Cardiac Conduction System & The Cardiac Cycle Flashcards Preview

Honors Anatomy & Physiology > Cardiac Conduction System & The Cardiac Cycle > Flashcards

Flashcards in Cardiac Conduction System & The Cardiac Cycle Deck (30)
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1
Q

Cardiac Cycle

what is it? contraction? avg. bpm @ about? what lets the heart beat?

A

all events that occur during 1 heartbeat
-contraction of atria followed by contraction of ventricles
Avg. 70 bpm, about .85 sec/beat
heart beats due to: Autorythmic Fibers

2
Q

Autorythmic Fibers

def? description? generate? form?

A

special cardiac muscle fibers

  • self-excitable
  • repeatedly generate action potentials
  • form Cardiac Conduction System
3
Q

Cardiac Conduction System

made up of/formed by %? known as? controls? influenced by?

A

1% of cardiac muscle cells form the electrical conduction system of the heart
-natural pacemaker
-controls heart beat rate
can be influenced by ANS
(electrical signal going through heart making heat beat/pump)

4
Q

steps in cardiac conduction system (5)

what transmits the electrical signals?

A

1) Begins in: SA node (sinoatrial node)
2) AV node (atrioventricular node)
3) Atrioventricular (AV) Bundle aka Bundle of HS
4) Right & Left Bundle Branches (septum)
5) Purkinje Fibers in Ventricles
intercalated discs in muscle cells transmit the electrical signals

5
Q

1) Begins in: SA node (sinoatrial node)

located? contraction occurs?

A
  • located in upper right atrial wall

- both atrium contract

6
Q

2) AV node (atrioventricular node)

located? what occurs?

A
  • located in floor of right atria

- atrium empties blood into ventricles

7
Q

5) Purkinje Fibers in Ventricles

contraction occurs?

A

both ventricles contract

impulses passes through p. fibers (nerve fibers) and then on to the cells of the ventricles

8
Q

Electrocardiogram (ECG or EKG)

what is it?

A

record of electrical changes accompanying a heart beat

electrodes placed on skin

9
Q

Electrocardiogram (ECG or EKG)

uses electrodes to record…. where? what?

A

2 arms, 2 legs, 4-6 around heart

look @ 12 different tracings of activity

10
Q

Electrocardiogram (ECG or EKG)

using electrodes can determine what (4)?

A

1) A normal conducting pathway
2) Enlarged heart
3) Damaged heart regions
4) Cause of chest pain

11
Q

Cardiac Cycle: Systole & Diastole

how do the cardiac chambers cycle?

A

cardiac chambers cycle btwn systole (contraction) & diastole (relaxation)

12
Q

Diastole

what happens?

A

Chambers fill w/ blood

13
Q

Systole

what happens? order occured?

A

chamber contracts & empties blood

atria contract 1st (atrial systole), then the ventricles (ventricular systole)

14
Q

heartbeat sounds

what does sound result from?

A

sounds result from turbulence in blood flow when VAVLES shut

15
Q

2 heartbeat sounds

A

Lubb sound

Dubb sound

16
Q

Lubb sound

A

long booming initial sound resulting from AV valves closing @ end of ventricular systole

17
Q

Dubb sound

A

from SL valves closing @ end of ventricular systole

18
Q

heartbeat sounds

why is there a pause ?

A

pause after Dubb sound due to relaxation period

19
Q

ECG waves

what are the 3 waves in order?

A

1) P Wave
2) QRS Wave
3) T Wave

20
Q

P Wave

A

Atrial contraction (depolarization)

21
Q

QRS Wave

A

Onset of Ventricular contraction (depolarization)

22
Q

T Wave

A

Ventricular relaxation (repolarization)

23
Q

Cardiac Output

what is it? formula?

A

Work done by heart

cardiac output = stroke volume x heart rate

24
Q

Cardiac Output formula w/ units?

A

CO (units mL/min)= SV (units mL/beats) x HR (units beats/min)

25
Q

Cardiac Output (CO) definition?

A

volume of blood ejected from the ventricle each minute

-stroke volume (sv)

26
Q

Stroke Volume (SV) involved in CO definition?

A

amount of blood ejected during each ventricle contraction (each beat)
(amount pushed out each beat, stress test-> measure SV)

27
Q

What affects cardiac output

what can be influenced?

A

factors influence either stroke volume or heart rate

28
Q

What affects cardiac output - stroke volumes influences? (3)

A
  • blood pressures @ end of diastole= preload
  • force of contraction= contractility
  • vascular pressure to overcome to push blood out of chamber= afterload
29
Q

What affects cardiac output - heart rate influences? (7)

A
  • ANS: exercise or stress increase HR & SV
  • Hormones: increase HR
  • Ions: Na+ & K+ decrease HR
  • Body Temp.: higher temp, increase HR
  • Age: newborns higher HR
  • Gender: females have higher resting HR
  • Physical Fitness: regular exercise tends to slow resting HR
30
Q

Electrocardiogram (ECG or EKG)

order of waves and what contracts?

A

p wave- atrial depolarization (SA node-> both atria)
qrs complex- onset of ventricular contraction (AV node-> both ventricles)
t wave- ventricular repolarization
(note: atrial repolarization is masked by QRS complex)