1. Cardiovascular Physiology
Review

2. Path of Blood Flow
Scenario:
• You inject a medication into the client’s arm
• Within a few minutes, some of that drug has reached the client’s liver and is being
deactivated
Question:
• How did it get there?

3. Simplified Path of Blood Flow
body
right left
heart heart
lungs

4. Anatomy of the Heart

5. Review Question
Tell whether the following statement is true or
false.
The pulmonary circulation moves blood through
the left side of the heart.

6. False Answer
Rationale: The right side of the heart pumps
blood to the lungs through the pulmonary
arteries, where gas exchange takes place. The
left side of the heart is considered systemic
circulation because blood is pumped to all
body tissues.

7. The Heart Layers

8. The Basics of Cell Firing
• Cells begin with a
negative charge: resting
membrane potential
• Stimulus causes some
Na+ channels to open Threshold
• Na+ diffuses in, making potential
the cell more positive
Resting
membrane
potential Stimulus

9. The Basics of Cell Firing (cont.)
• At threshold potential, Action
more Na+ channels open potential
• Na+ rushes in, making
the cell very positive: Threshold
depolarization potential
• Action potential: the
cell responds (e.g., by Resting
contracting) membrane
potential Stimulus

10. The Basics of Cell Firing (cont.)
• K+ channels open Action
potential
• K+ diffuses out,
making the cell
negative again: Threshold
repolarization potential
• Na+/K+ ATPase
removes the Na+ from Resting
the cell and pumps membrane
the K+ back in potential Stimulus

11. Cardiac Muscle Firing
• Cells begin with a negative
charge: resting membrane
potential
• Calcium leak lets Ca2+ Threshold
diffuse in, making the cell potential
more positive
Resting
membrane
potential Calcium
leak

12. Cardiac Muscle Firing (cont.)
• At threshold potential, Action
more Na+ channels potential
open
• Na+ rushes in, making Threshold
potential
the cell very positive:
depolarization
Resting
• Action potential: the
membrane
cell responds (e.g., by
potential Calcium
contracting)
leak

13. Cardiac Muscle Firing (cont.)
• K+ channels open Action
• K+ diffuses out, making potential
PLATEAU
the cell negative again,
but Ca2+ channels are Threshold
still allowing Ca2+ to potential
enter
• The cell remains
positive: plateau
Calcium
leak

14. Cardiac Muscle Firing (cont.)
• During plateau,
the muscle Action
contracts potential PLATEAU
strongly
Threshold
• Then the Ca2+ potential
channels shut
and it repolarizes
Calcium
leak

15. Question
Which ion channels allow cardiac muscle to fire
without a stimulus?
b. Na+
c. K+
d. Ca2+
e. Cl-

16. a. Ca2+ Answer
Rationale: In the SA and AV nodes, resting
cardiac muscle cells have open Ca2+ channels.
This allows Ca2+ to leak into the cells, making
them more positive (the cells reach threshold
this way without the need for a stimulus).

17. The Cell Passes the Impulse to Its
Neighbors

18. Heart Contraction
How would each of the following affect heart contraction:
• A calcium channel blocker
• An Na+ channel blocker
• A drug that opened Na+ channels
• A drug that opened K+ channels

19. Cardiac Cycle—Diastole
• Ventricles relaxed
• Blood entering atria
• Blood flows through AV valves into ventricles
• Semilunar valves are closed

21. Cardiac Cycle—Systole
• Ventricles contract
• Blood pushes against AV valves and they shut
• Blood pushes through semilunar valves into aorta and
pulmonary trunk

23. Question
Which of the following statements is true about
ventricular systole?
b. Atria contract
c. Ventricles contract
d. AV valves are open
e. Semilunar valves are closed

24. Answer
a. Ventricles contract
Rationale: During ventricular systole, the
ventricles contract. Because blood is being
forced from the ventricles, semilunar valves
must be open and AV valves closed. The atria
are in diastole (relaxation) during ventricular
systole.

25. Cardiac Cycle
Discussion:
• Arrange these steps in the proper order:
– Ventricles relax – First heart sound
– Systole – Semilunar valves open
– Diastole – AV valves close
– AV valves open – Semilunar valves close
– Ventricles contract – Second heart sound

26. Pressure, Resistance, Flow
• Fluid flow through a vessel depends on:
– The pressure difference between ends of the
vessel
º Pressure pushes the fluid through
º Pressure keeps the vessel from collapsing
– The vessel’s resistance to fluid flow
º Small vessels have more resistance
º More viscous fluids have greater resistance

27. Pressure, Resistance, Flow of Blood
• Blood flow through a vessel depends on:
– Heart creating pressure difference between ends
of the vessel
• Heart pushing the blood through
• Blood pressure keeping the vessels open
– The vessel’s resistance to fluid flow
• Constricting arterioles increasing resistance
• Increased hematocrit increasing resistance

28. Discussion
How will each of these factors affect arteriole size and
peripheral resistance?
• Lactic acid • Low PO2
• Cold • Histamine
• Endothelin • Heat
• NO • Adenosine

29. Blood Pressure
BP = CO x PR
Blood pressure = cardiac output × peripheral
resistance

30. Question
Tell whether the following statement is true or
false.
In patients with hypertension (high blood
pressure), peripheral resistance is increased.

31. True Answer
Rationale: In hypertension, blood vessels are
constricted/narrowed. Smaller vessels
increase resistance (it’s harder to push the
same amount of fluid/blood through a tube
that has become smaller).

32. Forces Moving Fluid In and Out of
Capillaries

33. Lymph Vessels Carry Tissue Fluid Back
to the Veins