissue matrix
- organized into lymphatic organs and lymphatic nodules
- capsule component or dense irregular connective tissue
- encapsulated: have complete CT capsule
- unencapsulated: incomplete or absent capsule
24
Q
lymph nodes
A
- small, round, oval, encapsulated structures
- along pathways of lymph vessels
- filter lymph and remove unwanted substances
- located deep and superficially
- typically in clusters
- when active can be swollen, palpable, and sore
25
afferent lymphatic vessels
- bring lymph into lobe
26
efferent lymphatic vessels
- draines node
| - originates at hilum
27
lymph node capsule
- seemed internal extension into to, trabeculae
| - subdivided node into components called nodules
28
outer lymph node cortex
- composed partly of lymphatic nodules
- has reticular fibres
- support germinal center
- houses proliferating B-lymphocytes and some macrophages
- has outer region called mantel zone
- has T-lymphocytes, macrophages and dendritic cells
- cortical sinus are tiny open channels lined my macrophages
29
inner lymph node medulla
- connective tissue fibres, medullary cords
- supports strands of B-lymphocytes, T-lymphocytesm and macrophages
- lead to sinuses
- medullary sinus is tiny open channels lines with macrophages
30
lymph flow through lymph nodes
- enters node through afferent lymphatic vessels
- makes was though lymphatic node sinuses
- lymph always monitored for presence of foreign material
- macrophages remove foreign debris from lymph
- lymph exits node through efferent vessel
- may enter nearby lymph node in cluster
- if lymphocyte contracts foreign substance an immune response is generated and lymphocytes undo cell division especially in germinal centres
- some remaining lymph in node
- others transported in lymph and blood to reach areas of infection
31
swollen lymph nodes
- become tender with infection
- sign that lymphocytes proliferating and fighting infection
- can palpate swollen superficial lymph nodes
32
spleen characteristics
- largest lymphatic organ
- in left upper abdominal quadrant
- posterolateral aspect convex and rounded
- concave anteromedial dodger that contain hilum where blood vessels and nerves enter
33
spleen
- supplied by splenic arteries
- drained by splenic valve
- surrounded by connective tissue capsule
- trabeculae extending into organ
- subdivided spleen into red and white pulp
34
white pulp of spleen
- clusters of T- and B-lymphocytes and macrohphages
- contains central artery
- lymphocytes suspended on reticular fibres
- lymphatic function
35
red pulp of spleen
has erythrocytes, platelets, macrophages, and B-lymphocytes
- cells in reticular CT, forming splenic cords
- has splenic sinusoids that have permeable capillaries so blood can exit easily
- splenic sinusoids drain to small venues leading into splenic vein
- platelet reservoir to re-enter blood as needed
36
splenic blood flow
- enters splenic artery, splenic arterioles, then into central artery
- continues through sinusoids of red pulp
- red pulp macrophages phagocytize (bacteria, foreign debris, old/defective erythrocytes and platelets)
- re-enters red pulp sinusoids
- then through venues and out splenic vein
- PALS is mostly T-cells
37
tonsils
- in pharynx
- hemicapsultaed
- help protect against foreign substances inhaled/ingested
- have invaginated tonsillar crypts to increase surface area to trap material
- have lymphatic nodules some with active germinal centers
38
3 types of tonsils
- pharyngeal
- palatine
- lingual
39
pharyngeal tonsils
- 1 in posterior all of nasophynx
| - when enlarged, termed adenoids
40
palatine tonsils
- 2 in posterolateral oral cavity
41
lingual tonsils
- several along posterior 1/3 of tongue
42
lymphatic nodules
- small clusters of lymphatic cells with come extracellular matrix, not completely surrounded by CT capsule
- scattered nodules termed diffuse lymphatic tissue
- in every body organ
- defend against infection
- sometimes group together to form larger structures (ex MALT)
43
MALT
- mucosa-associated lymphatic tissue
- in gastrointestinal, respiratory, genital, and urinary tracts in lamina properia of mucosa
- defend against foreign substances
- prominent in small intestines, especially ileum
- peters patches, found here, once anything gets past this it goes into blood stream
- large collection of lymphatic nodules
Anatomy Midterm #2
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