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B & L > Ward Anatomy/Histo > Flashcards

Ward Anatomy/Histo Flashcards

1
Q

Granulocytes

A

Neutrophils, eosinophils, and basophils > terminal cells

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2
Q

Non-granular leukocytes

A

Lymphocytes and monocytes > can still divide

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3
Q

Process of neutrophils leaving circulation

A
  1. Neutrophils express L-selectin and selectin receptors on their surface
  2. Endothelial cells express selectin receptors and E and P selectin on their surface
  3. Selectin binding slows down the neutrophil, making it roll across the endothelium
  4. Chemokines secreted by endothelial cells activate LFA-1 on the neutrophil surface
  5. Integrin and ICAM-1 firmly tether neutrophils to the endothelial surface
  6. Histamine and heparin are released by mast cells near injuries
  7. This makes the endothelium leaky as gaps develop
  8. A neutrophil extends a pseudopod between adjacent endothelial cells and pulls itself through the gap
  9. Chemo-attractants in peripheral tissues direct neutrophils where they are needed
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4
Q

Primary granules

A

Lysosomes

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5
Q

Neutrophil phagocytosis

A
  1. Neutrophils are able to recognize some bacteria or other pathogens innately. Other times they may be bound to immunoglobulins or complement before they can be phagocytosed
  2. Antibody receptors on neutrophil surface bind the pathogen and the neutrophil extends pseudopodia
  3. Pseudopodia surround pathogen and pull it into a phagosome
  4. Primary and secondary granules fuse with phagosome and kill/digest the pathogen inside a phagolysosome
  5. Debris can be exocytosed or kept in the neutrophil as a residual body
  6. Process often kills the neutrophil as well, creating pus
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6
Q

Secondary granules

A

Specific - allow a cell to carry out its function

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7
Q

Neutrophil secondary granules

A

Collaginase, phospholipase, lysozyme, other bacteriostatic/bactericidal enzymes (other granules contain phosphatase and metalloproteases that help it migrate out of blood vessels)

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8
Q

Function of eosinophils

A
  • Fight parasites and mitigate allergic reactions

- Degrades histamine and antigen-Ab complexes to reduce inflammation and limit immune reactions

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9
Q

Major basic protein function

A

Induces mast cell degranulation

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10
Q

Eosinophil cationic protein function

A

Creates pores in target cell membranes, ribonuclease against viruses

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11
Q

Eosinophil peroxidase function

A

Creates ROS to damage/kill targets

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12
Q

Where are eosinophils found?

A

LCT of digestive tract and reserve force in bone marrow

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13
Q

What secondary granules do basophils release?

A
  • Heparin (anticoagulant)
  • Histamine (vasodilation)
  • Leukotrienes (cause prolonged constriction of respiratory smooth muscle)
  • Peroxidase
  • Eosinophil chemotactic factor
  • Neutrophil chemotactic factor
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14
Q

What do basophils and mast cells do?

A

Initiate allergic reactions when they respond to antibodies released by plasma cells

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15
Q

Monocyte function

A

Monocyte-derived cells and microglia phagocytose pathogens and cellular debris; Monocytes present antigen to T helper cells (CD4) via MHCII

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16
Q

B lymphocyte function

A
  • i. Release immunglobulins and differentiate into peripheral plasma cells
  • Phagocytose antigens and present them on MHCII
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17
Q

B lymphocyte markers and surface proteins

A
  • LFA-1 (integrin) and selectin
  • Ig alpha and beta
  • CD19-22, 40, 127/IL-7
  • PD-1
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18
Q

LFA-1 and selectins function

A

Allows naive B cells to leave bloodstream as they differentiate

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19
Q

Ig alpha and beta function

A

Immunoglobulins form a transmembrane BCR with variable antigen sites to allow the B cell to do its job

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20
Q

CD19, 20, 21

A

marker/coreceptor for B cell activation

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21
Q

CD22, PD-1

A

inhibit B cell activity

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22
Q

CD40

A

Costimulatory, active in proliferating B cells, helps DCs and macrophages produce cytokines

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23
Q

CD127/IL-7 receptor alpha

A

Marker of B cell development

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24
Q

Plasma cells

A
  • B lymphocytes that have been activated by a helper T cell and enter peripheral circulation
  • Located in pathogen-rich LCT like GI and resp
  • release antibodies to bind and mark a variety of pathogens
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25
Q

Appearance of plasma cells

A

Large, circular, clock-face nucleus with clear Golgi body within pale pink cytoplasm

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26
Q

Erythrocytes appearance

A

pinkish, biconcave discs without nucleus

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27
Q

Reticulocytes appearance

A

immature RBCs containing basophilic granules

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28
Q

Platelets appearance

A

small central purple region and pale blue peripheral region; no nucleus

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29
Q

Neutrophils appearance

A

bi or tri-lobed nucleus in relatively clear appearing cytoplasm

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30
Q

Eosinophils appearance

A

multi-lobed nucleus with eosinophilic granules

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31
Q

Basophils appearance

A

multi-lobed nucleus obscured by many basophilic granules

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32
Q

Monocytes appearance

A

kidney-shaped nucleus in clear cytoplasm lacking granules

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33
Q

Lmyphocytes appearance

A

Non-granular leukocyte with large spherical nucleus and thin rim of pale blue cytoplasm

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34
Q

Where do T lymphocytes differentiate?

A

In the thymus

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35
Q

T lymphocytes function

A

Involved in cell-mediated immunity because their surface proteins recognize antigens presented on MHC of other phagocytic cells

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36
Q

T lymphocyte markers/surface proteins

A
  • LFA-1 and selectins
  • CD2, 3, 5, 28, 152/CTLA-4
  • TCR
  • FASL
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37
Q

CD2

A

marks T cells in thymus and interacts with adhesion molecules on other cells

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38
Q

CD3

A

T cell co-receptor helps to activate cytotoxic and helper T cells

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39
Q

What kind of T cell has CD4? What MHC does it use?

A

Helper T cell; MHC II

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40
Q

What kind of T cell has CD8? What MHC does it use?

A

Cytotoxic T cell; MHC I

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41
Q

Where are elevated levels of CD5 seen?

A

Lymphocytic leukemia

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42
Q

CD28

A

costimulatory molecule - activates T cells

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43
Q

CD152/CTLA-4

A

inhibitory molecule that competes with CD28 binding

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44
Q

Cytotoxic T cell function

A

Respond to antigens by killing infected, invasive or non-self cells

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45
Q

What happens once cytotoxic T cells are active and expressing CD38?

A

release lymphokines (recruit other immune cells), perforins (create holes in target cell), and granzymes (fragment DNA)

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46
Q

FASL surface protein

A

Triggers apoptosis in target cells

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47
Q

What cells are a major problem in graft-host rejection?

A

Cytotoxic T cells

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48
Q

Helper T cell function

A

Divide and recruit B, T, NK cells after recognizing antigens presented on MHCII

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49
Q

Th1 cell function

A

Activate macrophages

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50
Q

Th2 cell function

A

trigger B cells to become plasma or memory B cells

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51
Q

Memory T cells and marker

A
  • Have been previously exposed to their surface antigen and can be found in lymph nodes and peripheral tissues, awaiting re-activation
  • CD45(RO)
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52
Q

Suppressor T cell function and marker

A
  • Suppress autoimmune self-reactivity and inflammmation
  • Can suppress activity of other T cells, DCs, antibody formation by B cells(may result from having DC present a self-antigen to naïve T cell)
  • CD152(CTLA-4): inhibitory molecule - constantly expressed in regulatory T cells
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53
Q

NK cell function

A
  • Pre-programmed to destroy cells transformed by viruses or certain types of cancer when those transformations alter the expression of MHC1 surface proteins
  • Release perforins and granzymes to punch holes in target cell membranes and fragment their DNA
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54
Q

NK surface proteins

A

KIR, FASL, CD16, CD56 (NCAM)

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55
Q

KIR

A

killer Ig-like receptor that recognizes MHC

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56
Q

CD16

A

triggers events that lead to cell lysis following Ab recognition

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57
Q

CD56/NCAM

A

helps NK cell adhesion (and growth of axons)

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58
Q

Delta granules of platelets

A
  • Serotonin (vasoconstriction)

- ADP (platelet aggregation)

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59
Q

Alpha granules of platelets

A
  • Fibrinogen
  • Coagulation factors - allow fibrinogen to create a mesh around the platelet plug (XIII)
  • PDGF - stimulates division of nearby fibroblasts and smooth muscle cells to promote healing
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60
Q

Hematocrit

A
  • packed RBCs

- 45%

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61
Q

Plasma

A
  • extracellular content

- 55%

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62
Q

Buffy coat

A
  • leukocytes and platelets

- <1%

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63
Q

Plasma with clotting factors removed

A

Serum

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64
Q

Plasma function

A

Helps in immune and clotting function, as well as transport and maintaining osmotic pressure of blood

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65
Q

Albumin function

A

Maintains osmotic pressure of blood and transports hormones, bilirubin, and drugs

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66
Q

Erythrocyte function

A

Transport O2 and CO2

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67
Q

Hemoglobin function

A

Provides O2 to body

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68
Q

Red bone marrow function

A

Produces RBCs

69
Q

Erythropoietin function

A

Increases rate of RBC creation

70
Q

Thrombopoietin

A

Helps megakaryocytes produce platelets

71
Q

Order of cell type from most to least ABUNDANT

A
  • erythrocytes
  • platelets
  • neutrophils
  • lymphocytes
  • monocytes
  • eosinophils
  • basophils
72
Q

Order of cell type from biggest to smallest

A
  • NK cells
  • monocytes
  • neutrophils
  • eosinophils
  • basophils
  • lymphocytes (can be bigger than monocytes, but usually here)
  • erythrocytes
  • platelets
73
Q

Type A blood

A
  • A antigen

- Anti B antibodies

74
Q

Type B blood

A
  • B antigen

- Anti-A antibodies

75
Q

Type AB blood

A
  • A and B antigens

- No antibodies (universal receiver)

76
Q

Type O blood

A
  • no antigens

- Anti A and B antibodies (universal donor)

77
Q

Developmental landmarks of prenatal hemopoiesis

A
  1. Primordial phase (week 2)
  2. Hepatosplenothymic phase (month 2)
  3. Medullolymphatic phase (month 5)
78
Q

Primordial phase of hemopoiesis

A
  • Blood islands form in mesoderm of yolk sac.
  • lining of each island forms endothelial cells and cells inside develop into fetal erythrocytes.
  • Fetal erythrocytes: larger than adult, retain nuclei, contain fetal hemoglobin (binds strongly to O2).
79
Q

Hepatosplenothymic phase of hemopoiesis

A

In 6th week, liver produces fetal erythrocytes, granulocytes, platelets. Later the spleen produces erythrocytes, granulocytes, and platelets.

80
Q

Medullolymphatic phase of hemopoiesis

A
  • Bone marrow becomes primary source for all blood cells and platelets by 5th month.
  • By the end of the 2nd trimester, the thymus begins producing T lymphocytes
81
Q

Post-natal hemopoiesis

A
  • After birth, blood formation is restricted to the bone marrow and thymus.
  • Production of fetal hemoglobin halts.
  • Lymphocytes migrate and mature in thymus, spleen, lymph nodes, tonsils, or appendix.
  • If bone marrow is damaged or cannot meet the body’s need for blood, the liver, spleen, or lymph organs can resume hemopoiesis.
82
Q

Adult bone marrow is less hemopoietic because it regresses from ___________ _____ _________ to fat-storing ________ _________ over time (esp in long bones)

A

hemopoietic red marrow; yellow marrow

83
Q

Adult marrow is primarily found in…

A

vertebral bodies and pelvis, sternum, ribs

84
Q

All blood cells develop from a primitive…

A

Hemopoietic Stem Cell (HSC) aka the Pluripotent Hemopoietic Stem Cell (PPSC)

85
Q

Multipotent progenitor cells

A
  • Come from HSCs
  • Referred to as CFUs (colony-forming units)
  • Two types:
    1. Common Myeloid Progenitor (CMP, CFU-GEMM)
    2. Common Lmyphoid Progenitor (CLP, CFU-L)
86
Q

Derivatives of CLP cells

A
  1. Pre-B cell&raquo_space; B lymphocytes&raquo_space; Plasma cells
  2. Pre-T cell&raquo_space; Thymocytes&raquo_space; T lymphocytes
  3. Pre-NK cell&raquo_space; Natural Killer (NK) cells
87
Q

Derivatives of CMP cells

A
  1. Granulocyte/Monocyte Progenitor cell (GMP, CFU-GM)&raquo_space; granulocytes and monocytes
  2. Megakaryocyte/erythrocyte progenitor (MEP)
88
Q

Derivatives of GMP cells

A
  1. Predendritic cell (Pro-DC, can also come from CLP)&raquo_space; DCs
  2. Neutrophil progenitor (CFU-G)&raquo_space; several steps&raquo_space; Neutrophils
  3. Basophil/Mast cell progenitor (BMCP)
  4. Eosinophil progenitor (CFU-Eo)&raquo_space; several steps&raquo_space; Eosinophils
  5. Monocyte progenitor (CFU-M)&raquo_space; Monocyte&raquo_space; Macrophages (migrate peripherally)
89
Q

Derivatives of BMCP cells

A
  1. Basophil progenitor (CFY-Ba)&raquo_space; several steps&raquo_space; Basophils
  2. Mast cell progenitor (MCP, in spleen)&raquo_space; Mast cells (migrate peripherally)
90
Q

Derivatives of MEP cells

A
  1. Megakaryocyte Progenitor (MKP, CFU-Meg)&raquo_space; Megakaryoblast&raquo_space; Megakaryocyte&raquo_space; Platelets
  2. Erythrocyte Progenitor (ErP, CFU-E)&raquo_space; several steps&raquo_space; Erythrocytes
91
Q

Hemopoiesis of erythrocytes are up-regulated by…

A

erythropoietin, other growth factors, hypoxia, gain in altitude, blood loss

92
Q

How long does it take to go from erythrocyte progenitor to erythrocyte?

A

1 week

93
Q

These are found in bone marrow surrounding macrophages to clean debris

A

Erythroblastic islands

94
Q

Cells mature and then migrate into _________ __________ of marrow to enter circulation.

A

Sinusoidal capillaries

95
Q

Necessary components for production of RBCs

A
  • Iron
  • Folic acid
  • Vitamin B12
  • Protein precursors
96
Q

Maturation process of a RBC

A

Proerythroblast»basophilic erythroblast»polychromatophilic erythroblast»orthochromatophilic erythroblast (normoblast)»reticulocyte»erythrocyte

97
Q

What does a proerythroblast look like?

A
  • Large and round nucleus

- Basophilic cytoplasm (making ribosomes)

98
Q

What does a basophilic erythroblast look like?

A
  • Smaller nucleus

- More basophilic - peak # of ribosomes

99
Q

What does a polychromatophilic erythroblast look like?

A
  • Smaller nucleus

- Pinkish - start of Hb translation

100
Q

What does an orthochromatophilic erythroblast look like?

A
  • nucleus extruded

- pink in slight bluish background

101
Q

What does a reticulocyte look like?

A
  • No nucleus

- Pink with basophilic inclusions = ribosomes

102
Q

What does a mature erythrocyte look like?

A
  • No nucleus

- pink cytoplasm, biconcave

103
Q

Granulocytes develop from granulocyte/monocyte progenitor cells AKA

A

Myeloblasts

104
Q

What do myeloblasts look like?

A
  • Large nuclei

- Lack granules in cytoplasm

105
Q

Maturation of granulocytes (neutrophils/eosinophils)

A

Myeloblast&raquo_space; promyelocyte&raquo_space; myelocyte&raquo_space; metamyelocyte&raquo_space; band(stab) cell&raquo_space; neutrophil/eosinophil

106
Q

What does a myeloblast look like?

A
  • Round nucleus

- Bluish as ribosomes are produced; Golgi may be visible

107
Q

What does a promyelocyte look like?

A
  • Round nucleus

- Blue for ribosomes; Golgi visible

108
Q

What does a myelocyte look like?

A
  • Flattened oval nucleus
  • Neutrophils: pale blue cytoplasm
  • Eosinophils: eosinophilic granules more prominent
109
Q

What does a metamyelocyte look like?

A
  • Indented nucleus
  • Neutrophils: pale blue cytoplasm
  • Eosinophils: eosinophilic granules more prominent
110
Q

What does a band(stab) cell look like?

A
  • Horseshoe-shaped nucleus
  • Neutrophils: pale blue cytoplasm
  • Eosinophils: eosinophilic granules more prominent
111
Q

Hemopoiesis of thrombocytes

A

CMP&raquo_space; megakaryocyte/erythrocyte progenitor&raquo_space; megakaryocyte progenitor&raquo_space; megakaryoblast&raquo_space; megakaryocyte&raquo_space; platelets

112
Q

Megakaryoblasts

A

Chromosomes replicate repeatedly w/o cell division&raquo_space; exist only in bone marrow

113
Q

Mature megakaryocytes release…

A

Cytoplasmic fragments (platelets) into bone marrow sinusoids

114
Q

How long do platelets circulate?

A

7-10 days

115
Q

Protective surface mechanisms of immune system

A

Epithelial linings: skin and mucous membranes of Respiratory, GI, UG tracts (lysozyme, mucus, structural barrier)

116
Q

Innate immune system components

A
  • Cells: neutrophils, eosinophils, basophils, macrophages, and mast cells
  • Proteins & peptides: complement, acute phase proteins, and cytokines
117
Q

Adaptive immune system components

A
  • Builds on the innate immune system to build large numbers of lymphocytes with specificity for a particular antigen.
  • consists of cellular and humoral responses
118
Q

Lymphatic organs and tissues

A
  • Bone marrow (myeloid tissue)
  • Lymph capillaries & vessels
  • Lymph nodes
  • Mucosa Associated Lymphoid Tissue
  • Spleen
  • Thymus
119
Q

Cellular response components

A

APCs and T lymphocytes

120
Q

Humoral response

A

B lymphocytes, plasma cells, antibodies

121
Q

How do dendritic cells get rid of pathogens?

A
  • use pseudopodia to sample the external environment.
  • attack pathogens in the tissue and present antigens on their surface for to activate the adaptive immune response by other leukocytes.
122
Q

Memory B cells

A

circulate and pass through lymphoid organs for several years. If they re-encounter their antigen, they divide to produce plasma cells once again. This is the secondary immune response.

123
Q

B lymphocyte development

A
  • If surface antibody recognizes self&raquo_space; apoptosis to avoid autoimmune reaction
  • If does not recognize self&raquo_space; naive B cell leave bone marrow and circulates through blood and lymphoid tissue to fine non-self antigens
  • If does not encounter a non-self antigen&raquo_space; death
  • If found, B cell activates, divides, and becomes a plasma cell or memory B cell
124
Q

Positive selection of T cell

A

-Measure interaction with self-antigen to see if they will be able to interact with APCs

125
Q

Negative selection of T cell

A

-If interact with self too strongly&raquo_space; undergo negative selection and become apoptotic

126
Q

Once T cells survive they…

A

Leave the thymic medulla&raquo_space; circulate&raquo_space; reach lymphoid organs&raquo_space; if recognize specific antigen, they proliferate to create…Memory T cells, helper T cells, cytotoxic T cells, or regulatory (suppressor) T cells

127
Q

Memory T cells (CD45RO)

A

migrate to lymph nodes and wait to be triggered in the future.

128
Q

Helper T cells (CD4+)

A

if antibody receptor and CD4 surface molecules (interact with MHC II surface molecules of APCs) are co-activated, they recruit other immune cells to the area.

129
Q

Cytotoxic T cells (CD8+)

A

if antibody receptor and CD8 surface molecules (interact with MHC I surface molecules) are co-activated, they will release perforins, enzymes, and free radicals to kill non-self, infected, or cancerous cells.

130
Q

Regulatory (suppressor) T cells

A

modulate activity of the immune response with CD152 (CTLA-4), an inhibitory surface protein.

131
Q

Pre-NK cells develop from…

A

CLP cells in bone marrow and possibly thymus and lymph nodes

132
Q

Capsule of thymus

A

DICT with trabeculae subdividing lobes into lobules

133
Q

Blood-thymus barrier composed of…

A
  • Capillaries: continuous capillaries with tight junctions and thick basal lamina.
  • Surrounded by epithelial reticular cells (ERCs)
134
Q

Epithelial reticular cells provide…

A

Mechanical supporting framework for lymphocytes

135
Q

Cortex of thymus

A
  • Darker outer area
  • Macrophages
  • Small T cells enveloped by Epithelial Reticular Cells
136
Q

Medulla of thymus

A
  • Lighter inner area
  • Large T cells
  • Hassall’s corpuscles
137
Q

Epithelial reticular cells

A
  • Large, pale nuclei within eosinophilic cytoplasm.
  • ERCs form 3-dimensional “corrals” around multiple T cells to promote differentiation and proliferation.
  • Create the blood-thymus barrier.
  • Thymic (Hassall’s) corpuscles are from keratinized ERCs and increase in size and number with age
138
Q

Role of the thymus and T cell development

A
  • Immunoincompetent T cells enter the circulating blood and travel to the thymus.
  • They pass though the vasculature and enter the thymus at the corticomedullary junction to become thymocytes.
  • Thymocytes migrate to the periphery of the cortex, where positive selection occurs.
  • Surviving cells move deeper into the medulla as they mature and undergo negative selection.
  • Few survive
  • Self-reactivity of T cells is an excellent reason to have a blood-thymus barrier.
  • ERCs secrete hormones that regulate T cell maturation, proliferation and function within the thymus and peripheral lymphoid tissues. (thymulin, thymopoietin, thymosins)
139
Q

MALT

A
  • Non-encapsulated lymphocyte clusters found in the mucosa layer of several organ systems.
  • Allows lymphocytes to interact with antigens and antigen presenting cells (APCs) by sampling antigenic material as it enters the body.
  • Initiates both antibody-mediated and cytotoxic immune responses as appropriate.
140
Q

Subtypes of MALT

A

-Tonsils: Palatine, Pharyngeal, Lingual, Tubal
-BALT = Bronchi-associated lymphoid tissue
-NALT = Nasal-associated lymphoid tissue
-GALT = Gut-associated lymphoid tissue
&raquo_space;Lymph follicles along digestive tract
&raquo_space;Peyer patches in ileum
-TALT: Tear duct –associated lymphoid tissue
-CALT: Conjunctiva-associated lymphoid tissue
-MALT of the urogenital tract (no snappy abbreviation as yet).

141
Q

Waldeyer’s Ring

A

Interrupted circle of protective lymphoid tissue at the upper ends of the respiratory and alimentary tracts

142
Q

Lymph nodes function

A

Sample lymphatic fluid from body tissues for foreign antigens

143
Q

Lymph nodes composition

A
  • Fibrous CT capsule
  • Stroma = meshwork of reticular ribers that forms the framework of the node
  • Parenchyma = cortex, paracortex, and medulla; cells - B, T, APCs, and macrophages
  • afferent lymphatic vessels - leave through hilum
  • arteries and veins enter and exit through hilum (B and T lymphocytes reach the node via these vessels)
144
Q

What does having valves in afferent and efferent vessels do?

A

Prevents retrograde flow of lymph back into the node

145
Q

Primary lymphoid follicles

A

Naïve B lymphocyte clusters with no germinal center.

146
Q

Secondary lymphoid follicles

A

form in response to antigenic challenge.

147
Q

Germinal centers

A

pale center of Memory B cells isotype switching and dividing to make plasma cells.

148
Q

Mantle

A

dense accumulation of small lymphocytes migrating away from the germinal center.

149
Q

High endothelial venules

A

allow lymphocytes to leave circulation and enter lymph node
»B cells - cortex
»T cells - stay in paracortex
»APCs - migrate to paracortex to interact with helper T cells (Activated Helper T cells proliferate and newly-formed T cells migrate to the medullary sinuses to leave node)

150
Q

Medulla composition

A

Large tortuous lymph sinuses surrounded by lymphoid cells organized into medullary cords

151
Q

Medullary cords

A

lymphocytes, plasma cells, macrophages supported by reticular fibers

152
Q

APCs and lymphocytes migrate to ________ _______ and exit via efferent lymphatics

A

Medullary sinuses

153
Q

Spleen is protected (and sometimes lacerated) by ribs…

A

8-11

154
Q

What does the spleen do?

A
  • Filters blood
  • Forms lymphoid cells
  • Eliminates or deactivates blood-borne antigens
  • Destroys aged platelets and erythrocytes
  • Participates in fetal hemopoiesis
155
Q

External structure of spleen

A

-Covered by visceral peritoneum and capsule
»DICT (thicker at hilum)
»trabeculae extend from capsule into internal splenic sinuses

156
Q

Internal structure of spleen

A
  • Reticular fibers (type III collagen)

- red pulp and white pulp, separated from each other by marginal zone

157
Q

What purpose do the reticular fibers provide?

A

allows the spleen’s cells to be anchored without losing too much space

158
Q

White pulp

A
  • Pale-staining strips of lymphocytes and macrophages that surround central arteries are peri-Arterial Lymphatic Sheaths (PALS)
  • Lymphatics screen blood for antigens
159
Q

Where are T cells restricted in spleen?

A

To PALS to identify virus-infected cells or bacteria in circulation

160
Q

How do lymphocytes migrate back into the bloodstream?

A

Through small marginal sinuses

161
Q

Once central arteries enter the red pulp…

A

They lose their PALS and branch into penicillar arteries

162
Q

Penicillar aa

A

Have sheath of macrophages just before they open to splenic sinuses

163
Q

Splenic sinuses

A

large discontinuous capillaries with incomplete basal lamina.

164
Q

Cells and plasma leave sinuses to…

A

Mingle with cells of splenic cords or Bilroth (lymphocytes, macrophages, plasma cells) clustered around reticular fibers

165
Q

Splenic sinuses converge…

A

Form small veins&raquo_space; combine&raquo_space; splenic v.

166
Q

Damaged or old RBCs that cannot re-enter sinuses are…

A

destroyed by macrophages

167
Q

In red pulp, Hb…

A

Released, transported to liver (unconjugated on albumin) for recycling/excretion

168
Q

In red pulp, iron…

A

Released and stored in liver or transported to hemopoietic tissues for new RBCs

B & L (4 decks)

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