Lecture 6: Lymphatic System Flashcards
1
Q
Lymphatic System
A
- part of circulatory system
- network of organs, lymph nodes, lymph ducts and lymph vessels
- make and move clear fluid called lymph from tissues to bloodstream directionally toward heart
- regional system that moves fluid from periphery to central circulation
- major part of immune system
- maintains fluid balance in tissues; fights infection; and helps remove cellular debris and waste products
- lymph nodes are soft, small, round structures: usually cannot be seen or easily felt; located in clusters in various parts of body, such as neck, armpit, groin, and inside center of chest and abdomen
- pressure driven system based on principles of osmotic diuresis
2
Q
Initial Lymphatics
A
- endothelium of lymphatics in direct contact with microfilaments of surrounding connective tissue
- microfilaments pull endothelial cell junction open when tissue pressure rises: allows movement of fluid through
- without changes in tissue pressure, fluid cannot enter lymphatics and fluid will accumulate in interstitium leading to edema
3
Q
Vessels
A
- deeper vessels contain smooth muscles and valves
- one way vessel system that drains the 10% excess tissue fluid volume and plasma proteins that remain in the interstitium after normal capillary perfusion/filtration has taken place and returns it to subclavian veins; increased number of plasma proteins in interstitium pulls water in and leads to edema
- all lymph passes through lymph nodes before going back into venous circulation
4
Q
Starling’s Theory of Fluid Dynamics
A
- plasma hydrostatic pressure: comes from capillaries and pushes into tissues
- tissue hydrostatic pressure: pushes fluid into capillaries
- plasma colloidal osmotic pressure: fluid pulled into capillary
- tissue colloidal osmotic pressure: fluid pulled out of capillary
- fluid at arterial end of capillary will tend to flow into tissue spaces (filtration): due to plasma hydrostatic pressure and pushes fluid from capillary into tissue
- fluid on venous end of capillary tends to flow back into vessel (reabsorption): due to plasma colloidal pressure and pulls fluid from tissue into capillary
- 10% of fluid does not get back into venous circulation and is taken up by lymphatics: lymphatic drainage occurs when fluid and proteins are not reabsorbed into capillary
5
Q
Flow of Lymphatics
A
-pre-collectors –> collecting lymphatics –> lymph trunks –> thoracic duct and right lymphatic duct –> left and right subclavian veins
6
Q
Lymph Nodes
A
- act as filters: cleanses lymph of waste products and cellular debris
- vessels distal to nodes are called afferent lymph vessels
- proximal to nodes are efferent lymph vessels
- produce lymphocytes and macrophages
7
Q
Lymphatic Territories and Watersheds
A
- lymph drainage territories called lymphotomes: bordered and separated by watershed areas (separates fluid going to different parts of body)
- trunk divided into 4 quadrant lymphotomes: L and R thoracic and L and R abdominal
- thoracic drain into ipsilateral axilla
- UE’s drain into ipsilateral axilla
- abdominal drain into superficial inguinal nodes
- LE’s drain into ipsilateral superficial inguinal nodes
8
Q
Lymphedema
A
- swelling of soft tissues that results from accumulation of protein rich fluid in extracellular spaces
- most common in extremities
- classification: primary (idiopathic) and secondary (acquired)
9
Q
Stages of Lymphedema Using International Society of Lymphology’s Scale
A
- stage 0 or latent lymphedema: lymph transport impaired, no edema; may have early S&S (achiness, limb pain, and sensation of heaviness)
- stage I: soft, pits on pressure, reverses with elevation
- stage II: nonpitting and does not reduce on elevation, clinical fibrosis, skin changes present, ma get recurrent bacterial and fungal infections
- stage III: lymphostatic elephantitis, severe nonpitting, fibrotic edema connective scar tissue, atrophic skin changes (thickened, leathery, keratotic skin, skin folds with tissue flaps, warty protrusions-papillomas-leaking lymph fistulae
10
Q
Etiologic Factors of Primary Lymphedema
A
- unknown
- 3 types of malformations
- aplasia: nearly absent lymph collectors
- hypoplasia: less than normal lymph collectors; most common
- hyperplasia: grossly dilated and enlarged lymph collectors
11
Q
Etiologic Factors of Secondary Lymphedema
A
- filariasis (most common): parasitic infection carried by mosquitoes, can grow to 20 cm long and 1-2 cm in diameter, adult male has tale that whips, damaging endothelium, after worm death foreign proteins cause severe local inflammatory reactions: blocks larger lymph collectors
- invasive procedures used in diagnosis and treatment of cancer: surgery and local radiation
- bacterial or viral infection
- multiple abdominal surgeries
- repeated pregnancies
- liposuction
- crush injuries, compound fractures, severe lacerations, paralysis, lipedema, AIDS
12
Q
Pathogenesis of Lymphedema
A
- normal lymph load, but transport is inadequate
- increased lymph load and inadequate transport
- chronic inflammation exists in lymphedematous tissue
- chronic inflammation leads to progressive tissue fibrosis
- increased tissue channel size leads to increased distance for oxygen to travel leading to hypoxia
13
Q
Structural Impairments from Lymphedema
A
- aging or damaged vessels have fibrin physically narrowing or blocking tissue channels
- hypoplasia of collecting lymphatics
- growth spurt and increase in tissue mass causes body to outgrow or outstrip capacity of lymphatic system
- incompetent valves of initial lymphatics
- gaps and tears in initial lymphatic walls associated with trauma and inflammation: integrity of lymph system not in tact
- physical obstruction of collecting lymphatics associated with fibrosis, radiation therapy, tumor growth, surgical excision of lymphatics during tumor removal, and torn anchoring filaments associated with acute edema
- in filariasis the adult worm blocks the vessels-damage due to constantly motile adult worm and toxic effects of parasite secretory/excretory products
14
Q
Functional Impairment of Lymphedema
A
- anything that causes a lac of variation in total tissue pressure causes lymphedema
- bed rest, paralysis, prolonged immobility, spasm of collecting lymphatics, paralysis of collecting lymphatics and impaired contraction
15
Q
Clinical Manifestations of Lymphedema
A
- secondary lymphedema can develop immediately postoperative, weeks, months, or years after surgery
- S&S: full sensation, skin tightness, decreased flexibility in hand, wrist, ankle, difficulty fitting into clothing
- physical impairments: increased circumferential limb girth, postural changes, discomfort, neuromuscular deficits, integumentary complications
- healing time increased
- risk of injury increased and oxygenation and metabolism of waste and cellular debris decreased
- atrophic skin changes can occur: loss of hair and sweat glands, formation of keratotic patches on skin, development of papillomas
