Lab 5: PhysioEx. 5 and 6
Which is more likely to occur, a change in blood vessel radius or a change in blood vessel length?
A change in blood vessel radius because they occur on a daily basis.
Discuss the effect that polycythemia would have on viscosity and on blood flow.
An increase in RBCs, it would result in viscosity and decrease in blood flow.
Atropine is an acetylcholine antagonist. Does atropine inhibit or enhance the effect of acetylcholine?
As an acetylcholine anatgonist, atropine would increase the heart rate. (opposition)
Explain the effect on increasing the right flow tube radius on the flow rate, resistance and pump rate.
As the right flow tube radius is increased, blood flow increases, resistance decreases, pump rate increases.
Explain whether it would be better to adjust heart rate or blood vessel diameter to achieve blood flow changes at a local level.
At a local level, it is best to adjust the blood vessel diameter. Therefore, the effects will only be seen locally. Adjustments to the heart rate would have systemic effects.q
The cardiac muscle is capable of which of the following?
Autorhythmicity
The ______ receptor binds norepinephrine and epinephrine.
B-1 adrenergic
Which of the following correctly describes the relationship between blood vessel length, resistance and blood flow?
Blood vessel length is directly proportional to resistance and inversely proportional to blood flow.
Which of the following is directly proportional to blood flow?
Blood vessel radius and pressure gradient
Which of the following correctly describes the relationships between blood vessel radius, resistance and blood flow?
Blood vessel radius is inversely proportional and directly proportional to blood flow.
Describe how calcium channel blockers are used to treat patients and why
Calcium channel blockers reduce the force of contraction of the heart which would decreased blood pressure.
Describe how calcium channel blockers are used to treat patients and why.
Calcium channel blockers reduce the force of contraction of the heart, which would decrease BP.
Which is more likely to occur on a daily basis?
Changes in blood vessel diameter.
Distinguish the difference between cholergenic and adrenergic chemical modifiers.
Cholinergic modifiers affect acetylcholine action such as pilocarpine and atropine. Adrenergic modifiers affect epinephrine action such as ephinephrine itself.
After a heavy metal, when we are relatively inactive, we might expect blood vessels in the skeletal muscles to be somewhat ____ and the blood vessels in the digestive organs to be somewhat ___.
Constricted and dilated
Thrombocytopenia is a reduction in platelets. What effect do you think this could have on blood viscosity?
Decrease blood viscosity
Which mechanism had the greatest compensatory effect?
Decreasing the pressure in the right-most beaker (the destination beaker) had the greatest effect because this decreases afterload.
Explain the effect that decreasing the temperature had on the frog heart. How do you think a human heart would respond?
Decreasing the temperature of the frog heart decreased the heart rate. This effect would not be seen in humans because we are not poikilothermic animals.
Explain why pressure changes are not the best way to control blood flow
Diameter changes are much easier for the body to make. Pressure changes require the heart to beat harder, which is difficult for the heart to sustain.
Describe the benefits of administering digitalis.
Digitalis decreases the heart rate and increases the force of contraction, thus increasing stroke volume
Describe the effect that radius changes have on the laminar flow of a fluid.
Fully constricted vessels do not favor laminar flow because there is more blood in contact with the vessel and the blood does not flow as freely.
How could the human heart compensate for flow rate changes to maintain blood pressure.
If the flow rate increased, the heart must pump faster to maintain blood pressure.
What effect do you think aplastic anemia would have on blood flow?
Increased blood flow due to decreased viscosity
Digitalis
Increases force of contraction and decreased heart rate
Epinephrine
Increases the heart rate and mimics the sympathetic nervous system
Explain the effect that increasing the temperature had on the frog heart, how would a human heart respond?
Increasing temperature of the frog heart increased heart rate, it would not be the same in humans.
Explain the effect that the flow tube radius change had on flow rate.
Increasing the flow tube radius resulted in an increase in the flow rate
Explain the effect that the viscosity change had on flow rate. How well did the results compare with your predictions?
Increasing viscosity decreased fluid flow rate because it made the blood effectively thicker and increased the resistance to flow.
Describe the intrinsic factors that control stroke volume.
Intrinsic factors that control stroke volume are those that reside entirely within the heart. This includes the alteration of contractility.
Describe what the left and right beakers in the experiment correspond to in the human heart.
Left beaker stimulates blood coming from the lungs, the right beaker stimulates blood traveling to the systemic circuit.
The effect of potassium on the heart is
Negative chronotropic and negative inotropic
Verapamil is a calcium-channel blocker. Its effects could be described as
Negative chronotropic and negative inotropic
Describe the effect that obesity would have on blood flow and why.
Obesity would decrease blood flow. The decrease is a result of increased blood vessel length generated to serve the increase in adipose tissue.
Which of the following does not contribute to the viscosity of the blood?
Oxygen level in the blood
Describe the effect that pilocarpine had on the heart and why it had this affect.
Pilocarpine decreased the heart rate because it is an acetylcholine agonist. It decreased the frequency of action potentials.
Which of the following is not a formed element?
Plasma protein
What is the driving force for blood flow?
Pressure gradient
Describe why Ringer's solution is required to maintain heart contractions.
Ringer's solution includes the ions that are required for the spontaneous contractions and autorythmicity
Which organelle in the cardiac muscle cell stores calcium?
Sarcoplasmic reticulum
How does the body increase the blood vessel radius?
Smooth muscle relaxation
Describe the effect that increasing the calcium ions had on the heart.
The addition of calcium ions to the frog heart increased the heart rate.
Decribe the effect that increasing the calcium ions had on the heart
The addition of calcium ions to the frog increased heart rate.
Explain why the amplitude of the wave did not change when you increased the frequency of the stimulation.
The amplitude did not change because of the long absolute refractory period of cardiac muscle tissue, which ensures that the extrasystole doesn't occur during contraction.
Explain why you think blood vessel radius can have a larger effect on the body than changes in blood vessel length.
The blood vessel radius varies to a power of four, which is why the changes are greater than blood vessel length changes.
Explain how the body establishes a pressure gradient for fluid flow.
The body establishes a pressure gradient for fluid flow due to the pressure difference between the two ends of the vessel.
Which of the following is true of the cardiac action potential?
The cardiac action potential is longer than the skeletal muscle action potential.
Why is it only possible to induce an extrasystole during relaxation?
The extrasystole did not occur until relaxation and so we could not achieve wave summation or tetanus.
Increasing the flow tube length is analogous to increasing blood vessel length. How did this affect the flow rate?
The flow rate decreased.
Explain the effect that the change in blood vessel length had on blood flow rate.
The fluid flow rate did decrease as the flow tube length increased. This is analogous to an increase in blood vessel length that would result in a decrease in fluid flow rate.
Describe the components in the blood that affect viscosity.
The formed elements and plasma proteins affect viscosity. These include WBCs, RBCs, platelets, proteins such as albumin.
Describe the graph of flow versus viscosity.
The graph was not linear. It was exponential, it showed that the relationship between the viscosity and flow is inversely proportional.
Describe how the heart alters stroke volume
The heart alters stroke volume by altering contractility, the force of contraction. Increasing the force of contraction will increase stroke volume.
Explain how the heart could compensate for changes in peripheral resistance.
The heart can compensate for changes in peripheral resistance by increasing contractility.
What do you think would happen to the heart rate if the vagus nerve was cut?
The heart rate would speed up, it would go back to the 100 bpm the intrinsic rate.
Explain the effect that pressure changes had on flow rate.
The increase in pressure resulted in a corresponding increase in flow rate. A decrease in pressure would result in a decrease in flow rate.
Describe the effect that increasing the potassium ions initially had on the heart rate in this activity.
The initial effect of potassium ion addition was to decrease the heart rate. Excess potassium decreases the resting potential of the plasma membrane.
Which of the following do you think contribute to the inability of cardiac muscle to be tetanized?
The long refractory period of the cardiac action potential
Why do you think the plot was not linear?
The plot of radius vs. blood flow is not linear because of the exponential relationship between the two variables.
How does the plot differ from the plots for tube radius, viscosity, and tube length?
The plot was linear, others were curved.
Which of the following statements about the contractile activity is true?
The smaller waves represent the contraction of the atria.
Explain why the larger waves seen on the oscilloscope represent ventricular contraction
The ventricles are larger chambers; therefore, when they contract they generate more force, thus producing a larger wave.
Given the function of the heart, why is it important that cardiac muscle cannot reach tetanus?
The ventricles must contract and relax fully with each beat to pump blood.
What is the relationship between fluid flow and flow tube length?
They are inversely proportional to each other.
What is the relationship between fluid flow and viscosity?
They are inversely proportional to each other.
Describe how the sympathetic and parasympathetic nervous systems work together to regulate heart rate.
They can take turns dominating depending upon what is going on in the body
Describe the Frank Starling law in the heart.
This law states that, when more blood than normal is returned to the heart, the heart muscle will be stretched, resulting in a more forceful contraction of the ventricles.
Which of the following describes why the body might require an increase in vessel radius?
To provide more blood flow and therefore nutrients to a particular body part
Explain why wave summation and tetanus are not possible in cardiac muscle tissue.
Wave summation and tetanus are not possible because relaxation must complete before the next contraction can begin due to the long absolute refractory period.
Explain what happened when the pump pressure and the beaker pressure were the same.
When the pump pressure and the beaker pressure were the same, the flow stopped.
Explain what happened to the pump rate when you increased the stroke volume, why did this occur?
With increased stroke volume, the pump rate will decrease to maintain cardiac output.
If the human heart were experiencing hyperthermia, what do you think would be the effect on the heart rate?
a decrease in heart rate
The amplitude of the ventricular systole did not change with the more frequent stimulation because
a new contraction could not begin until the relaxation phase
The parasympathetic nervous system releases _____ to affect heart rate.
acetylcholine
The addition of the most of the ions resulted in
an erractic, decreased heart rate
An extrasystole corresponds to
an extra ventricular contraction
Vessel radius and fluid flow
are directly proportional
A cholinergic drug that worked the same as acetylcholine would
be an agonist and decrease heart rate
In the 32 Ringers solution, the frog heart
beast faster than baseline
In the 5C Ringers solution, the frog heart
beats slower than baseline
Pressure changes in the cardiovascular system primary result from
changes in the force of contraction of the heart
Extreme vagus nerve stimulation affects the heart by
completely stopping it
The effect of the parasympathetic nervous system on the heart is to
decrease the heart rate
Ectopic pacemakers can be caused by excessive leakage of K into cardiac cells, resulting in pacemakers appearing in abnormal locations in the heart muscle. This hyperkalemia decreases the resting potential of the cardiac muscle cell. What effect do you think this would you have on the force of contraction?
decrease. negative inotropic
Increasing viscosity resulted in
decreased flow rate
Pilocarpine decreased the heart rate. Typical of cholinergic agonists it
decreased the frequency of action potentials
What effect would a decreased hematocrit have on blood flow?
decreased viscosity, increased blood flow
The modifiers tested that decrease the heart rate were
digitalis and pilocarpine
During which portion of the cardiac muscle contraction is it possible to induce an extrasystole?
during relaxation
To increase the heart rate, the best choices would be
epinephrine and atropine
The general name for the process that maintains the internal body temperature in humans is
homeostasis
Organisms that usually maintain the same internal body temperature in spite of enviromental temperature changes are
homeothermic
An internal body temperature that is above the normal range is
hyperthermic
When the cardiac muscle cell is at rest, where is most of the potassium found?
in the cytosol
What effect would a 104 fever have on heart rate?
increase
The effect of increasing pressure was to
increase flow rate
When you increased the flow tube radius, the fluid flow rate
increased
What do you predict would be the overall affect on viscosity during dehydration?
increased viscosity, decreased flow
Norepinephrine affects the heart rate by
increasing the rate of depolarization and increasing the frequency of action potentials.
The usual pacemaker of the heart
is the sinoatrial node
The effect of atropine was to
mimic sympathetic nervous system
Blood flow is measured in
ml/min
Blood pressure is measured in
mm Hg
Where in the cardiac muscle cell is most of the sodium normally found?
outside of the cell
Viscosity most directly affects
peripheral resistance
Phase 2 of the cardiac action potential, when the calcium channels remain open and potassium channels are closed is called
plateau phase
Restin cardiac muscle cells are most permeable to
potassium
The ion that had the most pronounced effect on heart rate was
potassium
Arteries close to the heart need to be able to compensate for
pressure changes
The electrolytes in a Ringer's solution are required to
provide autorythmicity
The vagus nerve carriers
signals that decrease the heart rate
Without the Ringer's solution
spontaneous cardiac action potentials would not occur.
Vagal escape probably involves
sympathetic reflexes
Explain two ways that the heart can overcome excessive vagal stimulation.
sympathetic reflexes and the initiation of a rhythym by the Purjunkie fibers
The branch of the autonomic nervous system that dominates during exercise is
the systematic branch
The response that resumed the heartbeat after the vagus nerve stimulation is called
vagal escape
Parasympathetic stimulation reaches the heart through
vagus nerves, which are cranial nerves
The variable that you altered in this activity was
vessel radius
Which of the following variables has the greatest effect on blood flow?
vessel radius
