Download BLOOD COMPONENTS

Dr. Vince Scialli
BSC 1086
Rev. 12/28/06
LYMPHATIC SYSTEM
Lymph ~ fluid similar to plasma
Lymphatic Vessels ~ lymphatics
Tissue & Organs ~ spleen, tonsils, lymph nodes, appendix
Lymphoid Cells ~ lymphocytes & macrophages
FUNCTIONS
Produce, maintain, & distribute lymphocytes
Protects body by removing ANY foreign substances
Provides site for immune surveillance ~ Immune Ready
Returns excess interstitial fluid from cells to blood
Transport fats from digestive system to blood
LYMPHATIC VESSELS
Large system of drainage conduits for interstitial fluid
Excess tissue fluid is filtered out of capillary beds
Lymph Vessels return fluid to bloodstream
One way network ~ fluid flows ONLY toward heart
Similar in structure & size to veins ~ slight differences
Closely follow arteries & veins around body
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
LYMPHATIC VESSELS ~ Structure and Distribution
LYMPH CAPILLARIES ~ “terminal lymphatics”
Blind-ending ~ ONE WAY capillaries
Weave between tissue cells & blood capillaries
Widespread throughout body
Located where blood capillaries exist
Exception:
not near bone or teeth
Special Features ~ differ from blood capillaries
Much more Permeable than capillaries
Endothelial cells ~ are loosely joined cells
Form “flap-like mini valves” ~ one-way flow
Loose connective tissue “filaments”
Anchor flaps of lymph capillaries to tissue
 interstitial fluid volume &  pressure --->
 tension on filaments ----> flaps to open
Allows fluid & substances to enter lymph capillaries
Tissue Inflammation ---> large lymphatic openings which
allow the lymph capillaries to absorb large particles:
Debris . . . Bacteria . . . Viruses . . . WBC’s . . . Cancer Cells
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
LYMPH CAPILLARIES
Have Large lymphatic openings ~ good & bad
Allows spread of inflammatory cells throughout
body through the lymphatic stream
Metastasis ~ cancer spread
Infection spread
Lacteals ~ “specialized” lymph capillaries
Found in small intestinal mucosa ~ drains CHYLE
CHYLE ~ Lymph fluid containing fats
Transports lipids absorbed in digestive tract
LYMPHATIC COLLECTING VESSELS
Large & thick walled ~ Receive lymph from capillaries
via small lymphatic vessels
Have three tunics ~ similar to blood vessels
Similar to Veins but ~ Many more internal valves
Superficial Lymphatics ~ smaller ~ drain superficial
tissue & membranes
Deep Lymphatics ~ larger ~ accompany arteries & veins
Drain muscles of neck, limbs, trunk & major organs
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
LYMPHATIC TRUNKS
Formed by union of largest lymphatic collecting vessels
Superficial & Deep Lymphatic vessels form trunks
Trunks empty into Lymphatic Ducts
LYMPHATIC DUCTS
Drain lymph from lymphatic system into blood vascular
system at junction of the internal jugular & subclavian
veins in neck
Right Lymphatic Duct
Drains lymph from right arm & right side of upper
body
Empties lymph into right subclavian vein
Thoracic Duct
Drains lymph from left side & rest of body
Cisterna Chyli ~ sac like chamber at base of
thoracic duct
Receives lymph from lower abdomen, pelvis &
lower limbs via lumbar trunks
Empties lymph into left subclavian vein
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
Order of Lymphatic Drainage
Lymph Capillaries ---> Small Lymph Vessels
---> Larger Lymph Collecting Vessels ---> Lymph Trunks
---> Lymph Ducts ---> Subclavian Veins ---> Vena Cava
---> Heart
Lymph Transport
Low Pressure – Slow Pumpless System
Factors Promoting Lymph Transport:
1.
Milking action of skeletal muscles
Similar to venous circulation
2.
Thoracic pressure changes during breathing
Similar to venous circulation
3.
Presence of internal valves
Prevents back flow
Similar to venous circulation
4.
Lymph capillaries are bundled with blood
vessels in connective tissue sheaths
Pulsating arteries promote lymph flow
5.
Smooth muscle in walls (tunica media) of
lymphatic trunks & thoracic ducts contract
rhythmically . . . Similar to arteries
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
LYMPHOID CELLS ~ several types
Fight foreign invaders ~ “immunocompetence”
Lymphocytes
20 ~ 30% of circulating WBC’s
Produced in bone marrow, thymus, & lymph tissue
Survive 4 to 20 years ~ long lasting~ lymphopoiesis
T-lymphocytes ~ T-cells ~ thymus dependent cell
Majority of circulating lymphocytes ~ 80%
Controls Immune Response ~ “cell mediated”
Activate B-lymphocytes
Phagocytic activity stimulated
B-lymphocytes ~ B-cells ~ bone marrow derived
10-15% of circulating lymphocytes
Produce Plasma Cells ~ Release antibodies
NK Cells ~ natural killer cells
5-10% of circulating lymphocytes
Immune surveillance ~ “ready position”
Attack foreign cells, cancer cells, infected cells
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
LYMPHOID TISSUE
Lymphocyte Producing Tissue
Lymph Flow Tissue
Lymph Filtering Tissue
COMPOSITION OF LYMPHOID TISSUE
Reticular Fibers ~loose “parenchyma” fibers
Forms percolating filtering network within tissue
Lymphocytes ~ within matrix of reticular tissue
Continually changing population of B & T cells
In circulation ~ “ready position” ~ army
Lymphoid Nodules ~ lymphatic follicle
Packed B & T lymphocytes in parenchyma
Germinal Centers ~ areas of B-cell proliferation
Macrophages ~ phagocytes present on reticular fibers
Diffuse Lymphatic Tissue ~ not lymphatic organs
Scattered areas of lymphatic tissue present in all
body organs & in lymphoid organs
Concentrate in mucous membranes areas ~ MALT
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
MALT TISSUE ~ mucosal associated lymphatic tissue
Prevent pathogens in respiratory & digestive tract from
penetrating mucous membranes
Destroy excess bacteria in intestinal & respiratory tract
Prevent bacteria from breaching intestinal wall &
respiratory tree
Germinate “memory” lymphocytes for long term
immunity
Ready “MEMORY” Position
PEYER’S PATCHES ~ intestinal walls
Large isolated clusters of lymph follicles in wall of
distal portion of ileum (small intestine)
Follicle or nodule aggregates in small intestinal wall
APPENDIX ~ vermiform appendix
Blind pouch at junction of small & large intestine
Tubular off-shoot of the first part of large intestine
(cecum) at ileal cecal junction
Contains large numbers of lymph follicles
BRONCHIAL WALL FOLLICLES ~ respiratory tract
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
MALT TISSUE ~ Lymphoid Tissue
TONSILS
Part of MALT ~ not really organs
Large nodues on wall of pharynx ~ 5 tonsils
2
Palatine Tonsils ~ posterior pharynx ~ Removed
1
Pharyngeal Tonsil ~ Adenoids ~ nasopharynx
2
Lingual Tonsils ~ base of tongue ~ 2
Sit in Crypts or pockets
Crypts ~ invagination on exterior surface
of tonsils
Crypts trap bacteria which enters
lymphatic tissue
Have nodules that are composed of germinal centers
Germinal centers surrounded by loose aggregate
of lymphocytes
Function:
childhood immune response
Produce memory cells (T-lymphocytes)
stimulating immunity later on
Tonsilitis ~ inflammation of the tonsils
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
LYMPHOID ORGANS
Discrete encapsulated collections of diffuse lymphoid
tissue & lymphoid follicles
Lymph Nodes . . . Thymus . . . Spleen
Lymph Nodes
Discrete Organs ~ clustered along lymph vessels
Filters Lymph
Macrophages remove & destroy debris &
microorganisms (bacteria) in the lymph
Activated when needed to fight infection
Lymph Node Structure
Capsule ~ Outer fibrous layer provides support
Trabeculae ~ Connective tissue strands
Extend inward ~ Compartmentalize node
Cortex ~ Outer portion
Contains densely packed follicles
Germinal Centers ~ B-lymphocytes
Surrounded by macrophages
T-lymphocytes ~ throughout cortex circulate
on guard ~ for MEMORY
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
Lymph Node Structure
Medulla - Central portion of lymph node
Medullary cords
Thin processes ~ extend from cortex
Mostly macrophages ~ engulf & destroy
Some B-lymphocytes & plasma cells
Medullary Sinuses ~ lymph sinuses
Large lymph capillaries
Contain reticular fibers ~ connective tissue
Macrophages on fibers ~ phagocytize
Lymph Node Circulation ~ very slow
Lymph fluid percolates into reticular tissue
Circulating antigens activate lymphocytes
Lymph enters node via afferent lymphatic vessels
----> subcapsular sinus ----> smaller sinus of cortex
& medulla ----> exits node via efferent lymphatic
vessels at hilus
Many more afferent vessels than efferent vessels
Causes lymph flow stagnation
Slow circulation allows macrophage cleansing
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
OTHER LYMPHATIC ORGANS
Thymus & Spleen
DO NOT filter lymph as lymph nodes do ~ other
functions
NO afferent supply of lymph, but ALL have efferent
drainage
Both contain macrophages & lymphocytes
THYMUS
Location ~ lower neck area near base of heart
Active in infants to adolescence
Fibrous tissue & fat in adults ~ NOT ACTIVE
Two Thymic Lobes . . . Lobules separated by Septa
Outer Cortex & Central Medulla
Thymocytes release thymus hormones ~ Thymosin
Stimulate T-lymphocyte maturation
Promotes immunocompetence in infants ~ T-cells only
Stimulates T- lymphocyte maturation ~ NO B-cells
Blood-Thymus Barrier ~ Prevents premature maturation
& release of lymphocytes
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
SPLEEN
Largest Lymphoid Organ ~ 5 inches long, 3 inches wide
Left side of abdominal cavity ~ Beneath diaphragm
Large Blood Supply:
Splenic Artery & Vein
Several Functions:
Site for lymphocyte growth
Immune surveillance/response ~ READY POSITION
Stores T-cells & B-cells
Blood cleansing ~ RBC graveyard
Removes defective blood cells & platelets
Removes debris, foreign matter, viruses,
toxins
Stores RBC breakdown products for later reuse by
liver & bone marrow
hemoglobin, Fe, Heme
Site for Fetal Erythropoiesis ~ RBC production
Thrombocyte storage ~ platelets
Spleenectomy ~ spleen removal
Can live ok without spleen ~ often injured
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
Spleen Structure:
Capsule ~ Fibrous Connective Tissue
Have trabeculae extending inward ~ similar to
lymph nodes
White Pulp
White areas that surround central arteries of spleen
Many lymphocytes ~ suspended in reticular fibers
gives white color
Red Pulp
Remaining splenic tissue
Many RBC’s & macrophages
gives red color
Hilus
Groove on spleen surface
Marks border between gastric & renal arteries
Splenic blood vessels & lymphatic vessels contact
spleen at hilus
Many blood vessels
Easily hemorrhage due to injury & rupture
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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Dr. Vince Scialli
BSC 1086
Homeostatic Imbalances ~ Lymphoid Tissue
Lymphadenopathy ~ swollen lymph nodes
Lymphedema ~ swollen lymph vessels
Lymphoma ~ cancer of lymph nodes ~ many forms
Appendicitis ~ bacterial infection
Tonsilitis ~ bacterial or viral infection
Spleenomegaly ~ enlarged spleen
Hodgkins Disease
Auto-immune Diseases
Heart Failure & Cirrhosis
Splenic Damage ~ Removed by splenectomy
Spleen easily damaged due to blow to left abdomen
Not well protected ~ tears easily ~ internal bleeding
Lymphatic System ~ Chapter 22 ~ 5/5/2017
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