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The Lymphatic System: Structure, Function, and Defenses, Study notes of Physiology

An in-depth exploration of the lymphatic system, including its structure, function, and the various defenses it employs against infections. Topics covered include the right lymphatic duct, lymph formation, lymph nodes, the thymus and spleen, and innate and adaptive immune defenses.

Typology: Study notes

2009/2010

Uploaded on 12/07/2010

ephrayim921
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Lymphatic*System*&*Immunity
Chapter*14*Lecture*
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Download The Lymphatic System: Structure, Function, and Defenses and more Study notes Physiology in PDF only on Docsity!

Lymphatic System & Immunity

Chapter 14 Lecture

The Lymphatic System

‡ Lymphatic System

± Functions to:

‡ Drain excess interstitial fluid ‡ Transport dietary lipids ( i.e. lacteals ) ‡ Defend the body against disease-­‐causing agents ( immunity )

± Consists of:

‡ Network of vessels that transport fluids ‡ Cells and chemicals that travel in the fluids ‡ Glands and organs that produce the cells/chemicals

Lymphatic Pathways

‡ Lymphatic Capillaries

± ClosedȂended tubes

± Composed of simple squamous epithelium

± Extend into the interstitial spaces

‡ Run parallel to the capillary networks

± Fluid traveling through the lymphatic capillaries is termed

lymph

Lymphatic Pathways

‡ Lymphatic Trunks & Collecting Ducts

± Drain lymph from the lymphatic vessels

± Join one of two collecting ducts:

‡ 1) Thoracic duct ± Receives lymph from the lower limbs, abdominal regions, left upper limb, and left side of the thorax, head, and neck

‡ 2) Right lymphatic duct ± Receives lymph from the right side of the head and neck, right upper limb, and right thorax

± From the collecting ducts lymph drains into venous blood

‡ Lymph moves into the R and L subclavian veins

Tissue Fluid & Lymph

‡ Tissue fluid becomes lymph when it enters a lymphatic

capillary

‡ Tissue fluid formation

± Tissue fluid originates from blood plasma

‡ Pressure at the arteriole end of a capillary forces fluid out of the blood capillaries ± This becomes tissue fluid!

‡ Consistency is very similar to blood plasma (minus some plasma proteins)

Tissue Fluid & Lymph

‡ Tissue fluid becomes lymph when it enters a

lymphatic capillary

‡ Lymph formation

± Filtration from the plasma typically exceeds reabsorption

‡ Excess fluid drains into the lymphatic vessels, becoming lymph

± Important Role of Lymph:

‡ Returns lost plasma proteins to the blood

± Edema Ȃ excessive accumulation of tissue fluid in

interstitial spaces

Lymph Nodes

‡ Lymph Nodes

± Contain lymphocytes and macrophages

± Structure

‡ Encapsulated in connective tissue ± CT divides the node into lymphatic nodules

‡ Blood vessels and nerves join at the hilum

‡ Afferent vessels enter at various points

‡ Efferent vessels exit from the hilum

Lymph Nodes

‡ Lymph Nodes

± Location

‡ Occur in chains along the larger lymphatic vessels

± Functions

‡ Filter lymph ± Lymphocytes respond to pathogens in two ways: » Cell-­‐mediated immunity (T cells) » Antibody-­‐mediated immunity (B cells)

‡ Site of lymphocyte production ± What other tissue produces lymphocytes?