Ch 23_lecture_presentation

© 2012 Pearson Education, Inc.

23The Lymphoid System

PowerPoint® Lecture Presentations prepared bySteven BassettSoutheast Community College Lincoln, Nebraska


Introduction

The lymphoid system Lymphatic vessels Lymph (fluid connective tissue) Lymphoid tissues

Diffuse lymphoid tissues Lymph nodule

Lymphoid organs Lymph node Thymus: most active during infancy and youth. Spleen (the largest organ of the lymphatic system)

Plays central role in body’s defenses against viruses, bacteria, and other microorganismsLymphatic vessels originate in peripheral tissues and deliver lymph to the venous system.


An Overview of the Lymphoid System

Lymph consists of: Interstitial fluid, which resembles blood

plasma, but with a lower concentration of proteins

Lymphocytes, cells responsible for the immune response

Macrophages of various types


Functions of the lymphatic system

Primary functions of the lymphoid system: Produce, maintain, and distribute lymphocytes Maintain normal blood volume and eliminate

local variations in the chemical composition of the interstitial fluid

Provide an alternative route for the transport of hormones, nutrients, and waste products


Figure 23.2a Lymphatic Capillaries

A three-dimensional view of the associationof blood capillaries and lymphatic capillaries.Arrows show the direction of blood,interstitial fluid, and lymph movement.

Looseconnectivetissue

Endothelialcells

Lymphflow

Interstitialfluid

Venule

Smoothmuscle

Bloodcapillaries

Arteriole

Lymphaticcapillary


Structure of Lymphatic Vessels

Lymphatic capillaries (or terminal lymphatics) form a complex network within peripheral tissues.

Lymphatics contain internal valves that prevent backflow of lymph.

Lymphatic vessels (or lymphatics) carry lymph from peripheral tissues to the venous system. The right lymphatic duct receives lymph from the right side of

the thorax. The rest of the body’s lymph (most of the lymph) returns to

the venous system through thoracic duct. Thoracic duct joins the left subclavian vein at the junction of left internal jugular vein.

Large lymphatic trunks are located in the posterior thoracic and abdominal wall.


Figure 23.2b Lymphatic Capillaries

Sectional view through a cluster of lymphatic capillaries

Incompletebasal lamina

Lymphflow

Looseconnective

tissue

Lymphocyte

To largerlymphatics

Interstitialfluid

Interstitial fluid

Bloodcapillary

Lymphaticcapillary


Figure 23.3ac Lymphatic Vessels and Valves

The cross-sectional view emphasizesthe structural differences betweenblood vessels and lymphatic vessels.

Lymphaticvessel

Vein

Artery

Towardvenoussystem

Lymphaticvalve

Lymphaticvessel

From lymphaticcapillaries

Artery

Vein

A diagrammatic view of loose connectivetissue showing small blood vessels anda lymphatic vessel. Arrows indicate thedirection of lymph flow.


Structure of Lymphatic Vessels

Two sets of lymphatic vessels: Superficial lymphatic vessels travel with superficial

veins The subcutaneous layer next to the skin The loose connective tissues of the mucous membranes The loose connective tissues of the serous membranes

Deep lymphatic vessels are large lymphatic vessels that accompany the deep arteries and veins. Collect lymph from skeletal muscles and other organs of the

neck, limbs, and trunk, as well as visceral organs in the thoracic and abdominopelvic cavities


Figure 23.1 Lymphoid SystemTonsil

Cervicallymph nodes

Right lymphatic duct

Thymus

Thoracic duct

Cisterna chyli

Lumbarlymph nodes

Lymphaticsof lower

limb

Lymphaticsof upper limb

Axillary lymph nodes

Thoracic (left lymphatic) duct

Lymphatics of mammary gland

Spleen

Mucosa-associated lymphoidtissue (MALT)

Pelviclymph nodes

Inguinallymph nodes


Figure 23.4a Lymphatic Ducts and Lymphatic Drainage

The collecting system of lymph vessels, lymph nodes, and major lymphaticcollecting ducts and their relationship to the brachiocephalic veins

Right lumbar trunk

Inferior vena cava(cut)

Azygos vein

Rib (cut)

Superiorvena cava (cut)

Right bronchomediastinaltrunk

Right subclavian vein

Right internal jugular vein

Right jugular trunk


Right subclavian trunk

Brachiocephalic veins

Left internal jugular vein

Left jugular trunk

Thoracic duct

Left subclavian trunk

Left bronchomediastinal trunk

Left subclavianvein

First rib(cut)

Highestintercostalvein

Thoracicduct

Thoraciclymph nodes

Hemiazygosvein

Parietalpleura (cut)

Diaphragm

Cisterna chyli

Intestinal trunk

Left lumbar trunk


Figure 23.4b Lymphatic Ducts and Lymphatic Drainage

The thoracic duct collects lymphfrom tissues inferior to thediaphragm and from the left side ofthe upper body. The right lymphaticduct drains the right half of thebody superior to the diaphragm.

Drainageof thoracicduct

Drainageof right

lymphaticduct


Lymphocytes

Lymphocytes are the primary cells of the Lymphoid system, and they are responsible for specific immunity. They respond to the presence of

Invading organisms, such as bacteria and viruses Abnormal body cells, such as virus-infected cells or

cancer cells Foreign proteins, such as the toxins released by some

bacteria


Lynphocytes

Three different classes of lymphocytes in the blood: T cells (thymus dependent)

Cytotoxic T cells Helper T cells Suppressor T cells Memory T cells

B cells (bone marrow derived) Plasma cells (providing humoral immunity) Memory B cells (stay in the body to fight off the second time

infection easier)

NK cells (natural killer)


Figure 23.6a Lymphocytes and the Immune Response

BACTERIA

Macrophageactivation

Antigenpresentation

Activation ofcytotoxic T cells

Activation ofhelper T cells

Activation ofB cells

Destruction ofbacteria bycell lysis

Antibodyproduction byplasmocytes

Defenses against bacterial pathogensare usually initiated by activemacrophages.


Figure 23.7 Derivation and Distribution of Lymphocytes

The second group of stemcells migrates to the thymus,where subsequent divisionsproduce daughter cells thatmature into T cells.

One group remains in thebone marrow, producingdaughter cells that matureinto B cells and NK cellsthat enter peripheraltissues.

Mature T cells leave the circulation to take temporary residence in peripheraltissues. All three types of lymphocytes circulate throughout the body in thebloodstream.

Cell-mediatedimmunity

Antibody-mediatedimmunity

Immunologicalsurveillance

Peripheral Tissues

Red Bone MarrowThymus

Lymphoid stem cells

Mature T cell

Thymichormones

Production anddifferentiation of

T cells

Migrate tothymus

Transported bycirculatory system

Lymphoid stem cells

Mature T cell B cells NK cells

Lymphoid stem cells

Pluripotential stem cell

Interleukin-7

As they mature, B cellsand NK cells enter thebloodstream and migrateto peripheral tissues.


Lymphoid Tissues

Any tissue containing an abundance of lymphocytes

Diffuse lymphoid tissues—loosely packed lymphocytes within connective tissue

Lymphoid nodules—densely packed lymphocytes within loose connective tissue Tonsils

Pharyngeal tonsils(Adenoid) Lingual tonsils (at the base of the tongue) Palatine tonsils(at the entrance to oropharynx)

Aggregated lymphoid nodules (Peyer’s patches)


Figure 23.8c Histology of Lymphoid Tissues

The location of the tonsils and the histological organization of a single tonsil

Pharyngeal tonsil

Pharyngeal epithelium

Germinal centerswithin nodules

LM 50

Pharyngeal tonsil

Palatine tonsil

Lingual tonsil

Palate


Lymphoid Organs

Lymphoid tissues that are separated from surrounding tissues by a capsule

Lymph nodes Receive the lymph through afferent vessels and the

cleanest lymph will leave the node through efferent vessels.

Thymus Spleen


Figure 23.1 Lymphoid SystemTonsil

Cervicallymph nodes


Thymus

Thoracic duct

Cisterna chyli

Lumbarlymph nodes

Lymphaticsof lower

limb

Lymphaticsof upper limb

Axillary lymph nodes

Thoracic (left lymphatic) duct

Lymphatics of mammary gland

Spleen

Mucosa-associated lymphoidtissue (MALT)

Pelviclymph nodes

Inguinallymph nodes


Figure 23.9 Structure of a Lymph Node

Lymph node artery and vein

HilumLymph nodes

Lymphnodes

Lymphvessel

Efferent vessel

Trabeculae

Medulla

Cortex

Subcapsularspace

Deep cortex(T cells)

Capsule Medullary cord(B cells and

plasmocytes)

Afferentvessel

Medullary sinus

Outer cortex (B cells)

DividingB cell

Germinalcenter

Subcapsularspace

Outer cortex Capsule

Dendriticcells

Nuclei ofB cells

Capillary


Figure 23.10 Lymphatic Drainage of the Head and Neck

Periauricularlymph node

Retroauricularlymph node

Occipital lymph node

Parotid lymph node

Superficial cervicallymph node

Deep cervicallymph node

Sternocleidomastoidmuscle

Orbicularis oculimuscle

Infraorbitallymph node

Submandicularlymph node

Buccal lymph node

Mandibular lymph node

Submental lymph node

Parotid salivary gland


Figure 23.11a Lymphatic Drainage of the Upper Limb

Superficial lymphaticvessels and nodes thatdrain the upper limband chest of a male

Deltopectoral lymph node

Deltoid muscle

Pectoralis major muscle

Cephalic vein

Basilic vein

Axillarylymph nodes

Supratrochlearlymph node


Figure 23.11b Lymphatic Drainage of the Upper Limb

Superficial and deeper lymphatic vessels and nodes of the upper limb and chest of a female

Subclavianlymph node

Axillarylymph nodes

Pectoralis majormuscle (cut)

Axillaryvein

Subscapularlymph node

Pectorallymph node

Mammarygland

Centrallymph node

Parasternallymph node


Figure 23.12 Lymphatic Drainage of the Lower Limb

Superficial inguinallymph nodes

Deep inguinallymph nodes

Popliteal lymph nodes

Great saphenousvein


Figure 23.14b Lymphatic Drainage of the Inguinal Region

A superficial and deeper view of the inguinal region of a maleshowing the distribution of lymph nodes and lymphatics

Deep Inguinaland Iliac Lymph Nodes

SuperficialInguinal Lymph Nodes

Superficial inguinallymph nodes

Lymphaticvessels

Fascia

Anterior superior iliac spineExternal iliac artery

External iliac vein

Inguinalligament

Femoralartery

Deep inguinallymph nodes

Femoral vein

Greatsaphenous vein


Figure 23.15 Lymph Nodes in the Large Intestine and Associated Mesenteries

Inferior mesentericlymph nodes

Inferior mesentericartery

Distal portionof duodenum

Superior mesentericartery

Descending colon

Sigmoid colon

Rectum

Appendix

Appendicularlymph nodes

Transverse mesocoliclymph nodes

Cecum

Ileum

Ascending colon

Transverse colon

Superior mesentericlymph nodes

Ileocolic lymphnodes


Figure 23.16a Anatomy and Histological Organization of the Thymus

The location of the thymus on gross dissection;note the relationship to other organs in the chest

Right lobe

Diaphragm

Trachea

Thyroid gland

Rightlung

Leftlung

Left lobe

THYMUS

Heart


Figure 23.16bc Anatomy and Histological Organization of the Thymus

Anatomical landmarkson the thymus

Histology of the thymus. Note the fibrous septathat divide the thymic tissue into lobulesresembling interconnected lymphoid nodules.

Left lobe

Rightlobe

Septa

Lobule

SeptaMedulla Cortex

Lobule

Lobule

The thymus gland LM 50


Figure 23.16cd Anatomy and Histological Organization of the Thymus

Histology of the thymus. Note the fibrous septathat divide the thymic tissue into lobulesresembling interconnected lymphoid nodules.

Histology of the unusual structure of thymiccorpuscles. The small cells in view arelymphocytes in various stages of development.

A thymic corpuscle LM 550

Lymphocytes

Thymiccorpuscle

Reticularcells

SeptaMedulla Cortex

Lobule

Lobule

The thymus gland LM 50


Figure 23.17a Anatomy and Histological Organization of the Spleen

The shape of the spleen roughly conforms to theshapes of adjacent organs. This transverse sectionthrough the trunk shows the typical position of thespleen within the abdominopelvic cavity (inferior view).

Spleen

Aorta

Rib

Pancreas

Liver

Parietal peritoneum

Visceral peritoneum

Stomach

Diaphragm

Kidneys

Gastrosplenic ligament

Gastric area

Diaphragmatic surface

SPLEEN

Hilum

Renal area


Figure 23.17b Anatomy and Histological Organization of the Spleen

External appearance of the visceral surface of theintact spleen showing major anatomical landmarks.This view should be compared with that of part (a).

SUPERIOR

INFERIOR

Splenic lymphaticvessel

Splenic artery

Splenic vein

Hilum

Renalarea

Gastricarea


Aging and the Lymphoid System

With advancing age, the lymphoid system becomes less effective at combating disease.

T cells become less responsive to antigens. The number of helper T cells is reduced. B cells are less responsive. Antibody levels do not rise as quickly after

antigen exposure.

The net result is an increased susceptibility to viral and bacterial infection, and cancer.

Ch 23_lecture_presentation

Documents

Transcript of Ch 23_lecture_presentation