CHAPTER 19: THE HEART

The cardio vascular system has how many divisions?

2 major divisions

What are the 2 major divisions?

Pulmonary Circuit and Systemic Circuit

What is a Pulmonary Circuit

Carries blood to the lungs for gas exchange and returns it to the Heart

What is a Systemic circuit?

supplies blood to every organ of the body including other parts of the lungs and to the Heart Wall

Which side of the heart supplies the Pulmonary Circuit

The Right Side.

Explain the process of The Pulmonary Circuit

oxygen poor blood is pumped into THE PULMONARY TRUNK which divides into RIGHT and LEFT PULMONARY ARTERIES.

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The R and L PULMONARY ARTERIES transport blood to the air sacs ( alveoli ) of the lungs where carbon dioxide is unloaded and oxygen is picked up.

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The oxygen rich blood flows using the PULMONARY VEINS to get to the LEFT side of the heart.

Which side of the Heart supplies Systemic Circuit??

The Left Side

Explain the process of Systemic Circuit?

Blood leaves it by traveling through through AORTIC ARCH and passes down posterior to the heart.

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The AORTIC ARCH supplies the head neck and upper limbs then it travels through the THORAIC and ABDOMINAL CAVITIES and issues smaller arteries to the other organs before branching into lower limbs .

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After circulation to the entire body is done, the deoxygenated systemic blood returns to the right side of the heart by traveling through to big veins called the SUPERIOR vena cava

( drains the upper body) AND INFERIOR vena cava ( drains everything below the diaphragm.

The heart lies within a thick partition called the?

Mediastinum

Wha does the mediastinum contain?

The heart, great blood vessels ,esophagus, trachea and thymus

What is the red circle implying when looking at the heart?

The apex

What is the red line implying when looking at the heart

The Base

What is the pericardial sac aka pericardium?

A double walled sac that encloses the heart

What is the Fibrous Pericardium?

a tough fibrous sac that is the outer wall of the pericardium

What is the serous pericardium?

Thin membrane that is second to last layer that surrounds the heart

what is pericardial fluid

secreted by the serous pericardium. The fluid lubricates the membranes and allows the heart to beat with minimal friction

How many layers does the serous pericardium have

2

What are the 2 layers of the serous pericardium ?

parietal layer and visceral layer

Where is the parietal layer?

Lines the inside of the fibrous pericardium

Where is the visceral layer?

adheres to the heart surface and forms the outmost layer of the heart itself ( epicardium )

What is the yellow depicting?

Pericardial Cavity

What is the red depicting?

fibrous pericardium/Serous pericardium

What is the blue depicting?

parietal layer

What is the green depicting?

Visceral layer

What is depicted in the purple?

Myocardium

What is depicted in the orange

Endocardium

What is depicted in blue

Epicardium

What is depicted in the yellow?

Fibrous Pericardium

The heart wall consists of what three layers?

epicardium ,myocardium and endocardium

What is a Epicardium and what is it made up of?

is a serous membrane covering the heart surface and is

simple squamous epithelium overlying a thin layer of areolar tissue.

The epicardium allows travel from?

The largest branches of the coronary blood vessels

The Largest branches of the Coronary blood vessels travel through ….?

The Epicardium.

What is the endocardium?

smooth inner lining of the interior of the heart (chambers) and blood vessels, compromised of endothelial cells

What does the endocardium consists of?

similar to epicardium

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simple squamous eptithlieum overlying a thin areolar tissue layer. however it does not have a adipose tissue.

What is the myocardium?

between the endocardium and the epicardium

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composed of cardiac muscle, thickest layer and performs the work of the heart

Name the Heart layers in in order! ( inner to outer)

endocardium,

myocardium,

Visceral Layer of the Serous pericardium ( a.k.a epicardium)

Pericardial Cavity

Parietal Layer of the Serous Pericardium

Fibrous Pericardium

What is the fibrous skeleton?

framework of collagenous and elastic fibers and is spread in the walls between the heart chambers

How many functions does Fibrous Skeleton have?

4

What are the functions of the fibrous skeleton?

1. gives structural support for the heart, valves, and openings of the great vessels. Holds the orifices open and prevents them from excessively stretching when blood surges.

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2. Anchors the cardiomyocytes and gives them something to pull against.

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3. nonconductor of electricity/serves as electrical insulation between the atria and ventricle

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4. aid in refilling of the heart with blood after each beat.

The heart heart has how many chambers?

4 Chambers

What are the four chambers of the heart

Right and Left Atria and the Right and left Ventricle

What does the right and left atria do?

They are superior and receiving chambers for blood returning to the heart auricles. ( by way of great veins)

what do the right and left ventricles do?

They are inferior chambers and pump blood into the arteries and keep it flowing around the body.

What is a interventricular septum ?

Thick Muscular wall that separates the right and left ventricles

What is Anterior Interventricular Sulcus (Interatrial Septum)

front of the heart sits on top of the inter-ventricular septum.

in the surface of an organ ( basically encircling the heart near the base )

and separates the atria (from the ventricles).

What is Posterior Interventricular Sulcus (interatrial Septum)

back of the heart and sits on top of the inter-ventricular septum.

in the surface of an organ ( basically encircling the heart near the base )

and separates the atria ( from the ventricles).

What is a Trabeculae Carnae?

Internal Ridges in both right and left ventricles

What is the function of the Trabeculae Carnae?

stops the ventricular walls from sticking to each when the heart contracts.

allows the chambers to expand more when the refill.

What is Chordae Tendonae (Tendinous Cords)?

connect the Atrioventricular Valve cusps to conical papillary muscles on the floor of the ventricles.

What is the function of Chordae Tendinae?

stops the AV valves from flipping inside out of bulging into the atria when the ventricles contract.

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Where is in the Chordae Tendinae?

Papillary Muscles

What are the Valves of the Heart?

AtrioVentricular Valves, Right AV, Left AV

Semilunar Valves, Pulmonary/Aortic Semilunar Valve.

What is the function of Papillary Muscles?

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pillar-like muscles in the cavity of the ventricles with 2-3 attachments to heart floor/walls .

equally spread physical stress, coordinate timing of electrical conduction and provide redundancy..

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or to be short

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ensures proper cardiac valvular function.

What is the function of atrioventricular ( AV ) valves?

control the blood flow opening between the atria and ventricles

The right AV (tricuspid) valve has how many cusps?

three cusps

The left AV ( Mitral ) ) valve

has two cusps

What is the right AV valve called

Tricuspid VALVE

What is the left AV valve called

Mitral VALVE

What do semilunar valves consist of?

Pulmonary semilunar valves and Aortic semilunar valves

What is the function of semilunar valves

regulates the flow of the blood from the ventricles into the great arteries and open and close because of blood flow and pressure

What is the pulmonary semilunar valve

controls the opening from the right ventricle and/nto the pulmonary trunk. has 3 cusps

What is the Aortic semilunar Valve

controls the opening from the left ventricle into the aorta, has three cusps

What happens when ventricles relax?

Pressure drops inside the ventricles

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Semilunar valves close as blood attempts to back \\n up into the ventricles from the vessels

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AV valves open

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Blood flows from atria to ventricles

What happen when ventricles contract?

AV valves close as blood attempts to back up into the atria

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Pressure rises inside of the ventricles

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Semilunar valves open and blood flows into great vessels

What are the two arteries that provide Arterial Supply?

Right Coronary Artery and Left Coronary Artery, Both branch off the Ascending Aorta

In the RCA, What 2 branches exist and where are they located?

Right Marginal Branch and Posterior inter-ventricular branch.

located along the coronary sulcus under the right auricle.

Right Coronary Artery supplies the …

right atrium and sinuatrial node (pacemaker)

In the RCA, The Right Marginal Branch is located where and what is it?

Runs towards the Apex of the heart

Supplies lateral aspect of right atrium and ventricle

In the RCA, The Posterior Inter-Ventricular Branch is located where and what does it do ?

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Travels down the corresponding sulcus

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Supplies posterior walls of ventricles

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RCA --→ continues right margin of the heart--→posterior side----→sends a small branch----→ to the atrioventricler node ------→ becomes posterior InterV branch

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The Left Coronary Artery divides into how many branches and what are they

2,

The Anterior Inter-Ventricular branch and the Circumflex Branch

In the L.C. A, What does the Anterior inter -ventricular Branch do and where is it located

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Artery supplies blood to both ventricles and the anterior two- thirds of the inter-ventricular septum.

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travels down the anterior ventricular sulcus to the apex, rounds the bend and travel shortly up the posterior side of the heart. Joins the posterior interventricular branch (or L.A.D)

In the L.C.A, What does the Circumflex Branch do?

Supplies Blood to the left atrium and posterior \n wall of left ventricle

Describe the location of the Circumflex Branch

continues around the left side of the heart in the coronary sulcus and gives off left marginal branch and then ends on the posterior side of the heart.

The clinical name for Posterior interventricular branch is …..?

Left Anterior Descending (LAD) Branch.

Describe the location of The Left Marginal Branch

passes down the left margin of the heart and furnishes the blood to the left ventricle

The function of the circumflex branch ?

supplies the blood to the left atrium and posterior wall of the left ventricle

What is Venous Drainage?

route of blood leaving the organ

Coronary blood returns to the ????? ????? by way of the ????? ?????

Right Atrium, Coronary Sinus

The Coronary Sinus has three main veins/inputs that makes coronary blood return to the Right Atrium.. What are the three main veins/inputs?

Great Cardiac Vein , Posterior Inter ventricular Vein and the Left Marginal Vein

What is the Great Cardiac vein and what is its function?

\n Collects blood from the anterior portion of the heart and

Travels alongside anterior inter-ventricular artery

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In Detail:

* Carries blood from the apex towards the coronary sulcus, then arcs around the left side of the heart and empties into the coronary sinus

What is the function of the Posterior Inter-ventricular Vein?

collects blood from the posterior portion of the heart.

found in the posterior inter-ventricular sulcus

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also carries blood from the apex upwards and drains into the coronary sinus

What does the Left Marginal Vein do and where is it located?

empties into the coronary sinus and is

near the apex up the left margin.

What does the coronary sinus do and where is it?

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Collects blood from coronary veins and empties into right atrium

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Large transverse vein in the coronary sulcus on the posterior side of the heart

What is a Cardiomyocyte?

The muscle cells of the heart.

What do cardiomyoctyes look like ?

Muscle cells of the heart and have one central nucleus, striated, short and thick branched cells

What are intercalated discs?

join cardiocytes end to end with three features:

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1.Interdigitating folds ( Plasma Membrane)

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2\.Mechanical Junctions ( Fascia Adherens,Desmosomes)

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3\.Electrical Junctions ( gap junction )

What do Intercalated disc look like?

visible as a dark line

Intercalated discs have how many distinctive junctions/features

3 junctions

What is a function of a fascia adherens?

(mechanical junction:tightly join cardiocytes)-actin of the thin myofilaments is anchored to the plasma memebrane

and each cell is linked to the next by transmemebrane proteins.

What is a function of desmosomes?

(mechanical junctions) patches of mechanical linkage prevent the contracting cardiocytes from being pulled apart from each other

What is the function of Gap Junctions

(Electrical Junction) makes channels that allow the ions to flow between cells; allows cardiocmyoctye to stimulate their neighbors.

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Entire myocardium of either two atria or two ventricles acts like single, unified cell.

What is the (Cardiac) Conduction System?

coordinates the heartbeat / composed of an internal pacemaker and has nerve-like conduction pathways through the myocardium

generates and conducts rhythmic electrical signals.

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Put the conduction system nodes and bundles in order from first to last .

1. SA NODE FIRES
2. EXCITAION SPREADS THROUGH THE ATRIAL MYOCARDIUM
3. AV NODE FIRES
4. EXCITATION SPREADS DOWN AV
5. PURKINJE FIBERS DISTRIBUTE EXCITATION THOUGH VENTRICULAR MYOCARDIUM

What is a SA node and where is it located?

Sinautrial Node, patch of modified cardiomyocytes and acts a natural pacemaker that intitates each heartbeat and determines the heart rate.

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located in the right atrium, under the epicardium, near the superior vena cava.

What is the 1st stage of the conduction system ?

The Sinuatrial NODE makes an appearance

What happens in the 2nd stage of the cardiac conduction system

Signals from the SA Node spread throughout the atria

What happens in the third stage of the conduction system

Atrioventricular Node acts as an electrical gateway to the ventricles. while fibrous skeleton acts as an insulator to prevents currents from getting to ventricles by \n any other route.

What happens in the fourth stage of conduction system?

AV Bundles forks into right and left bundle branches,

Bundle branches pass through the interventricular septum and descend towards the apex.

What happens in the fourth stage of cardiac system

Nerve-like processes spread throughout ventricular myocardium. Cardiocytes then pass signal from cell \n to cell through gap junctions

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In more detail:

* Purkinje fibers are at the apex of the heart , they turn upwards and spread though the ventricular myocardium and distribute electrical excitation tot he cardiomyocytes of the ventricles. once completed, the cardiomyotyes encourage it by passing ions from cell to cell through their gap junctions

What is a Sinus Rhythm?

The normal heartbeat by the SA NODE (70 to 80 heartbeats)