Download lab 5 lymphatic system - Dr. Justo Lopez Website

LAB # 5
The Lymphatic System
1- List the functions of Lymphatic System.
2- Describe the exchange of blood plasma, extracellular
fluid, and lymph.
3- Describe the structure of a lymph node.
4- Explain how the lymphatic system drains into the
vascular system
5- Describe the gross anatomy and basic histology of
the spleen.
Functions of the Lymphatic System
1- Lymphocyte Production, Maintenance, and Distribution
2- Collection and Returning of Interstitial Fluid from
Tissues to the Circulatory System
3- Distribution of Nutrients, Waste, and Hormones from
Tissues to the Circulatory System
1- Lymphocyte Production, Maintenance, and Distribution.
Immature lymphocytes are produced
in the bone marrow.
B lymphocytes mature in the bone
marrow and T lymphocytes mature
in the thymus.
Lymphoid organs and tissues
After maturation, most of the lymphocytes move into lymph nodes, the
spleen and other lymphoid tissues.
2- Collection and Returning of Interstitial Fluid from Tissues
to the Circulatory System.
Fluid continually filters from the blood capillaries into the tissue spaces. But the
blood capillaries reabsorb only 85%.
15% (2 – 4 L/day) of the water and about half of the plasma proteins are not
absorbed by capillaries.
One function of the lymphatic system is to reabsorb this excess and to return it
to the blood.
85%
13
mm
Hg
7
mm
Hg
85
%
15
%
The Lymphatic System
Lymph
It is the recovered
fluid. Lymph is
usually a clear
colorless fluid,
similar to blood
plasma but low in
protein.
Lymphatic
Vessels
Diffuse
Lymphoid
Tissues
- Lymphatic capillaries Aggregates of lymphocytes
in the connective tissue of
- Lymphatic collecting mucous membrane and
various organs.
vessels
Mucosa-associated
- Lymphatic trunks
lymphatic tissue (MALT)
- Collecting duct
1- Peyer patches in the
Encapsulated
Lymphoid
Organs
They have well –
defined anatomical
sites and at least
partial connective
tissue capsules.
1- Lymph nodes
distal portion of the small
intestine.
2- Thymus
2- Vermiform appendix
3- Spleen
3- Tonsils (palatine tonsils
and pharyngeal tonsils or
adenoids).
Lymphoid Organs
Lymphoid Tissues
Lymphatic Vessels
1- Lymphatic Vessels
The lymphatic capillaries converge to form
collecting vessels.
The collecting vessels travel alongside veins
and arteries, and at irregular intervals they
empty into lymph nodes. In the lymph nodes,
bacteria are phagocytized and immune cells
monitor the fluid for foreign antigens.
The collecting vessels converge to
form lymphatic trunks.
The names indicates their locations and
part of the body they drain
1- Jugular trunks, 2- Subclavian trunks, 3Bronchomediastinal trunks, 4- Intestinal trunk,
and 5- Lumbar trunks
Lymphatic
system
Subclavian
veins
Cardiovascular
system
Pulmonary
circuit
Collecting
ducts (2)
Lymphatic
trunks
Superior
vena cava
Collecting
vessels
Blood
flow
The lymphatic trunks converge to form
collecting ducts.
1- Right lymphatic duct
2- Thoracic duct
Lymphatic
capillaries
Systemic
circuit
3- Lymphatic Trunks and Lymphatic Ducts
Lymph
Capillaries
Collecting
Vessels
Lymphatic
Trunks
Lymphatic
Ducts
Inferior Trunks
Thoracic duct
Cisterna Chyli
Right lumbar
trunk
Left lumbar
trunk
Intestinal
trunk
Inferior vena
cava
Right Lumbar Trunk
Intestinal Lumbar Trunk
Left Lumbar Trunk
Cisterna
Chyli
Thoracic
Duct
RIGHT
LEFT
Right Jugular
Trunk
Left
Subclavian
Trunk
Right Subclavian
Trunk
Right Lymphatic
Duct
Right subclavian
vein
Right
Bronchomediastinal
Trunk
Left
Jugular
Trunk
Thoracic Duct
Left Subclavian
veint
Superior
vena
cava
Left
Bronchomediastinal
Trunk
Superior Trunks
Right Jugular Trunk
Right Subclavian Trunk
Right Bronchomediastinal Trunk
Right Lymphatic
Duct
Inferior Trunks
Right Lymphatic
Duct
Right Lymphatic
Duct
Right side of the
tissues superior to
the diaphragm
Thoracic Duct
Thoracic Duct
Tissues inferior
to the diaphragm
and from left
side of the upper
body
2- Lymphoid Tissues and
Lymph Nodes
Lymphoid Tissues
Lymphoid tissues are areolar
concentrations of lymphocytes.
connective
tissues with
When lymphocytes are densely packed they form lymphoid
or lymphatic nodules or follicles.
The lymphatic nodules or follicles have no fibrous capsule
surrounding them.
Germinal center
It contains dividing
lymphocytes.
MALT (Mucosa-Associated Lymphatic Tissue)
It is the collection of lymphoid tissues that protect the
epithelia of the respiratory, digestive, urinary, and
reproductive systems.
Clusters of lymphoid nodules deep to the epithelial lining of
the intestine are known as Peyer’s patches.
The appendix vermiform is other
example of MALT. It walls contain
a mass of fused lymphoid
nodules.
Tonsils
They are large concentration of lymphoid nodules in the
walls of the pharynx.
Pharyngeal tonsil
or adenoid (single)
Palatine tonsils
(two)
Lingual
(two)
tonsils
Functions
They guard against ingested or inhaled pathogens.
Lymphoid Organs
Lymphatic organs have well-defined
anatomical sites and have connective
tissue capsule that separates the
lymphatic tissue from neighboring tissues.
- Lymph nodes
- Thymus
- Spleen
Thymus
Spleen
Lymph
nodes
Lymph nodes
They are the smallest and most
numerous lymphatic organs (about 450
in typical young adult).
They range in diameter from 1 mm to 25
mm (about 1 inch)
Lymph nodes are widespread but specially
concentrated in some
locations.
Cervical
lymph nodes
Axillary
lymph nodes
Lumbar
lymph nodes
Pelvic
lymph nodes
Inguinal
lymph nodes
Lymph
vessel
Lymph nodes are shaped like kidney
beans.
Efferent
vessel
Lymph node
artery and vein
Hilum
Trabeculae
Lymph nodes
Medullary sinus
Cortex
Subcapsular
space
Outer cortex
(B cells)
Deep cortex
(T cells)
Medulla
Medullary cord
(B cells and
Dense connective plasma cells)
Capsule
tissue
Afferent
vessel
Lymph
nodes
Lymph Node Functions:
1- They filter and purify the lymph
before return to venous circulation
(they remove 99% of cell debris,
bacteria, viruses, fungi).
2- They provide an early warning
system
against
infection
in
peripheral
tissue,
responding
before infections reach vital organs
of trunk.
3- The first step in immune
response takes place in the lymph
nodes (extracted antigens are
“presented” to lymphocytes).
The Thymus
The thymus is located in the mediastinum.
It atrophies after puberty.
The thymus is divided into two thymic lobes.
Septa divide lobes into smaller lobules.
Thymus
Right
lobe
Septa
Lobule
Left
lobe
Septa
Lobule
Medulla
Cortex
Lobule
The thymus gland
LM  50
Medulla
Septa
Cortex
Lymphocytes
Lobule
Thymic
corpuscle
Lobule
Reticular
cells
A thymic corpuscle
LM  550
The thymus gland
LM  50
T lymphocytes divide in the cortex and mature while they
migrate to the medulla.
Mature T cells leave thymus by medullary blood vessels.
The thymus secretes thymic hormones that stimulate T cell
differentiation.
The Spleen
It is the body’s largest lymphatic organ.
Parietal peritoneum
Visceral peritoneum
Spleen
Stomach
Diaphragm
Rib
Liver
Pancreas
Aorta
Gastrosplenic
ligament
Gastric area
Diaphragmatic surface
SPLEEN
Hilum
Renal area
Kidneys
Histology of the Spleen
White pulp of
splenic nodule
White pulp is
dominated by
lymphocytes.
Capsule
Red pulp
Red pulp contains a
large number of red
blood cells.
Trabecular
artery
The spleen
LM  50
Central artery in
splenic nodule
Functions:
1- Removal of abnormal and worn out blood cells.
2- Storage of iron recycled from red blood cells.
3- Initiation of immune responses by B cells and T cells.