Cardiology Lectures 4-6: Blood Pressure Flashcards

1
Q

What is blood pressure?

A

Blood Pressure is “the outwards (hydrostatic) pressure exerted by the blood on blood vessel walls”

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2
Q

What is the upper limit of systolic blood pressure?

A

140

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3
Q

What is the upper limit for diastolic BP?

A

90

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4
Q

What is the term for normal blood flow?

A

Laminar

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5
Q

What is the first Korotkoff sound?

A

Systolic BP

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6
Q

What is the fifth Korotkoff sound?

A

Diastolic Pressure is Recorded at the Fifth Korotkoff Sound (point at which sound disappears

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7
Q

What is the main driving force of the venous return to the heart?

A

MAP

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8
Q

What is MAP?

A

The average arterial blood pressure during a single cardiac cycle which involves contraction and relaxation of the heart

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9
Q

How do you calculate MAP?

A

(Diastolic x 2 + Systolic) divided by 3

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10
Q

What is the other way to calculate MAP?

A

BDP + 1/3 Pulse pressure

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11
Q

What is the normal range for MAP?

A

70-105

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12
Q

What is the lowest MAP that allows perfusion of coronary arteries, brain and kidney?

A

at least 60

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13
Q

What determines MAP?

A

CO and total peripheral resistance

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14
Q

What is total peripheral resistance?

A

Sum of resistance of all peripheral vasculature in the systemic circulation

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15
Q

What are the major resistance vessels?

A

Arterioles

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16
Q

Where are you baroreceptors?

A

Aortic arch

Carotid sinus

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17
Q

Which nerve signals to the medulla from the carotid sinus?

A

CN IX

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18
Q

Which nerve signals to the medulla from the aortic baroreceptors?

A

CN X

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19
Q

Why are baroreceptors important?

A

Short term BP regulations ie postural changes

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20
Q

What is postural hypotension?

A

Results from failure of Baroreceptor responses to gravitational shifts in blood, when moving from horizontal to vertical position

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21
Q

How is MAP controlled long term?

A

By hormones which control blood volume.

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22
Q

What two main factors control extracellular fluid volume?

A

Water

Sodium

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23
Q

What three mechanisms control long term blood pressure?

A

Rennin-Angiotensin-Aldosterone- System
Atrial Natriuretic Peptide
Antidiuretic hormone

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24
Q

Where is rennin released?

A

Kidneys

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25
Q

What does rennin do?

A

Stimulates the formation of angiotensin I

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26
Q

What converts angiotensin I to angiotensin II?

A

ACE

27
Q

What does angiotensin II do?

A
  1. Stimulates the release of aldosterone form the adrenal cortex
  2. Vasocontriction
  3. Stimulates thirst and the release of ADH
28
Q

What does aldosterone do?

A

Increased sodium and water retention therefore increasing plasma volume

29
Q

What cells release rennin?

A

Granular cells

30
Q

What makes up the juxtaglomerular region?

A

Macula densa
Extraglomerular mesangial cells
Granular cells

31
Q

What three things stimulate rennin release?

A

Hypotension in the renal artery
Stimulation of renal sympathetic nerves
Decreased sodium in the renal tubular fluid (sensed by the macula densa)

32
Q

When is ANP released?

A

Released in response to atrial distention

33
Q

What does ANP do?

A

Causes the excretion of salt and water therefore reducing the blood volume and pressure.
Acts as a vasodilator.
Decreases rennin release

34
Q

What is another name for ADH?

A

Vasopressin

35
Q

Where is ADH synthesized?

A

HYpothalamus

36
Q

Where is ADH stored?

A

Pituitary gland

37
Q

What stimulates secretion of ADH?

A

Reduced extracellular fluid volume

Increase extracellular fluid osmolarity

38
Q

How is plasma osmolarity monitored?

A

Osmoreceptors

39
Q

How does ADH increase BP?

A

Acts on the kidney tubules to increase the reabsorption of water
This increases extracellular output and blood pressure

40
Q

What affect does ADH have on blood vessels?

A

Vasocontriction

41
Q

What is the relationship between blood viscosity and length of blood vessel?

A

Directly proportional to the power of 4

42
Q

What is the relationship between blood viscosity and radius of the blood vessel?

A

Inversely proportional tot eh power of 4

43
Q

Which adrenoceptor acts on vascular smooth muscle?

A

alpha

44
Q

What is the vasomotor tone?

A

Blood vessels are partially constricted at rest

45
Q

What causes the vasomotor tone?

A

Tonic discharge of sympathetic nerves resulting in continuous release of noradrenaline

46
Q

What will increase the vasomotor tone?

A

Sympathetic stimulation

47
Q

What adrenoceptor causes vasodilation when acted on by noradrenaline?

A

beta

48
Q

Where are the alpha receptors situated?

A

Skin, gut, kidney arterioles

49
Q

Where are the beta receptors located?

A

Cardiac and skeletal smooth muscle

50
Q

True or false: Intrinsic controls of vasculature can over-ride extrinsic ones?

A

True

51
Q

What vessels contain most of the blood volume under resting conditions?

A

Capacitance vessels eg the veins

52
Q

What local metabolites cause vasodilation?

A
Decreased PO2
Decreased CO2
Decreased pH
Increased extra cellular K
Increased ECF osmolarity
Adenosine release
53
Q

What physical factors cause vasodilation

A

Warmth
Decreased MAP (myogenic)
Sheer stress

54
Q

What is the myogenic affect?

A

If the MAP rises- vasoconstirction occurs to limit flow and vice versa

55
Q

What humoral agents cause vasodilation

A

Histamine
Prostoglandin
Bradykinin
Nitric oxide

56
Q

Where is NO produced

A

Endothelium

57
Q

What humoral agents cause vasoconstriction

A

Seratonin
Thromboxane A2
Leukotrienes
Endothelin

58
Q

What physical factors cause vasocontriction

A

Cold

Increase MAP

59
Q

What amino acid is NO produced from

A

L-argenine

60
Q

Which enzyme catalyses the formation of nitric oxide

A

NOS

61
Q

What is the relatioship between sheer stress and NO production

A

Sheer stress increases calcium release which activates NOS and results in increase NO

62
Q

What is the consequence of an increased venomotor tone?

A

increased venous return to the heart

63
Q

What is the acute CVS response to exercise?

A
Increased sympathetic tone
Increased HR and SV
Vasodilation to smooth mucles and cardiac
Vasocontriction to gut and kidney etc
Increase SBP but decreased TPR and DBP
Post exercise hypotension
64
Q

What is the chronic CVS response to exercise?

A

Reduced BP