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anatomy and physiology mid-term > Chpater 20-21 > Flashcards

Chpater 20-21 Flashcards

1
Q

Lymphoid organs and tissues

A

provide structural basis of immune system by housing phagocytic cells and lymphocytes
– Structures include spleen, thymus, tonsils, lymph nodes, other lymphoid tissues

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2
Q

Lymphatic system

A

returns interstitial fluid and leaked plasma
proteins back to blood.
– Circulates ~ 3L interstitial fluid per day
– Once interstitial fluid enters lymphatics, it is called lymph
* Lymphatic vessels offer a one-way system, ensuring lymph flows
only toward heart

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3
Q

Lymphatic capillaries

A
  • Blind-ended vessels that weave between tissue cells and
    blood capillaries
    – Similar to blood capillaries, but more permeable
    – Can take up larger molecules and particles that blood
    capillaries cannot
    § Example: proteins, cell debris, pathogens, and cancer
    cells
    § Can act as route for pathogens or cancer cells to travel
    throughout body
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4
Q

What are the two specialized structures that increase permeability

A
  1. Endothelial cells overlap loosely to
    form one-way minivalves
  2. Minivalves are anchored by collagen filaments to matrix, so increases in ECF volume opens minivalves even more
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5
Q

Lymphoid cells consist of

A

(1) immune system cells found in lymphoid tissue and
(2)supporting cells that form lymphoid tissue structures

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6
Q

Lymphocytes

A

Cells of the adaptive immune system; mature into one of two
main types
– T cells (T lymphocytes)
– B cells (B lymphocytes)

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7
Q

T cells

A

manage immune response, and some also attack and destroy infected cells

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8
Q

T cells

A

manage immune response, and some also attack and destroy infected cells

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9
Q

B cells

A

produce plasma cells, which secrete antibodies
– Antibodies mark antigens for destruction by phagocytosis or other means

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10
Q

Macrophages

A

phagocytize foreign substances and help activate T cells

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11
Q

Dendritic cells

A

capture antigens and deliver them to lymph nodes; also
help activate T cells

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12
Q

Main function of lymphoid tissue

A

– Houses and provides proliferation sites for
lymphocytes

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13
Q

reticular
connective tissue

A

a type of loose
connective tissue
– Macrophages live on reticular fibers
– Spaces between fibers offer a
place for lymphocytes to occupy
when they return from patrolling
body

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14
Q

Two main types of lymphoid tissues

A

Diffuse lymphoid tissue

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15
Q

Two main types of lymphoid tissues

A

Diffuse lymphoid tissue
Lymphoid follicles (nodules)

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16
Q

Lymphoid follicles (nodules)

A

solid, spherical bodies consisting of tightly packed
lymphoid cells and reticular fibers
§ Contain germinal centers of proliferating B cells
§ May form part of larger lymphoid organs (nodes)
§ Isolated aggregations of Peyer’s patches and in appendix

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17
Q

Diffuse lymphoid tissue

A

loose arrangement of lymphoid cells and some reticular
fibers
§ Found in virtually every body organ
§ Larger collections in lamina propria of mucous membranes

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18
Q

Lymphoid organs are grouped into two
functional categories

A

Primary lymphoid organs
Secondary lymphoid organ

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19
Q

Primary lymphoid organs

A

areas where T and B cells mature—red bone marrow and thymus
§ T and B cells originate in bone
marrow, but only B cells matures
there; T cells mature in thymus

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20
Q

Secondary lymphoid organ

A

areas where mature lymphocytes first encounter their antigen and become activated
§ Nodes, spleen, MALT (mucosa-
associated lymphoid tissue) and
diffuse lymphoid tissues

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21
Q

Lymph nodes

A

principal secondary lymphoid organs of body
->Hundreds of nodes are found throughout body
– Most are embedded deep in connective tissue in clusters
along lymphatic vessels
– Some are nearer to body surface in inguinal, axillary,
and cervical regions of body where collecting vessels
converge into trunks

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22
Q

Two main functions of lymph nodes

A
  1. Cleansing the lymph: act as lymph “filters”
    § Macrophages remove and destroy microorganisms and
    debris that enters lymph
    – Prevent unwanted substances from being delivered to
    blood
  2. Immune system activation: offer a place for lymphocytes to become activated and mount an attack against antigens
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23
Q

whats spleen and its funtion

A

Largest lymphoid organ
* Functions
– Site of lymphocyte proliferation and immune surveillance and response
– Cleanses blood of aged blood cells and platelets; macrophages remove debris

24
Q

Mucosa-associated lymphoid tissue (MALT)

A

Lymphoid tissues in mucous membranes throughout body
* Protects from pathogens trying to enter body

25
Q

MALT found in

A
  • Tonsils: Form ring of lymphatic tissue around pharynx; appear as swellings of mucosa
    – Peyer’s patches: clusters of lymphoid follicles in wall of distal portion of small intestine
    – Appendix: offshoot of first part of large intestine
26
Q

Whats Thymus and its function

A

bilobed lymphoid organ found in inferior neck
– Extends into mediastinum and partially overlies heart
* Functions as lymphoid organ where T cells mature
– Most active and largest in size during childhood
– Stops growing during adolescence, then gradually atrophies
– Still produces immunocompetent cells, though more slowly

27
Q

How does thymus differ from other lymphoid organs

A
  1. Has no follicles because it lacks B cells
  2. Does not directly fight antigens
    § Functions strictly in T lymphocyte maturation
28
Q

Immune system

A

provides resistance to disease

29
Q

Immune system is made up two intrinsic systems

A

Innate (nonspecific) defense system
Adaptive (specific) defense system

30
Q

Innate (nonspecific) defense system

A

§ Constitutes first and second lines of defense
– First line of defense: external body membranes (skin and mucosae)
– Second line of defense: antimicrobial proteins, phagocytes, and other
cells (inhibit spread of invaders; inflammation most important mechanism)

31
Q

Adaptive (specific) defense system

A

Third line of defense attacks particular foreign substances (takes longer to react than innate)

32
Q

Humoral Immunity

A

B cells

33
Q

Cellular immunity

A

T cells

34
Q

Acid

A

acidity of skin and some mucous secretions inhibits growth; called acid mantle

35
Q

Enzymes

A

lysozyme of saliva, respiratory mucus, and lacrimal fluid kills many microorganisms; enzymes in stomach kill many microorganisms

36
Q

What modifications does the respiratory system

A

– Mucus-coated hairs in nose trap inhaled particles
– Cilia of upper respiratory tract sweep dust- and bacteria-laden mucus toward mouth

37
Q

Phagocytes

A

white blood cells that ingest and digest (eat) foreign invaders

38
Q

Neutrophils

A

most abundant phagocytes, but die fighting; become phagocytic on exposure to infectious material

39
Q

Macrophages

A

develop from monocytes and are chief phagocytic cells; most robust phagocytic cell
– Free macrophages: wander through tissue
spaces; example: alveolar macrophages
– Fixed macrophages: permanent residents
of some organs; examples: stellate
macrophages (liver) and microglia (brain)

40
Q

Process of Phagocytes

A
  1. Process starts when phagocyte recognizes and
    adheres to pathogen’s carbohydrate “signature”
    – Opsonization: immune system uses
    antibodies or complement proteins as
    opsonins that coat pathogens
    * Act as “handles” for phagocytes to
    grab on to, enhancing phagocytosis
  2. Cytoplasmic extensions (pseudopods) bind to
    and engulf particle in vesicle called phagosome
  3. Phagosome fuses with lysosome, forming
    phagolysosome
  4. Phagolysosome is acidified, and lysosomal
    enzymes digest particles
  5. Indigestible and residual waste is exocytosed
    from phagocyte
41
Q

Natural Killer (NK) Cells

A

Nonphagocytic, large granular lymphocytes that police blood and lymph
– Can kill cancer and virus-infected cells before adaptive immune system is activated
* Attack cells that lack “self” cell-surface receptors
* Kill by inducing apoptosis in cancer cells and virus-infected cells
* Secrete potent chemicals that enhance inflammatory response

42
Q

Inflammation

A

Triggered whenever
body tissues are injured
– Injuries can be due to trauma,
heat, irritating chemicals, or
infections by microorganisms

43
Q

Leukocytosis

A

release of neutrophils from bone marrow in response to
leukocytosis-inducing factors from injured cells

43
Q

Leukocytosis

A

release of neutrophils from bone marrow in response to
leukocytosis-inducing factors from injured cells

44
Q

Margination

A

endothelial cells of capillaries in inflamed area
project cell adhesion molecules (CAMs) into vessel lumen that grab onto passing neutrophils, causing them to slow and roll along, clinging to vessel wall

45
Q

Diapedesis

A

neutrophils flatten and squeeze between endothelial cells, moving into interstitial spaces

46
Q

Chemotaxis

A

inflammatory chemicals act as chemotactic

47
Q

Antimicrobial proteins

A

– Attacking microorganisms directly, or
– Hindering microorganisms’ ability to reproduce

48
Q

Antimicrobial proteins

A

– Attacking microorganisms directly, or
– Hindering microorganisms’ ability to reproduce

49
Q

Interferons

A

family of immune modulating
proteins
– Cells infected with viruses can secrete IFNs that
“warn” healthy neighboring cells
§ IFNs enter neighboring
cells, stimulating production of proteins that block viral
reproduction and degrade viral RNA

50
Q

Complement
system

A

consists of
~20 blood proteins that circulate in blood
in inactive form
– Activation enhances inflammation and
also directly destroys bacteria
§ Enhances both innate and adaptive defenses

51
Q

specific

A

recognizes and targets specific antigens

52
Q

systemic

A

not restricted to initial site

52
Q

systemic

A

not restricted to initial site

53
Q

memory

A

mounts an even stronger attack to “known” antigens (second and subsequent exposures)

anatomy and physiology mid-term (4 decks)

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