Download Lymphatic System

LYMPHATIC
IMMUNE SYSTEM
Chapter 14
Introduction

Intro to Immunity
Includes:
 Network of vessels that transports fluids
 Similar to cardiovascular
 Organs, etc:
 Lymph nodes/vessels/fluid, capillaries, veins/arteries,
thymus, spleen, bone marrow

Functions:
 Drain interstitial fluid back to the circulatory system
 Dietary lipid absorption/transport
 Initiate & regulate immune responses
Flow of Lymph


Lymphatic capillaries →
Lymphatic vessels →
Lymphatic Trunks →
Collecting Ducts →
Veins
The lymph will also pass
through lymph nodes
found along vessels
Lymphatic Capillaries




Closed-ended tubes
Form network with
blood capillaries
Thin-walled
Fluid inside is called
lymph
Lymphatic Vessels and Trunks

Lymphatic vessels
 Structure is very similar to veins

Lymphatic Trunks
 Larger vessels than lymphatic vessels; drain into
collecting ducts
Collecting Ducts

Two Main Ducts
 1) Thoracic Duct- collects
lymph drained from the
lower limbs, abdomen,
left upper limb, and left
side of the thorax, head,
and neck
 2) Right Lymphatic Ductcollects lymph drained
from right upper limb
and right side of the
thorax, neck, and head
Tissue Fluid




Interstitial fluid surrounding capillaries
Constant movement in and out of capillaries
Generally same composition as plasma (except
doesn’t contain plasma proteins)
Some excess fluid stays in tissue and is not
recollected by capillaries
Formation of Lymph


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
 Removing: Wastes, pathogens, carbon dioxide
Movement
of Lymph

Controlled by:
 Skeletal muscle
movement
 Pressure changes
(due to breathing)

Valves keep the
movement going in
one direction
Lymph Node Function


Filter foreign particles from blood before
returning the lymph to the blood stream
Immune surveillance
Lymph Nodes (outside structure)


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
Lymph Node (Inside structure)


Connective tissue encloses lymph node and
creates sub-compartments inside
Compartments are lymph nodules
 Lymph sinus: space inside the nodule
 Sinuses are filled with lymphocytes and
macrophages
Movie
Thymus




Bilobed structure found
in the chest region
Largest during childhood
Creates T-cells
Also an endocrine gland
 Releases thymosins
(make T-cells mature
after leaving the thymus)
Spleen “blood reservoir”



Largest lymphatic organ
Found near stomach
Similar structure to
lymph nodes
 Sinuses contain blood
instead of lymph

White pulp
 High in lymphocytes

Red pulp
 High in red blood cells,
lymphocytes, and
macrophages

Filters Blood
Immunity


Protection against pathogens
Pathogens include:
 Viruses
 Bacteria
 Fungi
 Protozoans
Types of Immunity



Innate vs Adaptive
Natural vs Artificial
Active vs Passive
Innate Defenses


Species specific
First line of defense:


Skin and mucous layers
Second line of
defense:

Chemical barriers


Tears, gastric juices, and
sweat
Interferons
Fever
 Inflammation
 Phagocytosis

Adaptive Immunity


Third line of defense
Lymphocytes are responsible
 Lymphocytes: WBCs specific for adaptive immunity
 Types of lymphocytes: B and T cells

Responds to specific antigen on the invading
pathogen
Cell Differentiation
Origin of Lymphocytes


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

Differences in response

1) Cellular Immune response
Attack up close
 Performed by T cells
 soldiers, destroying the invaders that the intelligence system
has identified (hand to hand combat)
 Signal other cells if needed for additional help


2) Humoral immune response
Attack from afar (produce antibodies)
 Can’t destroy without T cells help
 Performed by B cells
 body's military intelligence system, seeking out their targets
and sending defenses to lock onto them

Helper T 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


Known as Tc
Function:
 Attack cells infected
virus or cancerous cells
 Release destructive
enzymes into pathogen

Must be activated by a
matching antigen
B cells

Sequence of events:
1.
2.
3.
4.
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
Antibodies

Globular proteins; all immunoglobulins


Contain heavy and light protein chains
Contain variable region (area that is specific to antigen – foreign
body- attachment)
Antibody Types
Type
Found
Function/s
IgG
Plasma and tissue fluid
(passed down to fetus)
Activates complement system,
effective against bacteria,
viruses and toxins
IgA
Breast milk (passed down to
infant), tears, nasal fluid,
gastric juice, intestinal juice,
bile, urine
Control homeostasis
IgM
Plasma (in response to food
or bacteria)
Activates complement system
IgD
Surface of B cells (esp.
infants)
Activate B cells
IgE
Exocrine secretions (with
IgA)
Allergic reactions/response
Antibody Function

Two types:

1) Attack directly
 Allows antibody to more easily phagocytize cells,
eliminate them
 Types of Direct Attack:
1.
2.
3.
Agglutinate (Clump pathogens together)
Precipitate (Make pathogen insoluble)
Neutralize (Cover or destroy toxic part of antigen)
Antibody Function

2) Complement

Bind antigens


Starts a series of rxns that activate the complements circulating
in the plasma
Complement Function:
Opsonization- coating antigen-antibody complex
 Chemotaxis- bringing macrophages to the area
 Lysis- rupturing membranes
 Agglutination
 Neutralization

“And the Band Played On” reaction

Get out a piece of paper:
 Did you know about the AIDS struggles illustrated in
the movie BEFORE watching it?
 Did you find yourself angry at anytime during movie?
When?
 Did you find yourself sympathetic at anytime? When?
 Did you find yourself sad? When?
 Overall view of movie…
Memory
Cells
Memory Cells

Memory T and B cells
 Circulate after primary immune response

Body will be able to respond quickly during
secondary immune response
Natural vs. Artificial Acquired
Immunity

Natural:
 Through exposure to pathogen
 Resistance is the result of primary immune response

Artificial:
 Through vaccine injection
 Vaccine: bacteria or virus that has been killed or
weakened
 Contains antigens that stimulate primary immune
response
 Don’t produce severe symptoms of disease
 Ex: Measles, mumps, flu, rubella
Active vs. Passive Acquired
Immunity

Naturally Acquired Active:
 Occurs during pregnancy
 Certain antibodies (IgG) pass from maternal blood to
fetal blood
 Fetus acquires limited immunity against pathogens

Artificially Acquired Passive:
 Through injection of antiserum (ready-made
antibodies)
 Obtain from globulin proteins from people who have
already developed immunity against a certain disease
Allergic Reactions



Immune response to everyday, non-harmful
antigens (allergens)
Types: Delayed and Immediate
Delayed-reaction allergy:
 Exposure to allergen on skin
 Collects T cells and macrophages in the area
 Causes dermatitis
Allergic Reactions

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
Transplantation

Transplant tissue or organ
 Ex: Organ – liver, kidney, heart; Tissue – skin, bone

New transplant tissue/organ has its own antigens
 Recognized as foreign
 Starts immune response (which can often reject the
new transplant tissue/organ)


Tissue matching helps minimize reaction
Immunosuppressive drugs
 Suppress immune reaction, avoid rejection (usually)
Autoimmunity


Cytotoxic T cells cannot correctly identify self cells
and attacks self cells
Why?
 Pathogen borrows self antigens during attack
 Pathogen antigen is very similar to a self antigen
Disorder
Lupus
Description
Symptoms
profound fatigue, rashes, and joint pains,
Occurs in 1 out of 2,000 Americans severe cases: immune system attacks
organs (kidney, brain, lung)
Crohn’s
result from intestinal
inflammation
diarrhea, nausea, vomiting, abdominal
cramps, and pain that difficult to control
Psoriasis
common , affects more than 2%
of Americans, often runs in
families
skin or body covered with buildup of red
scales, skin rash
Diabetes
(Type 1)
destruction of the insulinproducing cells of the pancreas
See chapter 11
immune system targets the lining
(synovium) that covers various
joints
pain, swelling, and stiffness of the joints
Multiple
Sclerosis
immune system targets nerve
tissues of the CNS
possible blindness, paralysis, and
premature death
Grave’s
disease
immune system destruction or
stimulation of thyroid tissue
fatigue, nervousness, cold or heat
intolerance, weakness, changes in hair
texture/amount, and weight gain/loss
Rheumatoid
arthritis