Podcast
Questions and Answers
What is the main function of Peyer's patches and the appendix?
What is the main function of Peyer's patches and the appendix?
What is the term for the clusters of lymphoid follicles found in the wall of the small intestine?
What is the term for the clusters of lymphoid follicles found in the wall of the small intestine?
From which embryonic tissue do lymphoid organs (except the thymus) arise?
From which embryonic tissue do lymphoid organs (except the thymus) arise?
What is the term for the mucosa-associated lymphatic tissue found in the digestive and respiratory systems?
What is the term for the mucosa-associated lymphatic tissue found in the digestive and respiratory systems?
Signup and view all the answers
At what stage of embryonic development are the beginnings of lymphatic vessels and main clusters of lymph nodes apparent?
At what stage of embryonic development are the beginnings of lymphatic vessels and main clusters of lymph nodes apparent?
Signup and view all the answers
What structure forms as an outgrowth of the pharynx during embryonic development?
What structure forms as an outgrowth of the pharynx during embryonic development?
Signup and view all the answers
What is the function of lymphoid nodules in the walls of the bronchi?
What is the function of lymphoid nodules in the walls of the bronchi?
Signup and view all the answers
Which of the following lymphoid organs are poorly developed at birth?
Which of the following lymphoid organs are poorly developed at birth?
Signup and view all the answers
What is the term for the clusters of lymphoid follicles found in the wall of the small intestine, as well as similar structures found in the appendix?
What is the term for the clusters of lymphoid follicles found in the wall of the small intestine, as well as similar structures found in the appendix?
Signup and view all the answers
What is the origin of the lymphatic vessels?
What is the origin of the lymphatic vessels?
Signup and view all the answers
Study Notes
Lymphatic System
- Consists of three parts: lymphatic vessels, lymph, and lymph nodes.
- Returns interstitial fluid and leaked plasma proteins back to the blood.
- Provides the structural basis of the immune system with lymphoid organs and tissues.
Lymph Transport
- Lymph is propelled by pulsations of nearby arteries and contractions of smooth muscle in the walls of lymphatics.
Lymphoid Cells
- Lymphocytes are the main warriors of the immune system.
- Two main varieties: T cells (T lymphocytes) and B cells (B lymphocytes).
- T cells manage the immune response and attack and destroy foreign cells.
- B cells produce plasma cells, which secrete antibodies.
Other Lymphoid Cells
- Macrophages phagocytize foreign substances and help activate T cells.
- Dendritic cells capture antigens and deliver them to lymph nodes.
- Reticular cells produce stroma that supports other cells in lymphoid organs.
Lymphoid Tissue
- Houses and provides a proliferation site for lymphocytes.
- Furnishes a surveillance vantage point.
- Two main types: diffuse lymphatic tissue and lymphatic follicles.
- Diffuse lymphatic tissue comprises scattered reticular tissue elements in every body organ.
- Lymphatic follicles are solid, spherical bodies of tightly packed reticular elements and cells.
Lymph Nodes
- Principal lymphoid organs of the body.
- Embedded in connective tissue, in clusters along lymphatic vessels.
- Near the body surface in inguinal, axillary, and cervical regions of the body.
Thymus
- Differs from other lymphoid organs in important ways.
- Functions strictly in T lymphocyte maturation.
- Does not directly fight antigens.
- The stroma of the thymus consists of star-shaped epithelial cells (not reticular fibers).
Tonsils
- Simplest lymphoid organs.
- Form a ring of lymphatic tissue around the pharynx.
- Contain follicles with germinal centers.
- Are not fully encapsulated.
- Epithelial tissue overlying tonsil masses invaginates, forming tonsillar crypts.
Aggregates of Lymphoid Follicles
- Peyer’s patches: clusters of lymphoid follicles in the wall of the distal portion of the small intestine.
- Similar structures are also found in the appendix.
- Destroy bacteria, preventing them from breaching the intestinal wall.
- Generate “memory” lymphocytes.
MALT
- Mucosa-associated lymphatic tissue, including Peyer’s patches, tonsils, and the appendix (digestive tract).
- Lymphoid nodules in the walls of the bronchi (respiratory tract).
- Protects the digestive and respiratory systems from foreign matter.
Developmental Aspects
- Beginnings of the lymphatic vessels and main clusters of lymph nodes are apparent by the 5th week of embryonic development.
- These arise from the budding of lymph sacs from developing veins.
- Lymphatic organs (except the thymus) arise from mesoderm.
- The thymus (endodermal origin) forms as an outgrowth of the pharynx.
- Except for the spleen and tonsils, lymphoid organs are poorly developed at birth.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Learn about the lymphatic system, its three main components, and its functions in returning interstitial fluid and proteins back to the blood.
