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pharmacology > cardiovascular system > Flashcards

cardiovascular system Flashcards

1
Q

what does the cardiovascular system allow?

A

rapid transport of nutrients (oxygen, amino acids, glucose, fatty acids, water, etc.)The removal of waste products of metabolism (carbon dioxide, urea, creatinine, etc.) Also hormonal control, by transporting hormones to their target organs and by secreting its own hormones (e.g. atrial natriuretic peptide).Temperature regulation occurs by controlling heat distribution between the body core and the skin. It acts as a host defence by transporting immune cells, antigen and other mediators (e.g. antibody).

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2
Q

what does the cardiovascular system consist of ?

A
  • Heart ( biological pump)
  • Blood
  • Blood vessels / vascular system
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3
Q

right ventricle ?

A

from the pulmonary artery travels to the lungs as it is not oxygen rich. and then to the right atrium

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4
Q

arteries ?

A

carry blood away from the heart

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5
Q

veins ?

A

carry blood towards the heart , contain valves.

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6
Q

aorta ?

A

Blood leaves the left ventricle via a single large artery

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7
Q

what do the smallest arteires branch off into?

A

arterioles

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8
Q

blood vessels in order large to small ?

A

artery
arterioles
capillaries
venules

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9
Q

pulmonary semi lunar valve ?

A

located between the left ventricle ( not oxygen rich) and arteries.

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10
Q

atrioventricular AV valves ?

A

Located between the atrium and ventricle in each half of the heart are the which permit blood to flow from atrium to ventricle but not from ventricle to atrium. The right AV valve is called the tricuspid valve, and the left is called the mitral valve.

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11
Q

how does the opening and closing of the valves occur?

A

a passive process resulting from pressure differences across the valves. When the blood pressure in an atrium is greater than that in the ventricle separated from it by a valve, the valve is pushed open and flow proceeds from atrium to ventricle.

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12
Q

posterior vena cava ?

A

large vein that carries de-oxygenated blood from the lower body to the heart , to be transported to the lungs to be oxygenated.

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13
Q

pericardium

A

heart is located within a fluid filled membranous sac which allows it to contract and relax without disrupting the other organs as it is lubricated.

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14
Q

epicardium ?

A

The inner lining of the pericardium which is continuous with the covering of the heart itself

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15
Q

myocardium ?

A

the walls of the heart are composed of these cardiac cells. these are cardiomyocytes.

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16
Q

endocarium ?

A

inner surface of heart walls that are in contact with blood

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17
Q

how are the cardiac musle cells joined ?

A

gap junctions

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18
Q

what does this allow?

A

allow for the spread of excitation from one cell to another. They permit cardiac muscle to function as a whole. The myocardium also contains specialized cells that constitute the Conducting System and are essential for heart excitation.

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19
Q

how are the myocardium supplied with blood ?

A

– The Coronary Arteries

– Coronary Blood Flow

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20
Q

what’s the 2 phases of the cardiac cycle ?

A

– the contractile phase (systole)
– the relaxation (filling) phase
- (diastole) which is passive.

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21
Q

what causes the difference in pressure that allows the blood to be pushed into the heart chambers ?

A

alteration between contraction and relaxation

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22
Q

events leading to contraction ?

A

depolarisation of the plasma membrane which leads to the opening of the voltage gated Ca2+ channels. This allows the Ca2+ ions to flow into the cell from the sarcoplasmic recticlum. This leads to a rise in the cytosolic Ca2+ concentration and a contraction occurs.

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23
Q

what is the sarcoplasmic reticulum ?

A

a membrane-bound structure found within muscle cells that is similar to the endoplasmic reticulum in other cells. The main function of the SR is to store calcium ions (Ca2+).

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24
Q

what contracts first in the heart then what ?

A

atria them immediately the ventricles

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25
Q

the initial excitation of one cardiac cells eventually leads to what ?

A

excitation of all caridac cells due to gap junctions allowing the spread of electrical impulse.

26
Q

where does the initial depolarisation occur ?

A

arises in a small group of conducting- system cells, the sinoatrial (SA) node, located in the right atrium near the entrance of the superior vena cava.

27
Q

from the SA node what occurs next ?

A

The action potential then spreads from the SA node throughout the atria to the AV node

28
Q

where is AV node?

A

base of the right atria

29
Q

speed of propogation of action potentials through the AV node?

A

relatively slow

30
Q

what is the pacemaker for the heart ?

A

the SA node

31
Q

are the cardiac action potentials spontaneous ?

A

yes

32
Q

phase 0 ?

A

an influx of Na+ ions

33
Q

phase 1 ?

A

this is when the Action potential is reached as the threshold has been reached.

34
Q

phase 2?

A

depolarisation occurs as there is an efflux of K+ ions

35
Q

ARP ?

A

absolute refractory period (250ms

36
Q

RRP ?

A

relative refractory period

37
Q

how are the nodal tissues normally controlled ?

A

by the sympathetic and parasympathetic influences branches of the ANS.

38
Q

at rest what branch predominates ?

A

parasympathetic , acetylcholine influences.

39
Q

in terms of permeability to Na and calcium what does sympathetic do ?

A

increases permeability to na and ca which increases HR and lower permeability to K+ ions

40
Q

parasympathetic do to permeability?

A

increases permeability to K+ and decreases to Na and Ca which deceases HR

41
Q

in terms of phase what does SA nodal cells do ?

A

determine the HR by depolarisation

42
Q

equation of Cardiac output?

A

heart rate x stroke volume

43
Q

what is HR normal ?

A

50 to 70 at normal and upto 200 at maximal exercise

44
Q

what is stroke volume ?

A

Volume of blood pumped per contraction

45
Q

end diastolic volume ?

A

volume of blood in ventricle before contraction

46
Q

end systolic volume ?

A

volume of blood in ventricle after contraction

47
Q

stroke volume equation ?

A

SV = EDV – ESV

48
Q

normal SV ?

A

70 and 140ml

49
Q

frank starling principle ?

A

the stroke volume increases with end-diastolic volume (greater filling).This is the Frank-Starling principle. It is increased by expelling more end-diastolic volume

50
Q

what do catecholamines do to the force of contraction ?

A

increase it

51
Q

what happens when norephinephrine binds to B1 adreno-receptor ?

A

This leads to the adenylate cyclase enzyme converting ATP into cAMP which activates Protein Kinase A and ca2+ ions flow through the ion channels. These bind to the troponin and this enchances the actin -myosin interaction which leads to cardiac contractile force and velocity increasing.

52
Q

what is the arterial blood flow regulated by ?

A

baroreceptor and chemoreceptor reflexes. Also due to hormonal control which is long term. Drugs include Vasopressin and angiotensin II

53
Q

equation of arterial blood flow ?

A

cardiac output (CO) x total peripheral resistance (TPR)

54
Q

factors affecting TPR ?

A

– depends on blood viscosity

– depends on arteriolar radius (resistance  1/r4)

55
Q

what does equation mean ?

A

Arterial radius equation means that a small change in the diameter can cause a large change in the resistance.

56
Q

normal rate ?

A

120/80mmHg

57
Q

if the stroke volume increases what else increases ?

A

causes cardiac output to also increase as well as the arterial blood pressure.

58
Q

if blood viscosity increases and arterial diameter decreases what happens ?

A

peripheral resistance to increase and the arterial resistance.

59
Q

acetylcholine effect on the heart?

A

Acetylcholine slows heart rate through making the slope of “phase 4” depolarisation shallower on the SA node – hence reaching threshold later – through an action on muscarinic receptors (M2).

Noradrenaline and adrenaline does the opposite on the SA node but through an action on beta receptors (beta 1). In addition noradrenaline and adrenaline act on cardiomyocytes to increase intracellular calcium and increase contractility, this is also through beta 1 receptors.

60
Q

propanolol effect on heart ?

A

Propranolol is a beta receptor antagonist (non selective – so blocks all beta receptors). On the heart propranolol blocks the effect of noradrenaline and adrenaline on both the SA node and cardiomyocytes. As these catecholamines both steepen the slope on phase 4 depolarisation, the effect of propranolol is to make the slope shallower and increase the time it takes for the membrane potential to reach threshold. Hence rate will be reduced and any stress induced release of adrenaline and noradrenaline will be blunted

pharmacology (21 decks)

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