5. lymphatic system 09

7/29/2019 5. Lymphatic System 09

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LYMPHATIC SYSTEM

Network of organs and vessels

Low pressure

One-way system

leading to circulatory system


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FUNCTIONS OF LYMPHATIC SYSTEM

1.) Returns leakedfluid to blood2.) Transports digested lipids

and vitamins

3.) Activates immune responses


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LYMPHATIC SYSTEMStructures

1. Lymph Vessels

2. Lymph fluid and lymphocytes

3. Lymphatic organs and tissues

Lymph nodules

Lymph nodes Thymus

Spleen


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LYMPH VESSELS-CAPILLARIES

Larger, more

permeable than blood

capillaries

Closed ended

Endothelial cells

overlap

Pushed open by high

interstitial fluid pressure

direct fluidinwardonly


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LYMPH VESSELS

From lymph capillaries

lymph flows to Collecting vessels

Like veins with thinner

walls 1 way valves

Pass through lymphnodes

Unite to form

Lymphatic trunks


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21-6

Valve in a Lymphatic Vessel

Figure 21.4a Figure 21.4b

(a)

Valve

Copyright The McGraw-Hill Companies, Inc. Permission requ ired for reproduction or display.

(b)

Lymph

Lymph flows

forward through

open valves

Closed valves

prevent backflow

The McGraw-Hill Companies, Inc./Dennis Strete, photographer


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21-7

Route of Lymph Flow Lymphatic capillaries

Collecting vessels

Lymphatic trunks

2 Collecting ducts

Right lymphatic duct

Thoracic duct

Subclavian veins


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Route of Lymph Flow

Collecting ducts:


Right upper body

Into right subclavian vein

Thoracic duct

Begins as cisterna chylia sac in abdomen

Below diaphragm

Left upper body

Into left subclavian vein


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21-9

Lymphatic Drainage of

Mammary and Axillary Regions

Figure 21.6b

(b)


Right subclavian

vein

Axillary lymphnodes

Lymphatics

of breast

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.


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LYMPH FLUID

Extra leaked fluid from capillary exchange

Plasma, wastes, nutrients, a few plasmaproteins

15% of plasma not reabsorbed into capillaries

2-4 L/day or a bit more than 2-4 quarts/day

Digested fats from the lacteals.


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ELEPHANTIASIS

Tropical disease

Roundworms infect

lymph nodes

Block flow of lymph


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LYMPH- IMMUNE FUNCTIONS Production and maturation

oflymphocytes in Red bone marrow

Thymus

Spleen

Filtering of lymph forpathogens and destructionof pathogens in

Lymph nodes

Lymphatic nodules

Spleen


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Lymphatic Cells

LYMPHOCYTES Natural killer (NK) cells

Large lymphocytes that attack

and destroy bacteria,

T lymphocytes (T cells)

Attack invaders

B lymphocytes (B cells) Produce antibodies


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LYMPHOCYTE CIRCULATION

Most live 4 years, some 20 years Wander through the body

Concentrate in different sites


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LYMPHOCYTE LOCATIONS

Blood + Thymus gland

Spleen

Bone marrow


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LYMPHOCYTE PRODUCTION

Primary site Bone MarrowHemocytoblasts form 2 types of stem cells

1. One group forms B + NK cells

B cells enter blood

Go to lymph nodes + spleen NKcells migrate

through body

LYMPHOCYTE


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LYMPHOCYTE

PRODUCTION

2. One group goes to thymus

Here they form T cells

These then enter blood


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Lymphatic Cells

Macrophages Phagocytiticcells

Present antigen

Destroy invaders

Dendritic cells

Present antigens

Reticular cells Form framworkd

Present antigen

LYMPHATIC NODULES


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LYMPHATIC NODULES

(Lymphoid follicles) Small masses of Reticular connective tissue

Large numbers of lymphocytes and macrophages

Enmeshed within reticular fibers

No connective tissue capsule


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LYMPHATIC NODULES

Function Produce lymphocytes

Help fight infection

Found in

mucus membranes of

G.I. Tract

Respiratory tract

Urinary tract Reproductive tract

Called MALT-

Mucosa-associated

lymphatic tissue


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YMPHATIC NODULES Dense clusters of nodules in

Tonsils Payers patches

(in intestines)


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LYMPHATIC ORGANS

Encapsulated

Include:

Lymph nodes

Thymus

Spleen


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LYMPH NODES

Masses of lymph tissue

surrounded by aconnective

tissue capsule.

Functions

Filter lymph

Produce lymphocytes

Concentrated in

Mammary glands Axillae +

Digestive area

Groin & neck


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LYMPH NODE DETAILS

Contain T cells, B cells + macrophages

Filter lymph + destroy foreign microorganisms


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LYMPH NODE FUNCTIONFiltering Process

1.Lymph passes through the layers of the node2.Immune cells remove + destroy

antigens that pass through

IMMUNE CELLS IN LYMPH


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IMMUNE CELLS IN LYMPH

NODES

Macrophages engulf debris

+ pathogens

process them

present pathogensto lymphocytes

Dendritic cells

bind pathogens

present themto lymphocytes

Lymphocytes

Destroy pathogens

THYMUS GLAND


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THYMUS GLANDa. Where T cells mature

b. Big through age 12.

c. Atrophies with age.

SPLEEN


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SPLEEN Filters blood of pathogens

and dead cells

Macrophagesphagocytize bacteria andworn RBCs

Lymphocytes destroypathogens


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SPLEEN Stores and releases extra Blood at times of

need (Sympathetic Stimulation)

5. lymphatic system 09

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