ap test 3

Lymphatic system

Return excess fluid in body tissues to blood to maintain blood volume

Lymph

The interstitial fluid moves into lymphatic capillaries

Lymphatic capillaries

Small, closed-ended vessels that absorb interstitial fluid

Anchoring filaments

hold endothelial cells to nearby structures

Lacteals

lymphatic capillaries in GI tract

Hydrostatic pressure of interstitial fluid pushes

it into capillary

Metastasis

Develop in other locations in the body

Lymphatic vessels

Have valves to prevent pooling and backflow of lymph

are fed by lymphatic capillaries

Lymphatic trunks

are fed by lymphatic vessels

Jugular trunks drain

lymph from head and neck

Subclavian trunks drain

upper limbs, breasts, and superficial thoracic wall

Bronchomediastinal trunks drain

deep thoracic structures

Intestinal trunks drain

most abdominal structures

Lumbar trunks drain

lower limbs, abdominopelvic wall, and pelvic organs

Lymphatic ducts

are fed by lymphatic trunks

Largest lymphatic vessels

Bring lymph to venous blood circulation

Right lymphatic duct

Drains upper right quadrant of body

Delivers lymph to junction of right subclavian and right internal jugular veins

Thoracic duct

is largest lymphatic vessel

Saclike cisterna chyli at its base

Receives lipid-rich chyle from GI tract

Lymphedema

Accumulation of interstitial fluid due to interference with lymphatic drainage

Causes swelling and pain in affected area

Primary lymphoid structures

Involved in formation and maturation of lymphocytes

Red bone marrow and thymus

Secondary lymphoid structures

Do not form lymphocytes, but house them and other immune cells

Red bone marrow

Located between trabeculae of spongy bone

In flat bones of skull, ribs, and sternum, vertebrae, ossa coxae, heads of humerus and femur

hematopoiesis

production of blood’s formed elements

Formed elements include

T-lymphocytes and B-lymphocytes

T-lymphocytes migrate to

thymus to complete maturation

two thymic lobes

each surrounded by connective tissue capsule

Lymph nodes

filter lymph, remove unwanted substances

Small, oval, encapsulated structures

Cervical lymph nodes receive lymph from

head, neck

Axillary lymph nodes receive lymph from

breast, axilla, and upper limb

Inguinal lymph nodes in groin receive lymph from

lower limb and pelvis

Afferent lymphatic vessels

bring lymph to node

efferent vessel

drains a lymph node

Located at hilum

Trabeculae of capsule subdivide

node into compartments

The cortex contains

lymphoid nodules

Reticular fibers support a

germinal center

germinal center

Houses proliferating B lymphocytes and some macrophages

mantle zone contains

T-lymphocytes, macrophages, and dendritic cells

Cortical sinuses

are tiny open channels lined by macrophages

Node’s medulla contains

medullary cords

medullary cords

Connective tissue fibers that support B-lymphocytes, T lymphocytes, and macrophages

Medullary sinuses

are tiny open channels lined with macrophages

Macrophages remove

foreign debris from lymph

Lymphoma

enlarged lymph node

Hodgkin lymphoma

Affects young adults and people over 60

The spleen is the

largest lymphoid organ

Located in left upper abdominal quadrant

Lateral to left kidney and posterolateral to stomach

Splenic artery

supplies blood

splenic vein

drains it

Trabeculae from capsule

extend into spleen dividing red and white pulp

White pulp

Clusters of T- and B-lymphocytes and macrophages around central artery

Red pulp

Storage site for erythrocytes and platelets

Splenic cords

cells and reticular connective tissue in red pulp

Splenic sinusoids

very permeable capillaries

The spleen

filters and monitors blood

White pulp monitors spleen for

foreign materials and bacteria

Macrophages in red pulp

Phagocytize bacteria, debris, defective erythrocytes and platelets

Path of flow

splenic artery, central artery, sinusoids, venules, splenic vein

n first 5 months of fetal life

spleen makes blood cells

Pharyngeal tonsil

In nasopharynx

Called adenoids when enlarged

Tonsils

Immune surveillance of inhaled and ingested substances

MALT

Located in gastrointestinal, respiratory, genital, and urinary tracts

Peyer patches

large collections of lymphoid nodules within the wall of the GI tract

Pathogenic agents

are ones that cause harm

Cytokines

small proteins that regulate immune activity

Innate immunity

present at birth

Protects against variety of different substances (nonspecific)

Adaptive immunity

acquired/specific immunity

Response to antigen involves specific T- and B-lymphocytes

Characteristics of innate immunity

Prevents entry of potentially harmful substances

First line of defense is

skin and mucosal membrane

Second line of defense involves

internal processes

innate immunity activities of

neutrophils, macrophages, dendritic cells, eosinophils, basophils, and NK cells

Neutrophils and macrophages destroy

engulfed particles

Respiratory burst produces

reactive oxygen-containing molecules that help destroy the microbes

Dendritic cells destroy

destroy particles and then present fragments

Antigens are presented on

on dendritic cell surface to T-lymphocytes

Basophils and mast cells promote

inflammation

Basophils circulate

in the blood

Histamine increases

vasodilation and capillary permeability

Heparin acts as

an anticoagulant

Eicosanoids released from

their plasma membrane also increase inflammation

NK (natural killer) cells destroy

unhealthy/unwanted cells

immune surveillance (NK CELLS)

patrol the body, detect unhealthy cells

cytotoxic chemicals

Perforin

Granzymes

Perforin creates a

transmembrane pore in unwanted cell

Granzymes enter

pore and cause apoptosis of cell

Apoptosis is

cell death that causes shriveling rather than lysis

Eosinophils attack

multicellular parasites

Eosinophils Degranulate and

release enzymes and other toxic substances

Interferons

a class of cytokines that nonspecifically impedes viral spread

Complement system

group of over 30 plasma proteins

Classical pathway

Antibody attaches to foreign substance, then complement binds to antibody

Alternative pathway

Complement binds to polysaccharides of bacterial or fungal cell wall

Opsonization

complement protein (opsonin) binds to pathogen

Cytolysis

complement triggers splitting of target cell

Complement proteins form

membrane attack complex (MAC) that creates channel in target cell’s membrane

Margination

adherence of leukocytes to endothelial CAMs

Diapedesis

cells escape blood vessel walls

Chemotaxis

leukocytes migrate toward chemicals released from damaged, dead, or pathogenic cells

Kinins

stimulate pain receptors, increase capillary permeability, increase production of CAMs by capillary cells

Redness from

increased blood flow

Heat from

increased blood flow and increased metabolic activity within the area

Swelling from

•increase in fluid loss from capillaries

Pain from

stimulation of pain receptors