Lymphedema and Swelling Disorders Flashcards
Overview of the Lymphatic System
Lymph vessels absorb interstitial fluid from the skin and subcutaneous tissue = transport it to the circulatory system
Nutritional fatty acids are absorbed via intestinal lymph called ___
chyle
Lymphocytes are manufactured in bone marrow:
B Cells mature in bone marrow
T Cells mature in thymus
WBC circulate between vascular and lymphatic tissue
Primary Lymphoid Organs
Thymus
Bone marrow
Fetal liver
Thymus:
a lymphoid organ located in the anterior superior mediastinum = matures T cells for the immune system
Bone Marrow:
All blood cells are produced
Fetal Liver:
12 weeks gestation thru delivery; production and storage of blood stem cells prior to bone marrow development
Secondary lymph organs:
lymph nodes
spleen
peyer’s patches
Lymph Nodes:
small gland located in lymphatic system; high concentration of immune cells (B cells)
function as filters
cervical, abdominal, inguinal node beds
Part of the immune system
Structure of lymph nodes:
Generally located in the adipose tissue
Palpable sensitive nodes signify infection
Vary in size from 2-30 mm long, oval, round, kidney shape
600-700 lymph nodes in the body, majority found in the abdomen
Afferent vessels to Efferent vessels
Spleen:
located under the rib cage and above the stomach in the left upper quadrant of the abdomen
produces lymphocytes as needed
largest organ in the lymphatic system
acts primarily as a blood filter
RBCs are recycled in the spleen, WBC and platelets are stored in the spleen
acts as a blood reservoir (shock or hemorrhage)
Peyer’s Patches:
groupings of lymphoid follicles in the mucus membrane that lines your small intestine
similar to lymph nodes
Thoracic Duct:
the largest lymphatic vessel in the human body
1-5 mm diameter, 40 cm long
Located left and anterior to the spine
Drains into the venous Angle -> Junction of the internal Jugular and subclavian veins -> Superior Vena Cava
Cisterna Chyli:
a dilated sac at the lower end of the thoracic duct, functions as a temporary reservoir
collects mid to long chain fatty acids as chyle
Lymph Vessels:
thin-walled system for transporting lymph throughout the body
From distal to proximal
Lymph Node Function:
Filtering station for noxious matter such as mutated cells, bacteria, toxins and dead cells
Regulate the concentration of protein in the lymph = hydrostatic and osmotic pressure controls the balance of water between the lymph nodes and blood vessels
Lymph Nodes arrangement
Arranged in chains
~600 total = 100-200 are mesenteric
Size ranges from 2 – 30 mm
Outside: fibrous capsule
Afferent Vessels: entering node
Efferent Vessels: exiting node
Lymph Vessel types:
capillaries
pre-collectors
collectors
trunks
ducts
Lymph Vessels
Different from veins and arteries = NO central pump
Localized pump action via movement and muscle contraction
moves fluid distal to proximal to the subclavian and into the circulatory system
Lymphatic capillaries
collect interstitial fluid and dissolved particles including proteins, cell debris, and pathogens
Structurally adapted to promote absorption of large molecules from the interstitial spaces
surround blood capillaries in loose connective tissue
blind-ended (have a true start)
mini-valves ensure fluid only goes in one direction - towards the heart
Most often located near blood capillaries
lymph capillaries vs blood capillaries
lymph ones are much more permeable
lymph ones are much larger
large particles like pathogens and cancer cells cannot directly get into blood capillaries but they can lymphatic capillaries
lymph capillary walls
Walls are made of one layer of overlapping flat endothelial cells
Surrounded by fibrous network
Fixed in the connective tissue by anchoring filaments which prevent the collapse of the initial lymph vessel network
Endothelial junctions = overlapping endothelial cells can open and close
Do not contain one way valves = lymph can flow in any direction
exchange across capillary walls
fluid and solutes flows out of capillaries due to blood pressure
> “bulk flow”
interstitial fluid flows back into capillaries due to osmosis
> plasma proteins increase osmotic pressure in capillary
____ of fluid returns to capillaries and ___ fluid returns via lymph
85%
15%
Lymph Capillaries: Important Characteristics
Form a plexus throughout the body
Are larger in diameter than blood capillaries
Are able to absorb interstitial fluid as necessary = including solids
Have no valves inside the capillary vessels = lymph can flow in any direction
LYMPH FLOW
blood capillaries -> interstitial tissue -> lymph capillaries -> lymph collectors -> lymph trunks -> lymph ducts
Pre-Collectors
Channel the lymph fluid into the larger transporting vessels
Able to absorb fluid and molecules = similar to lymph capillaries
Connect lymph capillaries to collectors
Mostly function to move fluid from capillaries to collectors = few valves
Some areas of smooth muscle
Collectors
Transporting lymph vessels
Contain valves = determine direction of lymph fluid flow = distal to proximal or toward the nearest regional node bed = each valve segment called ‘lymphangion’
Contractions determined by autonomous regulation through the sympathetic nervous system
Lymph volume stretches the vessel wall and smooth muscle responds with a localized contraction
Exercise increases the frequency of contractions
