2. What is systole and diastole?
• Systole- a period of contraction in the heart
• Diastole- a period of relaxation in the heart
3. What causes the sounds of the
heart beat?
• The closing of valves! Not the contraction of
the muscles
4. Creation of Heart Sounds
“Lubb-Dubb”
• Ventricular Contraction (Systole)
• “Lub” – AV valves closing
• Cont. Vent. Contraction (Systole – 62% of
cardiac cycle)
• Finish Vent. Contraction
• “Dub” – Semilunar valves closing
• Slight split due to pressure diff. L/R
during INSPIRATION
• Vent. Relaxation
(Diastole – 38% of cardiac cycle)
• AV valves open – blood fills vent.
• Atrial contraction
5. Blood Pressure
• Systolic BP
– First sound when
releasing air in cuff
– Normal = 120 mmHg
• Diastolic BP
– Last sound heard
– Normal = 80 mmHg
• Hypertension
– Systolic >140 mmHg
– Diastolic >90 mmHg
7. Electrical Activity of the Heart
Sequence of Excitation
1. SA node (pacemaker)
-Location: R atrium near opening SVC
-Spontaneously generates depolarizing action potentials
-Determines heart rate
2. AV node -
Location: Base of R atrium
-Delay for complete atrial contraction
3. AV bundle (bundle of His)
-Location: Interventricular septum
4. Bundle branches (R and L branches)
-Location: Interventricular septum
5. Purkinje fibers
-Location: Ventricles
-rapidly distributes impulse throughout ventricles
-leading to ventricular contraction
8.
9. Electrocardiogram (ECG)
ECG – primary tool for evaluating electrical events of the heart;
records voltage differences generated by the heart
Standard Limb Leads
Lead I: RA → LA
Lead II: RA → LL
(most similar to normal fxn)
Lead III: LA → LL
*RL = ground
Einthoven Triangle
10. Electrocardiogram (ECG)
• Waves
– P Wave – depolarization of atria
– QRS complex – depolarization of ventricles/repolarization of atria
– T Wave – repolarization of ventricles
• Intervals
– PR – AV conduction time
– QT – electromechanical events of ventricles (dep & rep)
11. Pulse
Pulse – number of
heartbeats per minute
• Normal values for
resting heart rate (bpm):
– newborn infants:
100 to 160
– children 1 to 10 years:
70 to 120
– children >10 & adults:
60 to 100
– well-trained athletes:
40 to 60
Editor's Notes
During ventricular sustole, blood is ejected into the aorta from the left ventricle. The force of ejection causes the elastic walls of the aorta to strech, and the pressure inside the aorta reaches a peak. This maximum pressure is called the systolic pressure . During ventricular diastole, the aortic semilunar valves close, and the elastic fibers in the aorta recoil to force the blood forward. At this time the aortic pressure declines to a minimum level, refered to as the diastolic pressure . Usually the brachial artery is used to measure arterial blood pressure- bc it is at the same level as the heart so gravitational forces are neglegable. Hypertension- chronic elevations in BP, can cause serious disease. Often symtoms don ’t arise for 10 to 20 yrs ( heart can weaken during this time).
Pulse pressure is the difference btwn sys and dias press. Person w 120/80 would have PP of 40mmHg. MAP average pressure that drives blood through the systemic circ.. It is equal to the dias press plus one-third the PP. Person w/ 120/80
AP from SA node are sent to internodal pathways. The signals are spread across the walls of the atria, resulting in atrial contraction (systole). It also distribute signals to the AV node in the floor of the R atrium. When an AP reaches the AV node the atrial muscles relax. From AV node, impulses enter the ventricles by spreading along the AV bundle , left and right bundle branches , and Purkinje fibers . 12) Intercalated discs serve to transfer ________ from cell to cell. A) ionic currents B) action potentials C) the force of contraction D) electrical signals E) All of the answers are correct. Answer: E
