Anatomy exam 2- The heart

Atria are separated from the ventricles externally by a relatively deep

Coronary sulcus (or atrioventricular sulcus) that extends around the circumference of the heart

What does the anterior interventricular artery supply

Supplies the anterior surface of both ventricles and most of the interventricular septum

Where are the openings for the left and right coronary arteries?

The openings for these arteries are located in the wall of the ascending aorta immediately superior to the aortic semilunar valve

The right ventricle receives ______ blood from ______

The right ventricle receives DEOXYGENATED blood from the RIGHT ATRIUM

Left and Right Atria

Thin-walled chambers located superiorly

Left and right coronary arteries

Travel within the coronary sulcus of the heart to supply the heart wall

Trabeculae carnae in left ventricle are

more prominent than in the right ventricle

Fibrous skeleton insulates the atria from the ventricles to

prevent random muscle impulses from spreading between the atria and the ventricles

The atria receive blood

returning to the heart through both circulations

The pulmonary trunk divides shortly into

right and left pulmonary arteries, which carry deoxygenated blood to the lungs

The right coronary artery typically branches into the

right marginal artery and the posterior interventricular artery

The posterior right atrial wall is

smooth (does have pectinate muscle)

Preganglionic axons enter the

sympathetic trunk and ascend into the thoracic and cervical portions, where they synapse on ganglionic neurons

Postganglionic axons project from

the superior, middle, and inferior cervical ganglia and the T1-T5 ganglia, and travel directly to the heart through cardiac nerves

What does the innervation of the heart consist of

the sympathetic and parasympathetic componenents

As vagus nerves descend into the

thoracic cavity, they give off branches that supply the heart

Semilunar valves are located

within the walls of both ventricles immediately before the connection of the ventricle to the pulmonary trunk and aorta

Great cardiac vein

Runs alongside the anterior interventricular artery

Middle cardiac vein

Runs alongside the posterior interventricular artery

Characteristics of the posterior wall of the left atrium

Smooth posterior wall of left atrium contains openings for approximately four pulmonary veins Sometimes two of the these vessels fuse prior to reaching the left atrium, thus decreasing the number of openings through the atrial wall.

What does the circumflex artery supply?

Supplies the left atrium and ventricle

What does the posterior interventricular artery supply?

Supplies the posterior surface of both the left and right ventricles

What does the right marginal artery supply?

Supplies the right border of the heart

Way to remember effects of innervation

Sympathetic innervation Speeds the heart rate Parasympathetic innervation does the oPposite (decreases the heart rate)

Where does the sympathetic innervation arise from

Sympathetic innervation arises from the T1-T5 segments of the spinal cord

What are the coronary arteries considered

The coronary arteries are considered functional end arteries --deals with anastomoses

What is the anterior interventricular artery AKA

Also called the left anterior descending artery --- LAD/anterior descending branch/ or widow maker artery

Auricle

Anterior part of each atrium is a wrinkled, flaplike extension called an auricle because it resembles an ear

What does the heart act like?

The heart acts like two side-by-side pumps that work at the same rate and pump the same volume of blood; one directs blood to the lungs for gas exchange while the other directs blood to body tissues for nutrient and respiratory gas delivery

Pericardium

The heart is contained within the pericardium, which is a fibrous sac and serous lining.

Where is the heart located?

The heart is located left of the body midline posterior to the sternum in the mediastinum

How is the heart rotated

The heart is rotated such that its right side or right border (primarily formed by the right atrium and ventricle) is located more anteriorly while its left side or left border (primarily formed by the left atrium and ventricle) is located more posteriorly

Apex of heart

The inferior, conical end is called the apex. It projects slightly anteroinferiorly toward the left side of the body.

Inner (serous) portion of pericardium

The inner portion is a thin, double layered serous membrane called the SEROUS PERICARDIUM

_________ venous blood flows from the ______ _______, through the _________ ___________ opening when the valve is _______, into the _______ _______

DEOXYGENATED venous blood flows from the RIGHT ATRIUM, through the RIGHT ATRIOVENTRICULAR opening when the valve is OPEN, into the RIGHT VENTRICLE

Right atrioventricular valve Location Structure Function

Location: Between right atrium and right ventricle Structure: Three triangular-shaped cusps Chordae tendineae attached to free edges Function: Prevent back flow into right atrium when ventricles contract

Pulmonary semilunar valve Location Structure Function

Location: Between right ventricle and pulmonary trunk Structure: Three semilunar cusps No chordae tendineae Function: Prevents back flow of blood into right ventricle when ventricles relax

The heart exhibits autorhythmicity, what does this mean?

Meaning that the heart itself (not external nerves) is responsible for initiating the heartbeat

The serous pericardium is subdivided into: and what do these two subdivisions reflect

The inner serous pericardium is further subdivided into: (1)- parietal later of serious pericardium that lines the inner surface of the fibrous pericardium (2)- a visceral layer of serous pericardium (also called the epicardium) that covers the outside of the heart. The parietal and visceral layers reflect (fold back) along the great vessels, where these layers become continuous with one another.

The innervation by autonomic centers in the brainstem doesn't do what but can do what

The innervation by autonomic centers in the brainstem doesn't initiate a heartbeat, but it can increase or decrease the rate of the heartbeat

Endocardium

The internal surface of the heart and the external surfaces of the heart valves are covered by endocardium

What forms a thick wall between the right and left ventricles?

The interventricular septum

What arteries are the only branches of the ascending aorta?

The left and right coronary arteries

Inferior chambers

The left and right ventricles

What separates the left atrium from the left ventricle?

The left atrioventricular opening, which is covered by the left atrioventricular (AV) valve (also called the bicuspid valve since it has 2 triangular cusps) Also called the mitral valve, because the two triangular cusps resemble a miter (headpiece worn by bishop)

The left ventricular wall is what compared to the right ventricular wall?

The left ventricular wall is typically three times thicker than the right ventricular wall

Myocardium

The middle layer of the heart wall and is composed of cardiac muscle tissue. Thickest of the three heart wall layers It lies deep to the epicardium and superficial to the endocardium Myocardial layer is where myocardial infarctions (heart attacks) occur The arrangement of cardiac muscle in the heart wall permits the compression necessary to pump large volumes of blood out of the heart

Outer (fibrous) portion of pericardium

The outer portion of the pericardium is a tough, dense connective tissue layer called the FIBROUS PERICARDIUM. This layer is attached to both the diaphragm and the base of the great vessels.

Epicardium

The outermost heart layer and is also known as the visceral layer of the serous pericardium. Composed of a serous membrane and areolar connective tissue As we age, more fat is deposited in the epicardium, and so this layer becomes thicker and more fatty

What does the pericardium restrict

The pericardium restricts the hearts movements so that it doesn't bounce and move about in the thoracic cavity (makes it anchored to thoracic cavity), and prevents the heart from overfilling with blood

Base of heart

The posterosuperior surface of the heart, formed primarily by the left atrium, is called the base. The pulmonary veins that enter the left atrium border this base

The cardiovascular system consists of two circulations:

The pulmonary circulation and the systemic circulation

What two larger arteries exit the heart at its superior border

The pulmonary trunk and aorta

What separates the right atrium from the right ventricle

The right atrioventricular opening

What is the right atrioventricular opening covered by?

The right atrioventricular opening is covered by a right atrioventricular (AV) valve -- AKA the tricuspid valve (bc it has 3 triangular cusps)

Pericardial cavity

The thin space between the parietal and visceral layers of the serous pericardium is the pericardial cavity, into which serous fluid is secreted to lubricate the serous membranes and facilitate the almost frictionless, continuos movement of the heart when it beats. The pericardial cavity is a potential space with just a lining of serous fluid.

What is the issue with the branching of the right and left coronary arteries?

Their branching may differ among individuals.. may branch something that the other does and vice versa

Cardiac cycle

Time from the start of one heartbeat to the initiation of the next

The internal wall surface of each ventricle displays characteristic large, smooth, irregular muscular ridges called

Trabeculae carneae

Small cardiac vein

Travels close to the right marginal artery

The left and right bundles

conduct the impulse to conduction fibers called Purkinje cells that begin with the apex of the heart and extend through the walls of the centricles

The AV node normally slows

conduction of the impulse as it travels form the atria to the ventricles, providing a delay between activation and contraction of the ventricles

As blood is pumped into the arterial trunks, it pushes against the cusps, forcing

the valves open

Blood that enters an atrium is passed to

the ventricle on the same side of the heart

Each semilunar valve is composed of

three thin, half-moon-shaped, pocket like semilunar cusps.

Parasympathetic innervation decreases

the heart rate but generally tends to have no effect on the force of contractions

The anterior interventricular sulcus and the posterior interventricular sulcus are located between

the left and right ventricles on the anterior and posterior surfaces of the heart, respectively

Aorta conducts blood from

the left ventricle into the systemic circulation

Chordae tendineae attaches to

the lower surface of cusps of the right AV valve and prevent the valve from everting and flipping into the atrium when the right ventricle is contracting

Parasympathetic innervation comes from

the medulla oblongata by the left and right vagus nerves (CN X)

The left atrium receives blood from

the pulmonary circulation

Once gas exchange occurs in the lungs, the oxygenated blood travels through

the pulmonary veins to the left atrium

Sympatheic innervation increases

the rate and the force of heart contractions

Interatrial septum forms a thin wall between

the right and left atria

Inferior border of the heart is formed by

the right ventricle

The right AV valve is forced CLOSED when

the right ventricle begins to contract, preventing blood from flowing back into the right atrium

Pulmonary trunk carries blood from

the right ventricle into the pulmonary circulation

The heartbeat is initiated by

the specialized cardiac muscle cells of the SINOATRIAL (SA) NODE, which are located in the posterior wall of the right atrium, adjacent to the entrance of the superior vena cava

The right atrium receives blood from

the systemic circulation

The structural differences in the right atrium anterior and posterior walls occur because

the two walls formed from separate structures during embryonic development

Steps in conducting system of the heart

1- Muscle impulse is generated at the sinoatrial node.It spreads throughout the atria and to the atroventricular node by the internodal pathway 2-Atrioventricular node cells delay the muscle impulse as it passes to the atrioventricular bundle 3- The atrioventricular bundle (bundle of His) conducts the muscle impulse into the interventricular septum 4-Within the interventricular septum, the right and left bundles split from the atrioventricular bundle 5- The muscle impulse is delivered to Purkinje fibers in each ventricle and distributed throughout the ventricular myocardium

Three major vessels empty into the right atrium:

1- The superior vena cava drains blood from the head, neck, upper limbs, and superior regions of the trunk 2-The inferior vena cava drains blood from the lower limbs and trunk 3-The coronary sinus drains blood from the heart wall

Heart wall consists of three distinctive layers

1- an external epicardium 2- a middle myocardium 3- an internal endocardium

Left side of heart has muscle

3x thicker than the right

Where does the coronary sulcus drain

Directly into the right atrium of the heart

Electrocardiogram

Electrical currents within the heart can be detected during a routine physical exam using monitoring electrodes attached to the skin-- usually wrist, ankles, and 6 separate locations on the chest. Electrical signals are collected and charted as an electrocardiogram ECG/EKG Provides an accurate, compress assessment of the electrical activity of the heart

Myocardial infarctions (MI) & Coronary artery

Myocardial infarction (MI) commonly called a heart attack is a fatal condition resulting from sudden and complete occlusion (blockage) of a coronary artery

Great vessels

The arteries and veins entering and leaving the heart are known as great vessels because of their relatively large diameter

The heart is composed of four hollow chambers:

Two smaller atria and Two larger ventricles

The hearts anatomy ensures...

Unidirectional flow of blood through it Backflow of blood is prevented by valves within the heart

Coronary sinus

a large vein that lies in the posterior aspect of the coronary sulcus

Two large papillary muscles project from the left ventricles inner wall and

anchor the chordae tendineae that attach to the cusps of the left AV valve

Muscle impulse conduction along the Purkinje fibers is

extremely rapid, consistent with the large size of the cells, and the impulse spreads immediately throughout the ventricular myocardium

Left ventricle requires thicker walls to

generate enough pressure to force the oxygenated blood that has returned to the heart from the lungs into the aorta and then through the entire systemic circulation (whereas the right ventricle, in contrast, only has to pump blood to nearby lungs)

The AV node is located

in the floor of the right atrium between the right AV valve and the opening for the coronary sinus

Where do the sulci extend

inferiorly from the coronary sulcus toward the heart apex All sulci house blood vessels These vessels supply and drain the heart

Superior border of heart

is formed by the great arterial trunks (ascending aorta and pulmonary trunk) and the superior vena cava.

Purkinje fibers are

larger than other cardiac muscle cells

Where do the cardiac veins drain

All the cardiac veins drain into the coronary sinus

Under the influence of parasympathetic innervation, SA node cells initiate impulses

70-80 times per minute

What does an ECG provide

A composite tracing of all muscle impulses generated by myocardial cells It records the wave of change in voltage (potential) across the sarcolemma that (1) originates in the SA node (2) radiates through both of the atria to the AV node (3) passes through the AV node and the interventricular septum to the heart apex (4) stimulates the purkinje fibers in the ventricular myocardium

The atroventricular (AV) bundle,

AKA bundle of His, receives the muscle impulse from the AV node and extends into the interventricular septum before dividing into left and right bundles.

There is an opening in the fibrous skeleton that allows the

AV node to communicate with the next part of the conducting system, the atrioventricular (AV) bundle

The heart develops...

Blood pressure through alternate cycles of heart wall contraction and relaxation. Blood pressure is the force of the blood pushing against the inside walls of the vessels A minimum blood pressure is essential for pushing through the blood vessels

What is the heart innervated by

By the autonomic nervous system

Arteries

Carry highly oxygenated blood AWAY from the heart (exception: pulmonary arteries)

Veins

Carry low oxygenated blood BACK TO the heart (exception: pulmonary veins)

Conducting system

Certain cardiac muscle cells are specialized to initiate and conduct muscle impulses to the contractile muscle cells of the myocardium. Collectively, these specialized cells re called the hearts conducting system

Systemic circulation

Consists of the chambers on the left side of the heart (left atrium and left ventricle), along with all the other named blood vessels. It carries blood to all the peripheral organs and tissues of the body Blood that is high in oxygen (oxygenated) from the left side of the heart is pumped into the aorta, the largest systemic artery in the body, and then into smaller systemic arteries. Gas is exchanged with tissues from the bodies smallest vessels, called capillaries. Systemic veins then carry blood that is low in oxygen (deoxygenated) and high in carbon dioxide and waste products back to the heart (right atrium) Most veins merge and drain into the superior and inferior vena cava which drain blood into the right atrium. There, the blood enters the pulmonary circulation and the cycle repeats

Pulmonary circulation

Consists of the chambers on the right side of the heart (right atrium and right ventricle) as well as the pulmonary arteries and veins This circulation conveys deoxygenated blood to the lungs by PULMONARY ARTERIES to reduce carbon dioxide and replenish oxygen levels in the blood before returning to the heart in PULMONARY VEINS Oxygenated blood returns to the left side of the heart, where it then enters the systemic circulation

Fossa Ovalis

Inspection of the right interatrial septum reveals an oval depression called the fossa ovalis, also called the oval fossa

Pulmonary semilunar valve

Is beyond the conus arteriosus and marks the end of the right ventricle and the entrance into the pulmonary trunk

What do the right and left atrium have in common?

Like the right atrium, the left atrium also has pectinate muscles along its anterior wall as well as an auricle

Left atrioventricular valve Location Structure Function

Location: Between left atrium and left ventricle Structure: Two triangular shaped cusps Chordae tendineae attached to free edges Function: Prevents back flow of blood into left atrium when ventricles contract

Aortic Semilunar valve Location Structure Function

Location: Between left ventricle and ascending aorta Structure: Three semilunar cusps No chordae tendineae Function: Prevents back flow of blood into left ventricle when ventricles relax

______ blood flows from the ____ _____, through the ______ _______ opening when the valve is ____, into the ____ _____

OXYGENATED blood flows from the LEFT ATRIUM, through the LEFT ATRIOVENTRICULAR opening when the valve is OPEN, into the LEFT VENTRICLE

Typical ECG tracing for one heart cycle has three principal definitions

P wave above baseline QRS complex that begins Q and ends D with small downward deflection from the baseline and has a large deflection R above the baseline, and T wave above the baseline These waves are indicators of depolarization and depolarization within specific regions of the heart

Muscular ridges in the auricle and anterior right atrial wall is known as

Pectinate muscles

The left AV valve is forced closed when the

left ventricle begins to contract, preventing blood back flow into the left atrium

The cells of the SA node act as the

pacemaker, the rhythmic center that establishes the pace for cardiac activity

The right ventricle typically has three cone-shaped, muscular projectections called

papillary muscles which anchor numerous thin strands of collagen fibers called CHORDAE TENDINEAE

When ventricular contraction ceases, blood is

prevented from flowing back into the ventricles from the arterial trunk by first entering the pockets of the semilunar valves between the cusps and the chamber wall This causes the cusps to "fill and expand" and meet at the artery center, effectively blocking blood backflow

Right atrium receives venous blood from the

systemic circulation and the heart muscle itself

The muscle impulse travels from

the SA node to the atrioventricular (AV) node

Left coronary artery branches into

the anterior interventricular artery as well as the circumflex artery

What is the largest systemic artery in the body

the aorta

At the superior end of the ventricular cavity..

the aortic semilunar valve marks the end of the left ventricle and the entrance into the aorta

What are the sympathetic and parasympathetic nervous system collectively referred to as

the coronary plexus