PHYS quiz 7
Which happens first in response to a blood vessel injury?
vasoconstriction
Which of the following increases blood flow through a blood vessel?
vasodilation, relaxation of smooth muscles that surround the vessel, an increase in the vessel radius
Action potentials are normally conducted from your Purkinje fibers directly to your
ventricles
During each cardiac cycle, action potentials occur in the bundle of His before they occur in the
ventricles
During typical strenuous exercise
ventricular stroke volume increases from 60% to 90% of ventricular volume
Which of the following would increase ventricular stroke volume?
increased end-diastolic volume, decreased total peripheral resistance, leg skeletal muscle contractions
Epinephrine binding to b (beta)-adrenergic receptors normally causes
increased heart rate, increased ventricular contractility, vasodilation
Which of the following would normally increase cardiac output?
increased contractility, increased end-diastolic volume, epinephrine
Old erythrocytes are broken down in the
liver and spleen
Which of the following occurs at the site of a cut during hemostasis?
a fibrin meshwork is formed
Which of the following would normally cause increased blood flow to a tissue?
an increase in blood vessel radius
What directly causes heart valves to open or close?
blood pressure differences on the 2 sides of the valve
During a normal cycle of heart contraction, action potentials are propagated from the right atrioventricular (AV) node directlyto the
bundle of His
Circulatory shock
can be caused by a severe allergic reaction
An increase in erythropoietin secretion causes increased production of
erythrocytes
Which of the following is formed directly or indirectly from bone marrow stem cells?
erythrocytes, leukocytes, platelets
Which of the following is derived from bone marrow stem cells?
erythrocytes, natural killer cells, cytotoxic T cells
During hemostasis, fibrin binds to
fibrin
Fibrin normally
forms a clot, is made from fibrinogen, binds to other fibrin molecules, is required for blood clotting
Mature human erythrocytes contain
hemoglobin
The left semilunar valve closes whenever the blood pressure is
higher in the aorta than in the left ventricle
The mitral (bicuspid) valve closes when blood pressure is
higher in the left ventricle than in the left atrium
The right semilunar valve opens when blood pressure is
higher in the right ventricle than the pulmonary trunk
The tricuspid valve closes when blood pressure is
higher in the right ventricle than the right atrium
Contraction of leg skeletal muscles normally
increases hydrostatic pressure in leg veins, opens one-way valves in leg veins, increases blood flow back to the heart
Which of the following causes vasodilation?
nitric oxide
Which of the following normally causes an increase in heart rate?
norepinephrine binding to b (beta)-adrenergic receptors on heart cells
The cascade of coagulation factors at the site of a cut typically operates via
positive feedback
The refractory period of cardiac cell action potentials
prevents the heart from beating faster than about 4 times/second
Pacemaker potentials occur in some
sinoatrial node cells, atrioventricular node cells, smooth muscle cells
During exercise, there is increased blood flow to
skeletal muscles
On each cardiac cycle, in which of the following locations do action potentials occur earliest?
the atrioventricular (AV) node
During circulatory shock
the heart and brain do not receive enough blood
Circulatory shock can be life threatening because
the heart does not receive enough oxygenated blood
On each cardiac cycle, action potentials occur earliest in
the left atrium
Which of the following is true of cardiac pacemaker cells?
they have channels that allow sodium (Na+) through and are opened by repolarization, they have channels that allow calcium (Ca2+) through and are opened by depolarization, they can be found in the sinoatrial (SA) node