EXAM 2 : CHAPTERS 17 & 18 : PRACTICE EXAM
Purkinje fibers in the right ventricle.
A damaged right bundle branch will prevent the passage of the action potential to the:
The continuous capillaries of the brain form the blood brain barrier and if disrupted, pathogens and toxins could enter into the brain's interstitial fluid. (The capillaries in the brain that form the blood brain barrier are a modified type of continuous capillary, with specialized tight junctions that prohibit many materials from crossing into or out of the interstitial fluid around brain cells. This poison would partially destroy the blood brain barrier, allowing more potentially toxic substance and pathogens into the brain's interstitial fluid than would normally occur. )
A new form of biological warfare is a poison that destroys the tight junctions of the continuous capillaries in the brain. What effects would be expected?
2.8 L/minute (SV = (EDV - ESV)/beat => 40 mL/beat; Cardiac output= SV X HR => 40 mL/beat X 70 beats/minute)
A patient has a heart rate of 70 beats per minute, an EDV of 110 ml, and an ESV of 70 ml. What is the patient's cardiac output?
have elevated blood pressure because the arteries will no longer be able to stretch to accommodate small changes in blood volume.
An individual with arteriosclerosis would
Left Atrium
An insufficient mitral valve (bicuspid valve, or left atrioventricular valve) would allow the backflow of blood into the:
The arteries would either be noncompliant, or unable to stretch, or unable to recoil after stretching. (The elastic fibers in an artery allow the vessel to stretch and recoil to its original size after being stretched. Defective elastic fibers would make a vessel either noncompliant (not able to stretch) or unable to recoil to its original size after stretching. )
Arteries contain multiple sheets of elastic fibers between thin layers of smooth muscles. What would happen if these fibers became faulty?
There would be a decrease in contractility (Because the calcium ion influx slows, the potassium ion efflux is not affected and therefore will repolarize the cell quickly. The muscle cell will not be able to sustain the excitability to keep it in a contracted state.)
As their name suggests, calcium ion channel blockers block calcium ion channels in the sarcolemma of pacemaker and contractile cardiac muscle cells and slow calcium ion entry into the cell during an action potential. What effects would these drugs have on the myocardial cells? 1) The action potential would be shorter at the plateau phase of the cardiac muscle cell 2) There would be an increase in sodium channel reactivation 3) The conduction velocity would increase 4) There would be a decrease in contractility
Pressure
Blood movement is driven by a _____________ gradient.
100 mm Hg (MAP = diastolic pressure + 1/3 (systolic pressure - diastolic pressure). MAP is the average pressure in the systemic arteries during an entire cardiac cycle.)
Calculate the mean arterial pressure (MAP) if the systolic pressure is 120 mm Hg and the diastolic pressure is 90 mm Hg.
Decrease Depolarization of the Cell
Certain drugs used to treat dysrhythmias, called local anesthetics, work by blocking voltage gated sodium ion channels and slowing the entry of sodium ions into the cell during an action potential. What effects would you see?
The ventricles will contract more slowly.
Determine the impact if the connection between the sinoatrial (SA) node and the atrioventricular (AV) node becomes blocked. 1) The ventricles will contract more quickly. 2) The ventricular rhythm would not change 3) The ventricles will contract more slowly. 4) The atria will contract more forcefully.
decreased ESV (Increased contractility and SV would lead to a decrease in the ESV.)
Digoxin is a positive inotropic agent derived from the foxglove family of plants. Which of the following is an effect of digoxin? 1) decreased SV 2) decreased CO 3) decreased contractility 4) decreased ESV
Right Ventricle (The left ventricle loss of function would be most damaging because it provides enough pressure of blood to send to the rest of the body.)
Heart tissue dies during a myocardial infarction (MI), and a person's survival and recovery depend on the extent of cell death and the chamber(s) involved. In which chamber would the loss of function be most damaging to survival?
decreased; decreased (Blood loss will diminish the venous return and therefore decrease the preload. A decreased preload would cause a decrease in the stroke volume and therefore a decrease in the CO.)
Hemorrhage would lead to a __________ preload and therefore __________ cardiac output.
Beta-blockers decrease the rate and force of heart contraction, reducing cardiac output and lowering blood pressure. (The sympathetic nervous system is the "fight or flight" division of the ANS that prepares the body for stressors such as exercise, even mild exercise like position changes. Axons release the neurotransmitters norepinephrine and epinephrine onto cardiac muscle cells and the smooth muscle cells of blood vessels, to produce two immediate changes: (1) an increase in heart rate and contractility, which increases cardiac output; and (2) vasoconstriction of all types of vessels, but especially arterioles, which increases peripheral resistance. Both changes increase blood pressure. Beta-blockers are drugs that block the effects of the sympathetic nervous system on the heart, which decrease heart rate and decreases cardiac output. )
How do beta-blockers reduce blood pressure?
Anastomoses provide an alternate route of blood flow around a coronary artery that may be blocked. (Anastomoses are the formation of systems of blood vessels that provide collateral circulation to a particular area)
How might coronary artery anastomoses help a patient with a coronary artery disease? 1) Anastomoses prevent stenosis from occurring 2) Anastomoses increase sinoatrial node activity if heart failure were to occur 3) Anastomoses provide an alternate route of blood flow around a coronary artery that may be blocked. 4) Anastomoses can increase the frequency of action potential propagation within the myocardium
It will not change. (The cardiac output will remain the same, because CO = HR × SV = 2HR × SV/2.)
How will the cardiac output change if you double the heart rate but reduce the stroke volume by one-half?
Increase;decrease (Because the ventricles cannot pump blood adequately into the system, it should increase the volume of blood in the ventricles. Consequently, the blood in the systemic and pulmonary circuitry does not return back to the heart and thereby decreasing the end-diastolic volume.)
If the ventricles were diseased and failing to pump adequately, the end-systolic volume would _____ and in turn, this would cause the end-diastolic volume to ______.
contractility.
Inotropic agents affect: 1) depolarization. 2) stroke volume 3) heart rate. 4) contractility.
Atherosclerosis damages the endothelium by forming plaques, causing the artery to become very narrow, interfering with blood flow. (The leading cause of death in the developed world is atherosclerosis, an arterial disease that affects large and medium-sized muscular arteries. The disease is characterized by the formation of atherosclerotic plaques, which are buildups of lipids, cholesterol, calcium salts, and cellular debris within the arterial tunica intima. Atherosclerosis makes an artery narrow and hard through damage to the endothelium. This interferes with its function of delivering blood to capillary beds by decreasing the amount of blood that can flow through the artery. )
Many individuals suffer from atherosclerosis, an arterial disease that effects large to medium-sized muscular arteries. What does this disease do to the structure of an artery?
They were concerned her blood pressure would be extremely low, which could be fatal due to not enough oxygen reaching her cells, leading to organ failure. (Severe blood loss causes a significant decrease in blood volume, which decreases blood pressure. Hypovolemic shock is a life-threatening condition that results when you lose more than 20 percent (one-fifth) of your body's blood or fluid supply. This severe fluid loss makes it impossible for the heart to pump a sufficient amount of blood to your body. Hypovolemic shock can lead to organ failure.)
Mary was in a terrible car accident. When the emergency personnel arrived, they noticed she had significant blood loss. What was their concern about her blood pressure?
decreased blood flow through the kidneys and increased water retention due to ADH. (Extreme hypotension, or low blood pressure, decrease blood flow to the kidneys, which in turns decreases the filtration of fluid into the tubules of the kidneys. In addition, hormones such as ADH will trigger increased retention of water from the kidneys, further decreasing urine output. Reduced urine output decreases the loss of blood volume. )
Patients with extreme hypotension have reduced urine production because of
Most of the blood drains from the atria passively into the ventricles. (Passive ventricular filling occurs due to the body pushing the blood into the atria and into the ventricles without the help of atrial contraction. )
Sometimes health care providers will elect not to treat conditions such as atrial fibrillation in which there is no functional atrial contraction. Select the logic behind this.
pressure in the ventricles increases (During the isovolumetric contraction phase, the pressure in the ventricles rises rapidly as the ventricles begin to contract. This high pressure closes the AV valves.)
The AV valves close when __________.
decreased cardiac output (The baroreceptor response to high blood pressure results in vasodilation and decreased cardiac output.)
The appropriate baroreceptor reflex response to high blood pressure is:
has the same direction as the concentration gradient for sodium ions. (Both the concentration gradient for sodium ions and the concentration gradient for calcium ions drive the ions into the cell, because they move from high to low concentration.)
The concentration gradient for calcium ions... 1) is maintained by the Na+/K+ pump. 2) has the same direction as the concentration gradient for potassium ions. 3) drives calcium ions out of the cell. 4) has the same direction as the concentration gradient for sodium ions.
Veins would become noncompliant, or unable to stretch, but the effects would not be very noticeable. (Veins are very compliant, or able to stretch. Defective elastic fibers would make a vessel either noncompliant (not able to stretch) or unable to recoil to its original size after stretching. , However, veins are under lower pressure than arteries and so the effects of defective elastic fibers would be less obvious.
Veins contain fewer elastic fibers and less smooth muscle than arteries. What would happen if the elastic fibers became faulty?
Intercalated Discs
What characteristic differentiates cardiac muscle cells from skeletal muscle cells?
Plateau Phase
What do pacemaker cell action potentials lack?
The action potential would last for a longer duration.
What effects would one see if the Q-T interval is prolonged?
influx of sodium ions
What ion movement changes the membrane potential in a contractile cell from negative to positive during the rapid depolarization phase?
1) There will be low levels of oxygen in the blood. Due to decreased blood flow to the pulmonary circuit, there will be decreased levels of oxygen picked up from the lungs.
Which of the following effects will one see if there is a right-sided heart failure (failure of the right ventricle to pump adequately)? 1) There will be low levels of oxygen in the blood. 2) Blood will accumulate in the pulmonary capillaries 3) Blood pH levels will increase 4) There will be a backflow of blood from the left ventricle into the left atrium
Increase preload and contractility, and decrease afterload
Which of the following factors may contribute to an increase in stroke volume?__________. 1) Increase preload and contractility, and decrease afterload 2) when there is a low EDV and high ESV 3) when you have a weak contraction against high resistance 4) there are a low preload and contractility and a high afterload
The atria contract (After the atrial depolarization (P wave), the atria contract, allowing them to empty and causing the ventricles to reach their EDV.)
Which of the following happens immediately after the P wave?
acetylcholine
Which of the following is a chronotropic agent that decreases heart rate? 1) epinephrine 2) norepinephrine 3) acetylcholine 4) glucagon
Decrease in heart rate (The parasympathetic nervous system decreases the heart rate, not the sympathetic.)
Which of the following is not an effect of the sympathetic nervous system? 1) release of epinephrine and norepinephrine by the adrenal medulla 2) decrease in heart rate 3) increase in force of contraction of the heart 4) increase in heart rate
Mitral Valve (The mitral valve will be affected because the chordae tendinae connects with the bicuspid valve. Papillary muscles and chordae tendinea do not connect to pulmonary valves)
Which of the following valves would be affected if papillary muscles and/or chordae tendinae stopped functioning? 1) Pulmonary valve 2) Aortic Valve 3) Mitral Valve
increase in preload (Preload is not directly correlated with cardiac contractility.)
Which of the following will NOT occur if you increase cardiac contractility? 1) decrease the ESV 2) increase in stroke volume 3) increase cardiac output 4) increase in preload
Heart rate would increase, and cardiac output would decrease. (Heart rate would increase, and cardiac output would decrease ultimately because there would be a decrease in preload and therefore stroke volume.)
Which of the following would happen to cardiac output if sympathetic nervous system stimulation of the heart had positive chronotropic effects only?
increased blood volume
Which of these changes will result in increased blood pressure? 1) increased blood volume 2) increased vessel radius 3) decrease cardiac output 4) decreased blood viscosity
increase in blood volume (Increased ADH would increase the amount of water being retained in the body. This would increase the blood volume.)
Which of these would occur if you increased the levels of ADH in the body? 1) decrease in the number of aquaporins in kidney tubules 2) increase in urine production 3) increase in blood volume 4) decrease in water retention by the kidneys
P wave
Which wave on the electrocardiogram (ECG) corresponds with the ventricular filling phase of the cardiac cycle?
Thicker epithelium would decrease the diffusion of gases and nutrients between the blood and tissues. (Thicker epithelium would slow transport of substances across the epithelium, which would considerably decrease the efficiency of nutrient and gas exchange between capillaries and tissues. Capillaries generally are found in clusters called capillary beds that wind their way through the cells of most tissues in the body-exceptions include cartilage, the sclera and cornea of the eye, and epithelial tissue. The blood flow to a tissue through a capillary bed is known as tissue perfusion. As you might expect, tissue perfusion is tightly regulated to ensure that the metabolic needs of all tissues are met always.)
Why aren't capillaries made of thicker epithelium?
Nicotine is a vasoconstrictor which will increase peripheral resistance and blood pressure. (Vasoconstriction increases resistance, which raises blood pressure. Peripheral resistance and blood pressure are directly related: As peripheral resistance increases, blood pressure increases. For this reason, regular consumption of a vasoconstrictor such as nicotine will increase the risk of developing hypertension. )
Why does cigarette smoking put someone at risk for developing high blood pressure?
Tissue perfusion to the heart muscle decreases during systole, so if the heart is not contracting for a moment, perfusion will increase. (The perfusion pattern through the coronary circulation is the opposite of the rest of the systemic circuit, which generally increases during systole and decreases during diastole. In the heart, this is reversed because it squeezes its own arteries during ventricular systole, so heart tissue perfusion decreases during systole. During diastole, the ventricles relax, blood resumes flowing through the coronary arteries, and tissue perfusion to the cardiac muscle cells increases. This is one reason extreme increases in heart rate and/or force of contraction can be dangerous: The heart does not spend enough time in diastole and the myocardium is not adequately perfused.)
Why would tissue perfusion in the heart actually increase during the initial stages of ventricular fibrillation, when the heart produces no functional contraction?