Lecture 2: Blood Pressure Flashcards

1
Q

what do portal systems allow

A

transport of chemicals from one tissue to another without being diluted by mixing with blood at the heart

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2
Q

what is a portal system

A

2 capillary beds in series

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3
Q

what is a healthy blood pressure

A

120 / 75

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4
Q

what is the reciprocal of heart rate

A

RR interval, 60 / heart rate

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5
Q

what is stroke volume and average value for an adult

A
  • volume of blood pumped out of a ventricle during one beat of the heart
  • 70ml
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6
Q

what is cardiac output and average value for an adult

A
  • volume of blood pumped out of a ventricle per minute

- 4.9 L/min

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7
Q

what is end diastolic volume and average value

A
  • volume of blood in ventricle at the end of diastole

- 120ml

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8
Q

what is end systolic volume and average value

A
  • volume of blood remaining in ventricle at the end of systole
  • 50ml
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9
Q

what is ejection fraction (Ef) and average value

A
  • percentage of filled ventricular volume pumped out during a heart beat
  • 55-70%
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10
Q

how does vasoconstriction affect resistance and flow rate

A
  • higher resistance

- lower flow rate

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11
Q

by what power does flow increase as radius increases

A

power of 4

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12
Q

what causes vasoconstriction and dilation

A
  • CNS autonomic and endocrine systems
  • local regulation of pressure
  • immune system
  • haemostasis
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13
Q

where does exercise cause vasodilation and vasoconstriction

A
  • vasodilation in muscle and skin

- vasoconstriction in splanchnic (digestive) circulation

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14
Q

how is heart rate, systolic pressure and diastolic pressure affected when standing up

A
  • heart rate increases
  • systolic unchanged
  • diastolic increases
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15
Q

how is systemic blood pressure controlled

A
  • endothelial cells make NO, causing relaxation of muscle tissue
  • symapthetic system releases noradrenaline
  • hormones released by renal pituitary and adrenal systems
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16
Q

where are baroreceptors located

A
  • transverse aortic arch

- left and right internal carotid arteries

17
Q

what do chemoreceptors detect and where are they located

A
  • detect when O2 levels are low and feed back to the brain

- aortic and carotid bodies

18
Q

what is venous return

A

rate of blood flowing back to heart through the veins

19
Q

what is preload

A
  • initial stretching of cardiac myocytes during diastole, before contraction
  • ventricular filling
20
Q

what is volume overload

A

pathological state when preload is too large for the heart to pump out

21
Q

how does heart rate affect preload

A

decreased heart rate increases preload, as there is more time for the ventricles to fill

22
Q

what is afterload

A

resistance during systole

23
Q

what factors increase afterload

A
  • increased back pressure from aorta or pulmonary arteries

- if the exit valve fails to open completely

24
Q

what results from elevated afterload

A

pressure overload

25
features of the pulmonary circulation
- high capillary density - low vascular resistance - act as blood reservoir and filter - endocrine control of blood pressure by ACE
26
how does low O2 affect pulmonary circulation
- constriction of arterioles | - minimises amount of blood that is poorly oxygenated
27
what is hypertension caused by
- mismatch between blood volume and circulatory capacity - mostly idiopathic, hormones or brain medulla - secondary to kidney diseases
28
what can chronic hypertension lead to
- aneurysm or stroke - myocardial infarct - kidney failure - heart failure - cardiac hypertrophy
29
what is orthostatic hypotension and what is it caused by
- low blood pressure on standing | - drugs, hypovolaemia and age
30
signs and symptoms of cardiogenic shock
- tachycardia and tachypnoea are compensatory mechanisms - low urine output - hypotension - confusion - syncope - acidosis