With a cardiac rate of 70 bpm and a stroke volume of 70 ml, the cardiac output is equal to
4900 ml per minute.
The total blood volume (in liters) of an adult is approximately
Which of the following chemicals has a negative chronotropic effect on the cardiac rate by binding to muscarinic receptors and opening separate K+ channels resulting in hyperpolarization of the sinoatrial (SA) node membranes?
The cardiac control centers are located in the
medulla oblongata of the brainstem.
Which of the following variables does not contribute directly to the stroke volume ejected from the ventricle?
the increase in parasympathetic (vagus) nerve stimulation of the SA node and myocardium
The Frank-Starling law of the heart states that the
stroke volume is proportional to the end-diastolic volume (EDV).
The volume of blood pumped from the left ventricle through the systemic circulation is ________ that pumped from the right ventricle through the pulmonary circulation.
A positive inotropic effect would cause a(n)
increase in the contractility of the heart.
Which statement about veins is false?
A. Veins are called capacitance vessels due to their capacity to expand and hold more blood.
B. Sympathetic stimulation can contract the smooth muscles located in the walls of veins.
C. Due to the structure of the walls, veins have a higher compliance than the walls of arteries. D. Venous pressure averages about 100 mm Hg.
E. Veins contain about 66% (two-thirds) of the total circulating blood volume.
D. Venous pressure averages about 100 mm Hg.
(this multiple choice question has been scrambled)
A positive chronotropic effect is one caused by excitatory chemicals causing HCN channels of pacemaker cells to open sooner, causing faster depolarization of the SA node membranes and thus result in an increase in the cardiac rate.
In exercise, the initial cardiac rate increase occurs because the vagus nerve inhibition of the SA node is decreased
Sensory feedback information from pressure receptors located in the carotid sinus and the aortic arch is interpreted by the cardiac control centers.
Preload refers to the total peripheral resistance that opposes the ejection of blood from the ventricle.
The lower the peripheral resistance the lower the stroke volume (that is, they are directly proportional).
F They are inversly correlated
The Frank-Starling law of the heart describes the built-in, or intrinsic, property of heart muscle in which changes in the end-diastolic volume (EDV) produce changes in the strength of ventricular contraction.
Parasympathetic (vagus nerve) stimulation of the heart has a negative chronotropic effect but has no direct inotropic effect.
Contraction of the diaphragm during inhalation lowers the pressure in the chest cavity and also in the heart while increasing abdominal cavity pressure; thereby increasing the return of venous blood to the heart
In the pulmonary circulation, the
pulmonary artery carries oxygen-poor blood.
The atrioventricular (AV) valve
called the mitral valve, is also known as the bicuspid valve
The semilunar valves
direct blood ejected from the ventricles into the pulmonary artery and the aorta.
A muscular wall called a septum prevents the mixture of blood between the left and right sides of the heart.
The myocardial cells of the atria and ventricles are structurally and functionally separated from each other.
The work performed by the right ventricle is five to seven times greater than that performed by the left ventricle.
The cardiac valves open and close due to changes in pressure on either side of the valves.
Route of blood in the heart: Starting at Right Atrium
The terms systole and diastole refer, respectively, to the
contraction phase and relaxation phase of the ventricles.
During normal ventricular contraction, what fraction of the end-diastolic volume is ejected as the stroke volume?
At rest, each cardiac cycle lasts about 0.8 seconds; of which systole lasts ___ seconds, and diastole lasts ____ seconds.
During one cardiac cycle, the major difference between the left and the right halves of the heart is that the
right heart pumps blood with less force (at lower pressure) than the left heart
The first heart sound results from vibrations generated by the
closing of the AV valves.
Normally, both atria contract at the same time, followed shortly by both ventricles contracting at the same time
Venous blood returning to fill the heart (venous return) is greatest during systole.
The contraction of both atria is essential for life because it delivers about 80% of the total volume of blood to the ventricles for subsequent ejection
During both isovolumetric contraction and isovolumetric relaxation phases, all four valves in the heart (2 AV and 2 semilunar) are closed.
During inhalation particularly, the first heart sound may be “split” into two separate sounds as the tricuspid and mitral heart valves close individually.
A streptococcus bacterial throat infection in susceptible persons may lead to rheumatic fever and rheumatic endocarditis, resulting in damage to the heart valves and detectable murmurs.
Simple septal defects are usually congenital (from birth), resulting in the flow of blood from the right side of the heart to the left side of the heart since the pressure is higher on the right side.
The sinoatrial (SA) node region of the right atrium is the normal pacemaker of the heart because this region
a. demonstrates spontaneous electrical activity.b. depolarizes to threshold before other cardiac regions.c. has Ca2+ diffusing through Ca2+ channels into the cardiac fibers.d. develops pacemaker potentials during diastole.
Action potentials in myocardial cells (not SA node fibers) have a characteristic plateau phase, which is caused primarily by the
slow inward diffusion of Ca2+.
Which statement about the normal electrocardiogram (ECG) tracing is false?
The unipolar leads are found only on the chest.
The second heart sound (S2) is heard while the ECG is recordingthe corresponding
In the SA node region of the heart, spontaneous, automatic depolarization of the pacemaker fibers (diastolic depolarization) results from the more rapid entry of K+ ions down their electrochemical gradient.
As the pacemaker fibers of the atria depolarize to threshold, the inward current of Ca2+ produces not only the upward phase of the action potential but also the mechanical contraction that follows.
Diastolic depolarization occurs faster in response to epinephrine and norepinephrine (catecholamines) because stimulation of the β1-adrenergic receptors produces cAMP second messengers that keep the HCN channels open.
An ectopic pacemaker (or ectopic focus) is a cluster of myocardial cells located away from the SA node that take over and regulate the cardiac pace
The rate of impulse conduction from the SA node is slowed as it passes through the AV node, causing a time delay before the ventricles are excited.
The electrical depolarization of myocardial cells during the cardiac cycle stimulates the opening of voltage-gated Ca2+ channels in the sarcolemma that allows calcium ions to diffuse down its concentration gradient and into the cells.
The electrocardiogram (ECG) wave patterns that are designated P, QRS, and T represent recordings of single action potentials from specific regions in the heart.
F-Measures potential changes of all cells in heart
The blood vessel layer composed primarily of smooth muscle is called the tunica _______.
Which of the following statements about arteries and veins is false?a. Arteries have more smooth muscle than comparable veins.b. Arteries carry blood under higher pressure.c. Veins have one-way valves, promoting flow in only one direction.d. Veins collapse thereby providing the greatest resistance to blood flow in the circulatory system
Veins collapse thereby providing the greatest resistance to blood flow in the circulatory system.
The “business ends” of the circulatory system in which the exchanges of gases and nutrients occur, are important blood vessels known as
In the central nervous system (CNS), the type of capillary that lacks intercellular channels and helps form the blood-brain barrier, is called a
Which of the following mechanisms does not play an important role in the normal return of venous blood to the heart?
a. the inhalation (inspiratory) phase of normal breathingb. large skeletal muscle contractions (pump)c. the higher average hydrostatic pressure in the veins than that found in the heartd. standing upright, perfectly still
d. standing upright, perfectly still
Compared to larger arteries, smaller arteries and arterioles are less elastic and have a thicker layer of smooth muscle for their diameters.
Exposed to cytokines such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF), new blood vessels can form from pre-existing blood vessels – a process known as angiogenesis
Which of the following arrhythmias is best diagnosed by following changes in the P-R interval of the electrocardiogram (ECG)?
AV node block
Which of the following is not a basic function of the lymphatic system?a. transport interstitial (tissue) fluid back to the bloodb. transport lymph via thoracic ducts to the right and left subclavian veinsc. transport fat absorbed from the small intestine to the bloodd. help in the immunological defense against disease-causing agents
All of these are lymphatic system functions.
Due to the unique structure of lymph capillaries, lymph contains all of the following substances
Lymph fluid from around the body eventually flows into lymphatics that merge and drain directly into the
right and left subclavian veins.
Like veins, lymphatic vessels have the same three vessel layers and one-way valves to prevent the backward flow of lymph.
Lymph is formed by the filtration of blood plasma from capillaries, forming filtrate that ultimately returns to the blood to complete the cycle
Which function is not part of respiration?a. ventilation of air into and out of the lungs (breathing)b. gas exchange at the lungs and at the tissuesc. oxygen utilization by the tissue mitochondriad. immune defense against the invasion of foreign pathogens
d. immune defense against the invasion of foreign pathogens
Which of the following characteristics does not describe the type I alveolar cell of the lung?a. These cells secrete a pulmonary surfactant that enables inflation to occur.b. These cells make up 95% to 97% of the total surface area of the lung.c. These cells are flat and very thin.d. These cells are located very close to nearby capillary blood vessels.e. These cells are responsible for most of the gas exchange with bloo
a. These cells secrete a pulmonary surfactant that enables inflation to occur.
Gas exchange between the air and blood occurs entirely by the process of
Which of the following locations is not part of the conducting zone of the respiratory system?a. pharynx b. larynx c. trachea d. terminal bronchiole e. alveolus
function of the respiratory system?
air conduction into the respiratory zone b. air warming c. air humidification (moistening the air) d. air filtration and cleaning
Respiration is the mechanical process that moves air into and out of the lungs
The diffusion rate of gases is very fast partly because only two thin cells separate the air swirling in thealveoli from the blood that flows in the nearby capillary
In order to maximize the rate of gas diffusion between the air and blood, the air-blood barrier providedby the alveoli is extremely thin, and has a very small surface area
Gas exchanges can occur anywhere along the conducting passageways of the respiratory system.
F-Only bronchioles and aveoli
Air enters the terminal bronchioles from respiratory bronchioles, which are the narrowest of airways thatdo not have alveoli and do not contribute to gas exchange
Under normal conditions of ventilation, there exists only a “potential” space, known as the intrapleuralspace that exists between the two wet pleural membranes.
Air flow through the bronchioles, like blood flow through arterioles, is inversely proportional to the
frictional resistance to air flow.
Which statement about respiratory distress syndrome (RDS) is false?a. It is normally seen in premature infants born before their eighth month.b. It can result in the collapse of the alveoli.c. In this condition the surface tension within the alveoli is abnormally low.d. In this condition the type II alveolar cells are not yet functioning properly.e. This condition can be treated with the help of a mechanical ventilator and by administering exogenous surfactant
In this condition the surface tension within the alveoli is abnormally low.
Air flow through lung bronchioles follows the same basic principles as blood flow through arteriole blood vessels.
Inspiration occurs when the intrapulmonary (intra-alveolar) pressure is greater than the atmospheric pressure outside the body.
Lung elasticity is the primary force that exists to return the lungs to their original shape during exhalation.
Surface tension exerted by the thin film of water lining all alveoli opposes the expansion (or compliance) of alveoli during inspiration.
Surfactant molecules secreted from type II alveolar cells are composed mostly of phospholipid molecules together with hydrophobic surfactant proteins that serve to raise the surface tension of fluids lining the alveoli.