S1 Pharmacology > Cardiac Structure > Flashcards

Cardiac Structure Flashcards

(62 cards)

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1
Q

What is the innermost layer of the heart ?

A
  • endocardium
  • lines heart chambers + is coninuous with blood vessels
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2
Q

What is the middle layer of the heart ?

A
  • myocardium
  • thick + muscular layer = responsible for pumping blood
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3
Q

What is another name for the epicardium + where is it located ?

A
  • epicardium is also called visceral pericardium
  • outermost layer of the heart + part of serous membrane
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4
Q

What is the pericardial cavity ?

A
  • space between the visceral + parietal pericardium
  • fluid-filled to reduce friction
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5
Q

What are the 2 layers of the serous pericardium + what are there roles ?

A
  • visceral pericardium (epicardium) = lines surface of the heart
  • parietal pericardium = lines internal surface of fibrous pericardium
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6
Q

What does it mean that the heart tissue is “continuous with blood vessels”?

A
  • endocardium (inner heart lining) is directly connected to the lining of the blood vessels
  • ensuring smooth blood flow
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7
Q

Why is the myocardium of the left ventricle much thicker than the right ?

A
  • left pumps blood to rest of the body
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8
Q

What supplies blood to the heart ?

A
  • the coronary artery supplies oxygenated blood to the heart
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9
Q

Where do the coronary arteries branch off from ?

A
  • coronary arteries branch off from aorta
  • they branch into smaller vessels
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10
Q

How does coronary artery disease arise ?

A
  • when coronary artery cannot deliver blood adequately often due to plaque in arterial walls
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11
Q

What is myocardial infarction ?

A
  • blood supply to heart is completely blocked off so muscle dies
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12
Q

What are the functions of the pericardium ?

A
  • protects and anchors the heart
  • prevents overfilling of blood in heart
  • allows for heart to work in friction-free environment
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13
Q

What is the pericardium + what 2 things is it composed of ?

A
  • pericardium is double-walled sac around heart
    Made of :
  • superficial fibrous pericardium
  • deep two-layer serous pericardium (visceral + parietal )
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14
Q

What are the 2 circuits of the heart + what are there functions ?

A
  • pulmonary circuit - blood to and from lungs
  • systemic circuit - blood to and from rest of the body
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15
Q

Why are arteries considered as pressure vessels ?

A
  • maintain high pressure to carry blood away from heart
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16
Q

Why are veins considered capacitance vessels ?

A
  • can distend (expand) to match various blood volumes
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17
Q

What is the cardiac cycle ?

A
  • electrical, pressure and volume changes that occur in functional heart between two heart beats
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18
Q

What is the diastolic phase ?

A
  • myocardium is relaxing
  • allows chambers to fill with blood
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19
Q

What is the systolic phase ?

A
  • myocardium contracting
  • pumps blood out the chambers
  • systole = sounds like squeezing
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20
Q

What happens during atrial diastole ?

A
  • atria are relaxed
    • Blood flows passively from veins into the atria and into the ventricles (80% of blood flow).
    • AV valves are open.
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21
Q

What happens during atrial systole ?

A

• Atria contract, increasing pressure.
• 20% of blood is pumped into ventricles.
• AV valves remain open.

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22
Q

What occurs during ventricular filling ?

A

• 80% of blood flows passively into ventricles.
• Atrial systole pumps the remaining 20% into the ventricles.
• AV valves remain open.

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23
Q

What occurs during ventricular systole ?

A
  • AV valves close due to increased ventricular pressure, producing the “lubb” sound.
  • Isovolumetric contraction phase = volume stays the same (see separate flashcard)
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24
Q

What is the isovolumetric contraction phase ?

A
  • Ventricles contract, no blood leaving (pressure too low to open semilunar valves)
    – Ventricular ejection phase opens semilunar valves
    • Ventricular pressure»_space; pressure in arteries
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25
What occurs during ventricular diastole ?
- Ventricles relax; blood backflow, closes semilunar valves (“dubb”) - Blood once again flowing into relaxed atria and passively into ventricles
26
What causes the ‘lub’ sound + where is it loudest ?
- closure of AV valves - loudest at the cardiac apex
27
What causes the ‘dub’ sound + where is it the loudest ?
- closing of the SLV - Loudest at the base of the heart
28
Where is the tricuspid valve located ?
- between right atrium + right ventricle - has 3 cusps
29
Where is the bicuspid valve located ?
- between left atrium + left ventricles - has 2 cusps
30
blood flow through the heart
deoxygenated blood: - superior + inferior vena cava - right atrium through - tricuspid valve - right ventricles - pulmonary SLV - pulmonary artery - lungs Oxygenated blood: - pulmonary vein - left atrium - bicuspid valve - left ventricle - aortic SLV - aorta - body
31
Where is the aortic SLV located ?
- between left ventricle and aorta
32
Where is the pulmonary SLV located ?
- between right ventricle and pulmonary artery
33
What is the pulse ?
- surge of pressure in artery
34
What is tachycardia ?
- resting heart rate more than 100 bpm - caused by stress, drugs, heart disease
35
What is bradycardia ?
- heart rate less than 60 bpm - in sleep and endurance trained athelets
36
What are premature atrial contractions ?
- Occasional shortened intervals between one contraction and next (frequently occurs in healthy people)
37
What is the stroke volume ?
- volume of blood pumped by a ventricle per beat
38
What is the equation for calculating stroke volume ?
SV= end diastolic volume (EDV) - end systolic volume (ESV)
39
What is end diastolic volume (EDV) ?
- amount of blood in a ventricle at end of diastole
40
What is end systolic volume (ESV) ?
- amount of blood remaining in a ventricle after contraction
41
What is ejection fraction ?
% of EDV pumped by the ventricle
42
What is cardiac output + equation ?
- amount of blood pumped by each ventricle in one minute CO = HR x SV (ml/min) = (beats/min) x (ml/beat)
43
What factors affect heart rate ?
- autonomic innervation - ANS - hormones eg. Adrenaline
44
What factors stroke volume ?
- EDV + ESV
45
What is blood pressure ?
- force exerted by blood against blood vessel walls
46
What role do baroreceptors play in blood pressure regulation?
- Baroreceptors detect changes in blood pressure - increased pressure stretches the receptors - activating the vagus nerve - triggers the parasympathetic system to lower blood pressure.
47
When is blood pressure highest and lowest during the cardiac cycle?
- Highest during ventricular systole (when the ventricles contract). • Lowest during ventricular diastole (when the ventricles relax).
48
What factors increase blood pressure ?
- increased blood volume - increased heart rate - increased stroke volume - increased blood viscosity - increased peripheral resistance
49
What is preload ?
- tension applied before the muscle performs any work - equal to EDV - increasing in filling pressure (more blood entering the heart) = increased preload
50
What is afterload ?
- load that preloaded muscle has to work against - resistance ventricles must overcome to circulate blood into arteries/aorta - associated with ventricular wall stress after systolic ejection - estimated using VWS = Pressure x radius / 2 (wall thickness)
51
How does preload affect cardiac output ?
- increased preload (more blood in ventricles) = increased cardiac output
52
What is the Frank-Starling mechanism ?
- increased venous return (blood returning to heart) increases EDV which increases preload - preload is initial stretching of cardiac myocytes prior to contraction - as myocytes stretch they generate more force so increased stroke volume (pump out more blood)
53
How does afterload affect cardiac output ?
- increased afterload = decreased cardiac output - increased afterload (e.g., higher blood pressure or narrowed arteries) makes it harder for the heart to pump blood.
54
How does contractility affect cardiac output ?
- increased contractility = increased cardiac output
55
What is hypertension ?
- arterial pressure too high - heart has to work harder - left ventricle enlarges
56
What is the treatment for hypertension ?
- Change lifestyle factors • Drug therapy to reduce heart rate • Ca2+ channel blockers; reduce calcium flow into heart muscle and thus heart rate • Beta blockers (reduce stimulation by sympathetic nervous system) • Diuretics reduce blood volume • **ACE inhibitors interfere with renin- angiotensin pathway** - vasodilators
57
What is renin and when is it secreted ?
- secreted by the kidney in response to reduced blood pressure or blood volume
58
What is angiotensin and how is it formed ?
- Renin converts Angiotensinogen —> Angiotensin I
59
What is role of Angiotensin Converting-Enzyme (ACE) ?
- converts Angiotensin I —> Angiotensin II
60
What are the actions of angiotensin II in regulating blood pressure ?
- **Intense vasoconstriction** —> increases blood pressure • release of **Aldosterone** from adrenal cortex -> promotes **Na+ and H2O reabsorption** in kidney —> cause **increased blood volume** • Regulatory **negative feedback** on the release of **Renin**. • CNS: Stimulate thirst in hypothalamus, stimulate sympathetic outflow - increases **ADH secretion** from pituitary gland more H20 absorption
61
What do ACE inhibitors do to RAAS pathway ?
- inhibit formation of angiotensin II - decrease release of aldosterone - so less Na+ + H20 reabsorbed - so decreased blood volume = decreased blood pressure
62
What do ACE receptor blockers do ?
- Block angiotensin receptors on blood vessels and adrenal cortex • Produce vasodilation and decrease the activity of aldosterone
S1 Pharmacology
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