Human Anatomy CH 21 Flashcards
What is the main function of the lymphatic system?
Return excess tissue fluid to blood vascular system
What collects tissue fluid?
Lymphatic vessels
What is the function of the immune system?
Protects our bodies from foreign organisms and confers immunity to disease
What are the main components of the immune system?
Lymphocytes, lymphoid tissue, and lymphoid organs
Where do lymphatic vessels collect tissue fluid from?
Loose connective tissue
From the loose connective tissue, where is the fluid carried to?
Great veins in the neck
Once tissue fluid is within lymphatic vessels, what is it called?
Lymph
Where does lymph flow?
Only toward the heart
Where do lymphatic vessels collect tissue fluid from? Where does it return it to?
From: Tissue fluid and blood proteins
Returns to: Bloodstream
What are the smallest lymph vessels?
Lymph capillaries
Describe 2 characteristics of lymph capillaries
- First to receive lymph
- Highly permeable vessel
What collects from lymph capillaries?
Collecting lymphatic vessels
What are scattered along collection vessels?
Lymph nodes
What collects lymph from collecting vessels?
Lymph trunks
What empties in the veins of the neck?
Lymph ducts
List the order of lymphatic vessels (4)
- Lymph capillaries
- Collecting lymphatic vessels
- Lymph trunks
- Lymph ducts
Lymphatic capillaries are located near?
Blood capillaries
Where do the lymphatic capillaries receive tissue fluid from (non-specific)? What opens to allow fluid to enter?
Connective tissue; minivalves open
High permeability of lymphatic capillaries allows entrance of what?
Tissue fluid, protein molecules, bacteria, viruses, and cancer cells
What are lacteals?
Specialized lymphatic capillaries
Where are lacteals located?
Villi of small intestines
What do lacteals receive?
Digested fats
What is chyle?
Fatty lymph
What is fatty lymph?
Chyle
What do collecting lymphatic vessels accompany? What tunics are they composed of?
Blood vessels; same 3 tunics as blood vessels
Do lymphatic vessels contain more valves than veins do?
Yes
Does the heartbeat help aid the flow of lymph?
No
What 3 weaker mechanisms propels lymph?
- Bulging of skeletal muscles
- Pulsing of nearby arteries
- Tunica media of the lymph vessels
What is the function of lymph nodes?
Cleanse the lymph of pathogens
How many lymph nodes are in the human body?
500
Where are the superficial lymph nodes located?
Cervical, axillary, and inguinal regions
Where are the deep lymph nodes located?
Tracheobronchial lymph nodes, aortic lymph nodes, iliac lymph nodes
What is a Fibrous Capsule?
Capsule surrounding a lymph node
What are Trabculae?
Connective tissue strands extending inwards to divide lymph nodes into segments
Where does lymph enter and exist lymph nodes?
Enters: Convex aspect of a lymph node through afferent lymphatic vessels
Exits: At the hilum through efferent lymphatic vessels
What do collecting lymph vessels converge to form?
Lymph trunks
What receives lymph from lower limbs?
Lumbar trunks
What receives chyle from digestive organs?
Intestinal Trunk
What collects lymph from thoracic viscera?
Bronchomediastinal trunks
What receives lymph from upper limbs and thoracic wall?
Subclavian trunks
What drains lymph from the head and neck?
Jugular Trunks
Where are cisterna chyli located?
Union of lumbar and intestinal trunks
Where does the thoracic duct ascend along? What kind of circulation does it empty into?
- Vertebral bodies
- Venous circulation
What drains three-quarters of the body?
Thoracic duct
What duct is at the junction of the left internal jugular and left subclavian veins?
Thoracic duct
What duct empties into the right internal jugular and subclavian veins?
Right Lymphatic Duct
What are the 2 main functions of the immune system?
- Recognize specific foreign molecules
- Destroy pathogens effectively
What are the key cells of the immune system? What can it include?
- Lymphocytes
- Lymphoid tissue and lymphoid organs
Name all 6 lymphoid organs
- Lymph Nodes
- Spleen
- Thymus
- Tonsils
- Aggregated lymphoid nodules
- Appendix
What do infectious organisms trigger?
Inflammatory response
After an inflammatory response is triggered, what happens to invading organisms?
Attacked by macrophages, then lymphocytes
What is the function of a lymphocyte?
Must be able to effectively recognize a specific foreign molecule
What are antigens?
Any molecule that induces a response from a lymphocyte
What are the 2 main classes of lymphocytes?
- B Lymphocytes
- T Lymphocytes
What do Cytotoxic T Lymphocytes do? What are the 4 steps to this process?
Attack foreign cells directly
1. Bind to antigen-bearing cells
2. Perforate cell membrane
3. Signal cell to undergo poptosis
4. Destroy virus-infected cells and some cancer cells
What lymphocytes become plasma cells?
B lymphocytes
What is another “name” for Helper T and Cytotoxic T Cells?
Helper T: CD4+
Cytotoxic T: CD8+
What do B lymphocytes primarily respond to?
Bacteria and bacterial toxins
What does plasma cells do? What do they secrete?
- Mark cells for destruction by macrophages
- Secretes antibodies
Where do lymphocytes originate from?
Bone marrow
Which lymphocytes travel to the thymus gland? Which lymphocytes stay in the bone marrow?
- T lymphocytes
- B lymphocytes
What are 4 characteristics/qualities of activated lymphocytes?
- Are able to recognize a unique antigen
- Gain immunocompetence
- Travel through the bloodstream to meet and bind to a specific antigen
- Can proliferate rapidly
When a lymphocyte is activated, what presents the lymphocyte its antigen?
Macrophage or dendritic cell
T and B lymphocytes both produce clones of what?
- Effector lymphocytes
- Memory cells
What do effector lymphocytes do?
Respond immediately to infectious microorganisms, then die
What do memory cells do?
- Waits until the body encounters the antigen again
- Prevents subsequent infections of the same illness
What kind of cells are the basis for acquired immunity?
Memory cells
What tissue is the most important tissue of the immune system?
Lymphoid Tissue
What are the two “general” locations that lymphoid tissue can be found?
- Mucous membrane of digestive, urinary, respiratory, and reproductive tracts
- Lymphoid organs (except thymus)
What does MALT stand for?
Mucosa associated lymphoid tissue
What are the 2 primary lymphoid organs?
- Bone marrow
- Thymus
What are the 3 secondary lymphoid organs?
- Lymph nodes, spleen, tonsils
- Aggregated lymphoid nodules
- Appendix
What are the 2 functions of the lymphoid organs?
- Gather and destroy infectious microorganisms
- Store lymphocytes
What is the site in which immature lymphocytes develop into T lymphocytes?
Thymus
When in a human lifespan is the thymus most active?
Childhood
What does the thymus secrete?
Thymic hormones
With age, functional thymus tissue __________. What is the percentage of tissue that’s left?
- Atrophies
- 5%
What is the thymus composed of?
Cortex and medulla
What does the medulla of thymus contain?
Thymic corpuscles
How does the thymus differ from other lymphoid organs?
- Functions strictly in lymphocyte maturation
- Arises from epithelial tissue
What are the 3 functions of lymph nodes?
- Lymph percolates through lymph sinuses
- Most antigenic challenges occur in lymph nodes
- Antigens destroyed and activate B and T lymphocytes
What is the largest lymphoid organ?
Spleen
What are the 2 main blood-cleansing functions of the spleen?
- Removal of bloodborne antigens
- Removal and destruction of old or defective blood cells
Where is the site of hematopoiesis in the fetus?
Spleen
Where is the site of B cell maturation into plasma cells?
Spleen
What are 2 NON-blood-cleansing functions of the spleen?
- Storage of platelets
- Phagocytosis of bacteria and worn-out RBCs, WBCs, and platelets
What are the two “pulps”? Where are they found?
- White pulp
- Red pulp
- Spleen
What surrounds the white pulp?
Red pulp
What is the red pulp composed of? What is it responsible for (function)?
- Venous sinuses
- Splenic cord
- Responsible for disposing of worn-out RBCs
What is the white pulp made of? What are its 2 functions?
- Thick sleeves of lymphoid tissue
- Bloodborne antigens are destroyed as they activate the immune response
- Provides immune function of the spleen
What are the simplest lymphoid organs?
Tonsils
What are the 4 groups of tonsils?
- Palantine tonsil
- Lingual tonsil
- Pharyngeal tonsil
- Tubal tonsils
How are the tonsils arranged and what is their function?
Arranged in a ring to gather and remove pathogen
What are the tonsils made out of? What is this consisted of?
Lamina propria, consists of MALT
What is abundant in the walls of intestines?
MALT
What do aggregated lymphoid nodules and appendix do?
Fight against invading bacteria
What is the appendix?
Tubular offshoot of the cecum
What is located in the distal part of the small intestine?
Aggregated lymphoid nodules (Peyer’s patches)
What is leakage of fatty lymph into the thorax?
Chylothorax
What is the inflammation of a lymph vessel?
Lymphangitis
What is a viral disease caused by the Epstein-Barr virus that attacks B lymphocytes?
Mononucleosis
What is cancer of the lymph nodes?
Hodgkin’s Lymphoma
What is uncontrolled multiplication and metastasis of undifferentiated lymphocytes?
Non-Hodgkin’s Lymphoma
Where do lymphatic vessels and lymphatic nodes develop from?
Lymphatic sacs
What arises from mesodermal mesenchyme?
Spleen, lymph nodes, and MALT
Where does the thymus originate from?
Outgrowth of the endoderm
