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HOM > blood and lymph > Flashcards

blood and lymph Flashcards

1
Q

what are the 4 key functions of the blood

A

transport of nutrients, gases, hormones, waste. restriction of fluid loss during injury. defence from infection. homeostasis,

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2
Q

what are the routes of transport

A

paracellular and transcellular

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3
Q

what is the paracellular route

A

paracellular route is where molecules diffuse in between endothelial cells, regulated by tight and gap junctions.

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4
Q

what are the 3 transcellular routes

A

the transcellular route is for larger molecules where they are actively transported. this can happen through receptor mediated endocytosis, or transcytosis where cells take up extracellular medium through CAVEOLAE MEDIATED MACROPINOCYTOSIS. or via transendothelial channels such as vesicular vacuolar organelles which are interconnected vesicles forming channels across the cell

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5
Q

what is the endothelial cell permeability

A

organs where there is a lot of exchange such as filtration or nutrient absorption need greater permeability

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6
Q

how is greater permeability in endothelial cells achieved

A

fenestrated endothelial has looser junctions between the cells this is seen in endocrine glands, gi mucosa or glomerulus. there are discontinuous epithelium in the liver where are characterised by fenestrae without diaphragms and poorly organized basement membrane

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7
Q

what is a further advantage of discontinuous epithelium

A

these ECs have a high level of clathrin-mediated receptor endocytosis activity, further
increasing their ability to take up specific molecules.

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8
Q

where is continuous ec found

A

skin lung and heart, founds with caveolae, tec and intercellular clefts

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9
Q

how is transport controlled in the brain

A

formed by tighter endothelial junctions, a thicker basement membrane and a supporting layer of astrocytes. BBB prevents entry of lipophilic neurotoxins by an active transport mechanism mediated by p-glycoprotein

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10
Q

why is endothelial permeability important in organs

A

can charge during infection or tissue damage. antibodies and antibiotics cannot cross

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11
Q

what is a key hallmark of inflammation

A

flow of plasma and WBC, local endothelial cells increase permeability so that plasma protein can exit and reach the tissue

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12
Q

describe red blood cells

A

biconcave disk, enucleated, haemoglobin carriers,

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13
Q

components of blood by density using centrifuge?

A

first haematocrit, then buffy coat of WBC and platelets, then plasma containing water/proteins/nutrients/hormones

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14
Q

what is the life span of the RBC

A

3 months

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15
Q

where does erythropoiesis

A

bone marrow in adults, spleen and liver in fetus

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16
Q

describe erythrocytes

A

differentiate into erythrocytes by losing the nucleus ribosomes and organelles

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17
Q

how is erythropoiesis regulated

A

important to adjust to environment with different levels of oxygen. the hormone erythropoietin also has regulatory role

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18
Q

what does EPO do

A

produced by the kidney and regulated by negative feedback, low oxygen conc stimulates release of EPO stim release of erythrocytes

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19
Q

what does high levels of EPO result in (feedback loop)

A

high oxygen levels which then suppress production of EPO

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20
Q

what regulates the hypoxia response

A

regulated by the transcription factor Hif-A (hypoxia inducible factor)

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21
Q

what happens in normoxia

A

hif-A is hydroxylated and leads to degradation

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22
Q

what happens to hif-A in hypoxia

A

hydroxylases acitivity is reduced and hif1-a can activate transcription of EPO.

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23
Q

how are RBC eliminated

A

through macrophages in the liver and spleen. important because rbc release hb and iron which can damage kidney

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24
Q

what do erythrocytes carry on their surface

A

protein antigens that can be recognised by antibodies of a different individual

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25
Q

what do rh positive individuals have on their surface

A

rh antigen

26
Q

what are the role of wbc

A

fight infection, exit blood stream, active amoeboid movement to navigate through tissues and eliminate microbes

27
Q

name different types of granulocytes

A

neurtrophils, eosinophils, basophils

28
Q

what do neutrophils do

A

crucial for bacterial infections and most abundant

29
Q

what is role of eosinophils

A

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

30
Q

what do basophils do

A

produce histamine and heparin, role in allergy

31
Q

name the agranulocytes

A

t and b lymphyocytes, monocytes, megakaryocytes

32
Q

what do t lymph do

A

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

33
Q

what do b lymph do

A

produce antibodies

34
Q

what do monocytes do

A

differentiate into macrophages and dendritic cells that can mediate phagocytosis and activation of t cells

35
Q

what do megakaryocytes

A

large multinucleated cells whos segmentation gives rise to platelets. the latter are important in haemostasis, response of vessels to local injury/disruption

36
Q

outline process of haemostasis

A

endothelium rupture > vascular spasm > vessel decreases in diameter.

platelets aggregate at the site to form a plug. they release factors triggering coagulation reaction.

fibrinogen > fibrin by thrombin. fibrinolysis follows.

plasminogen > plasmin which breaks down fibrin

bradykinin a vasodilator releaxes muscles and restores blood flow

37
Q

functions of lymphatic system 4

A

returns interstitial fluid and plasma proteins into blood, filters blood by removing harmful agents, provides structural basis for immune system, transports dietary lipids from gastrointestinal tract to blood

38
Q

is lymphatic a closed circulation

A

no

39
Q

are lymphatic vessels more permeable than blood vessels

A

yes, allowing passage of proteins and even cells

40
Q

describe structure of lymphatic vessels

A

blind ends with openings in the form of overlaid flaps allowing passage of interstitial fluid called lymph

41
Q

how is lymph flow facilitated

A

muscle movements during breathing, exercise, good posture

42
Q

where is lymph filtered

A

in lymphoid tissues ending up in the thoracic duct which feeds into the subclavian vein and returns filtered blood into the circulation

43
Q

cells present in lymph

A

lymphocytes, macrophages, dendritic cells

44
Q

name lymphoid organs

A

primary lymphoid organs e.g. bone marrow and thymus. secondary lymphoid organs e.g. lymph nodes, spleen and mucosa associated lymphoid tissue

45
Q

what do primary lo do

A

produce blood cells

46
Q

what do secondary lo do

A

enable immune responses sites of immunosurveillance

47
Q

outline the role of the bone marrow

A

site of hematopoiesis, production of blood cells throughout life by hematopoietic stem cells. haematopoiesis declines with age by replacement of h tissue by fat

48
Q

outline the thymus

A

located behind the sternum above the heart and constitutes the site of mature t lymphocyte production. t precursors migrate to the thymus from the bone marrow

49
Q

what is the critical role of the thymus

A

selecting lymphocytes that will react with foreign and not self components.

50
Q

when does the size of the thymus change

A

decreases with age leading to reduced amount of naive t lymphocytes

51
Q

role of lymph nodes

A

drain interstitial fluid from peripheral tissues whilst removing harmful toxins and pathogens. lymph enters from afferent lymphatic vessels and filtered lymph exits through efferent vessels, the node is surrounded by a capsule

52
Q

role of spleen

A

remove old red blood cells and filter blood borne antigens. also serves as location for initiation of immune reponses to blood pathogens.

53
Q

why is spleen highly vascularised

A

to enable good filtration

54
Q

describe the structure of the spleen

A

surrounded by weak capsule, below capsule is RBC rich area called red pulp where blood antigens are filtered and rbcs removed and wbc rich area called white pulp where lymphocytes initiate immune reponses to blood pathogens

55
Q

what is mucosa associated lymphoid tissue

A

lymphoid tissues attached to mucosal surfaces of the gastrointestinal tract or respiratory tract to provide additional pathogen filtering

56
Q

how does lymphatics provide structural support for immune responses

A

the immune system produces lymphocyte clones with unique receptors for a specific microbial determinant and only a few of them are able to react with a specific antigen from an invading pathogen. these clones have to detect an invading pathogen anywhere in the body

57
Q

how do lymphatic clones achieve this detection

A

constant recirculation of lymphocytes through the lymphatic system. naive lymphocytes transit through the blood, nodes and spleen and return to the blood via the thoracic duct

58
Q

how do lymphocytes enter lymph nodes

A

through specialised venules called high endothelial venules

59
Q

where do b cells accumulate inside the node

A

follicles in the cortex, they recognise and bind antigens brought by lymph into the follicle

60
Q

where do t cells accumulate inside the node

A

paracortex right beneath the cortex, they recognise antigens on antigens presenting cells that arrive in the area

61
Q

how do lymphocytes encounter antigens

A

small extracellular antigens travel in soluble form form a certain tissue to the closest draining lymph node via the lymph. entire microbes and larger molecules are engulfed by APCs . APCs then migrate to the nearest lymph node to present antigen to the lymphocyte clone of relevance.

62
Q

where do blood borne antigens travel

A

to the spleen, either in soluble form or after being picked up by APCs in the blood

HOM (8 decks)

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