1. Cardiovascular System Part 2
Circulation
Heart Anatomy
Contraction
Blood Pressure
Cardiac Action Potentials
EKG

2. Circulation Pulmonary Circuit: Systemic Circuit: R. atrium
R. ventricle
Pulmonary arteries
Lung capillaries
Pulmonary veins
Systemic Circuit:
L. atrium
L. ventricle
Aorta
Systemic arteries
Organ & tissue capillaries
Systemic veins
Vena cavas

3. Circulation
Atherosclerosis= cholesterol and lipid buildup on and in the walls of vessels.
Increased thickening  increased pressure  thickening  decreased elasticity potential clotting

4. Circulation
Aneurysm= swelling or dilation of aorta or other blood vessels
May lead to rupture
May be caused by:
Aging breakdown of elastic fibers
Atheroscleosis
Genetic disorders
Infection

5. Heart Anatomy Myocardium= cardiac muscle tissue
Pericardium= tough fibrous sac around the heart

6. Heart Anatomy

7. Heart Anatomy

8. Contraction Heartbeat= one cardiac cycle; one contraction/ relaxation
Systole= contraction
Diastole= relaxation
Contraction of a chamber causes an increase in pressure that opens the valve to the next chamber.
“Lub-Dub” sound produced by the closing of AV and semilunar valves respectively.

9. Blood Pressure
Blood pressure= pressure exerted by the blood against the vessel walls
Normal = 120/80
120: systolic pressure; highest pressure
80: diastolic pressure; lowest pressure
Hypertension= high blood pressure  increased resistance to flow  enlargement and weakening of heart

10. Blood Pressure

11. Cardiac Action Potentials
Self-excitatory pacemaker cells=
Spontaneously produce action potentials
Intercalated discs=
Bridge plasma membranes between 2 cardiac cells
Offer almost a spontaneous contraction of many cardiac cells at once

12. Cardiac Action Potentials
Pacemakers:
Sinoatrial (SA) node:
initiates atrial contraction
Sends signal from location in the R. atrium through the left atrium
Atrioventricular (AV) node:
Located in the septum
When SA signal is received at AV node there is a slow response
The AV node sends the signal down the purkinje fibers
Ventricles contract

13. Cardiac Action Potentials

14. EKG (aka ECG) Electrocardiogram
Evaluates electrical events in the heart
Reads a potential difference between electrodes on the skin
Measures change in ECF currents, not in individual cells

15. EKG (aka ECG) P-wave= atrial depolarization
QRS-complex= ventricular depolarization (w/atrial repolarization)
T-wave= ventricular repolarization

16. EKG (aka ECG) Little to no summation in cardiac muscle:
No tetanic contraction
Refractory period:
Time after excitation when cells can not reach action potential
Allows for ventricular filling
Caused by the slow inactivation of sodium channels

17. EKG (aka ECG) Arrhythmia= Irregular heart rhythms Pacemakers irregular
Detectable by EKGs
Ex)
Bradychardia – fewer beats/min than average
Tachychardia – many more beats/min than average
Ventricular fibrillation – haphazard contractions

18. EKG (aka ECG) More arrythmias: http://www. rnceus. com/course_frame