1. Human cardiovascular physiology
Exercise 37
Human cardiovascular physiology

2. Cardiac cycle The relaxation period The contraction period
Concepts to memorize:
The two atria contract simultaneously
The two ventricles contract simultaneously
Diastole
The relaxation period
Systole
The contraction period

3. Steps of the cardiac cycle
The heart is in diastole
Heart pressure is low
The blood flows passively from the pulmonary and systemic system into the atria
The AV valves open
The blood flows into the ventricles
The atria contracts to force the residual blood into the ventricles

4. Cardiac cycle The ventricular pressure increases
The ventricular systole begins
The atria are in diastole and begin to be filled
The AV valves close
The semilunar valves open
The blood flows into the aorta and the pulmonary arteries

5. Cardiac cycle
The pressure in the aorta and pulmonary arteries increase
The semilunar valves close
The ventricles relax

6. The cardiac sounds (lub-dup pause)
First heart sound (S1- lub)
Represents the closing of the AV valves
It happens at the beginning of the systole
Second heart sound (S2- dup)
It represents the closing of the semilunar valves
It happens at the end of the systole

7. The cardiac sounds Murmurs It represents a turbulent blood flow
It is found when blood flows through narrow openings (stenosis)
Also found when there is backflow of blood (regurgitation) because of defected valves (insufficiency)

8. Cardiac cycle Auscultation of the mitral valve
Over the 5th intercostal space
In line with the middle of the clavicle
Auscultation of the tricuspid valve
Over the sternum

9. Cardiac cycle Auscultation of the pulmonary valve
Over the 2nd intercostal space
At left sternal margin
Auscultation of the aortic valve
At the right sternal margin

10. The pulse
It is palpation of the pressure wave that travels along the arteries
The pressure wave causes the expansion of the arterial wall
Parameters detected by the pulse palpation:
Pulse rate
It is the same as the heart rate
Normal: bpm

11. The pulse Pulse rhythm Pulse amplitude Superficial pulse points
Common carotid artery
Temporal artery
Facial artery
Brachial artery
Radial artery

12. The pulse Femoral artery Popliteal artery Posterior tibial artery
Dorsalis pedis artery

13. The blood pressure
It is the pressure that the blood causes to the wall of the vessels
It is reported in millimeters of mercury (mm Hg)
Arterial pressure:
Systolic pressure
Reflects the pressure in the arteries during ventricular ejection
It is the first reading
normal:120 mm Hg

14. The blood pressure Diastolic pressure
Reflects the pressure in the arteries during ventricular relaxation
It is the second reading
Normal: 80 mm Hg

15. The blood pressure Sounds of Korotkoff
Indicates the resumption of blood flow into the forearm when the pressure to occlude the artery is gradually released
First sound heard is the systolic pressure
The disappearance of the Korotkoff indicates the diastolic pressure

16. The blood pressure Venous pressure Normal: 30-90 mm Hg
They are affected by muscle activity, deep pressure, breathing, etc

17. The blood pressure Pulse Pressure (PP)
Systolic pressure – diastolic pressure
Mean arterial pressure (MAP)
MAP=diastolic pressure+PP/3
Narrow pulse pressure (>30mm Hg) = aortic stenosis, constrictive pericarditis, tachycardia

18. Effects of various factors on blood pressure
BP=CO * PR
Factors that increase PR:
Constriction of arteries
Increased blood viscosity
Increased blood volume
Hardening of the arteries walls

19. Effects of various factors on blood pressure
Factors that increase BP:
Age
Weight
Drugs
Exercise
Emotions, etc

20. Skin color It indicates local circulatory dynamics
Factors that influence skin color
Oxygen supply (cyanosis)
Temperature (cold, warm)
Hormones (thyroid hormones)
Autonomic nervous system
Fight or flight reaction
Collateral blood flow

21. Electrocardiogram (ECG)
Conduction of impulses through the heart
Generation of electrical impulses
Detection of the electrical impulses on the body’s surface
Electrocardiograph

22. Electrocardiogram

23. ECG - Waves P wave represents the depolarization of the atria
First wave, small and precedes atrial contraction
QRS complex ventricular depolarization; second wave
Precedes ventricular contraction
T wave indicates ventricular repolarization; third wave

24. ECG - Segments Flat Lines PR segment
From the end of P wave to the beginning of QRS complex
Represents the conduction through the AV node

25. ECG - Segments ST segment
From the end of QRS to the beginning of T wave
Represents the plateau of the ventricular action potential

26. ECG - Intervals Always include at least one wave PR interval (PQ)
P wave + PR segment
QT interval
From the Q wave to the end of T wave
QRS complex + ST segment + T wave

27. ECG - Intervals ST interval
From the end of the QRS to the end of the T wave
ST segment + T wave
Decreased conduction through atriaspread out P wave
PR segment = conduction through the AV node
PR intervalincreased conduction through AV node (sympathetic stimulation for example)decrease PR interval; decreased conduction through AV node increased PR interval
ST segment = Plateau of the ventricular action potential

28. The electrocardiogram (ECG) abnormalities
Tachycardia
HR above 100 bpm
Bradycardia
HR below 60 bpm
Fibrillation
Uncoordinated heart contractions