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103-theme 2 > blood pressure (theme 3) > Flashcards

blood pressure (theme 3) Flashcards

1
Q

what are the measurements and units of pressure?

A
  • Mm
  • Hg
  • kPa
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2
Q

what is a series capillary system? 3

A
  • 2 paths in a row
  • flow in both parts is the same
  • pressure is higher in the 1st path than the 2nd as energy is lost as blood experiences resistance
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3
Q

what is a parallel capillary system? 4

A
  • branching paths
  • flow is split between 2 paths
  • pressure is the same at the start of both paths
  • if paths have identical resistance they have the same pressure
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4
Q

what are portal systems? 2

A

when a capillary bed reassembles to a blood vessel that splits again into another set of capillaries
-allows transport of chemicals from one tissue to another without being diluted by mixing with blood at the heart

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5
Q

give an example of a portal system?

A
  • hepatic portal system
  • food absorbed in the capillaries of the gut, portal vein goes to the liver and breaks, liver sees nutrients in the blood at a high concentration
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6
Q

what factors control blood pressure? 3

A
  • cardiac output
  • blood volume
  • peripheral resistance
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7
Q

how do you find blood pressure mean?

A

p(diastolic)+(p(systolic)-p(diastolic)/3

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8
Q

what is stroke volume?

average level?

A
  • volume of blood pumped out of a ventricle during one beat of the heart
  • 70ml
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9
Q

what is heart rate?

average level?

A
  • measured in bpm
  • reciprocal is the RR interval which is 60/HR
  • 70 bpm
  • 0.86 seconds
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10
Q

what is cardiac output?

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

- 4.9L/min

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11
Q

what is the equation for cardiac output?

A

HR x SV

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12
Q

what does atrial systole add to the blood volume in the ventricles

A
  • atrial systole adds final 20-25% to total to fill the ventricles
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13
Q

what is end diastolic volume? 2

A
  • volume of blood in a ventricle at the end of filling

- associated with preload, how stretched the muscle is

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14
Q

what is end systolic volume?

average level?

A
  • volume of blood remaining in a ventricle at the end of contraction
  • 120ml
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15
Q

what is the equation for systolic volume?

average level?

A

SV=EDV-ESV

50ml

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16
Q

what is the ejection fraction?

average level?

A

percentage of filled ventricular volume pumped out during a heartbeat
58%

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17
Q

what does vasoconstriction do to the resistance?

A

makes radius smaller, leads to higher resistance and lower flow rate

18
Q

what is the relationship between flow and radius? 2

A
  • flow increases as the radius increases to the power of 4

- assuming the pressure stays the same

19
Q

what is the relationship between resistance and radius?

A
  • resistance decreases as radius increases to the power of 4
20
Q

what causes the dilation and constriction of individual blood vessels? 4

A
  • central regulation (CNS, autonomic, endocrine)
  • local regulation of pressure
  • immune
  • haemostasis
21
Q

what happens to circulation during exercise? 3

A
  • peripheral vasodilatation to muscles and skin
  • vasoconstriction to splanchnic circulation
  • increased systolic and decreased diastolic
22
Q

what happens to circulation when you stand up? 3

A
  • likely a drop in blood pressure then a compensatory recovery (increase back to normal)
  • peripheral vasoconstriction- arterial and venous and increased heart rate
  • increased diastolic, no change to systolic
23
Q

explain the control of systemic blood pressure? 4

A
  • local control–> endothelial cells release NO
  • neurological–> the autonomic system- sympathetic-noradrenaline
  • humoral–> renal/pituitary/adrenal
  • the kidney is central to blood pressure
24
Q

explain local vasomotor control? 7

A
  • endothelial cells release vasodilator compounds
  • NO which causes smooth muscle relaxation and vasodilation
  • controlled by local blood flow conditions
  • hydrostatic pressure
  • shear force
  • made greater by laminar flow
  • shear force is atheroprotective
25
Q

explain the autonomic control of blood pressure? 6

A
  • increase in sympathetic
  • constrict blood vessels
  • increased peripheral resistance
  • increased pressure
  • increased heart rate
  • increased cardiac output
26
Q

what do baroreceptors do? 3

A
  • detect pressure and feed back to the brain
  • located in the transverse aortic arch and the carotid sinuses of the left and right internal carotid arteries
  • decrease blood pressure
27
Q

what do chemoreceptors do? 2

A
  • detect oxygen levels are too low and feedback to the brain

- located in the carotid bodies and aortic bodies

28
Q

what is the frank-starling mechanism? 2

A
  • the stroke volume of the heart increases in response to an increase in the stretching of blood filling the heart (the end diastolic pressure)
  • as you put more blood into the ventricle, it pushes more blood out, meaning the ventricle can’t overfill with blood
29
Q

what is venous return?

A

-the rate of blood flowing back to the heart through the veins

30
Q

what is preload? 2

A
  • the initial stretching of the cardiac myocytes during diastole (prior to contraction)
  • depends on venous return
31
Q

what is volume overload?

A
  • results when preload becomes too large
32
Q

what factors increase preload? 7

A
  • increasing atrial contractility
  • increases ventricular compliance
  • decreased venous compliance
  • increased thoracic venous blood volume
  • increased central venous pressure
  • increased aortic pressure
  • decreased heart rate
33
Q

what is afterload? 5

A
  • the resistance that the chambers of the heart overcome in order to eject blood out of the heart
  • resistance during systole
  • increased by back pressure from aorta or pulmonary arteries
  • increases if the exit valve fails to open completely
  • pressure overload results from elevated afterload
34
Q

explain the thoracic pump? 5

A
  • pulls blood towards the right atrium
  • during inspiration
  • intrathoracic pressure becomes more negative
  • abdominal pressure is positive (compression of abdominal organs by the diaphragm)
  • creates a pressure gradient
35
Q

explain the muscle pump? 4

A
  • rhythmical contraction of limb muscles
  • as occurs during normal locomotor activity
  • squeezes blood out of nearby veins
  • venous valves ensure one-way flow to the heart
36
Q

describe pulmonary circulation? 8

A
  • high capillary density
  • low vascular resistance
  • acts as a blood reservoir
  • endocrine control of BP(ACE)
  • acts as a filter
  • if oxygen is low in a region of the lung, the arterioles constrict
  • poor ventilation –> reduced perfusion
  • this minimises the amount of blood which is poorly oxygenated
37
Q

explain coronary circulation? 3

A
  • cardiac muscle has high demand
  • most flow occurs during diastole
  • obtains blood almost before aorta
38
Q

what is hypertension? 6

A
  • high blood pressure (especially high diastolic pressure)
  • often asymptomatic
  • may result in coronary heart disease
  • caused by a mismatch in blood volume and circulatory capacity
  • most cases are idiopathic (hormones)
  • can be secondary to kidney disease
39
Q

what is orthostatic hypotension? 5

A

-low BP on standing
-decreased venous return
- dizziness or syncope
drugs
-hypovolaemia (too little blood volume)
-age

40
Q

what is cardiogenic shock? 7

A
  • tachycardia
  • tachypnea (compensatory mechanisms)
  • low urine output
  • hypotension
  • confusion
  • syncope
  • acidosis (due to failure to compensate)

103-theme 2 (9 decks)

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