ANAT1014 Cardiovascular System and Cardiac Cycle 26-09-11 Lecture Slides-1

8/12/2019 ANAT1014 Cardiovascular System and Cardiac Cycle 26-09-11 Lecture Slides-1

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ANAT1014

Cardiovascular system and cardiac cycleDr Abigail Rickard

26thSeptember 2011


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Reset your response device..

1. Press and release Go or Ch

button

2. While light flashes redand green

3. Press 4 then 1 to set channel

to 41

4. Then press Go or Ch5. Press and release 1/A light will

flash yellowto 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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Cardiaccycle - 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 membranepotential

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 isnever 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 1Transient outward K+current(Notch)

Phase 2Outward Ca2+ current(Plateau)

Phase 3Fast and Slow outwardrectifier K+currents (repolarisation)

Phase 4Resting membrane potentialN.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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Summary

Features of the cardiovascularsystem

Location and morphology of theheart

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

Documents

ANAT1014 Cardiovascular System and Cardiac Cycle 26-09-11 Lecture Slides-1