Anatomy of the Heart

Which of the following correctly describes ventricular ejection? Select all that apply.

- occurs when semilunar valves are open - lasts for about 0.25 second - occurs when atrioventricular valves are closed

Two hormones that increase heart rate are [dropdown 1] and [dropdown 2].

- thyroid hormone - epinephrine

The period of atrial systole lasts about [dropdown 1] while the period of ventricular systole lasts approximately [dropdown 2].

0.1 second 0.3 second

Which phases of a heartbeat shown in the diagram involve depolarization of any of the heart's four chambers?

1 and 3

In the diagram, which labeled structure is the pulmonary semilunar valve?

A

Which labeled blood vessel shown in the diagram is the left common carotid artery?

A

Which labeled structure in the figure acts as the natural pacemaker of the heart?

A

Which of the labeled diagrams shows coarctation of the aorta?

A

Describe the recent research that showed significant replacement of heart cells is possible as well as the presence of stem cells in heart muscle tissue.

A study of male heart transplant patients where the donor was female was conducted in order to determine if heart cells can be replaced. Because males have an X and a Y chromosome in all of their cells (except gametes) and females have two X chromosomes in all of their cells (except gametes), researchers analyzed the heart cells in the donor heart several years after the transplant took place. It would be expected that all of the cells would contain two X chromosomes since the heart came from a female. However, researchers were surprised to find that between 7% and 16% of the heart cells in the transplanted heart had been replaced by the recipients own cells. This was determined by the presence of a Y chromosome in those cells. In addition, the presence of cells with some of the characteristics of stem cells were present in both transplanted hearts and control hearts. It was determined that stem cells can migrate from the blood into the heart and differentiate into functional muscle cells.

What is the function of the foramen ovale during fetal life?

Allowing blood to flow directly from the right atrium into the left atrium.

Identify the groove found on the surface of the heart that marks the boundary between the right and left ventricles.

Anterior interventricular sulcus

Blood leaving the left ventricle passes through which of the following structures?

Aortic semilunar valve

Discuss the common nutrient sources used by cardiac muscle to produce ATP in a resting individual.

At rest, the heart relies exclusively on aerobic cellular respiration. At rest, the heart's ATP comes mainly from oxidation of fatty acids (60%), and glucose (35%) with smaller contributions from lactic acid, amino acids, and ketone bodies

In the diagram, which labeled structure prevents blood flow from the right ventricle back into the right atrium?

B

Which labeled structure in the figure is the AV node?

B

Which of the labeled steps in the diagram represents formation of the endocardial tubes?

B

In the diagram, which labeled structures are atrioventricular valves?

B and D

Which labeled structure in the figure represents the only pathway for conducting action potentials from the atria to the ventricles?

C

Which of the labeled diagrams shows an atrial septal defect?

C

Which of the labeled steps in the diagram represents formation of the primitive heart tube?

C

Which network of specialized cardiac muscle fibers provides a path for each cycle of cardiac excitation to progress through the heart?

Cardiac conduction system

Which of the following types of muscle contains the largest number of mitochondria per cell?

Cardiac muscle

Briefly describe why cardiac tissue cannot repair itself after damage?

Cardiac muscle lacks stem cells and mature cardiac muscle fibers cannot go through mitosis.

Which of the following blood vessels is used to distribute oxygenated blood to the myocardium?

Coronary artery

Which labeled structure in the figure is the ligamentum arteriosum?

D

Which labeled structure shown in the diagram is a remnant of fetal circulation that is not directly involved in adult circulation?

D

What type of tissue comprises the valves of the heart?

Dense connective tissue

Identify the structure found in a fetus that allows blood to flow directly from the pulmonary trunk into the aorta.

Ductus arteriosus

Which labeled blood vessel in the diagram is an artery carrying deoxygenated blood?

E

Which labeled structure in the figure carries the cardiac action potential directly into the contractile fibers of the ventricular myocardium?

E

In the diagram, where is the left auricle of the left atrium?

G

Which labeled structure shown in the diagram is a pouch-like extension that serves to slightly increase the capacity of an atrium?

G

Which of the following would lead to a decreased heart rate?

Increased potassium levels in plasma

Explain the difference in the functions of low-density lipoproteins and high-density lipoproteins and explain why one is called "good" cholesterol and the other is called "bad" cholesterol.

Low-density lipoproteins (LDL) transport cholesterol from the liver to body cells. Excess LDLs lead to the development of atherosclerotic plaque, so they are referred to as "bad" cholesterol. High-density lipoproteins (HDL) remove excess cholesterol from body cells and transport it back to the liver for elimination, so they are referred to as "good" cholesterol.

Which of the following terms identifies the anatomical region found between the lungs that extends from the sternum to the vertebral column and from the first rib to the diaphragm?

Mediastinum

An increase in the carbon dioxide levels in the blood leads to a change in the chemical composition of the blood. This input would be received by which part of the brain that regulates heart rate?

Medulla oblongata

Which layer of the heart wall consists of cardiac muscle tissue?

Myocardium

Which of the following electrocardiogram (ECG) waves represents atrial depolarization?

P wave

Identify the muscular ridges that are found on the anterior wall of the right atrium and extend into the auricles.

Pectinate muscles

Which of the following is used to reduce friction between the layers of membranes surrounding the heart?

Pericardial fluid

Describe what is happening during the phase of the cardiac action potential labeled 2 in the diagram.

Phase 2 is the plateau phase which occurs due to opening of voltage-gated slow calcium channels, which allows continued inflow of Ca2+ from ICF into the cytosol. This continuous inflow of Ca+2 causes sustained depolarization of the cardiac muscle cells.

Which valve below prevents blood from flowing back into the right ventricle?

Pulmonary semilunar valve

Which of the following chambers of the heart contains deoxygenated blood?

Right atrium and right ventricle

Which of the following correctly lists the sequence of structures that a cardiac action potential follows in order to excite normal contraction of the heart?

SA node, AV node, Bundle of His, Purkinje fibers

The second heart sound (dupp) closely follows which of the events listed below?

Semilunar valves closing

Which structure in the heart initiates action potentials that stimulate contraction of the heart at a constant rate of about 100 beats per minute?

Sinoatrial node

Which wave in an electrocardiogram represents repolarization of the ventricles?

T wave

What is the relationship between an individual who is exercising strenuously causing his or her heart rate to exceed 160 beats/minute and the Frank-Starling law of the heart?

The Frank-Starling law of the heart states that the more the heart fills with blood during diastole, the greater the force of contraction during systole. When an individual is exercising strenuously, it would not be unusual for the heart rate to exceed 160 beats per minute. When this happens, stroke volume usually declines because the filling time is reduced thus leading to a reduced end diastolic volume (EDV). The reduced EDV means that, according to the Frank-Starling law, the preload is lower and the stroke volume is also reduced.

Briefly describe what is happening at the stage of the ECG labeled 5 in the diagram.

The contractile fibers of the ventricles are repolarizing, which generates the T wave in the ECG.

Why is the myocardium of the left ventricle thicker than the myocardium of the right ventricle?

The left ventricle muscular wall is thicker than the right ventricle because it has to generate higher pressure to overcome the greater resistance of the longer systemic circulation route versus the shorter pulmonary circulation route. Basically, the more work a muscle does, the larger it gets.

Define arrhythmia and discuss different categories of arrhythmias.

The term arrhythmia or dysrhythmia refers to an abnormal rhythm as a result of a defect in the conduction system of the heart. Arrhythmias are categorized by their speed, rhythm, and origination of the problem. Bradycardia refers to a slow heart rate (below 50 bpm); tachycardia refers to a rapid heart rate (over 100 bpm); and fibrillation refers to rapid, uncoordinated heartbeats. Arrhythmias that originate in the atria are called supraventricular or atrial arrhythmias; those that originate in the ventricles are called ventricular arrhythmias.

Explain how the heart pumps blood into two separate closed circuits that are arranged in series.

The two circuits are the pulmonary and systemic circuits. Venous blood from the systemic circulation enters the right atrium. The blood moves from the right atrium into the right ventricle of the heart, which pumps blood through the pulmonary circuit eventually filling the left atrium. The blood moves from the left atrium into the left ventricle of the heart, which pumps blood through the systemic circuit back into the right atrium.

Through which structure does blood pass from the right atrium to the right ventricle?

Tricuspid valve

During heart transplants, the [___] nerves are severed resulting in a faster resting heart rate (approximately 100 beats per minute) after the transplant.

Vagus

Stimulation of which nerve reduces heart rate?

Vagus nerve

A patient presents with a fever, heart murmur, irregular heartbeat, fatigue, loss of appetite and night sweats. As a physician, your diagnosis would be that of endocarditis typically caused by

a bacterial infection

In comparison to a sedentary individual, a well-trained athlete will usually have all the following characteristics EXCEPT

a higher resting cardiac output.

In comparison to skeletal muscle fibers, the contractile fibers of the heart are depolarized for [___] period of time.

a longer

Pectinate muscles extend from the atrial internal wall into the pouch-like structures that increase the total filling capacity of the atrium. These structure are the

auricles

Positive inotropic agents often promote inflow of which cation to increase contractility of the heart?

calcium

The volume of blood ejected from the left ventricle into the aorta each minute is called the

cardiac output.

The difference between a person's maximum cardiac output and resting cardiac output is called the

cardiac reserve.

Trauma to the pericardium associated with bleeding into the pericardial cavity, might cause

cardiac tamponade

Which of the following is a corrective cardiac procedure in which a large piece of a patient's own latissimus dorsi muscle is wrapped around the heart and stimulated by an implanted pacemaker to assist the pumping action of a damaged heart?

cardiomyoplasty

The visceral layer of the serous pericardium is also considered to be the

epicardium

Which week of fetal development might be considered the stage of development of the heart with the chambers as they will be oriented for the rest of the individual's life?

fourth

Cardiac muscle fibers are electrically connected to neighboring fibers by

gap junctions.

The formula for calculating cardiac output (CO) is

heart rate multiplied by stroke volume

Which of the following selections lists conditions that would lead to increased stroke volume?

increased preload, decreased afterload, increased contractility

Contraction of the ventricles of the heart leads to blood moving directly

into arteries.

Which structure in the figure is labeled A?

left common carotid artery

Cardiac output is the volume of blood ejected from the [dropdown 1] ventricle into the [dropdown 2] each minute.

left or right aorta or pulmonary trunk

Which structure in the figure is labeled B?

left subclavian artery

Which of the following chambers of the heart is surrounded by the thickest layer of myocardium?

left ventricle

Prior to physical activity, the heart rate may climb. This anticipatory increase is caused by nerve impulses traveling to the cardiovascular center of the medulla oblongata that originate in the

limbic system

Cardiac tamponade may develop following a case of

pericarditis

The membrane that surrounds and protects the heart is called the

pericardium.

The coronary sulcus marks the external boundary between the [dropdown 1] and the [dropdown 2].

superior atria inferior ventricles

Which term refers to the period of time during a cardiac cycle when contraction of a chamber occurs and pressure within the chamber rises?

systole

Athletes tend to have higher cardiac reserves because

their hearts operate more efficiently due to training

Contraction of the atria of the heart leads to blood moving directly

through atrioventricular valves

The apex of the heart is normally pointed

to the left of the midline

Heart murmurs are often heard in individuals with abnormalities in the [dropdown 1] of the heart.

valves

Isovolumetric contraction is the phase of the cardiac cycle in which

ventricular pressure increases and ventricular volume remains the same.

During which of the following periods does the largest volume of blood enter the arteries?

ventricular systole