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Dentistry Yr 1 > Control of Blood pressure > Flashcards

Control of Blood pressure Flashcards

1
Q

What is cardiovascular homeostasis?

A
  • Controls blood pressure using baroreceptors
  • Controlled by medulla
  • Effectors are heart rate, stroke volume, caridiac output and vascular tone
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2
Q

What is the difference between systolic and diastolic blood pressure?

A
  • Systolic has a higher number than diastolic
  • Systolic force heart pumps whereas diastolic cause resistance of blood vessels.
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3
Q

What are the different ranges of blood pressure to highlight different conditions?

A
  • Normal range: 90/60-120/80mmHg
  • Hypotension: 90/60mmHg or lower
  • Hypertension: 140/90mmHg or higher
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4
Q

What is cardiac output?

A
  • Amount of blood pumped per ventricle/min.
  • CO = HR (heart rate) * SV (stroke volume).
  • To increase CO, you need to increase HR, SV or both.
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5
Q

What factors affect heart rate?

A
  • Intrinsic (reflexes, pacemaker rhythm) or extrinsic factors
  • Positive chronotropic factors (increase HR) e.g. caffeine, exercise, Ca2+, sympathetic stimuli
  • Negative chronotropic factors (decrease HR) e.g. sedative, beta blockers, parasympathetic stimuli, increasing K+ and Na+
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6
Q

How does the brain regulate heart rate?

A
  • Sympathetic division of ANS increases HR and contractility
  • Parasympathetic - vagus nerve decreases HR
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7
Q

What makes up the sympathetic division of the ANS that regulates heart rate?

A
  • Sinoatrial and atrioventricular nodes
  • Cardiac muscle.
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8
Q

What are the features of the baroreceptor reflex?

A
  • Blood pressure either hypertension (+) or haemorrhage (-)
  • Baroreceptors present in aortic arch and carotid sinus.
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9
Q

How does baroreflex work?

A
  • Low BP detected by baroreceptors
  • Cardiac output and vasoconstriction increased by medulla sending increased signals to SAN
  • BP increased (quick response)
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10
Q

What are the features of the chemoreceptor reflex?

A
  • Peripheral chemoreceptors in aortic arch and carotid body, central receptors in brain.
  • Chemoreceptors respond to decreased pO2, increased pCO2 and decreased pH.
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11
Q

Outline the chemoreceptor reflex

A
  • pO2 and pH increase, pCO2
  • Vasomotor center stimulated, increasing CO, HR and vasoconstriction
  • BP increases.
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12
Q

What are the features of the bainbridge atrial reflex?

A
  • Stretch receptors in both atria
  • Prevents damming of blood in atria and veins.
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13
Q

Outline the bainbridge atrial reflex

A
  • Due to high blood return from veins, mechano receptors stretch in myocardium of heart in atria.
  • Aferrent fibres in vagus nerve send info to cardiovascular centre medulla oblongata.
  • As a result of this, parasympathetic system shuts down, reduction in release of acetylcholine at the sinoatrial node.
  • Simultaneously sympathetic system increased, norepipherine released at SA node leading to increase in heart rate.
  • Positive chronotrophic result.
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14
Q

What is the equation for stroke volume?

A
  • SV = end diastolic volume (EDV) - end systolic volume (ESV).
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15
Q

What factors affect stroke volume?

A
  • Preload (amount ventricles are stretched by blood)
  • Contractility (cardiac cell contractile force)
  • Afterload (force exerted on ventricle wall during ejection)
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16
Q

Outline Frank-Starling law

A
  • Volume ejected in ventricular distole depends on volume in ventricle (EDV) - more volume = stronger contraction
  • Venous return increases (exercise) or decreases (blood loss) stroke volume
17
Q

Where do sympathetic nerve fibres innervate?

A
  • Sympathetic nerve fibres from vasomotor centre innervate smooth muscle for blood vessels except capillaries
18
Q

How does the diameter of arterioles affect blood pressure?

A
  • Diameter of arterioles changes vascular resistance - smaller diameter increases resistance, increasing blood pressure
19
Q

What is the role of the endothelium in vascular tone regulation?

A
  • Synthesises vasoconstrictions (endothelin-1, thromboxane A2) and vasodilators (nitrous oxide, prostacyclin).
20
Q

Outline the renin-angiotensin-aldosterone system (RAAS)

A
  • Controls blood volume using hormones
  • Renin stimulates angiotensinogen in liver, activating angiotensin 1
  • Angiotensin 1 converted into angiotensin 2 in lungs, increasing vasoconstriction and increasing BP
  • Angiotensin 2 turned into aldosterone in adrenal glands, reducing water reabsorption, increasing blood volume and pressure
21
Q

When is ADH released?

A
  • Released from pituitary gland because of reduced blood volume, increased osmolarity of plasma or increased angiotensin 2 levels
22
Q

What is the role of ADH in blood pressure control?

A
  • Increases water resorption in kidney by increasing Na+ diffusion, more osmosis of water from kidneys to blood
  • more blood volume = higher BP
  • Acts as a vasoconstrictor, increasing vascular resistance, increasing BP
23
Q

How does blood volume correlate with blood pressure?

A
  • Hypovolemic shock occurs when blood volume decreases by 20% from blood loss or dehydration
  • Body compensates by increasing HR by decreasing preload, stimulating vasoconstriction and RAAS.
24
Q

How does posture relate to blood pressure?

A
  • When supine, blood evenly distributed in veins
  • Increased SV, EDV and central venous pressure
25
Q

What causes fainting?

A
  • Temporary reduction in blood flow to brain
  • Triggered by vasovagal syncope (decreased HR and BP), cardiac syncope (heart problems) or decreased BP from standing up (orthostatic hypotension).
26
Q

Outline the commonly used antihypertensive drugs (RAAS).

A
  • Angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARB) reduce amount of angiotensin 2
  • Vasodilating and reduced water retention lower BP.
27
Q

Outline commonly used antihypertensive drugs (beta-blockers)

A
  • Heart beats more slowly and with less force
  • Blocks epinephrine action
  • Used for high BP, heart failure and angina
28
Q

Outline commonly used antihypertensive drugs (Ca2+ channel blockers)

A
  • Effect blood vessel smooth muscle contraction, electrical conduction of heart and caridac output
  • Doesn’t effect sympathetic stimuli
29
Q

Outline commonly used antihypertensive drugs (diuretics)

A
  • Increase urine production to excrete more water
  • Reduces oedema, blood volume and pressure
  • Different types target different parts of kidney, inhibiting sodium reabsorption - water follows sodium into urine
30
Q

What are the different types of blood pressure?

A
  • Normal range: 90/60-120/80mmHg
  • Hypotension: 90/60mmHg or lower
  • Hypertension: 140/90mmHg or higher
31
Q
A

Dentistry Yr 1 (20 decks)

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