Transcript Lymphatic System and Immunity

Lymphatic System and Immunity
22B
Organ Systems
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Integumentary
Skeletal
Muscular
Respiratory
Circulatory
Digestive
Excretory
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Nervous
Reproductive
Lymphatic
Endocrine
Lymphatic System
• Water and some dissolved
substances diffuse out of capillaries
into the space between cells
• Picked up by vessels of the
lymphatic system
• Once the watery solution is picked
up by the lymphatic system it is
called lymph
• Pressure on the outside is greater
than on the inside of the lymph
capillaries so lymph diffuses in
• Lymph capillary walls are a single
cell layer. Cells overlap and only
open in
Lymph Pathway
• Lymph capillaries- where lymph
is picked up
• Lymph vessels- lymph
capillaries combine to form
these, structurally similar to
veins
• Smooth muscle fibers in the
walls move lymph along
• One-way valves keep lymph
moving in 1 direction
• Lymph flows through numerous
lymph nodes
• Drains into two main ducts that
join the blood stream where
the jugular and subclavian veins
meet in the shoulder region
Lymphatic System
• Lymphatic system doesn’t just pick up and return
lymph to the bloodstream
• It also is a part of immunity
Pathogen
• Infectious agent
• Biological agent that causes disease or illness to its host
• Virus, bacteria, fungus…
(a) Streptococcus pneumonia,
(b) Pseudomonas aeruginosa,
(c) Candida, (d)
Staphylococcus aureus, and
(e) Escherichia coli. Infections
with any of these pathogens
can lead to sepsis. If a patient
does not receive medical
intervention within hours,
death is imminent.
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Line of Defense
• Skin- keeps things out
• Mucous membranes- line internal surfaces
exposed to outside. Nose, mouth, lungs, eyelids,
sex organs
Inflammatory Response
• Inflammatory Response
– Mast Cells- specialized cells
in connective tissue that
search for antigens
(unknown proteins) and
release signaling molecules
like histamine
– Histamine makes blood
vessels more permeable
allowing fluid and white
blood cells to flow to
infected area causing
inflammation
– Allergic reactions are an
inflammatory response so
you may take an
antihistamine
Leukocytes (White Blood Cells)
• Leukocytes
– Phagocytes – phagocytosis is the process where a cell
ingests solid material
• Neutrophils – eat and die, these dead cells are what form pus,
mobile traveling through blood and lymph
• Macrophages – big eaters, more stationary, embedded in various
tissues
• Natural Killer Cells
– Lymphocytes
• T Cells
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Helper
Cytotoxic or Killer
Suppressor
Memory
• B Cells
http://www.youtube.com/watch?v=BDr44vLNnPY
Types of Immunity
• Innate Immunity
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Quick
Nonspecific
Every animal has it, even sponges
Have it from birth
Macrophages play primary role
• Acquired or Adaptive Immunity
– Develops only in vertebrates
– Specific
– Lymphocytes play primary role
Innate or Nonspecific Immunity
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All living things have this
You are born with it
Responds the same to different pathogens
Involves humoral and cell mediated
components, but it is just a basic immune
response
Acquired or Adaptive Immunity
• Only in vertebrates
• Develops during your life
• Memory cells allow your body to respond specifically and
quickly to secondary infections which are infections from
pathogens your body has previously identified
• Vaccines- weakened pathogens that don’t cause disease
but allow your body to learn how to defend against that
disease
• Booster shots- additional vaccine that builds up your
immune system
• Serum- antibodies extracted from the blood of an immune
person or animal. Provides short term immunity, but could
allow a person’s body to learn how to fight an infection
Leukocytes
Lymph Nodes
• Numerous masses of tissue along the lymph vessels
• Filters and destroys bacteria, viruses, and other
foreign matter from lymph
Lymph Node Anatomy
• Layer of connective tissue surrounding
small groups of cells
• Pinhead to dime size
• All over the body, but usually more
numerous in the floor of the mouth,
neck region, armpit, and groin
Fixed Macrophages
• Engulf pathogens and digest them in vacuoles
• Lymph nodes around infected area may
become swollen as the fixed macrophages
fight the infection
• Severe Bacterial Infection
– Bacteria could overwhelm lymph node and grow
there
– Could enter blood stream and be carried to other
parts of the body
• Some things cannot be digested
– Tobacco smoke particles
– Asbestos
Lymphatic Disorders and Diseases
• Edema
– Body tissues swell with excess fluid
– Lymph vessels could be blocked causing
elephantiasis
– Backup of blood in systemic circulation due
to congestive heart failure
• Hodgkin’s disease- cancer that causes lymph
nodes, spleen, and liver to become
abnormally large
• Mononucleosis
– Lots of monocytes (another type of
leukocyte) in blood
– Virus that usually infects people who are
fatigued, stressed, and lacking proper rest
and nourishment
• Tonsillitis
– Inflammation of the tonsils
– May be caused by a variety of organisms and
viruses
Lymphatic Organs
• Tonsils
– In the pharynx region
– Several small lymph nodes covered
by connective tissue
• Thymus gland
– Between aorta and sternum
– Produces T lymphocytes
• Spleen
– Immediately inferior to the
diaphragm on the left side
– Similar to a large lymph node, but
it filters blood instead of lymph
Immunity
• Immune- body reacts to the presence of a pathogen by destroying it or rendering it
harmless
• Antigen (antibody generator)- any foreign substance (usually a protein) to which
the body responds by making chemicals or specialized cells that eliminate that
antigen, could be produced by a pathogen or on the surface of a pathogen
• Antibodies- proteins that circulate through the body dissolved in blood or lymph,
involved in destroying antigens, most of the time they tag foreign molecules or cells
and send out a chemical signal so macrophages or lymphocytes can come and
destroy the antigen
Lymphocytes
• A kind of white blood cell (leukocyte) responsible
for the bodies immune response
• Produced in red bone marrow
• All are initially alike but they mature into different
kinds
• Recognize specific antigens
2 Types of Lymphocytes
• T cells
– Develop in the thymus
– 70-80% of circulating
lymphocytes
– Cell mediated immunity
• B cells
– Develop in the bone marrow
– 20-30% of circulating
lymphocytes
– Humoral immunity
Cell Mediated Immunity
• Major Histocompatibility Complex (MHC)- set of cell
surface molecules that all cells in your body have.
Mediate the interaction of leukocytes with cells
• The cell‐mediated response involves mostly T cells
and responds to any cell that displays abnormal
MHC markers, including cells invaded by pathogens,
tumor cells, or transplanted cells.
Cell Mediated Immunity
Activation
• Antigen presentation occurs
– Macrophage ingests an antigen forming an antigenmacrophage complex
– Helper T cells with a matching receptor bind to the
complex
• Macrophage secretes a polypeptide called
interleukin-1
• Helper T cell secretes another polypeptide called
interleukin 2
• Helper T cells rapidly divide and activate the
other types of T cells
Types of T Cells
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Helper
Cytotoxic or Killer
Suppressor
Memory
Helper T Cells
• May cause plasma cells to produce antibodies
and other chemicals
• Some of those chemicals attract macrophages
Cytotoxic T Cells
• Attack body cells affected by antigen
• Attaches to affected cell and releases protein
that perforates the cell’s membrane and kills it
Suppressor T Cells
• Produced and released towards the end of the
fight
• Stop cytotoxic T cells, helper T cells, and
plasma cells
Memory T Cells
• Made during an infection
• Recognize antigen-macrophage complex if it
appears again and divides rapidly forming
cytotoxic and helper T cells
Humoral Immunity
• The humoral response (or antibody‐mediated
response) involves B cells that recognize
antigens or pathogens that are circulating in
the lymph or blood (“humor” is a medieval
term for body fluid).
Humoral Immunity
• Presence of an antigen and/or the presence of
interleukins released by an activated helper T
cell activate the B cells
• B cells divide and produce plasma cells that
have antibodies that bind to antigens
• B cells produce memory cells
Autoimmune Diseases
• Immune system cannot distinguish the body
from foreign invaders
• Body produces antibodies and cytotoxic T cells
that attack and damage cells of the body
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60 Minutes – Killing Cancer – Part 2
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Review Videos
Lymphatic System
https://www.youtube.com/watch?v=_GinTV94hUk
What is Lymph?
https://www.youtube.com/watch?v=2Bq2xopLew8
Lymphatic System and Immunity
https://www.youtube.com/watch?v=kjLwVqxwaIM