Review Questions And Complete
Solutions.
Lymphatic System - Answer a one-way return system of interstitial fluid and leaked plasma proteins
back to blood via lymphatic vessels
Lymphatic Capillaries - Answer -Blind-ended vessels that weave between tissue cells and blood
capillaries
-Similar to blood capillaries, but more permeable
-Can take up larger molecules and particles that blood capillaries cannot
What are the specialized structures that increase the permeability of lymphatic capillaries? - Answer -
Endothelial cells: overlap loosely to form one-way minivalves
-Minivalves: anchored by collagen filaments to matrix, so increases in ECF volume opens minivalves even
more
Lacteals - Answer -specialized lymph capillaries present in intestinal mucosa
-Absorb digested fat and deliver fatty lymph to the blood
How do larger lymphatic vessels vary from blood vessels? - Answer -Have thinner walls
-have more internal valves
-Anastomose more frequently
Lymphatic Trunks - Answer -are formed by union of largest collecting vessels
-drain large areas of body
Right Lymphatic Duct - Answer drains right upper arm and the right side of the head and neck
,Thoracic Duct - Answer drains the whole body besides what is drained by the right lymphatic duct
Lymphangitis - Answer -condition in which lymphatic vessels appear as painful red lines under the skin
-Caused by inflammation of larger lymphatic vessels that contain vaso vasora
How is lymph propelled through the lymphatic vessels? - Answer -Milking action of skeletal muscle
-Pressure changes in thorax during breathing
-Valves to prevent backflow
-Pulsations of nearby arteries
-Contractions of smooth muscle in walls of lymphatics
Lymphedema - Answer -severe localized edema
-Caused by anything that prevents normal return of lymph to blood
What do lymphoid cells consist of? - Answer -immune system cells found in lymphoid tissue and
-supporting cells that form lymphoid tissue structures
Lymphocytes - Answer -cells of the adaptive immune system
-they protect against antigens
-mature into one of two main types: T cells or B cells
T Cells - Answer -manage immune response, and some also attack and destroy infected cells
-originate in bone marrow, mature in thymus
B Cells - Answer -produce plasma cells, which secrete antibodies
-originate and mature in bone marrow
Macrophages - Answer -type of antigen-presenting cell
,-phagocytize foreign substances, help activate T cells, trigger inflammatory responses, and recruit
additional defenses
-widely distributed in connective tissues and lymphoid organs
-develop from monocytes
-biggest phagocyte
Dendritic Cells - Answer -type of antigen-presenting cell
-capture antigens and deliver them to lymph nodes and help activate T cells
-Found in connective tissues and epidermis
-Most effective antigen presenter known
-Key link between innate and adaptive immunity
Reticular Cells - Answer produce reticular fibers called stroma in lymphoid organs
Stroma - Answer network-like support that acts as scaffolding for immune cells
What are the main functions of lymphoid tissue? - Answer -Houses and provides proliferation sites for
lymphocytes
-Offers surveillance vantage points for lymphocytes and macrophages as they filter through lymph
What kind of tissue is lymphoid tissue composed of? - Answer reticular connective tissue
Diffuse Lymphoid Tissue - Answer -loose arrangement of lymphoid cells and some reticular fibers
-found in virtually every body organ
Lymphoid Follicles - Answer -solid, spherical bodies consisting of tightly packed lymphoid cells and
reticular fibers
-Contain germinal centers of proliferating B cells
-May form part of larger lymphoid organs
-found in isolated aggregations of Peyer's patches and in appendix
, Primary Lymphoid Organs - Answer -areas where T and B cells mature
-includes red bone marrow and thymus
Secondary Lymphoid Organs - Answer areas where mature lymphocytes first encounter their antigen
and become activated
Lymph Nodes - Answer - principal secondary lymphoid organs of body
-found all over the body, but are concentrated in the axillary, cervical, and inguinal regions
What are the functions of the lymph nodes? - Answer -cleansing/filtering of lymph
-activation of the immune system
Cortex of the Lymph Nodes - Answer -Superficial area of cortex contains follicles with germinal centers
that are heavy with dividing B cells
-Deep cortex houses T cells in transit
-Abundant numbers of dendritic cells are closely associated with both T and B cells
Medulla of the Lymph Nodes - Answer Medullary cords extend inward from cortex and contain B cells,
T cells, and plasma cells
Lymph Sinuses - Answer -Consist of large lymphatic capillaries spanned by crisscrossing reticular fibers
-Macrophages reside on fibers, checking for and phagocytizing any foreign matter
What is the path of circulation through lymph nodes? - Answer -enters convex side at afferent
lymphatic vessels
-subscapular sinus
-medullary sinus
-exits hilum via efferent lymphatic vessels