Chap 19 –
Lymphatic System
Homework: Read Chap 19.
Review anatomical
structures & physiology (per
diagrams).
Learning Objectives:
1.List the functions of the lymphatic system.
2. Describe the source of lymph & its transport.
4. Describe lymph tissue.
5. Describe lymph nodes (locations structure and distribution
of the lymph vessels.
3. Explain the, histology, function, etc.)
6. Name and describe other lymphoid organs of the body.
What’s the
Problem?
These patients have an imbalance called
___________.
Opening Discussion
What does the lymphatic system do? How
does it tie-in to what we have been
studying?
http://health.howstuffworks.com/adam-200102.htm
Circulatory Dilemma
Problem: Capillaries are known to be ‘leaky’
vessels. They leak about 3L of interstitial fluid into
tissue spaces daily.
All this fluid must be returned to the cardiovascular
system to ensure sufficient blood volume
How does it get returned?
Lymphatic System To The Rescue!
The lymphatic system - an elaborate
system of drainage vessels that collect
excess interstitial fluid and return it to the
bloodstream
Instructions:
1. Take time to reflect.
2. Review Figure 19.1
(page 680) and the
associated text,
“Distribution and
Structure of Lymphatic
Vessels”.
3. Write a 1-3 sentence
summary in your own
words of how it
basically works. Place
the summary in your
notes next to this slide.
4. Be prepared to share
with class.
Estimated Time: 3-5
minutes
How Does It Work?
Lymph Vessels
• A __________ system in which lymph
flows toward the heart
• Lymph vessels include:
– Microscopic, permeable, blind-ended
capillaries
– Lymphatic collecting vessels
– Trunks and ducts
Lymph Collecting Vessels
• Have the same three ______ as veins
• Have _______ walls, with more internal
valves
• Collecting vessels in the skin travel with
superficial veins
• Deep vessels travel with arteries
Lymph Capillaries
• Similar to blood _________, with modifications
– Remarkably ___________
– Loosely joined endothelial minivalves (withstand
interstitial pressure and remain open). Also, function as
one-way gates that:
a) Allow interstitial fluid to enter lymph capillaries
b) Do not allow lymph to escape from the capillaries
Lymph Capillaries continued
• During inflammation, lymph capillaries can
absorb:
– _____ debris
– __________
– ______ cells
• Cells in the lymph nodes:
– Cleanse and __________ this debris
• Lacteals – specialized lymph capillaries present
in intestinal mucosa
– Absorb digested fat and deliver chyle (fatty lymph)
to the blood
Lymph Transport
• The lymphatic system _______ an organ
that acts as a pump
• Vessels are ____-pressure conduits
• Uses the same methods as _____ to
propel lymph
– Pulsations of nearby arteries
– Contractions of smooth muscle in the walls of
the lymphatics
General Distribution of Vessels and
Regional Lymph Nodes
Label your
practice
diagram.
Page 682
Lymphatic Trunks
• Lymphatic trunks are formed by the union of the
largest collecting ___________
• Major trunks include:
– Paired ________, bronchomediastinal, subclavian, and
________ trunks
– A single intestinal trunk
• Lymph is delivered into one of two large ______
– _____ lymphatic duct – drains the right upper arm and
the right side of the head and thorax
– _______ duct – arises from the cisterna chyli and drains
the rest of the body
Lymphatic Trunks
Label
your
practice
diagram
Page 682
Lymphoid Cells
• ____________ are the main cells involved in the
immune response . The two main varieties are _
cells and _ cells (protect the body against foreign
antigens such as bacteria, viruses, & cancer)
• __________ – phagocytize foreign substances
and help activate T cells
• ________ cells – spiny-looking cells with
functions similar to macrophages
• ________ cells – fibroblastlike cells that produce
a stroma, or network, that supports other cell
types in lymphoid organs
Lymph Nodes
• Lymph nodes are the principal lymphoid
________ of the body
• Nodes are imbedded in _______ tissue
and clustered along lymphatic vessels
• Aggregations of these nodes occur near
the body surface in inguinal, _______, and
cervical regions of the body
Functions of Lymph Nodes
• Their two basic functions are:
– ____________ – macrophages destroy
microorganisms and debris
– ________ ______ __________ – monitor for
antigens and mount an attack against them
Lymph Node Structure
• ________ are bean shaped and
surrounded by a fibrous capsule
• Nodes are ______________ (trabeculae
extend inward)
• Nodes have two histologically distinct
regions: a _______ and a _______
Lymph Node Structure continued
Label your practice diagram.
Lymph Node Structure continued
• The cortex contains _________ with germinal
centers, heavy with dividing B cells
• __ _______ circulate continuously among the
blood, lymph nodes, and lymphatic stream
• _________ cords extend from the cortex and
contain B cells, T cells, and plasma cells
• Throughout the node are lymph _______
crisscrossed by reticular fibers. Macrophages
reside on these fibers and phagocytize
______ matter
Other Lymphoid Organs
• The ____, ______ gland, and _______
• _________ patches and bits of lymphatic
tissue scattered in connective tissue
• All are composed of reticular connective
tissue and all help protect the body
• Only lymph nodes filter lymph
Spleen
• _________ lymphoid organ, located on the
left side of the abdominal cavity beneath
the diaphragm
• Functions
– Site of lymphocyte proliferation
– Immune surveillance and response
– Cleanses the ______
– Stores blood ________
Spleen Structure, page 686
Two distinct areas of the spleen are:
_____ pulp – area containing mostly lymphocytes suspended on
reticular fibers and involved in immune functions
_____ pulp – remaining splenic tissue concerned with disposing of
worn-out RBCs and bloodborne pathogens
Thymus
• A bi-lobed organ that secrets hormones
(thymosin and thymopoietin) that cause T
lymphocytes to become immunocompetent
• The size of the thymus varies with age
– It increases in size and is most active during
________
– It stops growing during adolescence and then
gradually _________
Thymus continued
• The thymus _______ from other lymphoid
organs in important ways
– It functions strictly in T lymphocyte ________
– It does not directly fight _______
• The thymus consists of star-shaped
epithelial cells (not reticular fibers)
Tonsils
• Simplest lymphoid organs; form a ring of
lymphatic tissue around the _______
• Like little crypts - ____ and ______
bacteria and particulate matter
Other continued
• Peyer’s patches – isolated clusters of
lymphoid tissue, similar to tonsils
– Found in the wall of the distal portion of the
_____ _________
– Similar structures are found in the appendix
• _____ – mucosa-associated lymphatic
tissue (protects the digestive and
respiratory systems from foreign matter)