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HOM > Blood and Lymph Physiology > Flashcards

Blood and Lymph Physiology Flashcards

1
Q

functions of blood?

A

transport, hemostasis, defence from infection, homeostasis (pH and temperature)

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2
Q

effect of relaxation of blood vessel smooth muscle?

A

vasodilation, increased blood flow

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3
Q

effect of contraction of blood vessel smooth muscle?

A

vasoconstriction which decreases blood flow

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4
Q

what are the 2 routes of transport through capillary walls?

A

paracellular and transcellular

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5
Q

what is paracellular transport through capillary walls? what is transported this way?

A

molecules diffuse between endothelial cells. water and small solutes (radius < 3nm)- limited by tight junctions and gap junctions

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6
Q

what is transcellular transport through capillary walls? what is transported this way?

A

molecules actively transported through endothelial cells. transport of larger solutes

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7
Q

how are large solutes transported transcellularly across capillary walls?

A

receptor mediated endocytosis, transcytosis, transendothelial channels such as VVOs

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8
Q

what are VVOs?

A

vesicular vacuolar organelles

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9
Q

what are vesicular vacuolar organelles?

A

interconnected vesicles forming channels across the cell

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10
Q

what is transcytosis?

A

cells take up extracellular medium through caveolae mediated micropinocytosis and transfer to the opposite side of the cell

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11
Q

where are capillaries with fenestrated endothelium found?

A

in GI tract, glomerulus and endocrine glands

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12
Q

structure of fenestrated endothelium?

A

spaced cells form fenestrae (windows) connected through a porous diaphragm which acts as ‘sieve’ allowing only water and small molecules to pass

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13
Q

where are capillaries with discontinuous endothelium found?

A

in the liver

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14
Q

structure of discontinuous endothelium?

A

spaced cells with fenestrae without diaphragms and poorly organised basement membrane. high level of clathrin-mediated receptor endocytosis activity

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15
Q

how does water and small solutes pass in continuous non-fenestrated endothelium?

A

pass between the ECs

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16
Q

how do larger solutes pass in continuous non-fenestrated endothelium?

A

pass through ECs via transcytosis or transendothelial channels

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17
Q

why is the permeability of ECs particularly restricted in the brain?

A

to minimise risk of infection

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18
Q

what forms the blood brain barrier?

A

tight endothelial junctions, thick basement membrane, supporting layer of astrocytes

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19
Q

how do substances pass the blood brain barrier?

A

water, gases, lipid-soluble hormones pass by passive diffusion, selective transport of nutrients such as amino acids and glucose. antibodies too large to pass

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20
Q

how does the blood brain barrier prevent entry of lipophilic neurotoxins?

A

active transport mechanism mediated by P-glycoprotein

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21
Q

what is the key hallmark of inflammation?

A

flow of plasma and WBCs into site of injury or infection- important to protect tissue from infection- endothelial cells increase permeability to allow this

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22
Q

functions of RBCs?

A

responsible for carrying oxygen

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23
Q

adaptations of RBCs?

A

biconcave disc shape facilitates movement through capillaries, enucleated so increased capacity for Hb and ability to go through small capillaries

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24
Q

what species have nucleated RBCs?

A

fish and reptiles

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25
Q

how does a pulse oximeter measure blood oxygenation?

A

using absorption- Hb has different absorption spectra when bound with O2 versus in free form

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26
Q

where does erythropoiesis take place in adults?

A

bone marrow

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27
Q

where does erythropoiesis take place in the developing fetus?

A

liver and spleen

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28
Q

what happens to erythrocyte progenitor cells to become erythrocytes?

A

lose nucleus, ribosomes and organelles

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29
Q

what happens to erythrocytes at the end of their lifespan?

A

digested by macrophages in liver or spleen

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30
Q

importance of regulation of erythropoiesis?

A

important to adjust to environments with different O2 levels

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31
Q

where is erythropoietin produced?

A

kidney

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32
Q

when is erythropoietin released?

A

when O2 levels are low

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33
Q

role of erythropoietin?

A

stimulates erythrocyte release

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34
Q

negative feedback loop of erythropoietin?

A

release stimulated by low O2 levels, erythropoietin stimulates erythrocyte release, resulting high O2 levels suppress erythropoietin production

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35
Q

what regulates the erythropoietin response to hypoxia?

A

transcription factor Hif-a (hypoxia inducible factor)

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36
Q

role of Hif-a?

A

in normal conditions is hydroxylated leading to its degradation, in hypoxia activity of hydroxylase is reduced, Hif1-a can activate erythropoietin transcription

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37
Q

why is RBC elimination important?

A

damaged RBCs can release Hb and free iron which are then sequestered in the kidney and can cause local inflammation and damage

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38
Q

effect of deregulation of RBCs?

A

anaemia (low hematocrit), polycthemia (high hematocrit)

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39
Q

blood group if no antigens present?

A

O

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40
Q

what does being group O blood type mean?

A

both anti-B and anti-A antibodies in plasma so no antigens on RBCs

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41
Q

blood group if A and B antigens present?

A

AB

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42
Q

what does being in group AB blood type mean?

A

no antibodies in plasma for A or B so both A and B antigens present on RBCs

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43
Q

what does being in group A blood type mean?

A

anti-B antibodies in plasma so only A antigens present on RBCs

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44
Q

what does being in group B blood type mean?

A

anti-A antibodies in plasma so only B antibodies present on RBCs

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45
Q

what does it mean to be Rh positive?

A

having Rh antigen on surface of RBCs

46
Q

role of WBCs?

A

fighting infection

47
Q

how do WBCs move through tissues to eliminate microbes?

A

use active ‘amoeboid’ movement

48
Q

what are the granulocytes?

A

neutrophils, eosinophils, basophils

49
Q
A
49
Q
A
50
Q

what dyes make neutrophils visible?

A

neutral dyes

50
Q

what are the most abundant cells in the blood?

A

neutrophils

50
Q

what dyes make eosinophils visible?

A

acidic dyes (eosin)

50
Q

role of neutrophils?

A

crucial for bacterial infections

51
Q

role of eosinophils?

A

role in some parasitic infections. granules contain peroxides and enzymes toxic to parasites

52
Q

what dye allows basophils to be visualised?

A

basic dyes (methylene blue)

53
Q

role of basophils?

A

produce histamine and heparin. play role in allergy

54
Q

what are the agranulocytes?

A

T and B lymphocytes, natural killer cells, monocytes, megakaryocytes

55
Q

role of T lymphocytes?

A

kill infected cells or produce signals that assist function of other immune cells

56
Q

role of B lymphocytes?

A

produce antibodies

57
Q

role of natural killer cells?

A

important for antitumour responses

58
Q

role of monocytes?

A

differentiate into macrophages and dendritic cells that can mediate phagocytosis and activation of T cells upon infection

59
Q

role of megakaryotes?

A

large multinucleated cells, segmentation gives rise to platelets- important in haemostasis

60
Q

what is haemostasis?

A

response of vessels to local injury/disruption which aims to seal the wound and prevent haemorrhage

61
Q

what happens in haemostasis?

A

endothelium rupture followed by vascular spasm, decrease in vessel diameter by muscle contraction, platelets aggregate at the site forming plug that temporarily seals the wound. general inflammatory response recruiting WBCs to site to prevent infection

62
Q

what triggers the ‘coagulation’ reaction in haemostasis?

A

release of factors from platelets- ADP, serotonin, prostaglandin

63
Q

what seals the wound in haemostasis?

A

fibrinogen converted into fibrin by thrombin to form gelatinous mesh that provides long-lived stable seal

64
Q

once the tissue has healed in haemostasis what follows?

A

fibrinolysis, plasminogen converted into plasmin which breaks down fibrin. bradykinin (vasodilator) relaxes muscles and restores blood flow

65
Q

functions of the lymphatic system?

A

returns interstitial fluid + plasma proteins into blood, filters blood by removing harmful agents like toxins or microbes, structural basis for immune system, transports dietary lipids from GI tract to blood

66
Q

what is the pathway of lymphatic system?

A

one-way circulation from interstitial tissue of peripheral organs to the blood

67
Q

which are more permeable blood vessels or lymphatic vessels?

A

lymphatic vessels- allow passage of proteins and even cells

68
Q

structure of lymphatic vessels?

A

blind ends with openings in form of overlaid flaps that allow passage of interstitial fluid carrying small proteins and cells

69
Q

what facilitates lymph flow?

A

muscle movements during breathing, exercise, good posture

70
Q

where does lymph drain to?

A

thoracic duct which feeds into the subclavian vein and thus returns filtered blood into circulation

71
Q

what is elephantiasis?

A

infection of the lymphatic system with parasitic worms that causes oedema and tissue swelling as result of lymphatic obstruction

72
Q

cells present in lymph?

A

B cells, T cells, macrophages, dendritic cells

73
Q

where are B cells produced?

A

bone marrow

74
Q

where are T cells produced?

A

thymus

75
Q

role of macrophages?

A

clearing dead cells

76
Q

role of dendritic cells?

A

activating T cells

77
Q

what are the primary lymphoid organs?

A

bone marrow and thymus

78
Q

what are the secondary lymphoid organs/tissues?

A

lymph nodes, spleen, mucosa associated lymphoid tissue (MALT)

79
Q

role of primary lymphoid organs?

A

produce blood cells

80
Q

role of secondary lymphoid organs?

A

enable immune responses, sites of immunosurveillance

81
Q

what cells produce blood cells?

A

hematopoietic stem cells

82
Q

how does hematopoiesis decline with age?

A

replacement of hematopoietic tissue by fat

83
Q

colour and location of active bone marrow?

A

red, spongey part of bone

84
Q

colour of fat/adipose tissue relating to bone marrow?

A

yellow

85
Q

where does age-related decrease in hematopoietic count begin?

A

lower limbs

86
Q

where is the thymus located?

A

behind sternum, above heart

87
Q

where are T cell precursors from?

A

migrate from bone marrow to thymus

88
Q

selective function of thymus?

A

selecting lymphocytes that react with foreign and not ‘self’ components

89
Q

what is thymic involution?

A

size of thymus decreasing dramatically with age

90
Q

name of lymph nodes in neck?

A

cervical lymph nodes

91
Q

name of lymph nodes near groin?

A

inguinal lymph nodes

92
Q

name of lymph nodes under arm?

A

axillary lymph nodes

93
Q

what does lymph enter and exit lymph nodes from?

A

enters through afferent lymphatic vessels, exits through efferent lymphatic vessels

94
Q

what are lymph nodes surrounded by?

A

capsule

95
Q

regions in lymph node?

A

subcapsular sinus receives lymph, contains macrophages that capture toxins and microorganisms. below sinus cortex and medulla are dense cellular areas of lymphocyte residence

96
Q

location of the spleen?

A

attached to the lateral border of the stomach

97
Q

function of the spleen?

A

to remove old RBCs from the circulation and filter blood-borne antigens, serves as location for initiation of immune responses to blood pathogens

98
Q

structure of spleen?

A

surrounded by weak capsule, below capsule in RBC rich area called red pulp where blood antigens filtered and RBCs removed, WBC rich area called white pulp where lymphocytes initiate immune responses to blood pathogens

99
Q

what is the mucosa associated lymphoid tissue?

A

lymphoid tissues attached to mucosal surfaces of the GI tract (Peyer patches and lymphoid tissue of appendix) and respiratory tract (tonsils)

100
Q

purpose of MALT?

A

provide additional pathogen filtering in exposed tissues (GI tract and respiratory tract)

101
Q

why is constant recirculation of lymphocytes through the lymphatic system needed?

A

only a few lymphocyte clones that can react with a specific antigen from an invading pathogen and they have to detect an invading pathogen anywhere in the body

102
Q

what are naive lymphocytes?

A

ones that haven’t seen an antigen

103
Q

what do lymphocytes enter lymph nodes via?

A

High Endothelial Venules- specialised venules

104
Q

what do B cells home to in lymph nodes?

A

follicles in the cortex

105
Q

what do T cells home to in lymph nodes?

A

the paracortex beneath the cortex

106
Q

pathway taken by antigens/microbes in the body?

A

travel in soluble form to the closest draining lymph node via the lymph, entire microbes and larger molecules engulfed and broken down by antigen presenting cells present in every tissue- then actively migrate to nearest lymph node to present antigen to clones of relevance

HOM (9 decks)

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