Download 7 Heart physiology flashcards

Heart Physiology
1. What does the Bundle of His do to the
electrical signal that is trying to pass
through? Why do we need this?
2. Why is the AV node a slow conductor?
Slows it down to give the atria a chance to finish
contracting before the ventricles start to contract
3. What are the two types of fibers in the
heart?
Specialized fibers and contractile fibers
4. What can specialized fibers do?
Initiate an action potential without being
stimulated by a nerve.
5. What is the pathway of conduction in the
heart?
SA node  AV node  Bundle of His  Purkinje
fibers
6. How can the specialized fibers in the
heart generate their own action
potential?
They cannot maintain a stable resting membrane
potential. It gradually drifts to depolarization
because they gradually increase in permeability to
sodium ions.
7. What two things give the heart its rhythm?
The specialized fibers of the heart and the
autonomic nervous system
8. What neurotransmitter slows the heart
rate? To what branch of the ANS does it
belong?
9. What neurotransmitter speeds up the
heart rate? To what branch of the ANS
does it belong?
10. How does the sympathetic nervous system
speed up the heart rate?
Acetylcholine (Ach). Parasympathetic division
11. How does the parasympathetic nervous
system speed up the heart rate?
By decreasing sodium and calcium permeability
and increasing potassium permeability
12. What is the formula to measure cardiac
output (You can use Q or CO to represent
cardiac output)?
13. What is another name for the Ventricular
Ejection Volume?
Q = Stroke Volume × Heart rate
What is the abbreviation for this?
What is the approximate amount of blood
released during each ejection?
The cells there have a smaller diameter, and
there are fewer sodium channels
Norepinephrine (NE). Sympathetic division
By increasing sodium and calcium permeability
and decreasing potassium permeability
Stroke Volume
(SV)
~ 70ml
Heart Physiology
14. What is the formula for the Ejection
Fraction?
What is the approximate percentage of
blood ejected at rest?
During vigorous exercise?
SV/ EDV
EF is ~ 60% at rest
EF is about 90% during exercise
15. What is the End Systolic Volume of blood
left in the heart?
16. What does HR stand for?
17. What is the average liter per minute for
cardiac output for an adult?
50ml
18. What is the formula for cardiac output?
CO= HR x SV
19. What does SV stand for?
Stroke Volume
20. What is the definition of blood flow?
Quantity of blood that passes a given point in the
circulation in a given period of time.
21. What is the formula for cardiac reserve?
Max CO – Resting CO = Cardiac Reserve
22. If resting CO = 6 L/min and after exercise it
increases to 21 L/min, what is the cardiac
reserve?
23. What is the definition of EDV?
21 – 6 = 15 L/min
24. What is the definition of ESV?
25. If the end diastolic volume is 120 ml
And the end systolic volume is 50 ml
What is the stroke volume?
What is the ejection fraction?

26. What is the normal ejection fraction
percent?
27. If heat rate is 80 beats/minute, what is the
cardiac output?
28. If EDV = 130 ml and ESV = 50 ml:
a. What is the SV?
b. What is the EF?
c. What is the CO if HR is 80 bpm?
Heart Rate
70 L/min
EDV (end diastolic volume) is the amount of blood
that has poured into the left ventricle after
diastole (ventricle relaxation)
ESV (end systolic volume) is the amount of blood
left in the left ventricle after systole (ventricular
contraction)
SV = EDV - ESV
SV = 120 – 50 = 70 ml
EF = SV/EDV
EF = 70/120 = 58%
60%
(HR x stroke volume)
80 x 70= 5600ml/min
a. 130 – 50 = 80 ml
b. 80/130 = 62%
c. 80 bpm x 80 ml = 6400ml/min
Heart Physiology
29. If EDV = 110 ml and ESV = 60 ml:
a. What is the SV?
b. What is the EF?
c. What is the CO if HR is 75 bpm?
d. Is this heart diseased?
a. 110 – 60 = 50 ml
b. 50/110 = 45%
c. 75 bpm x 50 ml = 3750ml/min
d. yes, heart is diseased. (EF < 50%)
30. What is the equation for Ohm’s Law?
Q= ∆P/R
31. What two things influence Flow (Q)
through blood vessels?
32. How is “Pressure” difference related to
blood flow: indirectly or directly?
33. How is “Resistance” difference related to
blood flow indirectly or directly?
34. As the blood flow goes up in arterioles,
what happens to the resistance?
35. Is the pressure in the aorta higher or lower
than the pressure in capillaries?
36. As the blood flow in the aorta goes up,
what happens to the pressure difference?
37. Ohm’s Law is a formula to show the
relationship between cardiac output, blood
pressure, and peripheral resistance. Write
the formula to solve for cardiac output (Q),
and the formula to solve for blood pressure
(P), and the formula to solve for peripheral
resistance (R).
38. Using P=RQ, calculate P if:
a)R is 25 and Q is 5
b) R is 10 and Q is 5
c) R is 50 and Q is 5
Pressure and Resistance
39. Using R= P/Q, calculate R if:
a) P is 100 and Q is 5
b) P is 80 and Q is 5
c) P is 125 and Q is 5
a) R = 20
40. The patient presents with high blood
pressure, normal CO: Is peripheral
resistance high or low?
high blood pressure, normal CO, peripheral
resistance high
41. The patient presents with low blood
pressure, normal CO: Is peripheral
resistance high or low?
low blood pressure, normal CO, peripheral
resistance low
Directly
Indirectly
Resistance of the vessel goes down.
Higher
The pressure difference also goes up.
Q = P/R
P = QR
R = P/Q
a) P = 125
b) P = 50
c) P = 250
b) R = 16
c) R = 25
Heart Physiology
42. The patient presents with high CO, normal
blood pressure: Is peripheral resistance
high or low?
high CO, normal blood pressure: peripheral
resistance low
43. The patient presents with low CO, normal
blood pressure: Is peripheral resistance
high or low?
low CO, normal blood pressure, peripheral
resistance high
44. The patient presents with high CO, normal
peripheral resistance: Is blood pressure
high or low?
high CO, normal peripheral resistance: blood
pressure high
45. The patient presents with normal CO, low
peripheral resistance: Is blood pressure
high or low?
normal CO, low peripheral resistance: blood
pressure low
46. The patient presents with normal CO, high
peripheral resistance: Is blood pressure
high or low?
normal CO, high peripheral resistance: blood
pressure high
47. The patient presents with low CO, normal
peripheral resistance: Is blood pressure
high or low?
low CO, normal peripheral resistance: blood
pressure low
48. The patient presents with high blood
pressure, normal peripheral resistance: Is
cardiac output high or low?
high blood pressure, normal peripheral
resistance: cardiac output high
49. The patient presents with normal blood
pressure, low peripheral resistance: Is
cardiac output high or low?
normal blood pressure, low peripheral resistance:
cardiac output high
50. The patient presents with normal blood
pressure, high peripheral resistance: Is
cardiac output high or low?
normal blood pressure, high peripheral
resistance: cardiac output low
51. The patient presents with low blood
pressure, normal peripheral resistance: Is
cardiac output high or low?
low blood pressure, normal peripheral resistance:
cardiac output low
52. What three main factors affect cardiac
output (blood flow), and what are their
effects?
Blood viscosity (decreases CO)
Vessel length (longer vessel decreases CO)
Vessel diameter (larger increases CO)
Heart Physiology
53. What’s the most important regulator in
blood flow?
Vessel Resistance (larger diameter has less
resistance than smaller diameter vessel)
54. Which of the following are vasodilators,
and which are vasoconstrictors?
• Vasodilators
Bradykinin
Histamine
Nitric oxide
Elevated temperatures
Potassium/hydrogen ions
Lactic acid
Carbon dioxide
Adenosine/ ADP
• Vasoconstrictors
Norepinephrine
Epinephrine
Angiotensin
Vasopressin (ADH)
Thromboxane
Epinephrine
Norepinephrine
Bradykinin
Nitric oxide
Carbon dioxide
Vasopressin (ADH)
Potassium/hydrogen ions
Thromboxane
Lactic acid
Elevated temperatures
Adenosine/ ADP
Histamine
Angiotensin
55. In what three ways is the brain involved in
short term blood pressure control?
Vasomotor (causes arteriole constriction when
blood pressure is too low, and arteriole dilation
when BP is too high)
Cardioinhibitory (Vagus nerve signals heart to
decrease rate; parasympathetic)
Cardioacceleratory (sympathetic branch of the
ANS speeds up heart rate).
56. What organ is responsible for long term
control of blood pressure?
57. What vessels do sympathetic nerve fibers
innervate?
58. What effect do sympathetic nerves have on
arterioles?
Kidney
59. What are baroreceptors and what do they
respond to?
Nerve endings in the walls of arteries that
respond to stretch in a blood vessel. Therefore,
they fire an impulse when the blood pressure is
elevated, since that is what stretches the artery.
All vessels except capillaries
Causes vasoconstriction, which increases vascular
resistance.
Heart Physiology
60. Name two locations where baroreceptors
are found.
Carotid bifurcation (between common carotid and
internal and external carotid arteries) this area is
called carotid sinus.
Walls of the aortic arch.
61. What cranial nerve transmits signals from
the carotid sinus?
Aortic arch?
Carotid sinus: CN IX (Glossopharyngeal nerve)
62. As pressure increases, it causes an increase
in number of impulses from baroreceptors
to increase. When baroreceptor impulses
increase in the carotid sinus, what two
things happen?
63. What effect does this have on BP?
64. Are baroreceptors important in short term
or long term regulation of blood pressure?
65. What function do baroreceptors have in
the body?
-inhibition of vasoconstriction  vasodilation
-activation of the vagal center
66. Do baroreceptors trigger the sympathetic
or parasympathetic nervous system?
67. Standing up to quickly causes what type of
reaction to a person’s blood pressure, (BP)?
The Sympathetic Nervous System
68. What three drugs affect CO?
Atropine, Pilocarpine, and Propranalol
69. How does ATROPINE work?
How does it affect CO, HR, and BP?
Blocks parasympathetic system (increase in
sympathetic response, so HR speeds up, CO
increases, and BP increases)
When would a patient need atropine?
70. How does PILOCARPINE work?
How does it affect CO, HR, and BP?
Aortic arch: CNX (vagus nerve)
BP decreases
Short term regulation.
They maintain relatively constant pressure
regardless of body position.
It causes a decrease in the central blood volume,
and cardiac output which results in decreased
arterial pressure, (BP).
A patient whose BP is dangerously low (heroin
drug overdose)
Causes skeletal muscle neurons to release ACH.
Decreases HR, CO, and BP.
71. How does PROPRANALOL work?
How does it affect CO, HR, and BP?
Blocks sympathetic effect of heart.
Decreases HR, CO, and BP.
72. Which drug(s) decreases heart rate?
Pilocarpine and Propranalol
Heart Physiology
73. Which drug increases heart rate?
Atropine
74. Which drug blocks the parasympathetic
system?
75. What drug is derived from the foxglove
plant?
76. What effect does Digitalis have on the
heart rate?
Atropine
77.
What effect does Digitalis have on the force
at which the heart contracts?
Digitalis
Digitalis increases the heart rate.
Digitalis decreases the rate at which the heart
contracts.
78. What is the main disadvantage of using
Digitalis?
It is extremely toxic.
79. What is edema?
80. List 8 things that may cause edema.
Hints: high or low BP? What 2 types of vein
problems? What 2 types of plasma
problems? What heart problem? What
lymph problem? What parasitic infection?
Excessive accumulation of tissue fluid
High arterial blood pressure.
Venous obstruction.
Valve problems
Leakage of plasma proteins into interstitial fluid.
Decreased plasma proteins.
Cardiac failure
Obstruction of lymphatic drainage.
Elephantiasis