Chapter 23 - Lymphatic System Flashcards
What do lymphatic vessels transport?
Transport fluid called lymph from tissues to the venous systems?
Functions of the lymphatic system
- Produce, maintain, and distribute LYMPHOCYTES
- Maintain normal blood and interstitial fluid volume
- Alternate route for the transport of nutrients, hormones, and waste
Sizes of lymphatic vessels
- Small lymphatic capillaries
- Medium lymphatic vessels
- Large lymphatic trunks
- Lymphatic ducts
Lymphatic vessels are almost always found with ____
Blood vessels
Location of lymphatic vessels
- Most tissues
- Absent in avascular tissue and CNS
What is lymph?
Lymph is a fluid connective tissue
- Only occurs in lymphatic vessels
Where is lymph derived from?
- Interstitial fluid of the tissues
- Lymphocytes
- Macrophages
How is interstitial fluid derived from lymph?
- Originates from the plasma
- Water and dissolved materials leak out of capillaries due to diffusion and filtration
- 27L/day enters the interstitial spaces
- Fluid lacks proteins and has lower Oxygen
- Interstitial fluid moves into the lymphatic capillaries and is known as LYMPH
How much of interstitial fluid is absorbed
90%
Five facts explaining lymphatic capillaries
- Closed ended tubes
- In interstitial spaces
- Form networks
- Single layer of squamous cells with incomplete basal lamina
- Fenestrated
How do lymphatic capillaries differ from blood capillaries
- Large diameter
- Thinner walls
- Flat and irregular
- Have anchoring filaments to keep the passage open
- Overlapping endothelial cells
Explain the formation of lymph
- Interstitial fluid enters capillaries
- Overlapping cells function as one way valves
- Moves through fenestrations
- Large things such as viruses and debris follow
Characteristics of medium lymphatic vessels (4)
- Merging of lymph capillaries
- Similar to veins (interna, media, adventitia, and valves)
- Merge to form trunks
- Travel with arteries of same size
What are lymphatic trunks named for?
For the region the drain
Examples of lymphatic trunks
- Lumbar
- Intestinal
- Broncomediastinal
- Subclavian
- Jugular
What do lymphatic trunks drain into?
Lymphatic ducts
Two lymphatic ducts
Thoracic and right lymphatic
What do lymphatic ducts do? (3)
- Deliver lymph to venous circulation at subclavian
- Reintroduced to bloodstream
- Becomes part of plasma and is circulated
What does the thoracic duct drain?
- Lower body
- Left arm
- Head
- Neck
Route of the thoracic duct
- Arises from CISTERNA CHYLI
- Through diaphragm
- Ascends in front of vertebral column
- Empties into LEFT SUBCLAVIAN VEIN
What does the Right Lymphatic Duct drain?
- Right side of head
- Neck
- Right arm
Route of the Right Lymphatic Duct
- Starts in right thorax
- To the Right subclavian vein
The rate at which ducts drain (3)
- Unevenly drain fluid from body
- Thoracic does the majority
- It is much longer and drains the entire inferior half of the body
What are valves in lymph and what do they do?
- Occur at bulges
- Prevent backflow
How do valves prevent backflow?
- Pressure is lower in lymphatics than in veins
- Lymph is moved using similar methods to veins (skeletal muscles and breathing)
If drainage does not occur
lymphedema
Primary cells of the lymphoid system
Lymphocytes
What do lymphocytes allow for?
Specific (or adaptive) immunity
Multi-faceted immune response to the detection of specific foreign antigens
Specific immunity
Characteristics of NK-cells (5)
- Natural killer cells
- Derived directly from bone marrow
- NON-specific immunity
4, Detect chemical signals other than specific antigens (like other leukocytes) - Induce apoptosis
Characteristics of B-cells (3)
- Originate and develop in the bone marrow
- Stimulated by an antigen to produce antibodies
- Can survive for years as MEMORY CELLS, and become active once exposed to a similar antigen
Characteristics of T cells (4)
- Originate in the bone marrow but develop in the thymus
- Attack cells with antigens indicating viral infection or detrimental mutations (cancer)
- Induce apoptosis
- Have MEMORY CELLS similar to B-cells
Reticular connective tissue dominated by lymphocytes
Lymphoid nodules
What are lymphoid nodules NOT?
NOT organs
Digestive lymph nodules
M.A.L.T. (Mucosa associated lymphoid tissue)
Three types of M.A.L.T.
- Tonsils
- Aggregated lymphoid nodules
- Appendix
Where are the tonsils and what do they do?
- Positioned around the pharynx
- Remove pathogens that enter via air or food
Three types of tonsils with descriptions
- Pharyngeal tonsil - one nodule in nasopharynx (adenoids)
- Palatine tonsils - two nodules on the soft palate
- Lingual tonsils - two nodules at the base of the tongue
Line the mucosa of the small intestine
Aggregated lymphoid nodules
Bind tube at the beginning of the small intestine
Appendix
Areas of the appendix prone to infection
- Appendicitis
- Intestinal flora enter underlying tissues
Surrounded by a fibrous connective tissue capsule
Lymphatic organs
Examples of lymphatic organs
- Lymph nodes
- Thymus
- Spleen
Five components to lymph nodes
- Bean shaped
- Between several AFFERENT and one EFFERENT vessels
- Hilus
- Cortex
- Medulla
What is the hilus in lymph nodes?
Indented region where BV’s, nerves, and efferent lymph vessels connect
The cortex capsule has ____ that subdivide it
Trabeculae
Two regions of the cortex with their characteristics
- Outer cortex - consists of aggregated B-cells
2. Inner cortex - T cells enter blood here
What happens in the Medulla?
Where B-cells leave through the efferent vessel
Six locations of the lymph nodes
- Cervical
- Axillary
- Inguinal
- Pelvic
- Abdominal
- Thoracic
Where is the spleen found?
On the left side of stomach
This is the largest lymphatic organ
Spleen
Two sections of the spleen with meanings
- White pulp - resembles lymph node
2. Red pulp - large amounts of RBC (sinuses, macrophages, T/B cells)
Functions of the spleen
- Remove old RBC’s
- Store/recycle iron
- Initiate immune responses
- Blood reservoir
- RBC production in fetus
Where is the thymus?
In mediastium
What is special about the thymus?
- First lymph organ to develop
- Grows until puberty
- Shrinks with age
- Replaced by fibrous and adipose tissue
Two lobes with lobules of thymus
Cortex - mostly immature Tcells
Medulla - mostly reticular epithelial cells
What do T-cells in the thymus do? (3)
- Cortex produces T-cells
- Mature and migrate into medulla
- Enter blood vessels and go into circulation
What do Reticular cells in the thymus do? (2)
- Produce thymosin
- Promote T cell differentiation
