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Anatomy > Heart physiology > Flashcards

Heart physiology Flashcards

1
Q

Diastolic volume (DV), telediastolic volume (TDV) or end-diastolic volume (EDV)

A

it is the volume of blood within the ventricles at the end of the diastole (120 – 130 ml)

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2
Q

Stroke volume (SV) or ejection volume:

A

total volume of blood ejected during a ventricular systole (70 – 85 ml/beat).

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3
Q

End systolic volume (ESV)

A

volume of blood that remains in the ventricle at the end of the ventricular systole.

ESV = EDV – SV = 130 – 70 = 60 ml

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4
Q

Ejection fraction

A

represents the percentage of EDV (End diastolic volume) blood that is pumped with each heart beat:

EF = (SV/EDV) · 100

This value is around 55% in normal conditions and rises up to 75% during exercise.

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5
Q

Heart rate (HR)-Pulse

A

it is the number of heart beats or contractions per minute (At rest: 70 beats/min, although it may vary between 55 and 100).

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6
Q

Heart minute volume (Vm)

A

it is the volume of blood pumped by the heart in one minute. In a normal adult nearly 6 litres (5600 ml):

Vm = SV · HR

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7
Q

What happens during rest with the cardiac output?

A

At rest the cardiac output is about 5 l/min, but when the metabolic demand increases, the heart is able to increase the heart minute volume between 4 – 7 times.

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8
Q

How can we modulate the cardiac output?

A

The cardiac output can be modulated by intrinsic and/or extrinsic mechanisms that affect the SV or the HR.

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9
Q

How can we change the stroke volume?

A

Due to:

Intrinsic factors

  1. EDV (End diastolic factors)
  2. ESV (End systolic factors)
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10
Q

What are EDV (End diastolic factors)

A

• Venous return (Preload)
• Atrial contraction
• Time for ventricular filling
(duration of the diastole)

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11
Q

What are ESV (End systolic factors) ?

A

Force of ventricular contraction (Contractility)
• Degree of stretch on the heart (Frank-Starling law of the heart)
• Afterload
• State of the semilunar valves

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12
Q

Changes in stroke volume?

A
  • preload
  • contractility
  • afterload
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13
Q

Frank Starling law of the heart

A

The more the heart fills with blood during diastole, the greater force of contraction during systole.
This positive relationship is known as the Frank–Starling Law of the heart.

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14
Q

What are extrinsic factors?

A
  • hormonal changes

- control by the ANS

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15
Q

To what can a hormonal and ANS change lead?

A
  • Contractility of the heart

- Afterload/ peripheral resistance

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16
Q

By which receptors is contractility and peripheral resistance mediated?

A
  • Baroreceptors
  • Mechanoreceptors
  • Chemoreceptors
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17
Q

Which factors can lead to changes in the heart?

A
  • metabolic factors
  • physical activity
  • nervous mechanisms
  • humoral mechanisms
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18
Q

What are metabolic factors?

A
  • Temperature
  • pH
  • Metabolic activity
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19
Q

What do you understand by nervous mechanisms?

A
  • ANS
  • Baroreceptors
  • Mechanoreceptors
  • Chemoreceptors
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20
Q

What are humoral mechanisms?

A

Catecholamines

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21
Q

Afferent/ sensory

A

INPUT to cardiovascular center

  • from higher brain center
  • from propioreceptor
  • from baroreceptor
  • from chemoreceptor
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22
Q

Efferent/ motor

A

OUTPUT to effectors

  • Heart (Parasympathetic and Sympathetic)
  • Blood vessels
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23
Q

What do proprioreceptors do?

A

monitor joint movements

24
Q

What do baroreceptors do?

A

Monitor blood pressure (p-b)

25
Q

What do chemoreceptors do?

A

Monitor blood activity CO2, O2, H+

26
Q

What does the Parasympathetic system do?

A

decrease heart rate

27
Q

What does the sympathetic system do on the heart?

A

increase heart rate and contractility

28
Q

What does the sympathetic system do on the blood vessels?

A

vasocontriction

29
Q

Higher brain structures produce the changes of:

A

cerebral cortex, limbic system, hypotalamus

  • Anticipation of competition
  • Increase in body temperature
30
Q

The peripheral autonomic sensory signals reserve the signals from:

A
  • Mechanoreceptors
  • Baroreceptors
  • Chemoreceptors
  • Proprioreceptors
31
Q

The receptors (Baroreceptor etc.) send afferent signals to….

A

The cardiovascular center

32
Q

Mechanoreceptors

A

In ATRIA AND LARGE VEINS

Detect increases in blood volume.
• Information travels through VAGUS nerve (X) toward medulla oblongata.

Ex: When urine production increases… TRIGGER sympathetic response

33
Q

Baroreceptor

A

In arch of the aorta and carotid sinus

  • Detect changes in blood pressure.
  • VAGUS and GLOSOPHARYNGEAL nerves conduct information to medulla oblongata.

Ex: When BP increases, it is produced… INCREASE of parasympathetic activity DECREASE of sympathetic activity

34
Q

Chemoreceptors

A

In carotid bodies and aorta

Detect changes in PO2, PCO2, and pH.

Ex: When PCO2 increases and pH decreases, the medulla is informed and it is produced…
INCREASE of sympathetic activity DECREASE of parasympathetic activity

35
Q

Proprioreceptors

A

Monitor the position of muscles, joints, ligaments, tendons…
• As physical activity begins, proprioceptors send nerve impulses at an
increased frequency to the cardiovascular center.
• Proprioceptor input is a major stimulus for the quick rise in heart rate that occurs at the onset of physical activity.

Ex: When physical activity begins, it is produced… INCREASE of sympathetic activity

36
Q

In which nerve can we find the Parasympathetic?

A

Vagus nerve X

Causes decrease in heart rate

37
Q

In which nerve can we find the Sympathetic? Regarding to the heart

A

In cardiac accelerator nerves,

Causes increase in contractility and heart rate

38
Q

In which nerve can we find the Sympathetic? Regarding to the blood vessels

A

vasomotor nerve

The sympathetic division also continually sends impulses to smooth muscle in blood vessel walls via vasomotor nerves. The result is a moderate state of tonic contraction or vasoconstriction, called vasomotor

39
Q

How can we increase the heart rate? (syntifical)

A

Increased rate of spontaneous depolarisation in SA node and AV node

40
Q

How can we increase the stroke volume?

A

by increased contractility of atria and ventricles

41
Q

How can we decrease the heart rate?

A

By decreased rate of spontaneous depolarisation in SA node and AV node

42
Q

What does postive chronotropic effect mean?

A

The pacemaker cells increase the heart rate

43
Q

What does positive dromotropic effect mean?

A

The conductive cells increase the conduction speed of the electrical impulse (dromo- Trommel)

44
Q

what does positive entropic effect mean?

A

The contractile cells increase the contractile strength

45
Q

The Sympathetic system acts on:

A

Noradrenaline, ß- receptor and as a positive effect

46
Q

The parasympathetic system acts on:

A

Aceticholine, muscarinic M2 receptor in heart and negative effect

47
Q

What does negative chronotropic effect mean?

A

The pacemaker cells decrease the heart rate

48
Q

What does negative dromotropic effect mean?

A

The conduction cells decrease the conduction speed of the electrical impulse

49
Q

Substances released in blood that act on the smooth muscle of arterioles.

They influence:

A

Atrial pressure: afterload

  • Vasoconstriction
  • Vasodilation
50
Q

What happens after blood pressure falls below normal?

Regarding:

  • Vessels
  • Heart

And how does it happen?

A

Vessels: Vasoconstriction
Heart: increase HR and force of contraction

In Adrenaline and Noradrenaline (Adrenal medulla)
Angiotensin (Kidneys)
Antidiuretic hormone (ADH or vasopressin; hypothalamus). Very potent.
Endothelin (Endothelium)

51
Q

What happens after BP increases above normal?

regarding: vessels

And how does it happen?

A

Vessels: Vasodilation

Nitric oxide (Endothelium) Bradykinin
Histamine
Prostaglandins
Atrial Natriuretic peptide (Atrial myocytes)

52
Q

What happens by sympathetic stimulation?
Regarding:

  • Heart rate
  • Stroke volume
  • cardiac output
A

↑ HR; ↑ SV; ↑ CO

53
Q

What happens by parasympathetic stimulation?

Regarding:

  • Heart rate
  • Stroke volume
  • cardiac output
A

normalizes CO

54
Q

What happens by increase in venous return

Regarding:

  • Heart rate
  • Stroke volume
  • cardiac output
A

normal HR; ↑ SV; ↑ CO

55
Q

What happens by reduction of Heart rate?

Regarding:

  • Heart rate
  • Stroke volume
  • cardiac output
A

↑ EDV; ↑ or ↓ CO

56
Q

What happens by increase of Heart rate?

Regarding:

  • Heart rate
  • Stroke volume
  • cardiac output
A

↓ venous return ↓ SV ↓ CO

57
Q

What happens by exercise?

Regarding:

  • Heart rate
  • Stroke volume
  • cardiac output
A

↑HR↑SV↑CO

Anatomy (7 decks)

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