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Cardiorespiratory CC > NO in Vascular system > Flashcards

NO in Vascular system Flashcards

1
Q

Entonox

A

Mix of nitrous oxide (N2O) and oxygen (50:50)

Medical anaesthesia gas

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2
Q

Nitric Oxide Synthase

A

NO Synthesis

Both oxidase + reductase domains

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3
Q

NO synthesis

A

Oxygen essential –> converts aa l-arginine to citrulline
H+ produced
Enhanced in alkali, inhibited in acidic
Prevented in hypoxic conditions

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4
Q

NO synthase location

A

Brain
Macrophages
Vascular endothelium

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5
Q

NOS type I

A

nNOS or bNOS
Central or peripheral and neuronal cells
Calcium dependent

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6
Q

NOS type II

A

iNOS
Most nucleated cells particularly macrophages
Independent of intracellular Ca 2+
Inducible in presence of inflammatory conditions

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7
Q

NOS type III

A

Endothelial NOS, eNOS
Vascular endothelial cells
Ca2+ dependent

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8
Q

NO synthesis in Vascular Endothelium

A

Shear stress on endothelial wall by moving blood flow
–> opens Ca2+ channels
Ca2+ enters endothelium
Ca2+ binds to calmodulin
Calmodulin activates eNOS
NO diffuses from endothelium into surrounding smooth muscle + activates guanylate cyclase
–> converts GTP–>cGMP (makes muscles relax)

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9
Q

cGMP acts through 3 main groups of cellular targets

A

cGMP-dependent protein kinases (PKGs)
cGMP-gated cation channels
Phosphodiesterases (PDEs)

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10
Q

cGMP

A

inhibits contraction

makes muscle relax

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11
Q

NO Function in Vascular system

A

NO relaxes and dilates arteriolar smooth muscle

NO prevents unwanted intravascular coagulation

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12
Q

NO in lungs

A

relaxes bronchial smooth muscle

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13
Q

NO + Gas exchange

A

NO diffuses into blood + smooth muscle during hypoxia
In erythrocyte, reacts with oxyhaemoglobin to form nitrosohaemoglobin
–> displaces O2 from haemoglobin
–> NO IMPROVES O2 DELIVERY IN HYPOXIC TISSUE

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14
Q

Blood flow in Active muscles during exercise

A

Increases 10x

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15
Q

Coronary blood flow during exercise

A

increases 3x

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16
Q

Kidney blood flow during exercise

A

Decreases by nearly half

17
Q

Skin blood flow during exercise

A

Increases 4x

18
Q

Brain blood flow during exercise

A

Does not change

19
Q

Skeletal muscle blood flow during exercise

A

SNS produces general vasoconstriction of arterioles in muscle (mediated by alpha 1 adrenoreceptors)
–> reduces local muscle blood flow
Muscle which is exercising vasodilates
–> overcomes global symp. vasoconstrictor tone
–> increases local BF by opening arterioles

20
Q

Local vasodilators

A

Adenosine

NO- more important than adenosine in vasodilation in hypoxic muscle

21
Q

Acidosis

A

Triggers vasodilation in exercising muscle

By lactic acid

22
Q

NO storage

A

Can’t be stored in cells or organelles as is gas
Constantly synthesised at low levels in resting vascular endothelium
NO converted to nitrate –> stored in endothelium –> when hypoxia, converted back

23
Q

Nitroglycerin (GTN)

A

Essential drug for treating angina + MIs
Dilates coronary arteries
GTN –> nitrate in circulation

24
Q

Dipyridamole

A

Vasodilator
Increases adenosine conc. in blood
Increases size of blood vessels - BUT doesn’t affect atheroma blockage

25
Q

Nitrite –> NO

A

Hypoxic and environment

26
Q

Persistent pulmonary hypertension of the newborn (PPHN)

A

Raise pulmonary vascular resistance

–> NO to inspired gas dramatically improves lung function in these children

27
Q

Foetus pulmonary arterioles

A

Resting state is constriction

First breath - O2 rises + rapid synthesis of NO –> relaxation vascular smooth muscle –> vasodilation

28
Q

Pulmonary arterial resistance decreases in exercise

A

Pulmonary arterial walls thin
Increased flow through pulmonary arterioles may increase NO synthesis
Symp NS acts on beta 2 receptors on bronchial smooth muscle –> relaxes them + increases bronchial diameter
eNOS in pulmonary endothelium is highly sensitive to O2 partial pressure –> when O2 partial pressure rises, so does NO production

29
Q

No and coagulation

A

Base release of NO helps prevent leukocytes + platelets from adhering to surface of endothelium

30
Q

NO + digestive system

A

Nitrates in vegetables converted to nitrated by enzymes in saliva + nitrites enter the stomach
Acidic stomach= nitrite + ascorbic acid –> NO
NO in acidic conditions is bactericidal + kills harmful bacteria in food

31
Q

Nitrosamines

A

Carcinogenic

Nitrites converted into nitrosamines in SI

Cardiorespiratory CC (34 decks)

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