Lecture 15 Flashcards
The Lymphatic System helps to maintain the body’s fluid environment by _____ and _____ lymph from ____ back into the ___________
filtering; draining; tissues; bloodstream
The lymphatic system includes what structures (3)
- Lymphatic Vessels
- Lymph Nodes
- Several Organs
What is Lymph?
Interstitial fluid that has leaked out of blood capillaries, containing white blood cells (that have been absorbed by lymphatic capillaries)
What are Lymph Nodes?
small bean shaped structures where lymph is filtered
How do Lymph Nodes filter Lymph?
They trap foreign substances (bacteria, viruses) which then get destroyed by the immune cells present w/in the LN
What are the Lymph Organs? (3)
- Spleen
- Thymus
- Red Bone Marrow
What are the Primary Lymph Organs? (2)
Red Bone Marrow & Thymus
What are the Secondary Lymph Organs? (3)
- Lymph Nodes
- Spleen
- Lymphatic Nodules
Describe the general functions of Primary and Secondary Lymph organs.
Primary: these organs produce and mature immune cells
Secondary: where immune response is most active
What are Immunocompetent cells? What are the 2 groups?
Cells that are able to recognize and respond to antigens
- B lymphocytes
- T lymphocytes
What is Lymphatic Flow?
Them movement of lymph through the lymphatic system; from lymphatic capillaries through lymph nodes, into larger vessels and ducts; then draining into the venous system
Describe the presentation of Antigens.
Dendritic Cells capture Antigens and present them to T cells; initiating the immune response
Differentiate between B cells and T cells
B cells: manufactured in the bone marrow - involved in producing antibodies
T cells: manufactured in the thymus - involved in the cell mediated immune responses
What are the roles of the Spleen and the Thymus in the immune system?
Spleen: filters blood (removing old RBC and pathogens), produces antibodies & activates immune response
Thymus: where T cells are produced, mature, and become immunocompetent
Lymphatic capillaries are found throughout the body, except in…
Avascular Tissue
What are Anchoring Filaments?
The structures that help to hold capillaries in place, and react to changes in tissue pressure
When there’s swelling, what happens with the anchoring filaments?
The filaments pull on overlapping endothelial cells, which allows for more fluid to enter the lymphatic capillary
What are Lacteals?
specialized lymphatic capillaries in the small intestine that contains chyle (dietary lipids)
Lymphatic Capillaries merge to form…
Lymphatic Vessels
At intervals along the vessels, fluid flows through…
Lymph Nodes
What are the 5 major drainage trunks?
- Lumbar Trunks
- Intestinal Trunks
- Bronchomediastinal Trunks
- Subclavian Trunks
- Jugular Trunks
List the order of Lymph Flow including entrance.
- Plasma enters venous blood
- Lymphatic Capillaries
- Lymphatic Vessels
- Lymph Nodes
- Venous Blood
- Lymph Ducts
- Lymph Trunks
What is the function of the 5 major trunks?
Drainage
What do the Lumbar Trunks drain?
The Lower Extremities, Pelvis, Visceral Wall, Abdominal Wall, Kidneys
What do the Intestinal Trunks drain?
The Stomach, Intestines, Spleen, Pancreas, Liver
What do the Bronchomediastinal Trunks drain?
Lungs, Heart, Thoracic wall
What do the Subclavian Trunks drain?
Upper Extremities (arms)
What do the Jugular Trunks drain?
Head and Neck
What do Lymph Ducts do?
Returns lymph back to the circulatory system
Lymph ducts return lymph back to the circulatory system via what?
the Venous System
Trunks on which side of the body all have independent entries?
the Right Side
Which Lymphatic Duct is the main duct, and is responsible for draining both lower limbs as well left side of head, neck and chest?
Thoracic Lymphatic Duct (aka Left LD)
What is the Right Lymphatic Duct responsible for draining?
The right side of the Head, Neck, and Chest - and the Right Arm
What is the Left Lymphatic Duct / Thoracic LD responsible for draining?
the Lower Limbs, the left side of the Head, Neck, and Chest
What is the Cisterna Chyli?
it is the swelling of a thoracic duct ; into which lymph from the lower limbs and abdomen flows (lumbar and thoracic trunks)
State the order and steps at which Lymph flows (11).
- Capillary Beds; where plasma leaks from blood into.. 2. Interstitial Spaces; spaces between tissues and becomes..
- Interstitial Fluid; which is absorbed by..
- Lymphatic Capillaries; transforming into..
- Lymph; which is carried through the network of..
- Lymphatic Vessels; where it then travels through..
- Afferent Lymph Vessels; into..
- Lymph Nodes; and exit them via…
- Efferent Lymph Vessels; into..
- Lymphatic Ducts; where it returns back to the..
- Bloodstream
What is the role of Muscle Contraction and Breathing in Lymph Movement?
The contraction of muscles and breathing, push Lymph via the compression of Lymph Vessels
What are the 2 groups of Lymphatic Organs based on, and what are they?
based on: Function
- Primary Lymphatic Organs
- Secondary Lymphatic Organs/tissues
What occurs at the Primary Lymphatic Organs?
Lymphocytes (type of WBC involved in immune response) are formed and mature
What occurs at the Secondary Lymphatic Organs/tissues?
Immune response is activated at these sites
Where are Red Bone Marrows found?
in flat bones and the epiphyses of long bones
what happens at the Red Bone Marrow?
- B cells and Pre-T cells are formed
- B cells become immunocompetent
What does it mean when a B Cell becomes immunocompetent?
They are then able to recognize and bind to specific antigen
Where is the Thymus located?
beneath the sternum and above the heart
What do the Lymphatic Nodules do (secondary LO)?
They guard against pathogens in mucous membranes and skin
Describe the structure of the Thymus Gland.
- Bilobed
- Lobes are enclosed by a capsule
- Lobes are divided into 2 segments called lobules
Describe the structure of Lobules of the Thymus Gland.
Lobules are the 2 segments of thymus gland lobes - divided by trabeculae (extensions of the capsule)
-1st segment = cortex
(packed with developing T cells, dendritic cells, and macrophages)
-2nd segment = medulla
(packed with mature T cells - and reticular epithelial cells that produce thymic hormones)
Epithelial Cells of the Inner Medulla of the Thymus Lobule, produce what?
Thymic Hormones
Thymic Hormones serve what purpose?
They are crucial for T cell development
What structure is found in the Medulla of the Thymus?
Hassall’s Corpuscle
What is the function of Hassall’s Corpuscle
no one knows
What are the main structures of the Lymph Node?
- Capsule
- Trabeculae
- Stroma
- Parenchyma (cortex&medulla)
What is the Stroma of the Lymph Node?
the structural framework that supports and scaffolds the LN; consists of reticular fibres and trabeculae
What is the Parenchyma of the Lymph Node?
The functional tissue of the LN that is divided into 2 parts; cortex and medulla
What is the inner most chamber of the Lymph Node?
the Medulla
The Cortex of the Lymph Nodes contains what?
Densely packed Lymphatic Nodules, which contain B cells
In response to an antigen, what happens with the B cells of the primary lymphatic nodules, of the cortex of Lymph Nodes?
B cells activate; then proliferate and differentiate to form Secondary Lymphatic Nodules
The transformation of Primary Lymphatic Nodules in the cortex of LN, into Secondary Lymphatic Nodules; is marked by what their differentiation into what? (2)
- Plasma Cells
- Memory B Cells
What do Plasma Cells do? (secondary lymphatic nodule)
They produce antibodies that are specific to the encountered antigen
What are Antibodies?
proteins that can neutralize a pathogen, or mark them for destruction by other immune cells
What do Memory B Cells do? (secondary lymphatic nodule)
Long lived cells that provide immunity against future exposures to the same antigen
(have a faster response to remembered antigens if they ever enter the body again)
Of the Lymph Node, what structure does the Outer Cortex have that the Inner Cortex does not?
Lymphatic Nodules
The Inner Cortex of the Lymph Node is composed of what? (2)
- Dendritic Cells
- T cells
What are T cells and their role, in the Inner Cortex of the Lymph Node?
They are a type of WBC
responsible for attacking antigens
What are Dendritic cells and their role, in the Inner Cortex of the Lymph Node?
They are messenger cells
responsible for capturing antigens and transporting them to the lymph nodes - to present the antigen to the T cells
The Medulla of the Lymph Node is filled with what? (3)
- B cells
- Plasma Cells
- Macrophages
What is the difference between the B cells residing in the Primary Lymphatic Nodule of Lymph Nodes, and that of the Medulla?
Cortex: B cells here are naive (resting state) and have not yet encountered their antigen
Medulla: B cells here are in their differentiated state (eg: memory B cells or plasma cells)
What are Plasma cells and their role, in the Medulla of the Lymph Node?
They are B cells that have been activated and differentiated in response to an antigen
-they produce antibodies
What are Macrophages and their role, in the Medulla of the Lymph Node?
They are a “clean-up” cell
-they engulf and digest pathogens, dead cells, and debris (to clear infections and to aid in healing)
Which part of the Lymph Node is the final staging area for the immune response?
The Medulla
True or False:
Antibodies produced by plasma cells in the medulla can enter the circulation to fight infections throughout the body
True
State the order and steps for Filtration through Lymph Nodes (6)
- Afferent Lymphatic Vessels; where lymph enters the LN through the…
- Subscapular Sinus; outer layer of the LN - connecting to the…
- Trabecular Sinus; channels that run through the LN framework guiding lymph from subscap sinus to the…
- Medullary Sinus; the innermost area in the medulla of the LN (final filtration) then sends lymph to the…
- Efferent Lymphatic Vessels; where lymph are carried out of the LN and back into the…
- Bloodstream
As lymph moves through the node, foreign substances get trapped in what?
the Reticular Fibers
The Gastric Impression of the Spleen is where it contacts what?
the Stomach
The Renal Impression of the Spleen is where it contacts what?
the Kidney
The Colic Impression of the Spleen is where it contacts what?
the Colon
What is the Hilum of the Spleen?
it is a gateway indentation; where blood, lymphatic vessels, and nerves enter and leave the spleen
What is the Stroma of the Spleen?
the structural framework of the spleen, made up of a capsule, trabeculae, and fibers
The Parenchyma of the Spleen is divided into what 2 groups?
White Pulp and Red Pulp
The White Pulp of the Spleen’s Parenchyma contains what?
lymphatic tissue surrounding the splenic arteries
What occurs in the White Pulp of the Spleen’s Parenchyma?
Immune system checks blood for invaders and initiates immune responses - B&T cells & Macrophages function here
The Red Pulp of the Spleen’s Parenchyma contains what?
Venous Sinuses filled with blood and splenic cords made of splenic tissue
What occurs in the Red Pulp of the Spleen’s Parenchyma?
filtration of old or damages RBC and recycling of their parts
What is the overall function of the Spleen? (2)
Immune Response & Blood Filtration
Describe the Blood Flow through the Spleen. (7)
- Blood enters spleen through Splenic Artery
- Flows to Central Arteries (w/in white pulp)
- is then Filtered and participates in immune surveillance
- Enters Red Pulp for further filtration and recycling
- cleaned blood enters Venous Sinuses and then enters
- splenic vein where it connects to the other veins forming portal veins, where it then enters the
- Bloodstream
What is the Flow of Blood in Spleen (shortened) ? (3)
- Blood Flows ( body to spleen)
- Splenic Artery
- Central Arteries of White Pulp
