Introduction to Lymph System
What are the primary lymph organs?
Red bone marrow
Thymus
Describe lymph capillaries. Where are they located/not located?
-found throughout the body (lacteals: small intestine villi)
-NOT found in: avascular tissue, CNS, Splenic Pulp, bone marrow
What is interstitial fluid made of?
Plasma: mostly water (92%), small and large proteins, hormones, and nutrients
What are the 4 types of lymphatic tissues?
1. diffuse: dispersed along mucous membranes, Gi and respiratory tract
2. aggregated: monitoring intestinal bacteria populations (tonsils, adenoids, peyer's patches)
3. primary organs: bone marrow/thymus
4. secondary organs: lymph nodes/spleen
Describe the structure of the thymus
a soft, bi-lobed organ located in the mediastinum that is composed of lymphatic tissues (nodules) which atrophies after puberty
made up of a cortex, a medulla and epithelial cells
What are the secondary lymph organs?
lymph nodes
spleen
Describe lymphatic vessel formation and how they interact with lymph nodes.
-formed by merging lymph capillaries and possess one way valves (like veins)
-enter lymph nodes as AFFERENT vessel and leave node as EFFERENT vessel
Describe the formation of lymph.
1. osmotic pressure increases due to an increase in protein concentration in interstitial fluid
2. increase in pressure forces fluid into lymph capillaries
3.once fluid enters the lymph capillaries it is now called lymph
4. this process prevents edema
What is the structure of lymph nodes?
usually less than 2.5cm with a hilum containing efferent lymphatic vessels, artery, and vein (afferent vessels are on the surface)
enclosed in connective tissue capsule becoming nodules
Outer region = Cortex: germinal centers, B cells and macrophages
Inner region= Medulla: T cells, macrophages ,and plasma cells in medullary cords
What are the functions of the thymus?
Differentiation and selection of T-cells (go to mature)
Epithelial cells secretion of Thymosin
Name one function of the lymphatic system
returns extra fluid to bloodstream
Name the 6 main lymphatic trunks.
Lumbar Intercostal
Intestinal Broncho-mediastinal
Subclavian Jugular
give 3 functions of lymph
1. Returns small plasma proteins to the blood
2. Transports foreign particles to lymph nodes
3. Transport lipids and fat-soluble vitamins, absorbed in the intestines
Where are lymph nodes located?
located in groups/chains along large lymph vessels
- cervical
-inguinal
-supratrochlear
-axillary
describe the structure of the spleen
Resembles a giant lymph node–encapsulated & divided into nodules
Name one function of the lymphatic system
transport of dietary fats
Compare and Contrast the two lymphatic ducts.
both drain into the subclavian veins
1. Right Lymphatic Duct: drains right upper quadrant (25% of body)
2. Thoracic Duct: drains rest of body (about 75%)
Describe how lymph flows.
Much like venous return, this is a low pressure system. The presence of valves allows only one way flow.
Skeletal muscle pumping helps move lymph.
Low pressure in thoracic cavity during inspiration also causes lymph to flow.
What is one function of lymph nodes?
Removal and destruction of potentially harmful foreign substances from the lymph using macrophages.
What are the two types of splenic tissue?
1. White pulp: lymphocytes around artery
2. Red pulp: blood-filled sinuses formed by arterioles which release blood during hemorrhage
Name one function of the lymphatic system
immunity and disease fighter
Describe the pathway of lymph flow in the body.
-Lymphatic capillaries become afferent lymphatic vessels which flow in Lymph nodes where they will exit in efferent lymphatic vessels. The Efferent Lymphatic vessels will come together from lymphatic trunks. The lymphatic Trunks flow into one of two collecting ducts. Finally the Lymph will be returned to the subclavian veins.
What happens if lymph flow is obstructed? How does our body prevent this?
Edema: accumulation of excess tissue fluid resulting in swelling
Anchoring Filaments fight edema: tissue swells and pulls on filaments which draws fluid in
Name another function of lymph nodes.
Centers for proliferation of lymphocytes
What is the primary function of the spleen?
removal and destruction of large foreign bodies & worn blood cells by a large number of macrophages