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Anatomy 2FF3 > Cardiovascular Physiology > Flashcards

Cardiovascular Physiology Flashcards

1
Q

Characteristics of cardiac muscle tissue

A

Made up of cardiac cells –> individual cells but work as one unit

Has intercalated discs: connects ends of muscle cells to each other

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2
Q

What is found in the intercalated discs?

A

Desmosomes: type of cell junction that holds fibers together

Gap junctions: allow action potentials to conduct from 1 muscle fibre to its neighbour

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3
Q

Importance of the SA node

A

Natural pacemaker of the heart –> initiates AP 100/min

Nerve impulses from ANS + hormones can modify the speed

APs from SA node go throughout both atria via gap junctions + excite contractile fibers

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4
Q

Importance of the AV node

A

Located in the interatrial septum

AP slows down here (has smaller fibers + less gap junctions)

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5
Q

Why is it important that the AP slows down at the AV node?

A

The delay allows for the atria to empty their blood into the ventricles

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6
Q

What happens if the SA node gets damaged?

A

AV node picks up pace making tasks (at a slower rate)

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7
Q

Purpose of AV bundle

A

So AP can conduct from atria –> ventricles

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8
Q

Where are the R + L bundle branches found?

A

They extend down through the interventricular septum toward the heart apex

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9
Q

Purpose of purkinje fibers

A

APs rapidly conduct from heart apex –> ventricular myocardium

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10
Q

How to inotropes work?

A

A substance that alters the movement of calcium through its channels (affects strength of heart contractions)

Positive inotrope = more calcium (epinephrine)

Negative inotrope = less calcium

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11
Q

What does the P wave represent?

A

Small wave –> atrial depolarization

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12
Q

What does the QRS complex represent?

A

Depolarization of the ventricles (repolarization of the atria also occur; masked)

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13
Q

What does the T wave represent?

A

Ventricular repolarization

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14
Q

De/repolarization and heart muscle

A

Depolarization = contraction of heart muscle

Repolarization = relaxation of heart muscle

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15
Q

S1 heart sound

A

AV valve closure

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16
Q

S2 heart sound

A

SL valve closure

17
Q

S3 heart sound

A

Ventricular filling

18
Q

S4 heart sound

A

Atrial systole

19
Q

What are isovolumetric contractions?

A

Ventricles have started to contract but no change in volume

20
Q

What is isovolumetric contraction?

A

When all 4 valves are closed

21
Q

What is stroke volume?

A

Volume of blood ejected from LV/RV into aorta/PT

SV = EDV - ESV

22
Q

Which ventricle expels more volume?

A

They expel the same BUT L side has to travel farther –> more force

23
Q

What is cardiac output?

A

Volume of blood ejected from the LV/RV into aorta/PT

CO = HR x SV

24
Q

What is cardiac reserve?

A

Cardiac output (max) - CO (at rest)

In healthy youth, max is 4x the rest output

25
Q

Factors that regulate stroke volume (x3)

A
  1. Preload = degree of stretch on heart before contraction
  2. Contractility = force of contraction on individual muscle fibers
  3. Afterload = pressure ventricles must overcome before SL valves open
26
Q

Preload

A

More blood in ventricles = larger EDV = more stretch = larger output

Muscle stretch is proportionate to EDV

27
Q

Changes to preload

A

Heart rate: slow HR = longer ventricle diastole = more filled = more stretch

Venous return = more blood going into heart = more stretch

28
Q

Contractility

A

Intrinsic ability of myocardium to contact

Strength of contraction at any given time

29
Q

What changes heart contractility?

A

Calcium!

Positive inotropes = epinephrine

Negative inotropes = hypoxia, acidosis

30
Q

Afterload

A

Pressure ventricles must overcome before SL valves open

31
Q

Factors that affect after load (x2)

A

Blood pressure = increased = increased afterload

Vessel structure = narrow = increased afterload

32
Q

What does an increased afterload mean?

A

Decreased in SV and more blood will remain in ventricles

33
Q

Factors that regulate heart rate (x4)

A

ANS = sympathetic = increase

Chemical regulation = epinephrine & calcium = increase

Age = young age = increase

Increased body temp = increase

34
Q

Nervous system control of the heart

A

CV center on medulla oblongata

Affects rates of spontaneous depolarization in SA and AV nodes

Sympathetic stimulation can increase contractility and stroke volume

Anatomy 2FF3 (26 decks)

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