Ch. 1, Pg. 3 

The ventricles

• Are thicker than the walls of the atria because the purpose of the ventricles, as opposed to the atria, is to pump blood through the body requiring the ventricles larger muscles than the atriums.
• The right ventricle pumps blood to the lung for reoxygenation.
• The left ventricle pumps blood through the body to reoxygenate it.

Ch. 1, Pg. 3 

Apical impulse (aka the point of maximal impulse)

The impulse felt at the apex of the heart, when the left ventricle contracts, due to the apexs's colission with the chest wall. The apex collides with the chest wall because of the hearts natural tendency to rotate every time the left ventricle contracts. The apical impulse may be visualized on a thin individual.

An apical impulse is also called the point of maximal impulse because it is the point where left ventricle contraction is felt most strongly.

Ch. 1, Pg. 3

Sulci

Grooves on the outside surface of the heart where coronary arteries and their major branches lie.

Ch. 1, Pg. 3 

Coronary sulcus

Encircles the surface of the heart and separates the atria from the ventricles. It contains coronary arteries and epicardial fat.

Ch. 1, Pg. 3

Septum

An internal wall in the heart separating the right side of the heart from the left.

Ch. 1, Pg. 3 

Interatrial septum

An internal wall in the heart that separates the right atrium from the left atrium.

Ch. 1, Pg. 3 

Interventricular septum

An internal wall in the heart that separates the right ventricle from the left ventricle.

Ch. 1, Pg. 4 

Pulmonary circulation

The circulation of blood from the right side of the heart to the through the lungs to the left side of the heart.

• FYI: The right side of the heart is a low pressure system. The left side of the heart is a high pressure system.

Ch. 1, Pg. 4 

Systematic circulation

The circulation of blood through the body, from the left ventricle, for oxygenation of the body.

Ch.1, Pg. 4 

Stroke volume

The volume of blood ejected throught the body, from the ventricles, with each heart beat.

• FYI: Each ventricle holds about 150 mL of blood. About half the volume of blood (70-80 mL) is pumped into the body with each ventricle contraction.

Ch. 1, Pg. 4

Ejection fraction

The percentage of blood pumped out of each heart chamber. The ejection fraction is used to measure ventricular function. A ventricular ejection fraction of 40% or less is considered impaired ventricular function. Patients with congestive heart failure and myocardial damage may have ejection fraction complications.

Ch. 1, Pg. 5

Composition of the heart walls

Three tissue layers:

1. Epicardium: Outer layer.
2. Mayocardium: Middle layer.
3. Endocardium: Inner layer.

Ch. 1, Pg. 5

Endocardium

Composed of epithelium and connective tissue. The endocardium is continuous with the blood vessels creating a closed circuloratory system.

Ch. 1, Pg. 5

Composition of myocardium

A thick muscular tissue (the middle layer of the heart) that is reponsible for contracting the heart.

Subdivision of the mayocardium:

1. Inner mayocardial layer: the subendocardial area.
2. outer mayocardial layer: the subepicardial area.

FYI: the thickness of the mayocardium varies from the left and right sides of the heart. The left ventricle has the thickest mayocardium layer because it pumps blood through the entire body. The right ventricle has a relatively thick mayocardium, compared to the right and left atrium, because it needs to pump blood to the lungs.

Ch. 1, Pg. 6

The Epicardium

The outermost layer of the heart. The epicardium contains blood capillaries, fat, and nerve fibers. The main coronary arteries are located on the surface of the epicardium to oxygenate the epicardium before oxygenating the rest of the heart.

Ch. 1, Pg. 6

Ischemia

Decreased supply of oxygen to an organ or body part.

Ch. 1, Pg. 6

The pericardium

The pericardium is a double walled sac (the viceral and parietal layers) that enclose the heart to protect it from trauma and infection. The pericardium is anchored to the structures around the heart to immobilize it and decrease the chances of trauma to the heart. Between the viceral and parietal pericardium layers there is serous fluid to prevent friction of the heart on with pericardial sac.

.  

 Ch. 1, Pg. 6 

Two ways the heart can get compressed by the pericardium (cardiac tamponade)

1. Pericarditis, excessive secretion of serous fluid between the viceral and parietal pericardial layers (pericardial space), causing inflamation and compression of the heart.
2. Bleeding in the pericardial space due to trauma or surgery.

Compression of the heart, by the pericardium, (cardiac tamponade) causes inadequate pumping of the heart and, therefore, circuloratory failure.

 Ch. 1, Pg. 6 

Pericardiocentesis

Cardiac tamponades can be releived with a medical procedure called pericardiocentesis. In this procedure medical professionals insert a needle is inserted into the pericardial space and excess fluid is sucked out.

Ch. 1, Pg. 8

Cardiac muscle

Composed of fibers. Each fiber is composed of many muscle cells. Muscle cells contain mitochondrea, myofibrils, sarcomeres, and sacroplasmic reticulum (SR). Mitochondrea are responsible for the production of energy to the muscle by converting ATP to energy. Myofibrils, tube like structures made up of sarcomeres, are the basic protein units responsible for contraction of muscles. The sacroplasmic reticulum store calcium needed for muscle contraction. T-tubules conduct impuls on the muscle cell surface and cause calcium channels on the muscle surface to open and allow calcium to enter the cell and cause muscle contraction.

Muscle fibers fit together tightly at junctions called intercalated disks. The fibers are so tightly fitted in one another that it gives a synctium effect (an appearance that there are no junctions between the fibers). Gap junctions allow the the fibers in the muscle cell to communicate by the passage of ions and small molecules through the gap. The communication of gap junctions enables electrical impulses to quickly pass through the wall of a heart chamber and cause the atriums and ventricles to contract almost at the same time.

Ch. 1, Pg. 6

Sarcolemma

A membrane that encloses the muscle cells.

 Ch. 1, Pg. 7

Synctium

The resembalence of a network of cells with no seperation between individual cells.

Ch. 1, Pg. 8

A method for determining a mayocardial infraction in a patient

when a myocardial cell dies unique intramyocardial substances such as nutrients leak out of the the broken cell membrance and into the circuloratory system. If the unique substances in a mayocardial cell are found in a patients blood a mayocardial infraction may have occured.

Ch. 1, Pg. 8 

The heart synctiums

Two types of synctiums:

1. Atrial synctium: consists of the walls of the right and left atrium.
2. Ventricular synctium: consists of the walls of the right and left ventricle.

Impulses are normally generated from the atrial synctium and transferred into the ventricular synctium throught the atrioventricular junction (AV junction), a part of the hearts electrical system, allowing the atria to contract before the ventricles.

Ch. 1, Pg. 9 

Four valves of the heart

The four valves of the heart:

1. Two sets of atrioventricular valves (AV valves).
2.  Two sets of semilunar valves (SV valves).

The purpose of the valves are to make sure that blood in the heart only flows in one direction. When blood flows forward the valves open up. When blood flows backward the valves close.

Ch. 1, Pg. 9 

Atrioventricular valves (AV valves)

Separate the atrias from the ventricles. There are two kinds:

1. Tricuspid valve.
2. Mitral valve.

Ch. 1, Pg. 9 

The tricuspid valve

The atrioventricular valve (AV valve) that separate the right atrium from the right ventricle.

Ch. 1, Pg. 10 

Atrial kick

The additional 10% of blood that fill the ventricles when the atriums contract.

Ch. 1, Pg. 10 

Chordae tendineae (aka heart strings)

Thin strands of connective tissue attached one side to the atrioventriculer valves and on the other end to unique myocardium muscles called papillary muscles. when the papillary muscles contract they the chordae tendineae stretch and prevent the atrioventricular valves from bulging into the atriums.

Ch. 1, Pg. 10 

Semilunar valves (SL valves)

Semilunar valves prevent the backflow of blood from the pulmonary and aortic arteries back into the heart.

Ch. 1, Pg. 11 

Types of valvular heart disease

Types of valvular heart disease:

1. Valvular stenosis (a stenosed valve): valves that develop stiffeness, thickness, or narowness causing difficulty for blood to flow through the valves.
2. Valvular prolapse: the inversion of a valve. Occurs if one valve is larger than the other or if the chordae tendineae markedly or rupture.
3. Valvular regurgitation (aka valvular incompetence or valvular insufficiency): valves that do not stop the backflow of blood because they don't close properly. A valvular regurgitation may be caused by the myocardial infraction of a papillary muscle.

Ch. 1, Pg. 3 

Ch.1, Pg. 11

Heart sounds

Ch. 1, Pg. 12

Tracking blood flow through the heart and body

The blood flows through the body, starting from the atrium, in the following steps:

1. Blood reaches the right atrium from the superior and inferior venae cave as well as the coronary sinuses. 
2. The right atrium pumps the blood through the tricuspid valve into the right ventricle.
3. The right ventricle contracts, closing the tricuspid valve, and expelling the blood through the pulmonic valve into the pulmonary trunk.
4. The pulmonary trunk divides into the right and left pulmonary arteries which direct the blood the the right and left lungs for re-oxygenation (pulmonary circuit).
5. Blood low in oxygen passes through the pulmonary capillaries and reaches the alveolar sacs. Carbon dioxide and oxygen are exchanged. 
6. The re-oxygenated blood flows through the four pulmonary veins (there are two pulmonary veins leaving each lung) into the left atrium. 
7. The right atrium contracts and the blood flows through the mitral valve (bicuspid valve) and into the left ventricle. 
8. The left ventricle contracts, the mitral valve (bicuspid valve) closes, and the blood flows through the aortic valve and into the aorta artery.
9. The blood is distributed throughout the body (systemic circuit).

Ch. 1, Pg. 13

Systole and diastol

1. Systole: the contraction of the atriums and ventricles.
2. Diastole: relaxation of the atriums and ventricles. The may

Ch. 1, Pg. 13

Ch. 1, Pg. 13

Responsibilities of the conduction system are:

1. Correct timing between the atriums and ventricles systole and diastole.

Ch. 1, Pg. 13

During atrial diastole the right atrium receives blood from the venae cave veins and coronary sinus and the left atrium receives blood from the pulmonary arteries. As a result, the atrium distends, pressure increases, and blood flows through the atrioventricular (AV) valves into the lower pressure chambers of the ventricles. The atriums then undergo systole (an atrial kick) and expel another 30% of blood into the ventricles.

FYI: the right atrium diastole occurs a split second before left atrium diastole.

Ch. 1, Pg. 13

Ch. 1, Pg. 13

Coronary circulation

Ch. 1, Pg. 14

Coronary arteries

Ch. 1, Pg. 14

Epicardial coronary arteries

Ch. 1, Pg. 15

Coronary Artery Disease (CAD)

The occlusion of 50% or more (stenosis) of three major coronary arteries:

1. The left anterior descending (LAD) artery.
2. The circumflex (CX) artery.
3. The right coronary artery (RCA).

Ch. 1, Pg. 15

The Coronary Artery (RCA)

Ch. 1, Pg. 15

Ch. 1, Pg. 16

Ch. 1, Pg. 16

The coronary veins

Acute coronary syndrome is the partial or complete blockage of blood through a coronary artery -  which may result in a myocardial infraction, myocardial injury, or death. Typically coronary artery syndrome (ACS) is the result of atherosclerosis. However, in some cases, despite coronary atherosclerosis, the heart doest not get ischemic because of collateral circulation occurs.

Collateral circulation is the alternate vascular routes that tissue can get blood through. Collateral circulation, in some ACS patients, allows blood to reach tissue that would otherwise become ischemic.

General

Anemia

General

Ischemia

General

Hypoxia

Ch. 1, Pg. 16

Collateral circulation

Ch. 1, Pg. 16

Typical symptoms of angina pectoris include:

1. Tight feeling beginning in the chest and radiating to the arm, wrist, jaw.

Ch.1, Pg. 17

Causes of ischemia

Causes of ischemia include:

1. Increased demand of oxygen.
2. Decreased supply of oxygen.

Ch.1, Pg. 17

Ch.1, Pg. 17

Myocardial infarction (MI)

Myocardial infarction (MI) occurs when cardiac tissue dies to due to cardiac ischemia.

Ch.1, Pg. 17

Methods to restore blood flow to the heart from ischemia

Methods to restore blood flow to the heart:

1. Fibrolynitics (clot busting).
2. Coronary angioplasty.
3. Coronary bypass graft.

Ch.1, Pg. 18

Chronotropy, inotropy dromotropy

Chronotropy: change in heart rate.

Inotropy: change in myocardial contractility. (positive inotropy refers to an increase in contractility).

Dromotropy: the velocity of the AV conductivity of the heart.

Ch.1, Pg. 20

Blood pressure

Blood pressure is the force exerted by the circulated blood on volume on the walls of the arteries.

BP = peripheral vascular resistance (PVR) * cardiac output (CO)

Ch.1, Pg. 20

Ch.1, Pg. 20

Ch.1, Pg. 20

Cardiac output is the amount of blood pumped into the aorta each minute by the heart.

Cardiac output (CO) = Stroke volume (SV) * heart rate (HR)

Ch.1, Pg. 20

Ch.1, Pg. 21

Ch.1, Pg. 21

Heart failure

Ch.1, Pg. 21

Afterload is the pressure of resistance against which the ventricles must pump to eject blood. 

Afterload is influenced by:

1. Arterial resistance.
2. Ability of the arteries to stretch.
3. Arterial blood pressure.

Ch.1, Pg. 21

Vagal maneuvers are methods to stimulate the vagus nerve, resulting in stimulation of baroreceptors in the carotid arteries to slow conduction through the AV node.

Common vagal maneuvers include:

1. Coughing.
2. blow through an occluded straw.
3. Bear don as if having a bowel movement.

Ch.2, Pg. 30

Types of cardiac cells

The different types of cardiac cells include:

1. Myocardial cells (mechanical cells).
2. Pacemaker cells (pacemaker cells).

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 30

Types of cardiac cells

The types of cardiac cells:

1. Myocardial cells: cells made up of filaments that slide together (contract) when electrically stimulated. Cardiac myocardial cells (myocardium) form the thin layer around the atrium and thicker layer around the ventricles. 
2. Pacemaker cells: spontaneously conduct electrical impulses. AKA automatic cells or conducting cells.

Ch.2, Pg. 30

Typically a muscle contracts when a neurotransmitter crosses through the neuromuscular junction and binds to a receptor on the muscles surface. A unique characteristic of the heart is that pacemaker cells rather than the nervous system stimulate and cause contraction of the cardiac muscles.

The sinoatrial node is the hearts normal pacemaker and usually prevents other pacemaker cells from skewing the pacemaker routine. Normal concentrations of sodium, potassium, and calcium are important in maintaining automaticity. Increased electrolyte concentrations decreases automaticity. 

Ch.2, Pg. 30

Ch.2, Pg. 30

Ch.2, Pg. 31

Permeable

Ch.2, Pg. 31

Occurs when the intracellular space is more positively charged than the extracellular space, due to the movement of positively charged sodium ions into the intracellular space, the action potential reaches its second phase cycle - depolarization. An impulse is generated when the inside of the cell is more positively charged than the outside of the cell. 

When the atriums are stimulated (atrial depolarization) a P wave is generated on the ECG. When the ventricles are stimulated (ventricle depolarization) a QRS complex is generated on the ECG.

Ch.2, Pg. 32

Ch.2, Pg. 32

Repolarization

Repolarization is the regeneration of negative charge in the intracellular space, as opposed to its positive charge inside the cell when depolarizing. When re-polarization occurs, sodium stops flowing into the cell and potassium starts to flow out of the cell, causing the intracellular space to become relatively negatively charged compared to depolarization.

On the ECG, the ST-segment and T wave represent re-polarization. 

Ch.2, Pg. 33

Phase 0 (depolarization): sodium and calcium enter the cell and potassium leaves the cell. A current is generated and cardiac contraction begins. Phase 0 is expressed on the ECG as the QRS complex.

Phase 1 (early re-polarization): during this phase sodium channels partially close, chlorine enters the cell, and potassium leaves the cell. This causes a decrease is in positive charge inside the cell. On the ECG this is expressed as a small negative deflection. This is an electrical systole phase.

Phase 2 (plateau phase): during this phase calcium enters the cells of the atria, ventricles, and purkinje fibers. Simultaneously, potassium continues to leave. The plateau phase allows the myocardium to sustain contraction. This phase is responsible for the ST segment of the ECG display.

Phase 3 (final rapid re-polarization): potassium leaves the cell, sodium and calcium channels are closed. The intracellular space becomes increasingly negative. Phase 3 corresponds with the T wave (ventricular re-polarization) on the ECG.

Phase 4 (resting membrane potential): in this phase the heart returns to resting state. An excess of sodium is inside the cell and an excess of potassium is outside the cell. The sodium/potassium pump is activated and sodium is extricated from the cell while potassium is restored in the cell. At this point the heart is polarized (ready for discharge) and remains in this state until stimulated to discharge.

Ch.2, Pg. 34

Dysrhythmia/arhythmia + antiarhythmics

Dysrhythmia/arhythmia: irregular heart rhythm.

Antiarhythmics: Medications used to restore regular heart rhythm. 

Ch.2, Pg. 34

Ch.2, Pg. 34

Ch.2, Pg. 35

Ch.2, Pg. 35

Supernormal period

Ch.2, Pg. 35

Ch.2, Pg. 36

Sinoartial (SA) node

Ch.2, Pg. 37

AV junction

Ch.2, Pg. 37

Ch.2, Pg. 38

Ch.2, Pg. 38

Fascicles

Fascicles are small bundles of nerve fibers that the sub branches of the left bundle branch. The three fascicles are called:

1. Anterior fascicle.
2. Posterior fascicle.
3. Septal fascicle.

Ch.2, Pg. 38