Lymphatic System Summary

Fluid collection

the fluid that does not circulate back into the blood from the interstitial fluid is collected by lymphatic vessels

One Way System

The lymphatic vessels form a one way system in which lymph flows ONLY toward the heart

Lymphatic Capillaries

lymphatic transport system starts with highly permeable lymphatic capillaries, found between tissue cells and blood capillaries, in the loose connective tissue

Protein Transport

large molecules, such as protein, that are too large to enter blood capillaries can easily pass into lymphatic capillaries

Vessel Pathway

the lymph capillaries flow into the collecting lymphatic vessels and carry lymph to lymphatic trunks

Return to Circulation

lymphatic trunk drains fairly large areas of body and eventually empty lymph back into circulatory system via thoracic duct or right lymphatic duct

Mechanism of Flow

Lymphatic vessels are LOW pressure vessels that use the same mechanism as veins to return lymph to circulatory system - skeletal muscle compression, pressure changes during breathing, and valves to prevent back flow

Lymphocytes

(aka white blood cells) arise in red bone marrow and mature into either T cells or B cells

T cells- mature in thymus directly to kill virus infected cells or tumor cells and control immune response

B cells- mature in bone marrow, producing antibodies that neutralize foreign antigens

Macrophages

act as phagocytes and initiate T cell/lymphocyte activation

Dendritic Cells

in lymphocyte tissue and help in T cell/lymphocyte activation

Reticular Cells

produce in the stroma, network that supports the other cell types in lymphoid tissues

Diffuse Lymphatic Tissues

in every body organ to “patrol” and filter detecting + responding to foreign antigens that enter through mucosal surfaces

examples: pollen, bacteria, toxins, lipids

Lymphoid Follicles

form large part of typhoid organs or be found as aggregations

*think perter’s patch, tonsils, MALT, appendix

Principal Organs

lymph nodes which act as filters to remove and destroy microorganisms and other debris for the lymph BEFORE transported back to bloodstream

Internal Structure

each lymph node is surrounded by a dense fibrous capsule with an internal framework or storm, of reticular fibers that support the lymphocytes low direction f

Flow Direction

lymph enters the convex side of lymph node through afferent lymphatic vessels and exit via fewer efferent vessels, AFTER passing through several sinuses offensive Function D

Defensive Function

there are more afferent vs efferent vessels, meaning the lymph gets backed up slightly in the lymph node, which gives an opening for macrophages and lymphocytes to perform their defensive functions

Spleen

what structure is located on the left side of the abdomenal cavity directly below diaphragm?

Spleen

what structure’s main function is to remove old and defective RBCs and platelets aswell as foreign matter and debris from blood

Spleen

Which structure provides a site for lymphocyte proliferation and immune surveillance

Spleen

Which structure is surrounded by a fibrous capsule and contains both lymphocytes found in white pulp and macrophages found in red pulp

Thymus

secretes hormones that cause T lymphocytes to become immuno-competent (have a normal immune response)

Thymus

What structure differs from the lymphoid organs because it has no B cells, resulting in no follicles; it does not directly involve in fighting antigens, and the storm consists of epithelial cells NOT reticular cells?

MALT

are a set of lymphoid tissues located in mucous membranes throughout the body

Tonsils

are the simplest lymphoid organs that form a ring of lymphoid tissue around opening the pharynx

Peyer’s Patches

cluster of typhoid follicles, found in the wall of the distal portion of the small intestine ppendicA

Appendix

located off the first part of the large intestine and contain large number of lymphoid follicles