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Pharmacology > Cardiovascular physiology > Flashcards

Cardiovascular physiology Flashcards

1
Q

What is the flow of blood in the body

A
  • From the body to the Vena cava
  • Vena cava to the right atrium
  • RA to the the RV
  • RV to the pulmonary artery
  • Pulmonary artery to the lungs
  • Lungs to the pulmonary veins
  • To the left atrium
  • To the left ventricle
  • to the aorta
  • To the body
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2
Q

Meaning of diastole

A

Relaxation of the muscle

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3
Q

Meaning of systole

A

Contraction of the muscle

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4
Q

What is the flow of blood directly proportional to

A

Change in pressure. So the more blood that flows through a vessel, the higher the pressure.

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5
Q

What is stroke volume

A

The volume of blood that is pumped by one ventricle

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6
Q

What is cardiac output

A

Cardiac output is the volume of blood pumped in a minute per ventricle

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7
Q

What is Venus return

A

The volume of blood returning back to the heart
It should = cardiac output

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8
Q

How do action potentials cause ventricular/ atrial contractions

A
  • AP from adjacent cell causes volume gated CA2+ channels to open
  • ca2+ enters
  • this causes the sarcoplasmic reticulum to release ca 2+
  • the ca2+ binds so troponin causing contraction
  • the ca2+ unbinds causing relaxation
  • ca2+ is pumped back into the sarcoplasmic reticulum
  • ca2+ is exchanged for na+
  • na+ concentration is maintained by na+/k+ ATPase
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9
Q

What is the intercalated disk

A

It’s a disk that holds together numerous cardiomyocytes (singular building block of cardiac muscle) and causes synchronised contractions

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10
Q

In what type of muscle cells are intercalated disks found

A

Only cardiac muscles

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11
Q

What is the flow of electrical current in the heart

A
  • sinoatrial node
  • atrioventricular node
  • bundle of his
  • purkinje fibres
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12
Q

What is an ECG

A

Electrocardiography, electrodes are placed on the skin and measure the voltage produced by the heart against time

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13
Q

How is the cardiac output calculated

A

Stroke volume x heart rate

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14
Q

What determines the heart rate

A

The rate of depolarisation of autorhythmic cells

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15
Q

What slows down the heart rate

A

The parasympathetic nervous system

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16
Q

What increases the heart rate

A

The sympathetic nervous system

17
Q

What determines the stroke volume

A

The strength of the contraction of the ventricular myocardium (muscles)

18
Q

What influenced the strength of ventricular muscle contraction

A
  • Length/ tension relationship, ( if the muscles can reach a a length where it can produce its highest contractile force)
  • Contractility, changes in stroke volume without there being a change in the resting ventricular muscle length
19
Q

What are chronotropic effects

A

Effects that change the heart rate

20
Q

What transmitter causes a sympathetic effect on the body

A

Noradrenaline

21
Q

What transmitter has a parasympathetic effect on the body

A

Acetylcholine

22
Q

What happens when a sympathetic transmitter is released

A
  • Noradrenaline binds to the b1 noradrenaline receptor on the SA node and the myocyte membranes
    -this causes the opening of HCN (hydrogen cyanide) channels in the SA node which increases the influx of NA+
  • this then causes the ca2+ channels to open and so more ca2+ enters
    This results in more depolarisation and so the heart rate increase
23
Q

What happens when the parasympathetic transmittter is released

A
  • Acetylcholine is released and binds to cholinergic receptors
  • this reduces the amount of NA+ entering the cell
  • decreasing the amount of ca2+ Chanel’s opening so less ca2+ entering
  • this opens more k+ ligand gated Chanel’s so more k+
    Thus the heart rate slows down as less myocardial contraction
24
Q

What is vagal tone

A

A measure of the parasympathetic input into the heart rate.
The vagus is involved in the parasympathetic autonomic nervous system that reduces heart rate

25
Q

What is the sequences of the cardiac cycle

A

1)ventricular diastole
2) atriall systole
3) isovolumic ventricular contraction, when the ventricular pressure rises above atrial pressure and the mitral (2) valve closes
4) ventricular systole, the ventricle contracts
5) isovolumetric ventricular relaxation, when the pressure in the aorta is higher than in the left ventricle so it causes at aortic valve to close

26
Q

What is preload

A

The degree of stretch/ the length of the ventricular muscles before contracting at the end of ventricular filling

27
Q

What is ejection fraction

A

a fraction of the amount of blood pumped out/ the totoal amount of blood in the heart

28
Q

What is cardiac workload

A

How hard the heart must pump to supply blood to the places that need it

29
Q

What is starlings law of the heart

A

The force of contraction is directly proportional to the length of ventricle muscle during diastole

30
Q

What a re the three stages of starlings law

A
  • Almost empty chamber, the amount of blood doesn’t cause enough stretch so the myosin actin overlap isn’t optimal and cannot produce a lot of force
  • full ventricle, the vol. of blood causes the ventricular muscles to stretch optimally and so the actin/myosin overlap is optimal, there is also a high troponin c affinity to ca2+ and so maximal force can be produced.
31
Q

What are the two types of cardiac workload mechanisms

A

Extrinsic, factors affect the the stroke volume of the heart e.g. sympathetic nervous system causes the SV to increase without a change in the ventricular stretch/ length
Intrinsic, the level of stretch will determine how the SV of the heart and that is set

32
Q

What is extrinsic mechanism of cardiac workload

A

The sympathetic input into he cardiac cycle causes the stroke volume to increase without increasing the initial fibre length, an increase in Contractility.
Catecholamines (hormones made in the adrenal cortex) are responsible for this and cause harder but shorter contractions

33
Q

What controls the mean arterial pressure

A

The cardiac output and the the resistance of the arteries (caused by the diameter of the arteries)
MAP = CO x TPR
Total peripheral resistance

34
Q

What are the 4 ways in which the cardiac output can be effected

A
  • parasympathetic neurons, synapses on the SA and AV node cause the heart rate to drop thus causing the CO to drop
  • sympatheitc neurons, synapses on the SA node cause the heart rate to increase thus causing the CO to increase
  • sympatheitc neurons, synapses on the arteries cause the them to vasoconstric increasing peripheral resistance and so the MAP increases
  • sympatheitc neurons, synapses on the arteries cause the them to venoconstric pushing venous blood into the arteries.
35
Q
A

Pharmacology (17 decks)

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