1. Cardiovascular Physiology
Chapter 14a
Cardiovascular Physiology

2. Overview of the cardiovascular system
About this Chapter
Overview of the cardiovascular system
Pressure, volume, flow, and resistance
Cardiac muscle and the heart
The heart as a pump

3. Overview: Cardiovascular System
Table 14-1

4. Overview: Cardiovascular System
Veins
Capillaries
Arteries
Head and Brain
Arms
Lungs
Pulmonary veins
Ascending arteries
Superior vena cava
Pulmonary arteries
Right atrium
Aorta
Left atrium
Coronary arteries
Left ventricle
Abdominal aorta
Right ventricle
Heart
Inferior vena cava
Trunk
Hepatic artery
Hepatic vein
Hepatic portal vein
Liver
Digestive tract
Renal veins
Renal arteries
Ascending veins
Descending arteries
Venous valve
Kidneys
Pelvis and Legs
Figure 14-1

5. Pressure Gradient in Systemic Circulation
Blood flows down pressure gradients
Figure 14-2

6. Pressure Differences in Static and Flowing Fluids
The pressure that blood exerts on the walls of blood vessels generates blood pressure
Figure 14-3a

7. Pressure Differences in Static and Flowing Fluids
Pressure falls over distance as energy is lost due to friction
Figure 14-3b

8. Pressure created by contracting muscles is transferred to blood
Pressure Change
Pressure created by contracting muscles is transferred to blood
Driving pressure for systemic flow is created by the left ventricle
If blood vessels constrict, blood pressure increases
If blood vessels dilate, blood pressure decreases
Volume changes greatly affect blood pressure in CVS

9. Fluid Flow through a Tube Depends on the Pressure Gradient
Flow  ∆P ★
Figure 14-4a

10. Fluid Flow through a Tube Depends on the Pressure Gradient
Figure 14-4b

11. Fluid Flow through a Tube Depends on the Pressure Gradient
Figure 14-4c

12. As the Radius of a Tube Decreases, the Resistance to Flow Increases★
Figure 14-5

13. Flow Rate is Not the Same as Velocity of Flow
Flow (Q): volume that passes a given point
Velocity of flow (V): speed of flow
V = Q/A A= cross sectional area
Leaf in stream
Mean arterial pressure  cardiac output  peripheral resistance (varies by X-sec of arteries)
Figure 14-6

14. The heart is composed mostly of myocardium
Structure of the Heart
The heart is composed mostly of myocardium
STRUCTURE OF THE HEART
Aorta
Pulmonary artery
Superior vena cava
Auricle of left atrium
Right atrium
Pericardium
Coronary artery and vein
Right ventricle
Left ventricle
Diaphragm
(e) The heart is encased within a membranous fluid-filled sac, the pericardium.
(f) The ventricles occupy the bulk of the heart. The arteries and veins all attach to the base of the heart.
Figure 14-7e–f

15. Anatomy: The Heart
Table 14-2

16. Pulmonary semilunar valve
Structure of the Heart
The heart valves ensure one-way flow
Aorta
Pulmonary semilunar valve
Right pulmonary arteries
Left pulmonary arteries
Superior vena cava
Left pulmonary veins
Right atrium
Left atrium
Cusp of the AV (bicuspid) valve
Cusp of a right AV (tricuspid) valve
Chordae tendineae
Papillary muscles
Left ventricle
Right ventricle
Inferior vena cava
Descending aorta
(g) One-way flow through the heart is ensured by two sets of valves.
Figure 14-7g

17. Heart Valves
Figure 14-9a–b

18. Heart Valves
Figure 14-9c–d

19. Anatomy: The Heart
PLAY
Interactive Physiology® Animation: Cardiovascular System: Anatomy Review: The Heart

20. Cardiac Muscle (a) Intercalated disk (sectioned) Nucleus
Mitochondria
Cardiac muscle cell
Contractile fibers
(b)
Figure 14-10

21. Sarcoplasmic reticulum (SR)
Cardiac Muscle
Excitation-contraction coupling and relaxation in cardiac muscle Ca+2
Autorhythmic cells – pacemakers set heart rate ~ 70 / min
Auto or self generate action potentials – stimulate neighboring cells to generate action potentials 1 2 3 4 5 6 7 8 9 10
Ca2+ ions bind to troponin to initiate contraction.
Relaxation occurs when Ca2+ unbinds from troponin.
Na+ gradient is maintained by the Na+-K+-ATPase.
Voltage-gated Ca2+ channels open. Ca2+ enters cell.
Ca2+ induces Ca2+ release through ryanodine receptor-channels (RyR).
Local release causes Ca2+ spark.
Ca2+ is pumped back into the sarcoplasmic reticulum for storage.
Ca2+ is exchanged with Na+ by the NCX antiporter.
Action potential enters from adjacent cell.
Summed Ca2+ sparks create a Ca2+ signal.
ATP
NCX
3 Na+
2 K+
Sarcoplasmic reticulum (SR)
Myosin
Actin
Relaxation
Ca2+
Ca2+ stores
ECF
ICF
T-tubule
L-type Ca2+ channel
Ca2+ sparks
Ca2+ signal
Contraction SR
RyR
Figure 14-11

22. Cardiac Muscle Contraction
Can be graded
Sarcomere length affects force of contraction
Action potentials vary according to cell type

23. Myocardial Contractile Cells
Action potential of a cardiac contractile cell
Refractory period in cardiac muscle – long no tetanus
PX = Permeability to ion X 1
PNa
+20 2
PK and PCa
–20
Membrane potential (mV)
–40 3
PK and PCa
–60
PNa
–80 4 4
–100
100
200
300
Time (msec)
Phase
Membrane channels
Na+ channels open 1
Na+ channels close 2
Ca2+ channels open; fast K+ channels close 3
Ca2+ channels close; slow K+ channels open 4
Resting potential
Figure 14-13

24. Long refractory period in cardiac muscle