Cardiology Lecture 1- Physiology of the heart

In which parts of the heart the numbers are pointing to?

1. Superior vena cava

2. Right artrium

3. Triscupid valve

4. Inferior vena cava

5. Pulmonary valve

6. Right ventrincle

7. Aorta

8. Pulmonary arteries

9. Left atrium

10. Pulmonary veins

11. Mitral valve

12. Left ventrincle

13. Aortic valve

What is the function of a valve in a vein?

Τo prevent reverse blood flow.

How the heart looks like when is diastoled?

Like that.

How the heart looks like when is systoled?

Like that.

Can you describe me in steps the heart cycle?

Late diastole→ Atrial systol→ Isovolumic ventricular contraction→Ventricular ejection→Isovolumic ventricular relaxation

What are the three compartments of the thoracic cavity?

2 pleural cavities and the mediastinum

Why the left ventrincle has thicker wall than the right one?

Left: pumps the blood all around the body

Right: lungs

Describe the blood flow in more details.

• The oxygenated blood passes from the pulmonary veins and arrives to the left atrium

• It goes from the atrial valve into the left ventricle.

• When the left ventricle contracts that blood will be ejected through the aortic semilunar valve into the aorta and from there into smaller arteries.

• When it arrives back from the systemic venous circulation arrives back via the superior/inferior vena cava

• It will go to the right atrium from there the blood will go into the tricuspid valve into the right ventricle

• When the right ventricle contracts that blood will be ejected through the pulmonary arterial semilunar valve and will go to each lung

What is the role of pericardium?

Stops the heart from over-expanding because of its tough fibrous tissue→physical protection

What is the role of endocardium?

Ensures the smooth blood flow because of the thin endothelial wall→no turbulence in the flow

What is the role of the myocardium?

The myocardium is responsible for the contractile function of the cardiac pump (contains cardiac muscle).→middle and thickest layer

What is the septum?

It seperates the 2 sides of the heart.

Which are the hemodynamic parameters of the human heart?

1. Heart rate: 60-80 bpm

2. Stroke volume (the amount of blood ejected from the ventricle with each cardiac cycle): 100 ml

3. Cardiac output (the product of heart rate and stroke volume): 6-7 l/min

4. Ejection fraction (a measurement, expressed as a percentage, of how much blood the left ventricle pumps out with each contraction): 65%

5. LV maximal systolic pressure: 120 mm Hg

6. RV maximal systolic pressure: 25 mm Hg

7. Ventricular end-diastolic volum 150 ml

8. Ventricular end-systolic volume 50 ml

Which are the main coronary arteries?

1. Aorta

2. Left main coronary artery

3. Circumflex coronary artery

4. Left anterior descending coronary artery

5. Right coronary artery

Which are the main cells in the heart?

1. Cardiomyocytes

2. Endothelial cells

3. Fibroblasts

What is the main function of cardiomyocytes?

Contractility

What is the main function of endothelial cells?

1. Angiogenesis

2. Spatial organization

3. Paracrine signaling

What is the main function of fibroblasts?

1. Transmission of Electrical Impulses

2. ECM Deposition

3. Paracrine Signaling

What’s the structure of myocardial muscle cells?

1. Branched

2. Single nucleus

3. Attached to each other by intercalated disks.

What is the excitation-contraction coupling?

E-Cc oupling links the action potential (excitation) of the muscle cell membrane (the sarcolemma) to muscular contraction.

What are the intercalated disks?

Specialized junctions that attach myocardial muscle cells to each other.

What are the steps of E-C coupling?

1. Depolarization of the plasma membrane and its membrane invaginations (the t-tubular system) by an action potential``

2. Transduction of the depolarization signal to the sarcoplasmic reticulum (SR) membrane

3. Activation of Ca2+ release from the SR and subsequent global elevation of intracellular [Ca2+]

4. Interaction of Ca2+ with contractile proteins leading to muscle contraction

5. return of [Ca2+] back to levels at resting conditions and muscle relaxation

With which type of cell is generated the initial action potential?`

Sinus node cells

Where the arrows pointing at in this picture?

Here

How the depolarization is propagated?

1. Initial action potential is generated by sinus node cells. Then it moves via gap junctions between cells.

2. This electrical pulse travels through the network of conducting cell.

What is the anatomy of a muscle cells?

What is the conducting system of the heart?

1. Network of specialized tissue that stimulates contraction.

2. modified cardiac myocytes.

3. the heart can contract without any innervation.

What is the pathway of depolarization?

1. Electrical activity goes rapidly to AV node via internodal pathways.

2. Depolarization spreads more slowly across atria. Conduction slows through AV node.

3. Depolarization moves rapidly through ventricular conducting system to the apex of the heart.

4. Depolarization wave spreads upward from the apex.

Which are the four major determinants of cardiac output?

1. Preload

2. Afterload

3. Myocardial contractility

4. Heart rate

What is the definition of preload?

Volume of blood in ventrincles at end of diastole

Which are the causes that lead to preload?

1. Compliance of ventrincle→end-diastolic radius→preload→myocardial end-diastolic wall stress

2. Total blood volume, blood volume distribution, venous return, atrial contraction→end diastolic-filling pressure→preload→myocardial end-diastolic wall stress

3. Total blood volume, blood volume distribution, venous return, atrial contraction→end diastolic-filling pressure→end-diastolic radius→preload→myocardial end-diastolic wall stress

4. Hypertrophy→myocardial wall thickness→preload→myocardial end-diastolic wall stress

What is the law that describes lenght-tension relationship?

Frank-Starling law=>Stroke volume increases preload auguments

What is the definition of afterload?

Afterload refers to the amount of resistance left ventrincle must overcome to circulate blood.

What happens if the afterload augments?

Stroke volume decreases

In which pathological conditions afterload is increased?

In hypertension and vasoconstriction

What does it mean if the afterload, is increased?

That the cardiac workload also does

In which pathological conditions preload is increased?

1. Hypervolemia

2. Regurgitation of cardiac valves

3. Heart failure

What is the definition of contractility?

It is the intrinsic capacity to generate force.

Which are the methods for assessment of the ventrincular and cardiomyocytes functions?

1. In situ: ECG, echocardiography, MRI

2. Isolated perfused heart –Langendorff technique, working heart.

3. Isolated papillary muscle.

4. Isolated cardiomyocytes.

5. Permeabilized fibers and cells.

6. Isolated organelles.

7. Methods of biochemistry and molecular biology.

What is electrocardiogram?

It is a graph of voltage versus time of the electrical activity of the heart using electrodes placed on the skin which detect the electrical changes occured due to the cardiac muscle depolarization followed by repolarization during each cardiac cycle.

Tell me where is: P, R, T, Q, RP interval, ST segment, QT interval, PR intervla, atria and ventrincles?

What does P wave represent in a ECG?

It represents the depolarization of the atria

What does QRS compex represent in a ECG?

It represents the depolirization of the ventrincles.

What does T represent in a ECG?

It represents the repolarization of the ventrincles.

Describe briefly all the steps in a ECG?

1. Atria begin depolarizng

2. Atrial depolarization complete

3. Ventricular depolarization begins at apex and progresses superiorlu as atria repolarize

4. Ventrivular depolarization complete

5. Ventricular repolarization begins at apex and progresses superiority

6. Ventricula repolarization complete, heart is ready for the next cycle.

What abnormalities can you interpret from a ECG?

1. rhythm

2. conduction

3. electrical axis

4. myocardial mass (hypo-hypertrophy)

5. myocardial ischemia (a restiction in blood supply to myocardium)

What is a echocardiography?

It is a test that uses high frequency sound waves (ultrasound) to make pictures of the heart.

What is MRI?

With magnetic resonance imaging (MRI), a powerful magnetic field and radio waves are used to produce detailed images of the heart.