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BDS1 Cardiovascular System > Controlling the CVS > Flashcards

Controlling the CVS Flashcards

1
Q

What must arterial pressure be maintained at? (the accepted values for heart pressure for a healthy adult)

A

120/80mmHg

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2
Q

When must wide variations in blood flow to different organs occur (general)?

A

When the demand arises

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3
Q

What are the 4 main control systems involved in maintaining blood pressure?

A
  • Arterial BP
  • CO
  • The local circulation
  • Blood and ECF volume
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4
Q

What does MABP equal?

A

CO x TPR

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5
Q

What does CO equal?

A

HR x SV

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6
Q

What is the NTS in the feedback loop?

A

Nucleus Tractus Solitarius

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7
Q

What do arterial baroreceptors detect?

A

Pressure at different points in the arterial tree

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8
Q

Where are baroreceptors present?

A

In the carotid sinus and aortic arch
- Blood is going to the brain from the carotid artery - carotid arch detects pressure of blood as it leaves the heart - allows information to be relayed to the brain quickly

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9
Q

What do baroreceptors respond to?

A

Stretching (pressure changes)

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10
Q

Which baroreceptor is more important?

A

The carotid receptor as it is more sensitive (60-180mmHg)

  • It is the most sensitive around MAP
  • Input to NTS in brain
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11
Q

A decrease in the arterial pressure decreases the baroreceptors firing. What does this cause the SNS and PNS to do?

A
  • There is a reflex via the medullary cardiovascular centre which decreases the parasympathetic outflow to the heart
  • There is an increase in the sympathetic outflow to the heart, arterioles and veins
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12
Q

Where are alpha-2 adrenoreceptors found?

A

On the nerve terminals

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13
Q

What do bulbar circulatory centres do?

A

Inhibit the action of the vagal nucleus

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14
Q

What do alpha 2 adrenoreceptors activate and inhibit?

A

Activate: Vagal nucleus
Inhibit: Bulbar circulatory centres

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15
Q

What do beta 1 adrenoreceptors activate and inhibit?

A

Activate: Bulbar circulator centres
Inhibit: The vagal nucleus

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16
Q

What is the effect of the activation of the vagal nucleus by alpha-2 adrenoreceptors on the heart and blood vessels ?

A
  • Vagal nucleus releases ACh which attaches to M2 receptors which decreases cardiac output and decreases peripheral resistance
  • Also inhibits the action of the bulbar circulator centres so prevents them from secreting NA
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17
Q

What is the effect of the activation of bulbar circulatory centres by beta-1 adrenoreceptors on the heart and blood vessels?

A
  • Bulbar circulatory centres release NA which attaches to alpha-1 adrenoreceptors on the blood vessels and beta-1 adrenoreceptors on the heart to increase the peripheral resistance and cardiac output
  • Also inhibits the action of the vagal nerve so prevents the release of ACh
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18
Q

If blood pressure drops, what area if the brain does it affect and what is the response to this?

A
  • Positive output of sympathetic nerves

- Affects the adrenal medulla which causes BP to increase

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19
Q

What does Clonidine- alpha-2 agonists activate?

A
  • Activates presynaptic receptors in brain vasomotor centre to lower sympathetic output
  • In the NTS, fools the brain into thinking catecholamine levels are higher so responds by lowering tone to adrenal medulla
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20
Q

What can be a problem of prescribing Clonidine-alpha2 agonist as a drug to decrease blood pressure?

A
  • Problem = rebound hypertension
  • It keeps the blood pressure low but when the patient stops using the drug or forgets to take the drug then there is a huge rush in blood pressure which increases the chance of stroke etc
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21
Q

When is alpha-methyldopa prescribed as a medicine and what does it do?

A
  • Sometimes used in hypertension of pregnancy
  • It is used in pregnancy as it does not harm the baby
  • It is a prodrug
  • It is converted to alpha-methylnoradrenaline and acts as a central alpha-2 agonist
  • It inhibits DOPA-decarboxylase so reduces production of peripheral neurotransmitters
  • It decreases the amount of dopamine in the body
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22
Q

What is meant by a prodrug?

A

It has to be metabolised to have its affect

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23
Q

What can constrict the arteriolar radius?

A
  • Sympathetic nerves
  • Noradrenaline
  • Alpha-1 adrenoreceptors
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24
Q

What can dilate the arteriolar radius?

A
  • Sympathetic cholinergic nerves
  • Acetylcholine
  • Muscarinic
  • Plasma adrenaline
  • Beta-2 adrenoreceptors
  • Local controls
  • decrease in PO2
    Increase in K+
  • Increase adenosine
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25
Q

There is a well developed system which modulates local blood pressure/floe and can override central control systems. How does this work?

A
  • Local system is independent of nerves/hormones
  • BP modified by the local changes in TPR
  • Metabolites, blood gases and endothelium-derived factors are involved which override the central control systems
  • Adenosine produce by metabolising tissue - breakdown of ATP-cAMP-A
  • Also used in cardiology to dilate coronary vessels
26
Q

What are the functions of Nicorandil?

A
  • Opens ATP-sensitive K+ channels

- Hyperpolarises smooth muscle and closes L-type calcium channels

27
Q

What is Nicorandil mainly used to treat?

A
  • Angina
28
Q

What is capillary fluid shift mainly a property of?

A

Venous dilators

29
Q

What is capillary fluid shift caused by?

A

Reduced proximal capillary hydrostatic pressure

30
Q

What is meant by most dilators being mixed/balanced in related to blood vessels?

A

The have effects on both arteries and veins

- Hydralazine is an exception

31
Q

When is blood pressure greatest and lowest?

A
  • Greatest: on walking

- Lowest: in sleep

32
Q

What does blood pressure increase in response to?

A
  • Exercise
  • Stress
  • Sensory stimuli
33
Q

Does blood pressure increase or decrease with age?

A

Increases

34
Q

What is the optimal diastolic blood pressure?

A
  • 85mmHg

- Hypertension is defined when BP exceeds a specific threshold

35
Q

What faulty mechanism in the body causes chronically high blood pressure?

A

Baroreceptors reset to a higher level so they accept high BP as normal so don’t realise BP needs to be lower

36
Q

What % of cases are due to secondary hypertension?

A

5%

37
Q

What % of cases are due to primary hypertension?

A

95%

38
Q

Is primary hypertension a known or unknown cause?

A

Unknown

39
Q

Is secondary hypertension a known or unknown cause?

A

Known

40
Q

What are examples of secondary hypertension (known cause)?

A
  • Renal hypertension
  • Phaeochromocytoma
  • Aortic coarctation
  • Drug induces - sympathetic amines, COCs etc
41
Q

What are examples of primary hypertension (unknown cause)?

A
  • Salt intake
  • Cigarettes
  • Genetic predisposition
  • Stress
42
Q

What is hypertension?

A

High blood pressure

43
Q

What does hypertension cause damage to?

A
  • Arteries, heart, kidneys

- Damage to every system of the body as blood is flowing at higher pressure

44
Q

Are the symptoms of hypertension easy to identify?

A

No, hypertension does not normally have symptoms that are noticed by the patient, unless hypertension is very severe

45
Q

What are the varieties of cardiovascular DAMAGE that can be caused by hypertension?

A
  • Thickening of arteries
  • Deterioration in atherosclerosis
  • Aneurysms in cerebral arteries
  • Left ventricular hypertrophy
46
Q

What is atherosclerosis?

A

The build up of waxy plaque on the inside of blood vessels

47
Q

What are the varieties of cardiovascular DISEASE that can be caused by hypertension?

A
  • Malignant hypertension
  • Stroke
  • Renal disease
  • Cardiac hypertrophy and heart failure
  • Cardiac ischemia and angina
48
Q

What is the treatment for hypertension?

A
  • NON-PHARMOLOGICAL MEASURES
49
Q

What possible drugs can be used to reduce heart rate?

A

Beta-adrenoreceptor antagonists

50
Q

What possible drugs can be used to reduce stroke volume?

A
  • Beta-antagonists

- Some Ca2+ channel blockers

51
Q

What possible drugs can be used to reduce total peripheral resistance?

A
  • Alpha blockers: direct action on blood vessels

- ACE inhibitors: antagonise a substance which raises TPR

52
Q

What possible drugs can be used to reduce the volume?

A

Diuretics - increases the amount of urine excretion

53
Q

What possible drugs can be used to control central control systems?

A
  • Methyl-dopa

- Clonidine

54
Q

What is the first step for treatment of hypertension of a patient that is younger than 55?

A

ACE inhibitor

55
Q

What is the second step for treatment of hypertension of a patient that is younger than 55?

A
  • ACE inhibitor + calcium-channel blocker

- ACE inhibitor + Thiazide-type diuretic

56
Q

What is the third step for treatment of hypertension of a patient that is younger than 55?

A
  • ACE inhibitor + calcium-channel blocker + thiazide-type diuretic
57
Q

What is the fourth step for treatment of hypertension of a patient that is younger than 55?

A
  • ACE inhibitor + calcium-channel blocker + thiazide-type diuretic
\+ ADD 
- further diuretic therapy 
OR
- alpha blocker 
OR
- beta-blocker

consider seeking specialist advice

58
Q

What is the first step for treatment of hypertension of a patient that is 55 years or older or black patients of any age?

A
  • Calcium-channel blocker OR thiazide-type diuretic
59
Q

What is the second step for treatment of hypertension of a patient that is 55 years or older or black patients of any age?

A
  • ACE inhibitor and calcium-channel blocker

OR

  • ACE inhibitor and thiazide-type diuretic
60
Q

What is the third step for treatment of hypertension of a patient that is 55 years or older or black patients of any age?

A
  • ACE inhibitor + Calcium-channel blocker + thiazide-type diuretic
61
Q

What is the fourth step for treatment of hypertension of a patient that is 55 years or older or black patients of any age?

A
  • ACE inhibitor + Calcium-channel blocker + thiazide-type diuretic

ADD

  • Further diuretic therapy

OR

  • Alpha-blocker

OR

  • Beta-blocker

Consider seeking specialist advice

BDS1 Cardiovascular System (6 decks)

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