1. Cardiovascular Physiology
Blood
Heart
Peripheral Circulation
Solution of Nutrients/Wastes
Pump
Tubes
The primary function of the Cardiovascular system is to
1) deliver nutrients/oxygen and
2)remove wastes/CO2
from the cells in your body

2. Cardiac Physiology
The primary function of the HEART is to generate a Pressure gradient in the vascular system
Pressure gradient allows blood to move by BULK FLOW through the body & the lungs

3. Molecules move “down” gradients from “Hi” to “Lo”, spontaneously
A GRADIENT is a difference in any parameter over distance
Molecules move “down” gradients
from “Hi” to “Lo”, spontaneously
e.g. Pressure, concentration, temperature, energy

4. Bulk Flow Many molecules moving simultaneously in one
direction, from an area of high P to low P
PATMOS mm Hg
Lo P
Expiration
Hi P
Hi P
Inspiration
Lo P
PLUNGS mm Hg

5. kB = bulk flow constant ~ tube diameter
Poiseulle’s Law of Bulk Flow: Its all about PRESSURE
P P2
FB = kB(P1 - P2) L/min
FB = Bulk Flow L/min
kB = bulk flow constant ~ tube diameter
If P1 > P2, flow goes from 1 to 2
If P1 < P2, flow goes from 2 to 1
If P1 = P2, no flow occurs

6. Bulk Flow: Movement DOWN a Pressure Gradient

7. Cardiac Cycle The cardiac cycle links 1) Electrical 2) Contractile
3) Pressure
4) Flow
through the heart!

8. The Heart is surround by cardiac muscle
Pericardium
Myocardium
Endocardium
Myocardial Fibers

9. Myocardium Anatomy Myocardium is very similar to skeletal muscle
Except
Intercalated discs form Gap junctions between adjacent myocardial fibers
Myocardial fibers branch
SR and T-tubules are weakly linked….Ca2+ is slowly released upon excitation

10. Pacemaker Cells: Heart is Autorhythmic!

11. How do pacemaker cells spontaneously produce action potentials?
Pacemaker cells have an UNSTABLE resting membrane potential!
Prepotential: Few Na+ channels open,
Na+ influx = funny current
2) Depolorization: VG Ca2+ channels open
INFLUX of Ca2+
3) Repolarization: K+ channels open
EFFLUX of K+ 2 3 1
Drugs to treat Arrhythmias sometimes work on Ca2+ channels!

12. Myogenic signal propagates down Myocardium

13. Skeletal muscle AP look and behave like neural cells
Electrical Properties of the Myocardium
Plateau
Skeletal muscle AP look and behave like neural cells
Due to the SLOW CLOSING OF Ca2+,
Myocardium REPOLARIZES VERY SLOWLY

14. Excitation-Contraction Coupling of Cardiac Muscle
1) Action Potential 1
Ca2+
ECF
Sacrolemna
2) VG Ca2+ channels open,
CA 2+ Influx
ICF
RyR 2
3) Ca2+ influx triggers RyR channels
on SR to open
Calcium Induced Calcium Release 3 SR
Ca2+
VG Ca2+ Channel
4) Ca2+ pours out of SR
Ca2+ Spark!
T-tubule 4
Ca2+ Spark
5) Sparks sum to create Ca2+ signal 5
Ca2+ Signal
6) Ca2+ binds Troponin, cross-
bridge formation, Contraction!
Sarcomere
Calcium Sparks Video 6
Contraction

15. Myocardium contraction is GRADED!
Amount of Ca2+ entering myocardium is proportional to contraction strength
Ca2+
Force of Myocardium
Ca2+
Amount of Calcium INFLUX
Ca2+ Spark
Ca2+ Signal
# of Cross bridges Formed
Contraction
Amount of Calcium INFLUX

16. Excitation-Contraction Coupling in Myocardium vs. Skeletal Muscle
Refractory
Myocardium
Ca2+ Plateau prolongs the refractory period…..summation cannot happen!
Guarantees that Cardiac Muscle Contract-Relaxes Rhythmically!!!!!

17. Don’t get CONFUSED! Pacemaker Potentials Cardiac Muscle Excitation
Pacemaker EXCITATION >>>>>>>>>>>>>>>>>>>>.Cardiac Muscle Excitation- Contraction

18. Heart’s Electrical Conducting System
SA = 100 min-1
AV node = 40 min-1
AV bundle
Bundle branches
Purkinje Fibers min-1

19. More Funny Current (Na+) channels
Why do the SA pacemaker cells beat a higher frequency than AV, Bundle Branches & Purkinje?
SA NODE
AV NODE
SA Node has
More Funny Current (Na+) channels

20. What about Bundle Branches and Purkinje (10-30 min-1)?
SA Node
Atrial Muscle
AV Node
AV Bundle
Bundle Branches
Purkinje Fibers
Ventricular Muscle
No Plateau Phase
Shorter Refractory Period
Excitation involves Calcium PLATEAU
Huge Refractory Period

21. Ventricular Systole: Contraction Ventricular Diastole: Relaxation
Atria have Systole and Diastole TOO!

22. 1
Late diastole
Atria & Ventricles
START 5
Early Ventricular DIASTOLE. 2
Atrial systole S1 S2 3
Early Ventricular SYSTOLE 4
Late Ventricular Systole

23. Cardiac Cycle The cardiac cycle links 1) Electrical 2) Contractile
3) Pressure
4) Flow
through the heart!

24. High Ventricular Pressure Forces AV Valves Shut
Low Ventricular Pressure
Forces Aortic/Pulmonary Valves Shut

25. Valves respond to pressure! Guarantees One-Way Blood Flow
Chordae Tendinae
Papillary Muscle
Relaxed ventricular muscle (diastole)
Low pressure in ventricle
AV valve flops open
Aortic Valve Shuts
Contracting ventricular muscle (systole)
High pressure in ventricle
AV valve forced shut
Aortic Valve Opens

26. Blood Flow through heart is driven by Pressure!
Isovolumetric
CONTRACTION
Isovolumetric
RELAXATION

27. Blood Flow through Heart
R. AV
Valve
L. AV
Valve

28. Cardiac Cycle The cardiac cycle links 1) Electrical 2) Contractile
3) Pressure
4) Flow
through the heart!

29. Wiggers Diagram 3 5 1 2 4 1) No electrical activity
Atrial & Ventricular Diastole
Pressure is low
Volume is increasing 3 5 1 2 4
2) P-wave = Atrial Depol.
Atrial Systole
Atrial Pressure Rises
Ventricular volume increases
3) QRS = Atrial Repol, Ventricular Depol.
Ventricular Systole, Atrial Diastole
Ventricular Pressure rises dramatically
Atrial Pressure rises
Ventricular Volume flat, then decreases
as AV closes and Aortic and Pulmonary Valves Open
4) T-wave = Ventricular Repol.
Ventricular Diastole
Pressure drops dramatically in ventricle
& rises in Atria
Ventricular Volume decreases then is flat
as aortic and pulmonary valves CLOSE
5) No electrical activity
Atrial & Ventricular Diastole
Pressure & Volume slowly rise as blood fills