BMS 251 Chapter 19 Questions

What type of heart valve is associated with tendinous cords?

AV Valves

What occurs when the ventricles contract

AV valves close Semilunar valves open blood is ejected into the aorta

What occurs during the atrial reflex

An increase of heart rate occurs in response to an increase in blood volume within the atria

What are the functions of the three different types of blood vessels?

Arteries carry blood away from the heart, veins carry blood back to the heart, and capillaries are sites of gas exchange

What is happening mechanically during the Q-T complex of an ECG?

Atrial depolarization, ventricular depolarization, ventricular repolarization

Depolarization of cardiac muscle cells is caused by

Calcium channels closing

What is the function of the coronary sulcus?

Coronary arteries rest in the coronary sulcus to supply blood to the heart. The atria are separated from the ventricles externally by the coronary sulcus

What is the cardioinhibitory center and where is it located?

Decreases heart rate and is located in the medulla oblongata

What ionic event creates the depolarization phase of an nodal cells action potential?

Fast voltage-gated Ca2+ channels open and Ca2+ flows in

Preload is a measure of

Heart chamber volume prior to contraction

What is the difference between neuron depolarization and nodal cell depolarization?

In neurons, action potential depolarization is from Na+ entry; in nodal cells it is from Ca2+ entry

How does venous return affect total stroke volume

Increase in exercise causes an increase in venous return, which increases stroke volume

Positive chronotropic agents function by

Increasing cardiac output by boosting heart rate

Describe the structure and function of intercalated discs in cardiac muscle tissue

Intercalated disks tightly link the cardiac muscle cells together and permit the passage of action potentials

Bradycardia can be caused by

Introduction of acetycholine

During which stage of the cardiac cycle are all chambers relaxed and all valves closed?

Isovolumetric relaxation

Where around the heart is the serous fluid located?

Pericardial cavity

Sarcolemma of a cardiac muscle cell is equivalent to what structure of a typical cell?

Plasma membrane

In which wave of an ECG can ventricular systole be seen?

QRS complex

What is the circulation sequence for blood to pass through part of the heart?

Right atrium, right AV valve, Right Ventricle, pulmonary semilunar valve

What is the structures of the conduction system in order?

SA node, AV node, AV bundle, Purkinje fibers

What is the mediastinum?

Space between lungs

an increase in heart rate is caused by

Sympatheic firing of the medulla oblongata

Define cardiac output

The amount of blood pumped by a single ventricle in 1 minute

What different functions are served by the left and right sides of the heart?

The right side receives deoxygenated blood from the body and pumps it to the lungs. The left side receives oxygenated blood from the lungs and pumps it to the body.

Why are chordae tendineae required for the proper functioning of AV valves?

This prevents the valve from inverting and being pushed open

Explain why the walls of the atria are thinner than those of the ventricles, and why the walls of the right ventricle are relatively thin when compared to the walls of the left ventricle?

Ventricles pump the blood. The right ventricle pumps blood through pulmonary circuit. The left ventricle pumps blood through the systemic circuit. Systemic circulation requires more contractile force.

What voltage-gated ion channels are open during repolarization of cardiac muscle cells?

Voltage-gated K+ channels

Atherosclerosis can directly increases

afterload

Which valve will prevent blood from flowing backward from the left ventricle

aortic semilunar valve

Calcium channels in the nodal cells function to

causes depolarization and initiate cardiac action potential

How is blood prevented from back flowing from the pulmonary trunk into the right ventricle?

closing the the pulmonary semilunar valve

What two functions do intercalated disks serve?

connecting cells, communication

What type of vessels deliver blood to the heart tissue?

coronary arteries

Venous blood draining the heart wall enters the right atrium through the

coronary sinus

If cardiac muscle were weakened, would SV increase or decrease?

decrease

What is the inner layer of the heart wall?

endocardium

Heart murmur in an infant can be caused by

foramen ovale

What occurs if the foramen oval of the heart does not occur at birth?

heart murmur

How do positive chronotropic agents affect cardiac output?

increase heart rate

How does the heart respond to increased venous return?

increase stroke volume

Action potentials are spread rapidly between cardiac muscle cells by

intercalated discs

What units are used in measurements of perfusion?

mL/min/g

What is the appropriate unit for measuring cardiac output

ml/minute

What type of heart cell is influenced by chronotropic agents? Nodal cells or cardiac cells?

nodal cell

The pericardial cavity is located between the

parietal and visceral layers of the serous pericardium

Basic pattern of heart structures in order according to blood flow

right heart, lungs, left heart, systemic tissues, right heart

What heart valves are open during ventricular ejection?

semilunar valve

Which of the two autonomic nervous system divisions has an effect on the force of heart contraction?

sympathetic

Another term for the sinoatrial node is

the pacemaker

Why is it necessary to stimulate papillary muscles in the ventricle slightly earlier than the rest of the ventricular wall myocardium?

to pull on the AV cusps to prevent back flow