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Flashcards in REVIEW Deck (110)
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1

Syncitium

All of the muscle fibers contract as one (do not act individually)

2

Fibrous insulator

Surrounds AV valve openings between the atria and ventricles
- helps separate contractions, so atria goes before ventricles

3

How does blood come back through the venous system?

Enters thru superior/inferior vena cava (carries oxygen poor blood from the body ---> right atrium --> tricuspid valve (AV valve) --> right ventricle--> pulmonary valve --> pulmonary artery (off to the lungs) --> pulmonary vein (empties oxygen rich blood) --> left atrium --> mitral valve (bicuspid, left AV) --> left ventricle --> aortic valve --> aorta --> body

4

Pulmonary artery

Only place where deoxygenated blood is
- also occurs in the placenta for a short period of time

5

Pulmonary vein

Carries oxygenated blood

6

What are the semilunar valves?

Aortic (left) and pulmonary (right) valves
- 3 cusps (resembles Mercedes logo)

7

What are the bicuspid valves?

Just the mitral valve!
- has 2 triangular flaps

8

What are the tricuspid valves?

Right AV valve
- 3 irregular flaps

9

Where is contraction actually happening during the action potential curve?

The peak/plateau

10

Ventricular muscle AP

- phase 0: fast Na channels open, then slow Ca channels
- phase 1: K channels open (tip of peak)
- phase 2: Ca channels open more (plateau)
- phase 3: K channels open more (end of peak)
- phase 4: resting membrane potential

11

What is the difference between conduction system and cardiomyocytes?

Conduction system has slow, leaky Ca channels that are not found in cardiac myocytes (just fast Na channels)

12

Systole

Muscle stimulated by action potential and contracting

13

Diastole

Muscle reestablishing Na/K/Ca gradient and is relaxing

14

EKG

P: atrial wave
QRS: ventricular complex
T: ventricular repolarization

15

Right atrial pressure

Is generally low! (located on the low pressure side)
- diastole: blood comes in from great veins, passes thru ventricles
- contraction does not change pressure much
- when valves bulge back during peak of compression is the area of highest pressure

16

Ventricular pressure

- diastole: raises pressure slightly
- systole: isovolumic metric pressure (volume is not changing, just pressure)

17

Ventricular pressure needs to be higher than ______ in order to eject blood into the aorta

Aortic pressure

18

Aortic pressure

Peaks with ejection peak
- systole: aorta stretches to accomodate increase in volume
- elastic muscle maintains pressure, does not go back to 0 until you reach diastole

19

Incisura

At the start of relaxation, aortic valve closes and blood runs backward in the aorta

20

Sounds of the heart

- S1: AV valves close (start of systole)
- S2: aortic/pulmonic valves close
- S3: hear if you have watery blood splashing
- S4: end of diastole when atria contract (not heard unless you have hypertension)

21

Ejection fraction

Amount of blood that comes out
- should be around 60%
- used to calculate cardiac output

22

Cardiac output

Stroke volume x heart rate

23

Frank-Starling mechanism

Within physiological limits, the heart pumps all the blood that comes to it without excessive damming in the veins
- extra stretch on cardiac myocytes makes actin and myosin filaments interdigitate to a more optimal degree for force generation

24

Does the Frank-Starling mechanism have a limit?

Yes!
- if you bring back more blood than max cardiac output, you get backflow of blood

25

If you _____ cardiac muscle, then it performs more efficiently and you have stronger contractions

Stretch

26

Pathway of heartbeat

Begins in SA node --> internodal pathway to AV node --> impulse delayed in AV node (allows atria to contract 1st) --> AV bundle takes impulse into ventricles --> left and right bundles of Purkinje fibers take impulses to all parts of ventricles

27

What is the slowest place in the conduction pathway?

AV node! It pierces fibrous insulator to get signal into ventricles
- AV bundle is second slowest
- Purkinje fibers are the fastest (have to go the farthest in the shortest amount of time)

28

Conduction system

Regular, spontaneous action potentials (depolarization)
- SA node is the fastest (leakiest) to fire
- AV node next fastest to fire
- Purkinje fibers third fastest to fire

29

Conductance

Speed at which action potential is passed to the next cell
- Purkinje fiber is the fastest
- SA node/internodal pathways: medium speed
- AV bundles: medium slow
- AV node: slowest

30

Rhythmical discharge of sinus nodal fiber

Na leak causes resting potential to slowly increase to -40 (threshold) --> slow Ca channels open --> K channels open more --> after peak, it hits the sinus nodal fiber --> goes back to -50