A&P II Chapter 21 Lymphatic and Immune System

Question 1

What is lymph

Answer 1

clear, colorless fluid, similar to plasma but much less protein; looks milky after a fatty meal

Question 2

Functions of Lymphatic Systems

Answer 2

• Fluid recovery (helps to maintain fluid balance)
– absorbs plasma proteins and fluid (2 to 4 L/day) from tissues and returns it to the bloodstream
─ interference with lymphatic drainage leads to severe edema
• Immunity (protect body from infection and disease)
– fluids from all capillary beds are filtered through lymph nodes
– immune cells stand ready to respond to foreign cells or chemicals encountered
• Lipid absorption
– Lacteals (special lymphatic vessels) in small intestine absorb dietary lipids

Question 3

Components of Lymphatic System

Answer 3

Lymph, Lymphatic Capillaries/Vessels, Lymphatic Tissue (variety of lymphocytes & other cells), and Lymphatic Organs

Question 4

Route of Lymph Flow :
Example – lymphatic capillaries -> collecting vessels -> ——————– ->
Right and Left Subclavian Vein

Answer 4

lymphatic capillaries collecting vessels (course through many lymph nodes) lymphatic trunks (6 of these drain major portions of body) collecting ducts (2 of these form from the convergence of the 6 trunks).

Question 5

E. Mechanisms of lymph flow

Answer 5

• Lymph flows at low pressure and speed
• Moved along by rhythmic contractions of lymphatic vessels-stretching of vessels stimulates contraction
• Flow aided by skeletal muscle pump, thoracic pump
• Valves prevent backward flow

Question 6

F. Name of Lymphatic Cells

Answer 6

• T lymphocytes (T cells)
– Mature in thymus
• B lymphocytes (B cells)
– Activation causes proliferation and differentiation into plasma cells that produce antibodies (gamma/γ globulins)
• Antigen Presenting Cells (phagocytize and present antigenic material to T cells to alert immune system)
– macrophages (from monocytes)
– dendritic cells (in epidermis, mucous membranes and lymphatic organs)
– reticular cells (also contribute to stroma of lymph organs)

Question 7

G. Name of Lymphatic tissue

Answer 7

• Diffuse lymphatic tissue: lymphocytes in mucous membranes and CT of many organs
• Lymphatic nodules: dense oval masses of lymphocytes, congregate in response to pathogens; Peyer patches: more permanent congregation, clusters found at intestines.

Question 8

H. Name of Lymphatic organs
Function of lymph node and spleen

What is lymphadenopathy and lymphadenitis

Answer 8

• Lymph nodes
– cervical, axillary and inguinal regions close to surface, • Only organs that filter lymph•Two functions: cleanse the lymph & alerting the immune system

– thoracic, abdominal and pelvic groups deep in cavities
• Tonsils
– guard entrance to pharynx
• Thymus
– between sternum and aortic arch
• Spleen
– inferior to diaphragm, dorsolateral to stomach, largest lymphatic organ, – blood production in fetus
– blood reservoir
– RBC disposal – “erythrocyte graveyard” for old, fragile RBCs
– immune reactions: filters blood, quick to detect antigens (lymph node does lymph)

• Lymphadenopathy is a collective term for all lymph node diseases
─ lymphadenitis is inflammation of lymph node - swollen, painful node that is
responding to foreign antigen
─ lymph nodes are common sites for metastatic cancer - swollen, firm, and usually
painless

Question 9

I. Defenses against Pathogens
a) Nonspecific defenses: External barriers/Leucocytes and Cutaneous Defenses/Antimicrobial Proteins/Inflammation (Purpose, Cardinal signs, Major processes)/Fever

Answer 9

Defenses Against Pathogens (toxins, living orgs, & other agents that cause disease)
• Nonspecific defenses - broadly effective, no prior exposure (read the 1st para, P.808):
– external barriers: skin, mucous membrane etc
– phagocytic leukocyte cells, antimicrobial proteins, inflammation and fever
• Specific defense - results from prior exposure, protects against only a particular pathogen - immune system

A) Nonspecific defenses
i) External Barriers
• Skin
– dry and nutrient-poor, defensins (peptides from neutrophils) attack microbes
– lactic acid (acid mantle) is a component of perspiration – inhibits bacterial growth
• Mucous membranes: stickiness of mucus, lysozyme: destroys bacteria
• Subepithelial areolar tissue: viscous barrier

Question 10

b) Specific Defense (Immunity) -> Immune System, Characteristics, Forms of Immunity, other classifications

Answer 10

• Immune system – not an organ system but is about a group of widely distributed cells that recognize and destroy alien substances
• 2 characteristics: Specificity (directed against a particular pathogen) and
Memory (remembers pathogen - allows quick response)
• 2 forms: Cellular immunity: cell-mediated (T cells directly attack suspicious cells)
Humoral immunity: antibody mediated (B cells)
• Other classifications: Passive & Active and Natural & Artificial Immunity
 Natural active immunity (produces memory cells)
– production of one’s own antibodies or T cells as a result of infection or natural exposure to antigen
 Artificial active immunity (produces memory cells)
– production of one’s own antibodies or T cells as a result of vaccination [Vaccine: dead or attenuated (weakened) pathogen – stimulate immune response but no disease]
 Natural passive immunity (through placenta, milk)
– temporary, fetus acquires antibodies (Ab) from mother
 Artificial passive immunity (for the treatment of snakebites, rabies, tetanus)
– temporary, injection of immune serum (Ab) from another individual or animal who was exposed to a certain pathogen

Question 11

c) Antigens (Epitopes/Haptens)

Answer 11

Large complex molecules (can be free or part of cell membrane) that can trigger an immune response

Epitopes or antigenic determinants: certain regions of the molecule that stimulate an immune response

Haptens: molecules too small to stimulate immune response but binds to host macromolecule which initiates an immune response

Question 12

d) Lymphocytes (Types of Lymphocytes) -> T Lymphocyts and B Lymphocytes

Answer 12

 Specific immunity depends on lymphocytes & macrophages
 Types of lymphocytes in circulating blood
– 80% T cells (cell mediated)
– 15% B cells (antibody mediated)
– 5% NK cells (nonspecific immunity)

Question 13

e) Interleukins (Types)

Answer 13

Hormone like chemical messengers (cytokines) between leukocytes
2 types:
 Lymphokines: produced by lymphocytes
 Monokines : produced by macrophages

Question 14

f) Cellular Immunity ( 4 Classes of T Cells involve)

Answer 14

• T lymphocytes attack and destroy foreign cells and diseased host cells
• Involves 4 classes of T cells:
 Cytotoxic or killer (not NKs) T cells (TC): carry out attack on enemy cells
 Helper T cells (TH): help TC cells and in humoral immunity(B cell action)
& nonspecific defense mechanisms
 Suppressor T cells (TS): limit cell mediated attack and keep the system
under control; TH & TS are regulatory cells – accelerate or stop TC actions
 Memory T cells: forms from TC cells, responsible for memory - provide
immunity from future exposure to antigen

Both cellular and humoral immunity occur in 3 stages:

Question 15

g) Stages of Immunity

Answer 15

• Recognition (Fig: 21.23)
– B cell receptors bind antigen, take in and digest them, and then display the antigen fragments
– TH cell binds to B cells and secrete helper factors, B cell divides repeatedly, differentiate into plasma cells, produce antibodies specific to that antigen
• Attack
– antibodies released from plasma cells bind to antigen, render it harmless, ‘tag it’ for destruction (by neutralization, complement fixation, agglutination, & precipitation); note that the destruction is not by directly destroying the antigen, rather covering its pathogenic sites and marking it for destruction by other agents.
(Fig: 21.24 – plasma cell)
• Memory
– some B cells differentiate into memory cells

Question 16

h) Humoral Immunity

Answer 16

• B lymphocytes of humoral immunity does not directly attach to enemy cells, rather produces antibodies (also called an immunoglobulin or Ig) that bind to antigens and tag them for destruction
• Works in 3 stages (the 3 Rs of immunity)

Question 17

i) Types of Antibodies – Example of sites

Answer 17

• Immune system produces as many as 2 million different antibodies
• Somatic recombination
– DNA segments shuffled and form new combinations of base sequences to produce antibody genes

Question 18

Hypersensitivity (Allergy) -> Definition, Types of Hypersensitivity, Antibodies involved

Answer 18

• Excessive, harmful immune reaction against antigens that most people tolerate
• Reactions include:
 reactions to tissues transplanted from another person (alloimmunity)
 abnormal reactions to one’s own tissues (autoimmunity)
 reactions to environmental antigens called allergens (allergies)

Question 19

J. Autoimmune Diseases – Why autoimmune disease occurs? Example of autoimmune diseases (see Type III hypersensitivity)

Answer 19

• Failure of self tolerance
– Immune system fails to distinguish “self” and “nonself” antigens and produces autoantibodies that attack own body tissues. Three possible reasons are:
– cross-reactivity: an Ab formed against a bacteria may attack other host cell
– abnormal exposure of self-antigens: breakage in bl barriers exposes self antigens that are not otherwise exposed
– changes in structure of self-antigens: viruses, drugs may change self-antigens causing the immune system to consider those as “nonself”

• Type III Hypersensitivity (Immune Complex)
− IgG or IgM forms antigen-antibody complexes that gets deposited between layers
of tissues and trigger intense inflammation and tissue necrosis (acute
glomerulonephritis and in systemic lupus erythematosus)

Question 20

Immunodeficiency Diseases -> Why it occurs?

AIDS/HIV, level of helper T cells in the blood, signs/symptoms/HIV transmission

Answer 20

immune system fails to respond vigorously enough
• Severe Combined Immunodeficiency Disease (SCID)
– hereditary lack of T and B cells
– highly vulnerable to opportunistic infection

Signs and symptoms
– early symptoms: flulike chills and fever
– progresses to night sweats, fatigue, headache, extreme weight loss, lymphadenitis
– normal TH count is 600 to 1,200 cells/L of blood but in AIDS it is < 200 cells/L
• person susceptible to opportunistic infections (Toxoplasma, Pneumocystitis, herpes simplex virus, CMV or TB
– thrush: white patches on mucous membranes may appear
– Kaposi sarcoma: cancer originates in endothelial cells of blood vessels causes purple lesions in skin

• Through blood, semen, vaginal secretions, breast milk, or across the placenta
• Most common means of transmission
– sexual intercourse (vaginal, anal, oral)
– contaminated blood products
– contaminated needles
• Not transmitted by casual contact
• Undamaged latex condom is an effective barrier to HIV Treatment Strategies
• HIV is evolving resistance to the “triple cocktail”

Question 21

The only lymphatic organ with both afferent and efferent lymphatic

Answer 21

lymph node

Question 22

Which cell are involved in nonspecific resistance but not in specific denfense

Answer 22

natural killer cells

Question 23

The respiratory burst is used by what to kill bacteria

Answer 23

neutrophis

Question 24

which is a macrophage

Answer 24

a microglial cell

Question 25

the cytolytic action of the complement system is most similar to the action of what

Answer 25

perforin

Question 26

what becomes antigenic by binding to larger host molecules

Answer 26

Haptens

Question 27

Name the order of the humoral immunity

Answer 27

endocytosis of an antigen
antigen display
secretion of interleukin
clonal selection and
antibody secretion

Question 28

the cardinal signs of inflammation include what

Answer 28

redness
swelling
heat
pain

Question 29

A helpter T cell can bind only to another cell that has

Answer 29

MHC-II proteins

Question 30

Which results from a lack of self tolerance

Answer 30

systemic lupus erthematosus

Question 31

any organism or substance capable of causing disease is called

Answer 31

Pathogen

Question 32

Mucous membranes contain an antibacterial enzyme called

Answer 32

Lysozyme

Question 33

What condition in which one or more lymph nodes are swollen and painful to the touch

Answer 33

lymphadentis

Question 34

The movement of leukocytes through a capillary or venule wall is called

Answer 34

Diapedesis emigration

Question 35

in what process complement proteins coat bacteria and serve as binding sites for phagocytes

Answer 35

Opsonization

Question 36

Any substance that triggers a fever is called

Answer 36

purogen

Question 37

The chemical signals produced by leukocytes to stimulate other leukocytes are called

Answer 37

Interleukins

Question 38

Part of an antibody called the_______binds to part of an antigen is called___________

Answer 38

antigen binding site and epitope

Question 39

self tolerance results froma a process called ________in which lymphocytes programmed to react against self antigens die.

Answer 39

Clonal deletion

Question 40

Any disease in which antibodies attack ones own tissue is called a______disease

Answer 40

autommune