Chapter 20 Lymphatic system Flashcards
Where is the lymphatic system not found?
bones
bone marrow
teeth
CNS
What is the structure of lymphoid organs and tissues?
reticular connective tissue (except in thymus)
house immune cells (lymphocytes)
what is the primary purpose of the lymphatic system? secondary?
primary: immune surveillance
secondary: maintain blood volume
how does the lymphatic system provide immune surveillance?
using leukocytes to protect the body by neutralizing invading pathogens
how does the lymphatic system maintain blood volume?
lymphatic vessels collect fluid -> cleans it -> returns it to the veins which transports fluid to the heart
does the lymphatic system have a cycle?
no, it is unidirectional, only travelling towards the direction of the veins close to the heart
what is the order of the fluid travelling through the lymphatic vessels?
Lymphatic capillaries
lymphatic collecting vessels
lymphatic trunks
lymphatic ducts
what is the structure of lymphatic capillaries?
minivalves
blunt ended
what is the structure/function of the minivalves of the lymphatic capillaries?
anchored by collagen fibers
composed of the overlapping of squamous endothelial cells
they are forced open when interstitial fluid pressure is increased
they are the most permeable
what is fluid called when traveling through the blood vessels?
plasma
what is the fluid called when traveling through the open (no man’s land) space between vessels
interstitial fluid
what is the fluid called when traveling through the lymphatic vessels?
lymph
describe lymph when it first enters the lymphatic vessels
It’s dirty with possible bacterial or cancer cells, because large particles are able to enter easily
All lymphatic vessels drain into where?
2 ducts that then drain into veins
where are the lymphatic ducts located?
where the internal jugular and subclavian veins merge
what are the two lymphatic ducts named?
right lymphatic duct
thoracic duct
what portion of the body does the right lymphatic duct receive fluid from?
the upper right body
what portion of the body does the thoracic duct receive fluid from?
left side of body AND all lower extremities
what does lymphangitis mean?
inflammation of the lymphatic vessels
what does lymphangitis look like on the body? how is it caused?
red streaks appearing on skin
caused usually by bacterial infection
what is lymphedema?
swelling of limbs by accumulation of interstitial fluid
what causes lymphedema?
poor lymphatic drainage either because of tumors
or because of removal of lymphatic vessels during cancer surgery
explain how lymph flow is similar to venous blood flow?
muscle contractions and surging arteries push lymph through vessels
valves prevent backflow
which of lymphatic vessels contain smooth muscle? why?
trunks and ducts to push fluid towards the veins
Once again, list the two functions of the lymphatic system?
immune surveillance
maintain blood volume
Describe the structure of lymph nodes
there are HUNDREDS of nodes
they appear along lymphatic vessels
where can you find lymphatic nodes? what are the three exact locations of where they are concentrated?
they are concentrated where lymphatic vessels merge
located at:
axillary (armpit)
inguinal (groin)
cervical (neck)
what is the main function of lymph nodes?
to clean the lymph
Describe how the structure of the lymph node helps it do its job
has 5 vessels enter the node, and only 2 that allow for fluid to exit - this creates more time for fluid within node to be cleaned
is composed of immune cells - which allow for the screening and consuming of potential infectious agents
does it take 1 node to clean fluid before returning to veins?
no, it take running through several nodes before fluid is cleaned sufficiently
why would lymph nodes become swollen?
infection
cancer
what are buboes?
very large and painful infected lymph nodes
what are buboes commonly associated with?
Yersinia pestis - a bacteria that causes the bubonic plague
how does the lymphatic system contribute to secondary cancer sites?
tumor cells can travel within the lymph fluid, get stuck in lymph nodes and begin growing
what is a lymphoma?
any tumor of the lymphoid tissue
what is the structure of the spleen? location?
largest lymphoid organ (fist-sized)
contains macrophages
left upper quadrant of abdomen
what is the function of the spleen?
removes old/defective RBCs (recycling the iron)
performs immune surveillance (w/macrophages)
why can the body live without the spleen?
the liver and bone marrow can take over its functions
what is MALT? stands for?
Mucosa Associated Lymphoid Tissue
- concentrated groups of lymphoid tissues (reticular tissue) holding immune cells
what are the three large examples of MALT?
tonsils
Peyer’s patches
appendix
where are smaller examples of MALT located?
in respiratory, genitourinary, and GI tracts
where are the tonsils located?
around the entrance to pharynx
what is tonsilitis and what is it caused by?
inflammation of the tonsils
usually due to bacterial infection
what are Peyer’s patches?
isolated clusters of immune cells forming nodules in outside wall of small intestine and around the appendix
what is the function of Peyer’s patches?
protect the body from infection by intestinal bacteria
what is the function of the tonsils?
combatting pathogens that enter the body in food or air
where is the appendix located?
offshoot of distal part of the large intestine
what is the appendix’s job?
they get to know the microbes within our gut in order to provide long-term immunity
where is the thymus located?
in the upper chest above the sternal angle and heart
when is our thymus at its largest?
childhood
when does our thymus begin to atrophy?
after puberty
what is the thymus’ function?
site of T-cell maturation
what defines maturation of T-cells
they are active and working
what is the function of T cells?
help distinguish self from not-self
how does the thymus teach T-cells to do their job?
kills off any T cells that incorrectly target “self” microbes
what is the path T cells take to maturation and where do they travel after?
from bone marrow to thymus for maturation
matured T cells leave thymus and travel to secondary lymphoid tissue such as lymph nodes, spleen, and MALT
