chapter 17 unit 1

Flashcards covering key concepts, anatomy, physiology, and ECG findings from the Unit 1 cardiac lecture transcript.

Through which vessels is oxygenated blood delivered to the atrium?

Pulmonary veins

What is the function of the valves in the heart?

Prevent back flow of blood

What is the most superficial layer of the pericardium?

Fibrous pericardium

What would happen if the chordae tendineae stopped functioning?

Blood would leak back into the atria from the ventricles

Which functions are associated with the heart?

To help maintain homeostasis of blood pressure, to produce a hormone called atrial natriuretic peptide, and to pump blood through two different sets of vessels, or circuits

The visceral pericardium is the same as which layer of the heart wall?

Epicardium

The right side of the heart receives deoxygenated blood from which circuit?

Systemic circuit

Which statement best describes the apex of the heart?

Inferior tip of the heart and points toward the left side

Which blood vessel is associated with the coronary sinus?

Great cardiac vein

Which coronary artery supplies the left ventricle?

Circumflex artery

Which opening in the interatrial septum connects the right and left atrium in a fetus?

Foramen ovale

Which vessel carries oxygenated blood?

Pulmonary vein

What are the three layers of the heart wall from deep to superficial?

Endocardium, myocardium, & epicardium

How might anastomoses help a patient with coronary artery disease?

They provide alternate routes of blood flow when a vessel is blocked

Which cardiac chamber has the thickest wall?

Left ventricle

Blood in the right atrium should travel through which valve to enter the right ventricle?

Tricuspid valve

What valve prevents the back flow of blood from the right ventricle to the right atrium?

Right atrioventricular valve (tricuspid)

What blood vessels do ventricles always pump blood into?

Arteries

What is the clinical name for the mitral valve?

Bicuspid valve

Which vessel is guarded by a semilunar valve at its base?

Pulmonary trunk

Which condition is not a risk factor for coronary artery disease or myocardial ischemia?

Low blood pressure

Which structure is associated with the atria?

Pectinate muscles

Where does the right ventricle send blood?

Pulmonary trunk

Both the left and the right atria receive blood from what type of vessels?

Veins

What are the three layers of the heart wall from superficial to deep?

Epicardium, myocardium, & endocardium

Which ion channels are time-gated closing channels?

Calcium ion channels

What kind of ion channels are unique to pacemaker cells?

HCN channels

Autorhythmicity in the heart is a function of which cells?

Cardiac pacemaker cells

What activity is occurring in the heart during the Q-T interval on an electrocardiogram (ECG)?

The ventricular cells are undergoing action potentials

Which electrocardiogram (ECG) finding measures heart rate?

R-R interval

What cardiac dysrhythmia does a patient have with a resting rate of $110\,\text{beats per min}$?

Tachycardia

What does the P wave on an electrocardiogram (ECG) represent?

Depolarization of cells in the atria

What obscures atrial repolarization on an electrocardiogram (ECG)?

QRS complex

The right and left atria depolarize and contract following the arrival of the action potential from where?

Sinoatrial (SA) node

What normally serves as the pacemaker of the entire heart?

Sinoatrial (SA) node

A damaged atrioventricular (AV) node primarily affects the length of which ECG interval?

P-R interval

How does the total refractory period of cardiac muscle compare to skeletal muscle?

It is longer than the total refractory period for skeletal muscle

What part of an electrocardiogram (ECG) represents ventricular repolarization?

T wave

What provides a graphic representation of all the action potentials occurring in the heart?

Electrocardiogram

Which cardiac dysrhythmia is immediately life-threatening and manifests on the ECG with chaotic activity?

Ventricular fibrillation

When looking under a microscope, what visible structures join cardiac muscle cells?

Intercalated discs

Which pacemaker cell population has an intrinsic rate of depolarization at about $20\,\text{times per min}$?

Purkinje fiber system

What phase is initiated by a rapid influx of sodium ions into contractile cells, creating a positive membrane potential inside the cell?

Rapid depolarization phase

What event does the S-T segment represent on an ECG?

Ventricular plateau phase

What allows the atria and ventricles to depolarize and contract separately?

Atrioventricular (AV) node delay

Which electrocardiogram (ECG) finding represents ventricular depolarization?

QRS complex

What percentage of the total number of cardiac muscle cells are pacemaker cells?

$$1\%$$

During what part of the action potential will calcium ions enter the contractile cells?

Plateau phase

Which structural component is uniquely found in cardiac muscle?

Intercalated discs

Which cell population does not spontaneously generate action potentials in the cardiac conduction system?

Contractile cells

Which ions are involved in a contractile cell action potential?

Sodium, calcium, potassium

Which wave on the electrocardiogram (ECG) corresponds with the ventricular filling phase of the cardiac cycle?

P wave

What is the degree of stretch experienced by the ventricles before they contract called?

Preload

What is the volume of blood pumped per ventricle per heart beat?

Stroke volume (SV)

Inotropic agents affect which property of the heart?

Contractility

High-pressured blood in the ventricles forces which valves open?

Semilunar valves

Approximately how much blood is pumped from each ventricle during the ventricular ejection phase?

$$70\,\text{mL}$$

Which term refers to the force the ventricles must overcome to eject blood into their respective arteries?

Afterload

What percentage of atrial blood flows passively into the ventricles?

$$80\%$$

Which hormone decreases cardiac output by decreasing blood volume and preload?

Atrial natriuretic peptide

Which chamber generates the highest pressure during systole?

Left ventricle

During what phase is the S2 heart sound heard?

Isovolumetric relaxation phase

What largely determines preload?

End-diastolic volume (EDV)

Which hormones increase cardiac output?

Aldosterone, antidiuretic hormone, norepinephrine

Which event can be heard most easily with a stethoscope?

Closing of atrioventricular valves

Which term refers to the degree of stretch experienced by the sacromeres in the ventricles cells before they contract

Preload

Which hormone decreases cardiac output by decreasing blood volume and preload?

Atrial natriuretic peptide

What two values are needed to calculate cardiac output (CO) for a ventricle?

Stroke volume (SV) and heart rate (HR)

Which of the following paths does an action potential in the heart normally take?

SA node, atrial contractile cells, AV node, AV bundle, right and left bundle branches, Purkinje fibers, ventricular contractile cells

Which of the following chemical messengers decreases heart rate?

Acetylcholine

Which of the following factors would increase cardiac output to the greatest extent?

Increased heart rate and increased stroke volume

Calculate the end-systolic volume (ESV) if the end-diastolic volume (EDV) in a resting heart is 110 ml and stroke volume (SV) is 70 ml.

40ml

Approximately how much blood is pumped from each ventricle during the ventricular ejection phase?

70 ml

According to the Frank-Starling law, a bigger preload will result in __________.

a stronger contraction

Which cranial nerves have a negative chronotropic effect on heart rate?

Vagus nerves (CN X)

Amount of blood in the ventricle at the end of a contraction

End-systolic volume (ESV)

Amount of blood in the ventricle after it has filled during diastole

End-diastolic volume (EDV)

Amount of blood pumped into the pulmonary and systemic circuits in 1 minute

Cardiac output (CO)

Volume of blood per heartbeat pumped out by one ventricle

Stroke volume (SV)