Lymph flows torwards...
Structure of lymphatic Capillaries
Endothelial cells overlap to form one-way minivalves and are anchored by collagen filaments, preventing collapse of capillaries
Lymphatic Cappilaries are absent from...
Bones, Teeth, Bone Marrow, CNS
Lymphatic Collecting vessels travel with?
- •Collecting vessels in the skin travel with superficial veins
- •Deep vessels travel with arteries
- •Nutrients are supplied from branching vasa vasorum
Right lymphatic duct drains?
right upper arm and the right side of the head and thorax
arises from the cisterna chyli and drains the rest of the body
Each Duct empties lymph into
venous circulation at thejunction of the internal jugular and subclavian veins on its own side of the body
Lymph is propelled by?
- Pulsations of nearby arteries
- Contractions of smooth muscle in the walls of the lymphatics
phagocytize foreign substances and help activate T cells
capture antigens and deliver them to lymph nodes
Reticular cells produce...
stroma that supports other cells in lymphoid organs
Lymphatic follicles (nodules) are....
solid, spherical bodies of tightly packed reticular elements and cells
- Principal lymphoid organs of the body
- Embedded in connective tissue, in clusters along lymphatic vessels
- Near the body surface in inguinal, axillary, and cervical regions of the body
Lymph Node Function.
- 1.Filter lymph—macrophages destroy microorganisms and debris
- 2.Immune system—lymphocytes are activated and mount an attack against antigens
extend inward from the cortex and contain B cells, T cells, and plasma cells
Lymph sinuses contain....
Circulation in the Lymph Nodes
- •Enters via afferent lymphatic vessels
- •Travels through large subcapsular sinus and smaller sinuses
- •Exits the node at the hilus via efferent vessels
Largest Lymhoid Organ?
- Served by splenic artery and vein, which enter and exit at the hilus.
Function of the spleen.
- •Site of lymphocyte proliferation and immune surveillance and response
- •Cleanses the blood of aged cells and platelets and debris
Structure of the Spleen
- •Two distinct areas
- •White pulp around central arteries
- •Mostly lymphocytes on reticular fibers and involved in immune functions
- •Red pulp in venous sinuses and splenic cords
- Rich in macrophages for disposal
- of worn-out RBCs and bloodborne pathogens
Thymus size with age...
- •In infants, it is found in the inferior neck and extends into the mediastinum, where it partially overlies the heart
- •Increases in size and is most active during childhood
- •Stops growing during adolescence and then gradually atrophies
•Simplest lymphoid organs
at posterior end of the oral cavity
grouped at the base of the tongue
in posterior wallof the nasopharynx
surrounding the openings of the auditory tubes into the pharynx
trap and destroy bacteria and particulate matter
Peyer’s patches and the appendix
- Destroy bacteria, preventing them from breaching the intestinal wall
- •Generate “memory” lymphocytes
- •Clusters of lymphoid follicles
- •In the wall of the distal portion of the small intestine
- •Similar structures are also found in the appendix
Mucosa-associated lymphatic tissue (MALT)
- Peyer’s patches, tonsils, and the appendix (digestive tract)
- Lymphoid nodules in the walls of the bronchi (respiratory tract)
- Protects the digestive and respiratory systems from foreign matter
lymph nodes are apparent
by the _______ week of embryonic development
- These arise from the budding of lymph sacs from developing veins
Lymphatic organs (except
the thymus) arise from?
The thymus (endodermal
origin) forms as an outgrowth of the...?
organs are poorly developed at birth?
lymphoid Except for the spleen and tonsils,
Innate Immunity is...
Adaptive Immunity is ?
2 Lines of defense for Innate Immunity
- First line of defense is external body membranes (skin and mucosae)
- Second line of defense is antimicrobial proteins, phagocytes, and other cells. Inflammation is its most important mechanism
Adaptive Defense does what?
- Attacks particular foreign substances.
- Takes longer to react.
Keratin is resistant to?
weak acids and bases, bacterial enzymes, and toxins
Protective Chemicals that inhibit or destroy microorganisms
- •Skin acidity
- •Lipids in sebum and dermcidin in sweat
- •HCl and protein-digesting enzymes of stomach mucosae
- •Lysozyme of saliva and lacrimal fluid
Respiratory system barriers.
Macrophages develop from?
Monocytes to become the chief phagocytic cells.
Kupffer cells live where?
microglia cells live where?
Free macrophages wander...?
through tissue spaces
Become phagocytic on encountering infectious material in tissues.
coating of pathogen by complement proteins or antibodies
Natural Killer (NK) Cells
- Large granular lymphocytes
- Target cells that lack “self” cell-surface receptors
- Induce apoptosis in cancer cells and virus-infected cells
- Secrete potent chemicals that enhance the inflammatory response
- Triggered whenever body tissues are injured or infected
- Prevents the spread of damaging agents
- Disposes of cell debris and pathogens
- Sets the stage for repair
- Histamine (from mast cells)
- Blood proteins
- Kinins, prostaglandins (PGs), leukotrienes, and complement
- Attack microorganisms directly
- Hinder microorganisms’ ability to reproduce
- also activate macrophages and mobilize NKs
Lymphocytes produce what type of interferon?
Most (other than lymphocytes) WBCs produce what type of interferon?
Fibroblasts produce what type of interferon?
- ~20 blood proteins that circulate in an inactive form
- Include C1–C9, factors B, D, and P, and regulatory proteins
- Major mechanism for destroying foreign substances
- Amplifies all aspects of the inflammatory response
- C1 binds to the
- antigen-antibody complexes
Alternative complement pathway
Triggered when activated C3, B, D, and P interact on the surface of microorganisms
Benefits of moderate fever
- Causes the liver and spleen to sequester iron and zinc (needed by microorganisms)
- Increases metabolic rate, which speeds up repair