Chapters 19, 20, 21 Flashcards
The most correct sequence in the cardiac conduction system is
SA node > AV node > AV bundle > bundle branches > Purkinje fibers.
A normal heartbeat of 70 - 80 beats per minute is referred to as
sinus rhythm
Closure of the AV valves occurs when
ventricular pressure exceeds atrial pressure.
During a normal cardiac cycle which phase has the longest duration?
quiescent period
When the atria begin depolarizing, which of the following is occuring?
ventricular filling
If the time of ventricular filling were increased in duration
the end diastolic volume (EDV) would be greater.
Atrial depolarization causes
the P wave
Atrial systole begins
immediately after the P wave
Cells of the sinoatrial node ____________ during the pacemaker potential.
depolarize slow
During isovolumetric contraction, the pressure in the ventricles
rises rapidly
Isovolumetric contraction occurs during the _________ of the electrocardiogram.
R wave
Most of the ventricle filling occurs
during atrial diastole
The long absolute refractory period of cardiocytes
prevents tetanus
The pacemaker potential is a result of
Na+ inflow.
The plateau in the action potential of cardiac muscle results from the action of
slow Ca2+ channels.
This is the correct sequence of events of the cardiac cycle.
ventricular filling → isovolumetric contraction → ventricular ejection → isovolumetric relaxation
When the left ventricle contracts, the _____ valve closes and the _____ valve is pushed open.
mitral; aortic
_____________ increase(s) stroke volume.
Increased venous return
Cardioinhibitory centers in the _____________ receive input from __________.
medulla oblongata; chemoreceptors in the aortic arch
Congestive heart failure (CHF) of the right ventricle
can cause systemic edema.
The Frank-Starling law of the heart states that stroke volume is proportional to
end diastolic volume. (EDV)
The volume of blood ejected by each ventricle in one minute is called
cardiac output.
These have the most control of perfusion of a capillary bed.
precapillary sphincters
Arteries are sometimes called the _______________ vessels of the cardiovascular system because they have strong-resilient tissue strucure.
resistance
The outermost wall of an artery or vein is called the __________________ and in large arteries and veins contains the ______________.
tunica externa; vasa vasorum
Vasomotion is associated with the presence of
smooth muscle in the tunica media.
Increasing preload increases the cardiac output because
stretching the mycardial cells increases the force of contraction due to the length/tension relationship.
Chronotropic effects
can increase or decrease the heart rate.
Bradycardia
can be a normal condition, as during sleep or in a well-trained athelete.
Stimulation of the heart by the sympathetic nervous system
increases heart rate.
Potassium has the greatest potential for causing chronotropic effects because
it is important for returning the cardiocyte to its resting membrane potential.
Cardiac output
changes in response to exercise or other stimulation.
Blood vessels that connect two capillary networks are called
portal systems.
The tissue layer of a vessel that differs most in thickness when comparing arteries and veins is the
tunica media.
These have the most control of perfusion of a capillary bed.
precapillary sphincters
The baroreceptors
All of the above.
All of these factors may increase peripheral resistance except
blood type.
Venous pooling in a soldier standing at attention for a prolonged time occurs mainly when this mechanism fails.
skeletal muscle pump
_______________ has the most important effect on blood velocity.
vessel radius
Hypertension is commonly considered to be a chronic resting blood pressure higher than
140/90
Most blood is in the
veins.
Reactive hyperemia is a result of ________________ to increase perfusion into a tissue.
local control
The medullary ischemic reflex results in
increased circulation to the brain.
The vasomotor center of the __________________ controls blood vessels throughout the body.
medulla oblongata
The velocity of blood flow decreases when
viscosity increases.
Vasomotion is associated with the presence of
smooth muscle in the tunica media.
Blood flow is pulsatile in arteries and veins, but it is steady in capillaries.
False
Blood flow through a capillary bed is regulated by precapillary sphincters.
True
Generalized vasomotion can raise or lower blood pressure throughout the body.
True
Reduced capillary reabsorption of fluid can lead to edema. Which of the following does not contribute to edema?
extreme muscular activity
The most important mechanism of exchange between blood and tissue fluid is ________________.
diffusion
The venous return of blood back to the heart is encouraged by
gravity acting on the large veins above the heart.
______________ shock occurs when bacterial toxins trigger vasodilation and increase capillary permeability.
Septic
________________ by the capillaries at their venous end.
Waste products are taken up
Decompensated shock is normally corrected by the body’s homeostatic mechanisms.
False
Generalized vasomotion can raise or lower blood pressure throughout the body.
True
Most tissue fluid is reabsorbed by the lymphatic system.
False
Myocardial infarction can lead to _______________ shock.
cardiogenic
The most important force driving filtration at the arterial end of a capillary is
blood hydrostatic pressure.
The most important force driving reabsorption at the venous end of a capillary is
blood colloid osmotic pressure.
The three main functions of the lymphatic system include all but which of the following?
waste removal
Which of the following inhibitors of microbial growth is a component of the perspiration on our skin?
lactic acid.
_____________ are the largest of the lymphatic vessels and they empty into the _______________.
Collecting ducts; subclavian veins
______________ are found especially in the mucous membrane, standing guard against parasites and allergens.
Eosinophils
________________ are secreted by cells infected with viruses, alerting neighboring cells and protecting them from becoming infected.
Interferons
All these belong to the second line of defense except
the gastric juices.
All these forces help lymph to flow except
the lymphatic node pump.
Complement fixation can lead to any of the following effects except
endogenous pyrexia.
