Download Immune

BIOL 2030 Human Anatomy & Physiology II
Why do we have a Lymphatic (Immune )
System?
3 main functions of Lymphatic
System
1) H2O balance
30l leaks out/day… How
many liters not reabsorbed
back into blood directly?
2) Fat absorption
Part of villi found in
intestines
3) Immunity (defense)
We will focus on this aspect
http://dxline.info/img/new_ail/elephantiasis.jpg
What is lymph anyway?
Lymph… fluid that
leaks out of
capillaries into
“interstitial spaces”
due to pressure
gradients.
10mmHg
0mmHg
30mmHg
0mmHg
Blood colloid
osmotic pressure
opposes this flow
90% of fluid returns to blood, remaining lymph then
gathers in lymph vessels, eventually returning to the blood
Take 5!!!
Edema results from an interruption
of the aforementioned processes
On the basis of what you know about
fluid movement, explain the
following:
a) edema due to < plasma protein [ ]
b) edema due to > capillary
permeability to the point plasma
proteins leak out
c) edema due to > b.p.
How does lymph get back into the blood?
1) Enters lymph
capillaries (no
basement membrane
and only loosely
associated epithelia)
2) capillaries form
lymph vessels
3) lymph vessels
have one-way
valves
How does lymph get back into the blood?
4) muscular
contractions push
lymph towards heart
*smooth muscle,
*skeletal muscle,
*ventilation muscles
5) Major lymph vessels
segregated into 2
routes, each entering
either the right or left
subclavian veins
What comprises the lymphatic system?
• Lymph vessels
• Mucosa assoc. lymphatic tissue
“MALT”
•Diffuse L.T.
• Lymphatic nodules
•Tonsils
• Encapsulated L. T.
• Lymph nodes
• Spleen
• Thymus
• Cellular components (ex. WBCs)
♪Born and raised in the Peyer’s patch♫ ?
• Diffuse Lymphatic Tissue:
located below mucosa, around
nodules and within nodes and
spleen
• Lymphatic nodules: small
clumps of dense lymphatic
tissue (many lymphocytes,
some macrophages, reticular
cells etc.)
U. Mich. Med. School
• Peyer’s patches: collections of lymph nodules
associated with the distal small intestine and appendix
What are tonsils and do we really need them?
• Tonsils are
patches of dense
lymphatic tissue
•They surround
opening into
alimentary canal
•Can become
chronically
infected
•Diminish in
adults
Tonsilectomy
What is a lymph node…and do I have any?
Lymph nodes are
small structures inline with lymph
vessels
They filter lymph
and host
lymphocytes
Superficial
clusters in:
groin, armpit, and
neck
CA Metastasis!!!
What is a lymph node…and do I have any?
Lymph nodes
Pg. 775
What’s so special about a spleen?
Size
Location
Functions:
•Detects and
responds to foreign
substances and
worn out RBCs
•Blood reservoir
•Harbors
lymphocytes and
macrophages
What’s so special about a spleen?
• Open and
closed
circulation
• Varying blood
flow rates:
seconds - 88%
minutes - 10%
hours - 2%
What is so fasthinating thymuses?
Size
Location
Functions:
•Aids in
Lymphocyte
production
(T cells)
•Blood-thymic
barrier
•Must leave
thymus to “work”
Positive & Negative selection
Refer to Fig. 22.9
What does it mean to be “immune”?
Immunity is the ability to
resist foreign substances
2 Types…
1) Innate immunity
Generic response to
“invaders”
=
Nonspecific Resistance
2) Adaptive immunity
Specific response to
specific “invaders”
=
Specific Immunity
Why is innate immunity a general response?
Four basic aspects of Innate
Immunity...
1) Mechanical mechanisms
2) Chemical mediators
3) Cells
4) Inflammation
What are the mechanisms of innate immunity?
1) Mechanical Mechanisms
•Mostly covered with skin
•Natural openings (eyes, ears,
nose, throat, vagina, urethra,
and anus)
•Protected via:
eyes = tears
ears = cerumen (wax)
nose = hair, mucus & cilia
throat = saliva
others = mucus
Pathogens need an entrance to
the body!
What are the mechanisms of innate immunity?
2) Chemical Mechanisms
Many of the former
substances have chemical
properties that also inhibit
pathogens
Examples:
Tears and saliva = lysozyme
Others (see table 22.1)
histamine
complement
interferon
pyrogens
What are the mechanisms of innate immunity?
2) Chemical Mechanisms
Complement proteins are
special globulins that usually
exist in an inactive form but
can be activated.
C3-C7 stimulate
phagocytosis, inflammation
and chemotaxis
C9s form MACs or
membrane pores, resulting in
cell lysis
What are the mechanisms of innate immunity?
3) Cellular Components
Leukocytes originate where?
Leukocytes reside in various places such as?
They are effective where?
In order to arrive where they need to…
Chemotaxis = to move or “arrange” in response to
chemical signals
Chemical signals include:
complement, leukotrienes, kinins, histamines
What are the mechanisms of innate immunity?
3) Cellular Components (cont.)
Important cellular function is Phagocytosis
Which Leukocytes are phagocytic?
Neutrophils
= small, 1st to arrive, “kamakazies”,
release lysosomal enzymes, H2O2, die
easily
Macrophages = big cells w/ many lysosomes,
can devour many particles, clean-up
(including dead neutrophils) also: secrete
chemicals interferon, complement etc.
What are the mechanisms of innate immunity?
3) Cellular Components (cont.)
Other cell types
involved:
Motile (mast cells non-motile)
Basophils and
=
Activated via innate OR
Mast cells
adaptive immunity
Release histamine, leukotrienes
Eosinophils
= Motile, release enzymes breaking
down basophil/mast cell products
Recognize tumor cells, cells with
Lymphocytes
=
viruses in them…not specific
(Natural Killer cells)
immunity!
What are the mechanisms
of innate immunity?
4) Inflammation
•Complex reaction involving
previously mentioned
chemicals and cells.
• Local inflammation
red, hot, swollen, pain, loss
of function
• Systemic inflammation
all of the above PLUS
a) red marrow > neutrophils
b) pyrogens stimulate fever
c) widespread vascular
permeability possible (shock
and death)
Fig. 22.8
Now what was adaptive immunity again?
Adaptive immunity has…
specificity and memory
Divided into 2 approaches for 2
different types of pathogens
Extracellular (bacteria etc.)
= antibody-mediated
immunity
Intracellular (viruses, CA etc.)
= cell-mediated
immunity
How is adaptive immunity specific and how
does it remember?
Depends on antigens and their
receptors
Antigens = substance that can
cause an immune response
(usually foreign can be self)
How is adaptive immunity specific and how
does it remember?
Depends on antigens and their
receptors
Receptors = polypeptide
chains that can bind to
specific antigenic
determinants. On cell
membranes and antibodies
How is adaptive immunity specific and how
does it remember?
Also utilize Major
histo-compatibility
molecules (MHC
molecules)
MHC class I = “kill
me”
How is adaptive immunity specific and how
does it remember?
MHC class II = “kill
these guys”
Antigen presenting
cells include: B-cells,
macrophages,
monocytes and
dendritic cells
How is adaptive immunity specific and how
does it remember?
MHC class II = “kill
these guys”
When these cells
encounter lymphocytes
that can recognize these
antigens they are
stimulated…
Jenner’s Story… From milkbarn to history books
Jenner’s Story… From milkbarn to history books
How do vaccines work?
What are
antibodies?
… Antigen
receptors formed
by B-cells
(Plasma cells).
Antibodies aid in
antigen
destruction in
various ways...
Immunoglobulins (type of
gammaglobulins)
see table 22.5
How do vaccines work?
If you are exposed to
the antigen, you
produce an immune
response. The next
time you are
exposed you have a
stronger response
(often inhibiting
infection).
3-14 days
<3 days
What are the mechanisms
of innate immunity?
Hitch!
• What is the antigen in this scenario
• Is it an innate response adaptive or both? How can you tell?
• Is this a primary or secondary exposure?
• Refer to Table 22.5 and determine what specific type of
immunoglobulin is involved AND what type of cells?
• Where did the puffiness come from (what caused it) AND what
effect would this have on his blood pressure?
http://www.youtube.com/watch?v=erGR662mcQE
How do vaccines work?
B cells:
How does cell-mediated immunity work?
T cells:
Helper T cells
Cytotoxic T cells
Memory T cells
Helper T cells can
activate B cells or
T cells
Costimulation –
molecular signals from
presenting cell necessary
to activate
How does cell-mediated immunity work?
T cells:
Helper T cells
Cytotoxic T cells
Memory T cells
Cytotoxic T cells
bind to target cells
and cause lysis. Also
release cytokines
Memory cells persist
& stay in circulation
How does cell-mediated immunity work?
T cells:
Innate
Adaptive
What are the different types of acquired
immunity?