Chapter 22- Heart

What is a cardiac cycle?

A cardiac cycle is the time from the start of one heartbeat to the initiation of the next.

What's essential to circulate blood throughout the body?

A minimum blood pressure.

What is the fibrous pericardium?

A tough outer sac.

What is the heart enclosed in?

A tough sac called the pericardium.

What is an auricle?

A wrinkled flap like extension on the anterior part of each atrium.

What is the function of the anterior interventricular artery?

Also called the left anterior descending artery; supplies the anterior surface of both ventricles and most of the interventricular septum.

What is the atrioventricular valve?

Also known as the tricuspid valve and it seperates the right atrium from the right ventricle.

What is the fossa ovalis?

An oval depression in right atrium.

What is the function of arteries?

Arteries carry blood away from the heart.

What does autonomic innervation control?

Autonomic innervation does not initiate a heartbeat, but it can increase or decrease the rate of the heartbeat.

What do cardiac muscle fibers contract as a single unit?

Because they are all connected with low resistance cell-to-cell junctions called gap junctions.

The left atrioventricular valve/ Bicuspid

Between left atrium and left ventricle and blood is oxygenated.

The aortic semilunar valve

Between left ventricle and aorta/ aortic arch and the blood is oxygenated and goes out to the body system.

The right atrioventricular/tricuspid valve

Between right atrium and right ventricle and blood is deoxygenated.

The pulmonary semilunar valve

Between right ventricle and pulmonary trunk and the blood is deoxygenated and goes to the lungs.

What is the right ventricle?

Chamber that receives deoxygenated venous blood from the right atrium to be pumped to lungs.

What is the left ventricle?

Chamber that receives oxygenated blood from the left atrium to be pumped throughout body.

What is the left atrium?

Chamber that receives oxygenated blood from the lungs (forms the base of the heart posteriorly).

What is the right atrium?

Chamber that receives venous blood from systemic circulation.

What is the contraction of a chamber called?

Contraction of a chamber is called systole.

What does contraction of the myocardium force?

Contraction of myocardium forces blood either from the atrium to the ventricle or from ventricle to the attached blood vessel.

What is pulmonary circulation?

Conveys deoxygenated blood from the right side of the heart through blood vessels to the lungs for picking up oxygen and release of carbon dioxide.

What are cusps?

Cusps are triangular flaps that hang down into the ventricle.

What is the blood pathway of the right atrium?

Deoxygenated venous blood flows from the right atrium to the right ventricle through the right atrioventricular valve. The right atrioventricular valve is forced closed when the right ventricle begins to contract, preventing blood back flow into the right atrium.

What happens during a single cardiac cycle?

During a single cardiac cycle all chambers within the heart experience alternate periods of contraction and relaxation.

What are the two parts of the pericardium?

Fibrous pericardium and the serous pericardium.

What is the pathway of the impulses from the SA node?

Impulses from the SA node travel via gap junctions to the left atrium and the atrioventricular (AV) node located in the floor of the right atrium.

What do intercalated discs do?

Intercalated discs electrically and mechanically link cells together. Therefore, an electrical impulse is distributed immediately and spontaneously throughout the myocardium.

What does the left coronary artery branch into?

It branches into the anterior interventricular artery and the circumflex artery.

What does the right coronary artery branch into?

It branches into the right marginal artery and the posterior interventricular artery.

Where does the electrical impulse that initiates the heartbeat come from?

It comes from specialized cardiac muscle cells called the sinoatrial (SA) node or the pacemaker.

What does parasympathetic innervation do?

It decreases heart rate but generally has no effect on force of contraction.

What does the heart exhibit and what does it mean?

It exhibits autorhythmicity, which means it is capable of initiating its own heartbeat independent of external nerves.

What does the left ventricle have thicker walls?

It has thicker walls in order to generate enough pressure.

What does sympathetic input to the heart do?

It increases the rate and force of heart contractions.

What is the heart innervated by?

It is innervated by both the sympathetic and parasympathetic divisions of the autonomic nervous system.

Where is the SA node located?

It is located on the posterior wall of the right atrium adjacent to the opening of the superior vena cava.

What is the heart functionally?

It is two side-by-side pumps that work at the same rate and pump the same volume of blood- one pump directs blood to the lungs and the other directs blood to most body tissues.

What is blood flow through the heart and why?

It is unidirectional because of four valves within the heart.

What does the aortic semilunar valve mark?

It marks the end of the left ventricle and the beginning of the aorta.

Where does sympathetic innervation start?

It starts with neurons located in T1-T5 segments of the spinal cord.

Where does the impulse go when it leaves the AV node?

It travels into the atrioventricular (AV) bundle (bundle of His), which extends into the interventricular septum.

What does the lub sound of the heart mean?

Known as S1 represents the closing of the atrioventricular valves (right and left) and occurs at beginning of ventricular contraction or systole.

What does the dub sound of the heart mean?

Known as S2 represents the closing of the semilunar valves (pulmonary and aortic) and occurs at the end of ventricular systole and the beginning of diastole.

What is the serous pericardium?

Layer composed of parietal and visceral layers; forms pericardial cavity.

What are the two sounds the heart makes?

Lub and dub.

What is systemic circulation?

Moves oxygenated blood from the left side of the heart through blood vessels to be pumped to body's system/cells.

Where does the left atrium receive blood from?

Oxygenated blood from the lungs travels through the pulmonary veins to the left atrium.

Where does parasympathetic innervation start?

Parasympathetic innervation starts with neurons in the medulla oblongata via the left and right vagus nerves (CN X).

Where do postganglionic axons project from and where do they travel to?

Postganglionic axons project from all three cervical ganglia and travel to the heart via cardiac nerves.

Where do preganglionic axons enter and what do they synapse on?

Preganglionic axons enter the sympathetic trunk and synapse on ganglionic neurons.

What are the two types of circuits?

Pulmonary circulation and systemic circulation.

What is the function of the left ventricle?

Pumps oxygenated blood to the entire body, (except for the lungs), and therefore has to generate a great deal of force.

What type of blood does the right ventricle receive?

Receives deoxygenated venous blood from the right atrium.

What type of blood does the right atrium receive?

Receives oxygen poor blood from systemic circulation.

What is the relaxation of a chamber called?

Relaxation of a chamber is called diastole.

What is the function of the pericardium?

Restricts heart movements so that it moves only slightly within the thorax.

What is the position of the heart?

Slightly left of midline deep to the sternum in a compartment of the thorax known as the mediastinum.

What happens to the AV bundle within the septum?

The AV bundle divides into left and right bundles (bundle branches).

What do purkinje fibers do with the impulse?

The Purkinje fibers spread the impulse superiorly from the apex to all of the ventricular myocardium.

What makes up the cardiac plexus?

The anatomical components of both divisions .

What is located at the superior end or roof of the left ventricle?

The aortic semilunar valve.

What are the only branches given off by the ascending aorta just superior to the aortic semilunar valve?

The coronary arteries.

What are the three layers of the heart wall?

The epicardium, myocardium, and the endocardium.

What is blood pressure?

The force of the blood pushing against the inside walls of blood vessels.

What is the interatrial septum?

The forms a thin wall between right and left atria.

Venous return of blood from the heart wall muscle occurs through what?

The great cardiac vein, the middle cardiac vein, and the small cardiac vein.

How does the heart generate blood pressure?

The heart generates blood pressure through alternate cycles of the heart wall's contraction and relaxation.

What is the function of the heart?

The heart propels blood to and from most body tissues via two basic types of blood vessels called arteries and veins.

What is the apex of the heart?

The inferior conical end that projects slightly towards the left side of the body.

What does the inner wall of each ventricle display?

The inner wall of each ventricle displays large, irregular muscular ridges called trabeculae carneae.

What is the endocardium?

The internal surface of the heart chambers and external surface of the heart valves and is composed of simple squamous epithelium, and a layer of areolar CT.

What is the myocardium?

The middle layer of the heart wall composed of cardiac muscle tissue; thickest of the three layers

What is the epicardium?

The outermost heart layer, known as visceral layer of the serous pericardium. Composed of a serous membrane and areolar connective tissue.

What is the base of the heart?

The posterosuperior surface of the heart that is mainly the left atrium.

What are the four chambers of the heart?

The right atrium, the right ventricle, the left atrium, and the left ventricle.

What are the three veins that drain into the right atrium?

The superior vena cava, the inferior vena cava, and the coronary sinus.

What do all three major coronary veins do?

They all drain into the coronary sinus, which drains into the right atrium.

What is the function of papillary muscles?

They anchor chordae tendineae attached to the right atrioventricular valve cusps.

What are the left atrium and ventricle separated by?

They are are separated by the left atrioventricular valve AKA the bicuspid or mitral valve.

What are purkinje fibers?

They are conducting fibers that begin at the apex of the heart and extend through the walls of the ventricles.

What do gap junctions comprise of?

They comprise of the intercalated discs shared by adjacent cardiac muscle fibers which allow a flow of ions necessary for synchronous beating of cardiac muscle cells.

What to the bundle branches do with the impulse?

They conduct the impulse to conducting fibers called Purkinje fibers.

What do the chordae tendineae prevent?

They prevent the cusps from flipping into the right atrium when the right ventricle contracts.

What do the right and left coronary arteries do?

They travel within the coronary sulcus and supply the heart wall muscle with oxygen and nutrients.

What is the superior vena cava?

This drains blood from the head, neck, upper limbs (superior portion of trunk).

What is the coronary sinus?

This drains blood from the heart wall.

What is the inferior vena cava?

This drains blood from the lower limbs and trunk.

What is the interventricular septum?

This forms a thick wall between the right and left ventricles.

What is diastole?

This is the period between contractions where the myocardium of each chamber relaxes and fills with blood.

What is the function of the circumflex artery?

This supplies the left atrium and ventricle.

What is the function of the posterior interventricular artery?

This supplies the posterior surface of the left and right ventricles.

What is the function of the right marginal artery?

This supplies the right border of the heart.

T or F: Left ventricular wall is typically three times thicker than the right.

True.

How many cusps does the left atrioventricular valve have?

Two.

What does the right ventricle typically have?

Typically has three cone-shaped muscle projections called papillary muscles.

What is the great cardiac vein?

Vein that runs alongside the anterior interventricular artery.

What is the middle cardiac vein?

Vein that runs alongside the posterior interventricular artery.

What is the small cardiac vein?

Vein that travels close to the marginal artery.

What is the function of veins?

Veins carry blood back to the heart.

When is the left atrioventricular valve is forced shut?

When the left ventricle contracts.

What happens when the right ventricle contracts?

When the right ventricle contracts it sends blood through the pulmonary semilunar valve up through the pulmonary trunk out the pulmonary arteries to the lungs.