10.6 The Lymphatic System Flashcards
(50 cards)
What is the lymphatic system?
a system closely associated with the circulatory system and consists of lymphatic vessels and the lymphoid organs
What are the 3 main functions of the lymphatic system that contributes to homeostasis?
- lymphatic capillaries absorb excess tissue fluid and return it to the bloodstream
- lymphatic capillaries absorb fats from the digestive tract and transport them to the bloodstream
- lymphoid organs help to defend the body against disease
What do lymphatic vessels do?
- form a one-way system that begins with lymphatic capillaries
- drain excess fluid from the tissues and return it to the circulatory system
- have valves to prevent backflow
What are lymphatic capillaries?
tiny, closed-ended vessels whose walls consist of simple squamous epithelium, richly supplied in most regions of the body
What do lymphatic capillaries do?
absorb excess tissue fluid
What is tissue fluid?
mostly water, but contains solutes (ie. nutrients, electrolytes, oxygen) derived from the plasma and cellular products (ie. hormones, enzymes, wastes) secreted by cells
What is lymph?
tissue fluid contained within lymphatic vessels
What do lymphatic capillaries join to form?
form lymphatic vessels that merge before entering one of two ducts, the thoracic duct or the right lymphatic duct
What does the larger, thoracic duct do?
returns lymph collected from the body below the thorax and the left arm and the left side of the head and neck, into the left subclavian vein
What does the right lymphatic duct do?
returns lymph from the right arm and right side of the head and neck into the right subclavian vein
What does lymph do on its way back to the circulatory system?
percolates through various lymph nodes, where any foreign material present can be recognized by the immune system
What is the structure of the larger lymphatic vessels similar to?
circulatory veins
What is the movement of lymph within lymphatic capillaries largely dependent on?
skeletal muscle contraction
What happens to lymph forced through lymphatic vessels as a result of muscular compression?
prevented from flowing backward by one-way valves
What is edema?
a localized swelling caused by the accumulation of tissue that has not been collected by the lymphatic system
When does edema occur?
if too much tissue fluid is made and/or if not enough is drained away
What can edema lead to?
- tissue damage
- death
What are lymphoid organs?
organs that contain large numbers of lymphocytes
What are lymphocytes?
the type of white blood cells that is mainly responsible for adaptive immunity
What are primary lymphoid organs?
where lymphocytes develop and mature
ie. red bone marrow and thymus
What are secondary lymphoid organs?
where some lymphocytes become activated
ie. lymph nodes and spleen
What is red bone marrow?
contains a network of connective tissue fibres, along with stem cells that are ever capable of dividing and producing blood cells
Describe the cells produced by the red bone marrow.
- some become the various types of white blood cells
- packed around thin-walled sinuses filled with venous blood
- differentiated blood cells enter the bloodstream at these sinuses
Where is red bone marrow present in children?
most bones
