Lymphatic System
Download
Report
Transcript Lymphatic System
Put
excess fluid in tissue spaces back into
the blood stream
Immunity
Lymphatic
capillaries →
Lymphatic vessels →
Lymphatic Trunks →
Collecting Ducts →
Veins
The
lymph will also pass through
lymph nodes found along these
vessels
Closed-ended
tubes
Form network with
blood capillaries
Thin-walled
Fluid inside is called
lymph
Lymphatic
vessels
• Structure is very similar to veins
Lymphatic Trunks
• Larger vessels than lymphatic vessels; drain into
collecting ducts
Two Main Ducts
• Thoracic Duct- collects
lymph drained from the
lower limbs, the
abdomen, the left upper
limb, and the left side of
the thorax, head, and
neck
• Right Lymphatic Ductcollects lymph drained
from the right upper
limb and the right side
of the thorax, neck, and
head
Interstitial
fluid surrounding capillaries
Constant movement in and out of
capillaries
Generally same composition as plasma
except plasma proteins
Some excess fluid stays and is not
recollected by capillaries
Volume
pressure of interstitial fluid
causes some of the fluid to enter
lymphatic capillaries
Lymph will return to the bloodstream but
will be filtered along the way
Controlled
by
• Skeletal muscle movement
• Pressure changes due to breathing
Valves
keep the movement going in one
direction
Usually
small and bean shaped
Afferent lymphatic vessels
• carry lymph into lymph node
• Come in at various points along convex surface
Efferent Lymphatic vessels
• Carry lymph out of lymph node
• Come out at hilum (area on the concave side)
Blood Vessels and nerves enter at hilum
Connective
tissue encloses lymph node
and creates sub-compartments inside
Compartments are lymph nodules
Space inside the nodule is called a lymph
sinus
Sinuses are filled with lymphocytes and
macrophages
Filter
foreign particles from blood before
returning the lymph to the blood stream
Immune
surveillance
Bilobed
structure
found in the
mediastenum
Largest during
childhood
Creates T-cells
Also endocrine
gland- releases
thymosins to make Tcells mature after
leaving the thymus
Largest lymphatic organ
Found in upper left
quadrant near stomach
Similar structure to
lymph nodes except
sinuses contain blood
instead of lymph
White pulp- high in
lymphocytes
Red pulp- high in red
blood cells, lymphocytes,
and macrophages
Filters Blood
Protection
against pathogens
Pathogens include
• Viruses
• Bacteria
• Fungi
• Protozoans
Innate
vs Adaptive
Natural
Active
vs Artificial
vs Passive
Species
resistance
First line of defense- skin and mucous layers
Second line of defense
• Chemical barriers
Tears, gastric juices, and sweat
interferons
• Fever
• Inflammation
• Phagocytosis
Third
line of defense
Lymphocytes
Responds
are responsible
to specific antigen on the
invading pathogen
Undifferentiated
lymphocytes made by fetal
bone marrow
T cells
• Lymphocytes travel to thymus and become T cells
• T cells either circulate in blood or are found in
lymph system
B
cells
• Made in marrow
• B cells either circulate in blood or found in the
lymph system
Cellular
Immune response
• Attack up close
• Performed by T cells
Humoral
immune response
• Attack from afar
• Performed by B cells
Antigen-presenting
cells processes and
displays antigen of pathogen
Displayed antigen must be matched with
a circulating helper T cells antibody
receptor
Helper T cell is activated
Cytotoxic T
cells- attack cells infected
virus or cancerous cells
must be activated by a matching antigen
B
cell must match with an antigen
Activated Helper T cell secrete cytokines
Cytokines make B cell proliferate to form
plasma cells and memory cells
Plasma cell secrete antibodies
Globular
proteins
Five Types
• Immunoglobulin G (IgG)- in plasma and tissue fluids;
•
•
•
•
activates complement system
IgA- in exocrine gland secretions
IgM- in plasma; activates complement system
IgD- found on surfaces of B cells; activates B cells
IgE- in exocrine gland secretions; associated with
allergic reaction
Attack
Directly
• Agglutinate- clump pathogens together
• Precipitate- make pathogen insoluble
• Neutralize- cover or destroy toxic part of antigen
Activate
compliment
• Done by shape change of IgG and IgM
• Starts a series of rxns that activate the compliments
circulating in the plasma
Compliment
Function
• Opsonization- coating antigen-antibody complex
• Chemotaxis- bringing macrophages to the area
• Lysis- rupturing membranes
• Agglutination
• Neutralization
Memory T
and B cells- circulate after
primary immune response
Body
will be able to respond quickly
during secondary immune response
Immune
response to everyday, nonharmful antigens (allergens)
Delayed-reaction allergy
• Exposure to allergen on skin
• Collects T cells and macrophages in the area
• Causes dermatitis
Immediate-reaction
allergy
• Occurs within minutes
• First exposure- B cells become sensitized; IgE is
attached to basophils and mast cells
• Subsequent exposures- mast cells and basophils
secrete several substances including histamine
• These substances produce the reactions seen in
allergy reactions
Transplant
tissue or organ
Antigen is recognized as foreign and
starts immune response
Tissue matching helps minimize reaction
Immunosuppressive drugs- suppress
immune reaction
Cytotoxic T
cells cannot correctly identify
self cells and attacks self cells
Why?
• “catalogue” is incomplete
• Pathogen borrows self antigens during attack
• Pathogen antigen is very similar to a self antigen