Lymphatic System and Immunity

Topics: Immune system, Lymphatic system, White blood cell Pages: 19 (1991 words) Published: December 8, 2013
21/04/2013

Lymphatic System & Immunity

Manuel Desco
Dept. Bioingeniería

Principles of Human Anatomy and Physiology, 11e

Anatomy and Physiology I

1

INTRODUCTION
 The ability to ward off the pathogens that produce disease is called resistance
– Lack of resistance is called susceptibility

 Resistance to disease can be grouped into two broad areas – Nonspecific resistance: general defensive mechanisms
effective on a wide range of pathogens
– Immunity: activation of specific lymphocytes that combat a particular pathogen or other foreign substance
• cell-mediated immunity
• antibody-mediated immunity

 The body system that carries out immune responses is the lymphatic system

Principles of Human Anatomy and Physiology, 11e

Anatomy and Physiology I

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LYMPHATIC SYSTEM STRUCTURE AND
FUNCTION
 Lymphatic system:
– Lymph: similar to interstitial
– Lymphatic vessels:
• capillaries vessels nodes trunks  subclavian veins

– Organs involved
– (specialized reticular tissue containing large numbers of lymphocytes)







red bone marrow
thymus
spleen
lymph nodes
diffuse lymphatic tissue
– tonsils, adenoids & peyers patches

Principles of Human Anatomy and Physiology, 11e

Anatomy and Physiology I

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Anatomy and Physiology I

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Lymphatic System

Principles of Human Anatomy and Physiology, 11e

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Lymphatic Vessels & Circulation
 Closed-ended lymphatic capillaries
in spaces between cells
– All body except avascular tissue
• (cartilage, epidermis & cornea)

 Combine to form lymphatic vessels
– anchoring filaments keep tube
from collapsing under outside pressure
– overlapping endothelial cells open when
tissue pressure is high (valves)
– Respiratory and muscular pumps

 In the GI (lacteal) transport digested fats
from the small intestine into blood
Principles of Human Anatomy and Physiology, 11e

Anatomy and Physiology I

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Lymph Trunk and Ducts
 Lymph trunks
– formed from the exiting vessels of
lymph nodes

 Right side head, arm & chest empty
into right lymphatic duct and rest of
body empties into thoracic duct
 The thoracic duct is the main
collecting duct
– It drains lymph into left subclavian
vein

Principles of Human Anatomy and Physiology, 11e

Anatomy and Physiology I

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Principles of Human Anatomy and Physiology, 11e

Anatomy and Physiology I

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LYMPHATIC SYSTEM STRUCTURE AND
FUNCTION
 Lymphatic system
functions:
– to drain interstitial fluid
– return leaked plasma
proteins to the blood
– transport dietary fats
from GI to blood
– protect against invasion
by nonspecific defenses
and specific immune
responses

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Anatomy and Physiology I

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Lymphatic Organs & Tissues
 Widely distributed throughout the body
 Primary lymphatic organs
– provide environment for stem cells to divide & mature into immunocompetent B and T lymphocytes
• red bone marrow  B cells and pre-T cells
• thymus  T cells mature from pre-T cells

 Secondary lymphatic organs & tissues
– sites where most immune responses occur
• lymph nodes, spleen & lymphatic nodules

Principles of Human Anatomy and Physiology, 11e

Anatomy and Physiology I

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Thymus Gland
 Large organ in infants (70 g) but atrophied as adult (3 g) – Keeps large in many animals

 2 lobed organ in mediastinum
 Capsule & trabeculae divide
it into lobules
– Each lobule has cortex &
medulla

 Before the thymus atrophies,
it populates the secondary lymphatic
organs and tissues with T cells
– Some T cells continue proliferating in the thymus

Principles of Human Anatomy and Physiology, 11e

Anatomy and Physiology I

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Lymph Nodes [ganglios linfáticos]
 About 600 Bean-shaped organs, 1-25 mm long, located
along lymphatic vessels, usually grouped
– scattered...
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