anat1014 cardiovascular system and cardiac cycle 26-09-11 lecture slides
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ANAT1014
Cardiovascular system and cardiac cycle Dr Abigail Rickard
26th September 2011
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Reset your response device..
1. Press and release Go or Ch button
2. While light flashes red and green
3. Press 4 then 1 to set channel to 41
4. Then press Go or Ch
5. Press and release 1/A light will flash yellow to confirm
6. If this doesnt happen try again.
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Overview
What is the cardiovascular system?
What are the features of the heart?
What does the heart do?
How does the heart function?
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Components of the cardiovascular system
Heart Aorta Vena Cavae Capillaries Venules
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Systemic circulation
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Cardiac cycle - Blood flow through the heart Superior & inferior vena cave
Pulmonary artery/vein
Aorta
Bicuspid and tricuspid valves
Right/Left atrium/ventricle
Diastole/Systole
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Valves
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Valves in action
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The bicuspid valve is between...
1 2 3
57%
0%
43%
1. The left atrium & left ventricle
2. The right atrium & right ventricle
3. The left ventricle & systemic arch
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Coronary circulation
Coronary ostia Left coronary artery Right coronary artery Coronary sinus
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Myocardial energy metabolism
High dependence on aerobic metabolism (70-80% available O2 at rest) Primary metabolic substrates are fatty acids Glycogen and lactate
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Heart muscle types
Purkinje Fibres Atrial Cells Ventricular cells
Shape Long and broad Elliptical Long and narrow
Length (m) 150-200 ~ 20 50-100
Diameter (m) 35-40 ~ 5 10-25
Intercalated disc/ gap-junctions
Very prominent; abundant gap junctions; fast end-to-end transmission
Side-to-side as well as end-to-end transmission
Prominent end-to-end transmission
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Ventricular myocyte features
Cross-striations (myofibrils)
Thick myosin filaments
Thin actin filaments
Cross bridge formation (cycling)
Mitochondria
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What features allow for the rapid electrical conductance in purkinje
fibres?
1 2 3 4
0% 0%
50%50%
1. Mitochondria
2. Myosin and actin filaments
3. Intercalated discs and gap junctions
4. I dont know, I wasnt listening
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Cardiac cycle - Electrical activity across the heart Sinoatrial node (SAN)
Atrioventricular node (AVN)
Purkinje fibres
Wave of depolarisation
Repolarisation/ Hyperpolarisation
Resting membrane
potential
ECG- P, QRS, T waves
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Cardiac electrical activity Pacemaker Cell (SA node)
Intrinsic depolarisation known as automaticity
N.B. Membrane potential is never flat
Ca2+ - induced Ca2+ release from intracellular Ca2+
storage organelle called endoplasmic reticulum
- 65 mV
- 40 mV
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Cardiac electrical activity Ventricular Cell
Phase 0 - RAPID inward Na+ current (Upstroke, depolarisation)
Phase 1 Transient outward K+ current (Notch)
Phase 2 Outward Ca2+ current (Plateau)
Phase 3 Fast and Slow outward rectifier K+ currents (repolarisation)
Phase 4 Resting membrane potential N.B. Notice upstroke of action potential is FLAT
- 80 mV
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The movement of which ions are responsible for the upstroke of the
ventricular action potential (Phase 1)?
1 2 3 4
25%
0%
13%
63%
1. Na+
2. Ca2+
3. K+
4. Mg2+
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Cardiac electrical activity Whole heart P wave - Atrial depolarisation
PR interval - AV nodal conduction
QRS complex - Ventricular Depolarisation
T Wave - Ventricular repolarisation
QT interval - Ventricular depolarisation and repolarisation
P
R
Q S
T
PR
interval
QT
interval
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Which of the following represents the time for conduction across the AV
node?
1. P-R interval
2. Q-T interval
3. R-R interval
4. T wave
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Summary
Features of the cardiovascular system
Location and morphology of the heart
Cardiac cycle
Electrical activity of the heart
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Next time.....
Regulation of cardiac cycle
Blood flow and pressure
Malfunctions and their consequences