CHAPTER 22 The Lymphatic and Immune System and Resistance to Disease
I. LYMPHATIC VESSELS
A. FUNCTION
1. picks up interstitial fluid that has filtered
from capillaries and returns to circulation
2. one-way system
3. lymph
a. fluid entering lymphatics
B. STRUCTURE
1. lymphatic capillaries
a. smallest vessels
b. not in CNS, bone, teeth,
c. more permeable than normal capillaries
1. endothelial cells (EC) loose junctions
form minivalves
2. fine filaments attach to EC
a. open capillaries in response to
increase in tissue fluid not collapse
b. close capillaries in response to
increase in lymph
d. proteins, bacterial, cellular debris will
enter the lymphatic capillaries.
e. LACTEALS
1. specialized lymphatic capillaries in
intestinal villi for absorption of
lipids from the diet (milky appearance)
2. lymphatic collecting vessels
a. larger thicker walled vessels
b. similar to veins but thinner walls
c. many valves to prevent backflow
3. lymphatic trunks
a. large collecting vessels join
b. major trunks:
1. lumbar
2. intestinal
3. bronchomediastinal
4. subclavian
5. jugular
4. lymphatic ducts
a. final vessel
1. 2 ducts - right/left sides
2. empty lymph into venous circulation
at junction of internal jugular and
subclavian vein (right or left)
b. right lymphatic duct
1. lymph from right upper arm and right side of head, thorax
c. thoracic duct (larger)
1. left side of body and lower right
2. collects lymph in cisterna chyli
at 2nd lumbar vertebra
C. LYMPH FLOW
1. Valves to prevent backflow
2. action of skeletal muscles help move lymph
3. in abdominal, thoracic cavities respiration
changes pressures to aid movement
4. rate
a. 3 liters fluid filtered at capillaries every
24 hrs
b. 3 liters fluid enters lymphatics/ 24 hr
c. edema if rate not balanced
II. LYMPH NODES
A. FUNCTIONS
1. filtration of lymphatic fluid
2. location of major nodes:
a. inguinal
b. axillary
c. cervical
3. MACROPHAGES
a. engulf bacteria, cancer cells, debris
4. LYMPHOCYTES
a. mature and attach foreign matter
B. STRUCTURE
1. capsule
a. outer layer of connective tissue
2. lobule arrangement of compartments
a. loose connective tissue
3. cortex
a. lymphocytes or follicles
b. B and T lymphocytes located here
4. medulla
a. contains macrophages . 5. afferent lymphatic vessels
a. lymph enters subcapsular sinus
6. efferent lymphatic vessels
a. less efferent that afferent so it allows
time for cleaning lymph
7. can become inflammed by bacteria present
III. LYMPHATIC TISSUES
A.SPLEEN
1. left upper abdominal cavity region
2. maturation or proliferation of lymphocytes
3. clears damaged RBCs, bacteria, virus, toxins
debris from blood
4. stores hemoglobin breakdown products until needed
5. fetal hemoglobin production
6. stores platelets
7. venous sinuses for large volume of blood
8. Structure:
a. capsule
1. thin, easy to rupture
b. red pulp
1. venous sinuses with RBCs and macrophages
c. white pulp
1. immune function
B. THYMUS GLAND
1. 2 lobes
2. lower neck into mediastinum
3. secretion
a. thymosin
b. thymopoietin
4. epithelial cells
a.not reticular CT as in other lymphatic tissue 5. other CT layer reaches inward dividing into lobules
6. cortex
a. many lymphocytes
7. medulla
b. less lymphocytes, stains lighter
C. TONSILS
1. named by location
a.. palatine
b. lingual
c. pharyngeal (adenoids)
2. not fully encapsulated
3. crypts
a. invaginations that trap particles
b. immune cells made to these bacteria
that have a memory for later immune
responses
D. PEYER'S PATCHES
1. lymphatic nodules in SI
CHAPTER 22 THE IMMUNE SYSTEM
I. INTRODUCTION
A. Immune response
1. body defenses to foreign matter
2. antigens
a. foreign substance
3. pathogens
a. cause disease
B. Specific body defenses
1. directed at one particular target
C. Nonspecific body defenses
1. a general response to an invading agent or infection
II. NONSPECIFIC BODY DEFENSES
A. Species resistance
1. innate
2. pathogens of one species not a pathogen in another
B. Mechanical barrier
1. skin
2. mucous membrane
C. Chemical barrier
1. pH - microbes generally won't survive acid (Stomach)
2. pH skin - normal flora of skin breaks down sebum
and gives it acid pH
3. Lysozyme
a. tears, saliva,
b. attacks cell wall of bacteria
4. Mucus
a. traps
D. Phagocytosis
1. macrophages
2. neutrophils
3. process of phagocytosis
a. processes extend from cell and engulf debris
b. phagosome - sac formed
c. fuses with a lysosome
1. phagolysosome
d. enzymatic digestion of particle
4. opsonization
a. coating of particle to attract phagocyte
E. Release of chemicals
1. neutrophils release defensins to destroy cells
F. Natural killer cells
1. lymphocytes
2. in circulation
3. attack tumor cells and virus infected cells
G. INFLAMMATORY RESPONSE
1. response to tissue injury
2. increases circulation to injury site
a. introduce WBCs
b. clotting factors
3. heat & redness (from hyperemia), pain, swelling
4. histamine - one mediator
a. vasodilation
b. increases capillary permeability
5. mediators of inflammatory response:
a. histamine
(antihistamine to block effect)
b. prostaglandins
(aspirin and ibuprofen to block synthesis)
c. lymphokines
d. complement
6. phagocytes are attracted to area
a. neutrophils leave circulation
1. margination
2. diapedisis
3. in response to chemotactic agents
7. pus
a. accumulation of WBCs and debris
b. abscess - encapsulated by CT
c. may move to surface
H. COMPLEMENT
1. 20 plasma proteins
2. cascade to activate
3. C1-C9 and factors B,D,P
4. activation of complement
a. complements other immune responses
1. releases chemical mediators
2. cell lysis
b. by classical or alternate pathway
CLASSICAL PATHWAY
antibodies bind to antigen on cell
then C1 binds - Complement fixation
ALTERNATE PATHWAY
Uses factors B,D, P that recognize polysaccharide molecules on the microbial surface
I. INTERFERON
a. protein produced by viral infected cells
b. doesnot help infected cells
c. benefits neighboring uninfected cells
d. virus is a piece of DNA or RNA with a protein envelope that cannot replicate without a host
when virus enters a cell(or leaves) it may tag the plasma membrane of the infected cell; immune systems can then recognize the infected cell
e. also attracts immune cells
III. SPECIFIC BODY DEFENSES
A. B-lymphocytes
1. recognize specific antigens
a. usually a large protein
b. hapten
1. small molecule that binds to a normal
plasma protein to become and antigen
2. produce antibodies (Ab) (Primary Immune Response)
a. immunoglobulins (Ig)
b. production of clonal cells in response to
an antigen
1. plasma cells - produce Ab
2. memory cells - will produce Ab with
subsequent exposure
(secondary immune response)
3. Immunization or (vaccination - artificial)
a. naturally acquired active immunity
b. naturally acquired passive immunity
c. artificially acquired active immunity
d. artificially acquired passive immunity
IDENTIFY THE TYPE OF IMMUNIZATION:
DIPTHERIA, PERTUSSIS, TETANUS (DPT) INNUCULATIONS
BABY RECEIVES IMMUNITY FROM MOTHERS MILK
SOMEONE RECOVERS FROM CHICKEN POX
SOMEONE IS BITTEN BY A FOX (MAYBE RABID). THEY ARE GIVEN SERUM
FROM SOMEONE WHO HAS BEEN IMMUNIZED.
4. ANTIBODY STRUCTURE
a. at least one monomer unit
1. 2 heavy chains
2. 2 light chains
3. form a Y shape
b. variable region
1. antigen- binding site
2. top of Y - 2 sites - bivalent
c. constant region
1. cell surface binding site
5. Antibody classes
a. IgD
b. IgM
c. IgG
d. IgA
e. IgE
What are the major functions of the above 5 classes?
6. Function of antibodies
a. antigen-antibody complex
1. inactivate
b. complement fixation
c. neutralization
d. agglutination - clumping
e. precipitation - large molecules cross-link
and settle out
f. encourage phagocytosis
7. Monoclonal antibodies
a. a single type of antibodies
b. mixture of a B lymphocyte with a cancer cell
that continously produces a substance
B. CELL-MEDIATED IMMUNE RESPONSE
1.T cells
a. cytotoxic T cells
b. helper T cells
c. suppressor T cells
2. have cell surface antigen receptors
a. CD4 (T4)
b. CD8 (T8)
3. need to recognize antigens on surface of cells
a. cell-to-cell interaction
4. response is a direct attack on the cell
i.e. destruction of cell
5. mediators include cytokines
6. MHC
a. major histocompatability complex
b. cell surface antigens not identical in most people
1. one type on somatic cells
2. one type on immune cells
c. the MHC proteins are on the antigen-
presenting cells (macrophages)
present antigen to T cells
7. T cells also proliferate after exposure to the
apropriate MHC
a. enhanced by cytokines
1. interleukins
b. secrete lymphokines as chemotaxic agents
8. T cells
a. Helper - stimulate assistance from other
lymphocytes
b. Cytotoxic - damage cells, cell lysis
targets virus infected cells and tumor cells
chemicals released:
perforin - chemical to damage
Tumor necrosis factor TNF -slow death
c. Suppressor - inhibit activity of B and T cells
IV. DISORDERS
A. ORGAN TRANSPLANT REJECTIONS
1. Types
a. autograft - same person
b. isograft - identical twins
c. allografts - same species, usually relatives
d. xenografts - another species
2. Match many cell surface antigens MHC
3. Cytotoxic cells
4. immunosuppressant drugs to prevent rejection
B. IMMUNODEFICIENCIES
1. AIDS
2. HODGKIN'S DISEASE
C. HYPERSENSITIVITIES
1. allergen
a. antigen that elicits abnormal response
2. Immediate hypersensitivities TYPE I
a. anaphylaxis
1. IgE stimulate histamine release from
mast cells and basophils
2. local or systemic
3. asthma, shock
3. Antibody-dependent cytotoxic TYPE II
a. transfusion reaction
4. Immune complex TYPE III
a. precipitation of complexes in tissues
b. autoimmune disorders
c. ex. rheumatoid arthritis, lupus, Hashimoto's
thyroiditis
5. Delayed hypersensitivities TYPE IV
a. T cells that are slow to appear
include cytotoxic T cells
b. dermatitis