Lymph and lymphatic vessels - Linn-Benton Community...
Transcript of Lymph and lymphatic vessels - Linn-Benton Community...
L Y M P H A N D L Y M P H A T I C V E S S E L S
Cardiovascular System
Copyright © 2010 Pearson Education, Inc. Figure 19.2
Large veins (capacitance vessels)
Large lymphatic vessels
Arteriovenous anastomosis
Lymphatic capillary
Postcapillary venule
Sinusoid
Metarteriole
Terminal arteriole
Arterioles (resistance vessels)
Muscular arteries (distributing vessels)
Elastic arteries (conducting vessels)
Small veins (capacitance vessels)
Lymph node
Capillaries (exchange vessels)
Precapillary sphincter Thoroughfare channel
Lymphatic system
Venous system Arterial system
Heart
Figure 20.2a
Cervical nodes Entrance of right
lymphatic duct into vein
Internal jugular vein
Entrance of thoracic
duct into vein
Thoracic duct
Cisterna chyli
Lymphatic
collecting vessels
Axillary nodes
Aorta
Inguinal nodes
Regional
lymph nodes:
(a) General distribution of lymphatic collecting vessels
and regional lymph nodes.
Drained by the right
lymphatic duct
Drained by the
thoracic duct
Lymphatic System
Outflow of fluid slightly exceeds return
Consists of three parts
1. A network of lymphatic vessels carrying lymph
1. Transports fluid back to CV system
2. Lymph nodes
1. Filter the fluid within the vessels
3. Lymphoid organs
1. Participate in disease prevention
Lymphatic System
Functions
1. Returns interstitial fluid and leaked plasma proteins back to the blood
2. Disease surveillance
3. Lipid transport from intestine via lacteals
Figure 20.1
Lymphatic
system:
Lymph duct
Lymph trunk Lymph node
Lymphatic capillary
Blood capillaries
Lymphatic collecting vessels, with valves
Heart Arterial system Venous system
Tissue
fluid
Tissue cell Blood capillaries
Lymphatic capillaries
(a) Structural relationship between a
capillary bed of the blood vascular
system and lymphatic capillaries.
Filaments anchored
to connective tissue
Fibroblast in loose
connective tissue
Endothelial cell
Flaplike minivalve
(b) Lymphatic capillaries are blind-ended tubes in which
adjacent endothelial cells overlap each other,
forming flaplike minivalves.
Lymph
Interstitial fluid which enters lymph capillaries
Lower concentration of proteins than blood
Electrolyte differences
Hydrostatic and colloid osmotic pressure regulate exchange
Figure 19.17
HP = hydrostatic pressure
• Due to fluid pressing against a wall
• “Pushes” • In capillary (HP
c)
• Pushes fluid out of capillary
• 35 mm Hg at arterial end and
17 mm Hg at venous end of
capillary in this example • In interstitial fluid (HP
if)
• Pushes fluid into capillary
• 0 mm Hg in this example
OP = osmotic pressure
• Due to presence of nondiffusible solutes (e.g., plasma proteins) • “Sucks” • In capillary (OP
c)
• Pulls fluid into capillary • 26 mm Hg in this example • In interstitial fluid (OP
if)
• Pulls fluid out of capillary • 1 mm Hg in this example
Arteriole
Capillary
Interstitial fluid
Net HP—Net OP
(35—0)—(26—1)
Net HP—Net OP
(17—0)—(26—1)
Venule
NFP (net filtration pressure)
is 10 mm Hg; fluid moves out NFP is ~8 mm Hg;
fluid moves in
Net
HP
35
mm
Net
OP
25
mm
Net
HP
17
mm
Net
OP
25
mm
Figure 19.2
Large veins (capacitance vessels)
Large lymphatic vessels
Arteriovenous anastomosis
Lymphatic capillary
Postcapillary venule
Sinusoid
Metarteriole
Terminal arteriole
Arterioles (resistance vessels)
Muscular arteries (distributing vessels)
Elastic arteries (conducting vessels)
Small veins (capacitance vessels)
Lymph node
Capillaries (exchange vessels)
Precapillary sphincter Thoroughfare channel
Lymphatic system
Venous system Arterial system
Heart
Lymphatic Vessels
One-way system, lymph flows toward the heart
Lymph vessels (lymphatics) include:
Lymphatic capillaries
Lymphatic collecting vessels
Lymphatic trunks and ducts
Lymphatic Capillaries
Similar to blood capillaries, except…
Not continuous
No basement membrane = very permeable
Take up cell debris, pathogens, and cancer cells
Endothelial cells overlap to form one-way mini-valves
Figure 20.1b
Filaments anchored
to connective tissue
Fibroblast in loose
connective tissue
Endothelial cell
Flaplike minivalve
(b) Lymphatic capillaries are blind-ended tubes in which
adjacent endothelial cells overlap each other,
forming flaplike minivalves.
Lymphatics
Collecting vessels
Capillaries join to form larger vessels = lymphatics Empty into thoracic duct or right lymphatic duct
Similar to veins, except Have thinner walls, with more internal valves
Anastomose more frequently
More valves
Occasionally modified to form nodes
Lymphatic Ducts
Lymph is delivered into one of two large ducts
Right lymphatic duct
Drains the right upper arm and the right side of the head and thorax
Thoracic duct
Arises from the cisterna chyli and drains the rest of the body
Connect with subclavian veins
Figure 20.2b
Left jugular trunk
Internal jugular veins
Left subclavian trunk
Left subclavian vein
Esophagus
Trachea
Left lumbar trunk
Left bronchomediastinal
trunk
Entrance of thoracic
duct into vein
Thoracic duct Hemiazygos vein
Intestinal trunk
Inferior vena cava
Right jugular trunk
Right lymphatic duct
Right subclavian trunk
Right subclavian vein
Right broncho-
mediastinal trunk
Brachiocephalic veins
Superior vena cava
Azygos vein
Cisterna chyli
Right lumbar trunk
(b) Major lymphatic trunks and ducts in relation to veins and
surrounding structures. Anterior view of thoracic and abdominal wall.
Ribs
Figure 20.2a
Cervical nodes Entrance of right
lymphatic duct into vein
Internal jugular vein
Entrance of thoracic
duct into vein
Thoracic duct
Cisterna chyli
Lymphatic
collecting vessels
Axillary nodes
Aorta
Inguinal nodes
Regional
lymph nodes:
(a) General distribution of lymphatic collecting vessels
and regional lymph nodes.
Drained by the right
lymphatic duct
Drained by the
thoracic duct
Lymphatics
Lymph Transport
No pump
Lymph movement similar to venous return
Valves
Skeletal muscle contraction
Thoracic pump
Pressure gradients
Also contraction of nearby arteries and smooth muscle within vessels
Movement is slow and sporadic
Edema
Lymphedema
Prevention of return of lymph to blood
May be due to:
Osmotic changes
Blockage of lymph vessels
Parasites
Inflammation
Surgery
Elephantiasis
Lymphatic Tissues
Tissues house and provide a proliferation site for lymphocytes
Furnish a surveillance vantage point
Mucosa-associated lymphatic (MALT)
Respiratory, digestive, urinary, reproductive systems
Peyer’s patches
Junction of large and small intestine
Figure 20.9
Smooth muscle in
the intestinal wall
Lymphoid nodules
(follicles) of
Peyer’s patch
Lymph Nodes
Solid, spherical, well-defined organs
Distributed along course of lymphatic vessels
Concentrated
Cervical region
Behind the ear, inferior mandible and lateral neck
Axillary region
Abdomen
Along abdominal aorta and mesenteric arteries
Inguinal region
Lymph Nodes
Functions
1. Filter lymph
Macrophages destroy microorganisms and debris
2. Immune system
Lymphocytes are activated and mount an attack against antigens
Lymph Nodes
Structure
Outer parenchyma
Inner medulla
Medullary sinuses
Macrophages
Cortex contains follicles with germinal centers, heavy with dividing B cells
Copyright © 2010 Pearson Education, Inc. Figure 20.3
Macrophage
Medullary sinus
Reticular fiber
Lymphocytes
Reticular cells on
reticular fibers
Figure 20.2a
Cervical nodes Entrance of right
lymphatic duct into vein
Internal jugular vein
Entrance of thoracic
duct into vein
Thoracic duct
Cisterna chyli
Lymphatic
collecting vessels
Axillary nodes
Aorta
Inguinal nodes
Regional
lymph nodes:
(a) General distribution of lymphatic collecting vessels
and regional lymph nodes.
Drained by the right
lymphatic duct
Drained by the
thoracic duct
Abdominal
Figure 20.4
Afferent
lymphatic
vessels
Efferent
lymphatic
vessels
Capsule
Trabeculae
Hilum
Cortex
• Lymphoid follicle
• Germinal center
• Subcapsular sinus
Medulla:
• Medullary
cord • Medullary
sinus
Follicles
Trabecula
Subcapsular
sinus
Capsule
Medullary
cords
Medullary
sinuses
(b) Photomicrograph of part of a
lymph node (72x) (a) Longitudinal view of the internal structure
of a lymph node and associated lymphatics
Spleen
Largest lymphoid organ
Macrophages remove old RBC’s, platelets and bacteria
Production of RBC’s
In fetus and severely anemic patients
Splenic contraction
May return 200-300 mls of blood to circulation from sinuses
Figure 20.2a
Cervical nodes Entrance of right
lymphatic duct into vein
Internal jugular vein
Entrance of thoracic
duct into vein
Thoracic duct
Cisterna chyli
Lymphatic
collecting vessels
Axillary nodes
Aorta
Inguinal nodes
Regional
lymph nodes:
(a) General distribution of lymphatic collecting vessels
and regional lymph nodes.
Drained by the right
lymphatic duct
Drained by the
thoracic duct
Spleen
Figure 20.6a,b
Arterioles and
capillaries
Capsule
Trabecula
Venous sinuses
Red pulp
Splenic cords
White pulp
Central artery
Splenic artery
Splenic vein
(b) Diagram of spleen histology
Splenic
artery
Splenic
vein Hilum
(a) Diagram of the
spleen, anterior view
Big spleen!
Thymus
Involution
Stops growing during adolescence and then gradually atrophies
Replaced by adipose and connective tissue
Figure 20.7
Cortex
Medulla
Thymic (Hassall’s)
corpuscle
Thymus
Thymus
Hormones
Thymopoetin and thymosin
Assist in lymphocyte differentiation
Tonsils
Simplest lymphoid organs 3 pairs
Palatine tonsils
Posterior end oral cavity
“Sore throat”
Lingual tonsils
Grouped at the base of the tongue
Pharyngeal tonsils
Adenoids
Posterior wall of the nasopharynx
Figure 20.8
Tonsil
Tonsillar crypt
Germinal centers
in lymphoid follicles
Pharyngeal tonsil
Palatine tonsil
Lingual tonsil
Tonsillitis
Questions?
Remember HW due on Tuesday and in Lab! Quiz Study Guide is in the “Exams” Section