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Heart, Lungs and Blood > physiology of the cardiovascular system > Flashcards

physiology of the cardiovascular system Flashcards

1
Q

What are the components of the cardiovascular system?

A

Cardiopulmonary unit
- Left side and right side
- Pulmonary artery and vein
- Arteries, arterioles, capillaries, venules and veins
- Portal systems
- Hepatic portal system
- Hypothalmus and anterior pituitary (hypopyseal)
- Intra-renal circulation
- Intra-cranial circulation
- Intra-coronary circulation

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2
Q

What is the function of the cardiovascular system?

A
  • Rapid convective transport of
    • Oxygen
    • Glucose
    • Amino acids and fatty acids
    • Vitamins
    • Water
    • Waste products of metabolism e.g. carbon dioxide, urea and creatine
  • Homeostatic control
    • Hormones
    • Temperature
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3
Q

What is the cardiopulmonary unit?

A

The cardiopulmonary unit includes the heart and lungs, which work together to pump oxygen-poor blood to the lungs and oxygen-rich blood to the rest of the body. The cardiopulmonary unit is responsible for oxygenating the blood and removing carbon dioxide.

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4
Q

What is stroke volume?

A

Stroke volume is the volume of blood pumped by the left ventricle per beat.
denoted as SV

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5
Q

What is cardiac output?

A

Cardiac output is the volume of blood pumped by the heart per unit time, measured in L/minute.
Denoted as Q

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6
Q

What is perfusion?

A

Perfusion is the passage of blood through the circulatory system to the body’s tissues, measured in mL of blood per minute per gram of tissue.

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7
Q

What is preload?

A

Preload is the degree to which the ventricles are filled at the end of diastole, just prior to systolic contraction, measured as end-diastolic volume in mL.
denoted as EDV

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8
Q

What is contractility?

A

Contractility is the innate ability of the myocardium to contract.

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9
Q

What is afterload?

A

Afterload is the resistance against which the left ventricle must eject the stroke volume from the heart, measured as aortic pressure during systole divided by cardiac output.

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10
Q

What is compliance?

A

Compliance is the ability of a blood vessel to expand and contract with changes in pressure, measured as unit of volume change per unit of pressure change.
denoted as C

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11
Q

Where is the initiation of heart rate located?

A

The initiation of heart rate is located in the atria through the atrial reflex.

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12
Q

What are the electric signals that affect heart rate?

A

The electric signals that affect heart rate are from the conduction system of the heart.

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13
Q

What are the two main factors that affect heart rate?

A

The two main factors that affect heart rate are autonomic innervation and hormones.

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14
Q

What is venous return?

A

Venous return is the amount of blood returning to the heart.

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15
Q

What does preload refer to?

A

Preload refers to the degree to which the ventricles are filled at the end of diastole, just prior to systolic contraction.

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16
Q

What is filling time?

A

Filling time is the time taken for blood to return to the heart.

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17
Q

What is afterload?

A

Afterload is the resistance against which the left ventricle must eject the stroke volume from the heart.

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18
Q

What are the main factors that affect stroke volume?

A

The main factors that affect stroke volume are venous return, filling time, autonomic innervation, hormone release, and vasoconstriction or vasodilation.

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19
Q

What is venous return, and how does it affect stroke volume?

A

Venous return refers to how full the circulation is and is a measure of the filling volume. It is the primary determinant of preload, or the end-diastolic volume, and affects stroke volume because a more full circulation leads to a larger stroke volume.

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20
Q

What is filling time, and how does it affect stroke volume?

A

Filling time refers to how quickly the blood is returning, and it also affects stroke volume. This is because a longer filling time leads to a larger preload, which increases the end-diastolic volume and ultimately increases the stroke volume.

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21
Q

How does autonomic innervation affect stroke volume?

A

Autonomic innervation affects stroke volume through its impact on the tone of the heart, or how hard the heart is contracting. Increased contractility leads to a smaller end-systolic volume, which ultimately increases the stroke volume.

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22
Q

How do hormones affect stroke volume?

A

Hormones generally increase stroke volume by increasing the speed and force of contraction, which reduces the end-systolic volume and leads to a larger stroke volume.

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23
Q

How does vasodilation or vasoconstriction affect stroke volume?

A

Vasodilation or vasoconstriction affects stroke volume through its impact on afterload, or the resistance against which the left ventricle must eject the stroke volume from the heart. Higher resistance increases the workload of the heart and leads to a larger end-systolic volume, which ultimately decreases the stroke volume.

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24
Q

What is the formula for calculating stroke volume?

A

Stroke volume is equal to end-diastolic volume (EDV) minus end-systolic volume (ESV): SV = EDV - ESV.

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25
Q

What is the cardiac pacemaker that initiates heart rate?

A

The cardiac pacemaker that initiates heart rate is the SA node.

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26
Q

What are the two divisions of the autonomic nervous system that influence heart rate?

A

The two divisions of the autonomic nervous system that influence heart rate are the sympathetic nervous system and the parasympathetic nervous system.

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27
Q

How does the sympathetic nervous system affect heart rate?

A

The sympathetic nervous system increases heart rate.

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28
Q

How does the parasympathetic nervous system affect heart rate?

A

The parasympathetic nervous system decreases heart rate.

29
Q

What are the two hormones that increase heart rate?

A

The two hormones that increase heart rate are epinephrine and norepinephrine.

30
Q

What is the effect of thyroid hormone on heart rate?

A

Thyroid hormone increases heart rate.

31
Q

What is the Frank-Starling mechanism?

A

The Frank-Starling mechanism is a mechanism by which the stroke volume of the heart increases in response to an increase in the volume of blood in the ventricles before contraction when all other factors remain constant.

31
Q

What is the Bainbridge reflex?

A

The Bainbridge reflex is an increase in heart rate due to increased blood volume in the atria.

32
Q

What is the Frank-Starling mechanism?

A

The Frank-Starling mechanism is a mechanism by which the stroke volume of the heart increases in response to an increase in the volume of blood in the ventricles before contraction when all other factors remain constant.

33
Q

What causes the Frank-Starling mechanism?

A

The Frank-Starling mechanism is caused by the length-tension relationship of cardiac muscle fibers.

34
Q

What is the length-tension relationship of cardiac muscle fibers?

A

The length-tension relationship of cardiac muscle fibers is the relationship between the degree of stretching of the muscle fibers and the force of contraction that they can generate.

35
Q

What is the significance of the Frank-Starling mechanism?

A

The Frank-Starling mechanism allows the heart to increase its stroke volume in response to an increase in venous return, which allows the heart to meet the body’s increasing demand for oxygen.

36
Q

What is a pressure-volume diagram?

A

A pressure-volume diagram is a graph that shows the relationship between the pressure and volume of a gas or fluid at different stages of a process.

37
Q

What is the significance of a pressure-volume diagram in cardiology?

A

A pressure-volume diagram can be used to visualize the changes in pressure and volume that occur during the cardiac cycle, which can provide insights into the function of the heart.

38
Q

What is the x-axis of a pressure-volume diagram in cardiology?

A

The x-axis of a pressure-volume diagram in cardiology represents volume

39
Q

What is the y-axis of a pressure-volume diagram in cardiology?

A

The y-axis of a pressure-volume diagram in cardiology represents pressure.

40
Q

What are the different components involved in the extrinsic control of the circulation?

A

Autonomic vasomotor nerves, renin-angiotensin-aldosterone, epinephrine (adrenaline), antidiuretic hormone/arginine vasopressin, natriuretic peptides, other hormonal control, and sensory nerve vasodilation

41
Q

What are the components of the autonomic nervous system?

A

Brainstem, cranial nerves and sacral outflow, end organ ganglia, preganglionic fibers (ACh), spinal ganglia, postganglionic fibers (NA), and distant ganglia (coeliac and hypogastric ganglia and the adrenal medulla) (ACh).

42
Q

What is the resting heart rate in the absence of extrinsic control of the heart, and what system predominates to decrease it during rest and sleep?

A

The resting heart rate in the absence of extrinsic control of the heart is approximately 100 bpm. During rest and sleep, the parasympathetic nervous system predominates and decreases the heart rate to a resting rate of 60-75 bpm.

43
Q

What is the role of the sympathetic nervous system in controlling the cardiovascular system?

A

The sympathetic nervous system prepares the body for energy expenditure, emergency, or stressful situations. Sympathetic stimulation increases heart rate and myocardial contractility.

44
Q

How do most blood vessels regulate their diameter, and what allows for vasodilation?

A

Most blood vessels lack parasympathetic innervations and their diameter is regulated by sympathetic nervous system input, so that they have a constant state of sympathetic tone. A decrease in sympathetic stimulation or tone allows vasodilation.

45
Q

How do the opposing actions of the sympathetic and parasympathetic nervous systems affect the cardiovascular system, and what is the net effect at any given time?

A

Most organs receive innervations from both systems, which usually exert opposing actions. At any given time, the effect of the autonomic nervous system on the heart is the net balance between the opposing actions of the sympathetic and parasympathetic systems.

46
Q

What are the functions of sympathetic receptors in the heart?

A

α1: Inotropy, Chronotropy, Dromotropy
α2: Vasoconstriction
β1: Inotropy, Chronotropy, Dromotropy
β2: Inotropy, Chronotropy, Dromotropy

47
Q

What are the functions of sympathetic receptors in the vessels?

A

α1: Vasoconstriction
β2: Vasodilation

48
Q

What are the functions of parasympathetic receptors in the heart?

A

M2: No effect

49
Q

What are the functions of parasympathetic receptors in the vessels?

A

α1: No effect
β2: No effect

50
Q

What is the function of the α1 receptor in the heart and vessels?

A

In the vessels, the α1 receptor causes vasoconstriction. In the heart, it increases inotropy, chronotropy, and dromotropy.

51
Q

What is the function of the α2 receptor in the heart and vessels?

A

In the vessels, the α2 receptor causes vasoconstriction. It has no effect on the heart.

52
Q

What is the function of the β1 receptor in the heart and vessels?

A

In the vessels, the β1 receptor has no effect. In the heart, it increases inotropy, chronotropy, and dromotropy.

53
Q

What is the function of the β2 receptor in the heart and vessels?

A

In the vessels, the β2 receptor causes vasodilation. In the heart, it increases inotropy, chronotropy, and dromotropy.

54
Q

What is the function of the M2 receptor in the heart and vessels?

A

The M2 receptor has no effect on the vessels or the heart.

55
Q

What is Inotropy?

A

Inotropy refers to the force of muscular contraction of the heart.

56
Q

What is Chronotropy?

A

Chronotropy refers to the rate of contraction of the heart.

57
Q

What is Dromotropy?

A

Dromotropy refers to the conduction velocity of the electrical impulses in the heart.

58
Q

What is the Renin-Angiotensin-Aldosterone system (RAAS)?

A

The Renin-Angiotensin-Aldosterone system (RAAS) is a hormonal system that regulates blood pressure, fluid and electrolyte balance, and systemic vascular resistance.

59
Q

Where is renin mainly released from?

A

Renin is mainly released from Juxtaglomerular cells in the afferent arteriole of the renal glomerulus.

60
Q

What stimulates the release of renin?

A

Renin release is stimulated by sympathetic nerve activation (acting through β1-adrenoceptors), renal artery hypotension (caused by systemic hypotension or renal artery stenosis), and decreased sodium delivery to the distal tubules of the kidney sensed by cells in the Macula Densa.

61
Q

What does angiotensin converting enzyme (ACE) do?

A

Angiotensin converting enzyme (ACE) cleaves angiotensin I to form angiotensin II. ACE is found in vascular endothelium, especially in the lungs, and in other tissues as well.

62
Q

What are the effects of angiotensin II on the cardiovascular system?

A

Angiotensin II constricts resistance vessels, increases systemic vascular resistance, and stimulates sodium and water retention by the body. It also acts on the adrenal cortex to release aldosterone, stimulates the release of vasopressin, and facilitates norepinephrine release from sympathetic nerve endings. Additionally, it stimulates cardiac and vascular hypertrophy.

63
Q

What is the role of aldosterone in the RAAS?

A

Aldosterone is a steroid hormone produced by the adrenal cortex in response to angiotensin II. Its main role is to increase sodium and water retention in the body by stimulating the distal tubules and collecting ducts of the kidneys to reabsorb sodium and excrete potassium. This leads to an increase in blood volume and blood pressure.

64
Q

What are the physiological effects of the RAAS?

A

The RAAS helps to regulate blood pressure, fluid and electrolyte balance, and cardiovascular function. Its effects include vasoconstriction, sodium and water retention, release of aldosterone and vasopressin, and stimulation of sympathetic nervous system activity.

65
Q

What is the role of aldosterone in plasma volume control?

A

Aldosterone increases the amount of sodium reabsorbed from the distal tubule and collecting duct of the kidney, and increases the amount of water reabsorbed as well, fine-tuning absorption and increasing blood pressure.

66
Q

How does epinephrine affect the cardiovascular system?

A

Epinephrine stimulates all major adrenergic receptors including alpha 1 and 2 and beta 1 and 2 receptors, causing vasoconstriction and increasing heart rate and contractility.

67
Q

What is the role of ADH/arginine vasopressin in plasma volume control?

A

ADH is released in response to a reduction in plasma volume, and causes arteriolar vasoconstriction via V1 receptors and increases the amount of water reabsorbed from the renal tubules via V2 receptors.

68
Q

What are natriuretic peptides and how do they affect plasma volume?

A

There are two types of natriuretic peptides, ANP and BNP, produced by the heart mainly in response to atrial distention. They act to increase renal sodium excretion in response to increased stretching of the atria due to increased atrial blood volume.

Heart, Lungs and Blood (51 decks)

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