1. The Heart

2. The Heart right pulmonary arteries left atrium atrioventricular valve
semilunar valves
right atrium
superior vena cava
right pulmonary veins
Inferior vena cava
septum
aorta
left pulmonary arteries
pulmonary trunk
left ventricle
left pulmonary veins
right ventricle

3. The Heart

4. The Heart

5. The Heart

6. Control of the Heartbeat
You cannot hold your pulse even for a single beat.
Your heart continues beating regularly if you are knocked unconscious, and may even continue beating for a while after you die.
The impulse that triggers the heartbeat actually originates from within the heart itself.
There are nerves (autonomic NS) that connect to the heart but they do not initiate or control the heartbeat
A cardiac cycle is defined as a complete cardiac movement, including systole, intervening pause, and diastole

7. Control of the Heartbeat
The contraction phase is systole, while the filling phase is diastole
A bundle of specialized muscle tissue, located in the wall of the right atrium, stimulates the muscle fibres to contract and relax rhythmically.
The sinoatrial node (S-A node) = the pacemaker
Atria contract while ventricles relax, and the ventricles contract while atria relax.
Heart sounds are created primarily from turbulence in blood flow created by valves closing, not from contraction.
Why do heart sounds come in pairs?

9. Control of Heartbeat
The Atrioventricular (AV) node is also located on the right side of the heart, just beneath the surface of the interventricular septum.
The Bundle of His, is a band of nerve fibers that originates at the AV node, then passes along the interventricular septum to the ventricles.
The right and left bundle branches proceed along the right and left sides of the interventricular septum to the tips of the two ventricles.
The Purkinje Fibers are the tree-like terminal branchings of the right and left bundles.

10. Control of Heartbeat After the SA node fires:
the electric signal spreads throughout the muscles of both atria
Atrium contract
The impulse then passes through the AV node to the Bundle of His
The signal is then divided between right and left bundle branches
When they reach the terminals of the Purkinje fibers they leap across to the cardiac muscle fibers
Ventricles contract
All this happens in less than a second.

12. Electrocardiographs (ECGs)
Represents (and measures) the electric activity of the heart
A normal ECG graph appears as follows:

13. An upward deflection of the wave represents an electric impulse traveling towards a sensor

14. ECGs
Each of the letters designates a different phase of the cardiac cycle.
P wave: generation of the electrical impulse at the SA node and its subsequent spread through the atria.
PR interval: During this interval the impulse travels through the atria and the AV node.

15. ECGs
QRS complex. The time necessary for the impulse to spread through the bundle of His and its branches to complete ventricular contraction
ST segment. The ST segment represents the period between the completion reversal of charges in the ventricular muscle tissue.
T wave. The T wave represents the return to normal state of ventricular muscle tissue that occurs after ventricular contraction.

18. Chemical Regulators
When you are relaxed, your S-A node fires regularly
around 70 times a minute.
This firing rate adjusts, however, to meet your body’s needs.
Read the Chemical Regulators section on p. 305
There are two negative feedback loops described
Fill in the worksheet with the appropriate information for each of these loops

19. Control of Heartbeat
Physical activity is not the only trigger for an increased heart rate.
The nervous system releases adrenaline when you are nervous, angry, or excited, or after a sudden shock or sharp pain.
“fight or flight” response:
a physiological change that prepares the body for anticipated activity
attack, defence, or escape.
As the heart rate increases, so does blood flow to the muscles, resulting in more oxygen being delivered to the muscle cells.

20. Adrenaline

21. Cardiac Output
The amount of blood pumped by the heart is often referred to as the cardiac output
= volume of blood pumped from each ventricle per unit of time.
a measure of the level of oxygen delivery to the body
Indicates the total level of work the muscles must perform
Two factors affect the cardiac output
heart rate (HR) = number of times the heart beats in a unit of time (minute)
stroke volume (SV) = the amount of blood forced out of the heart with each heartbeat
cardiac output = SV × HR
Average person has a stroke volume of about 70 mL and a resting heart rate of about 70 beats per minute, for a cardiac output of about 4900 mL/min.

22. Cardiac Output
Out of Shape
Average
Extremely Fit

23. Cardiac Output Individual A = Average
Individual B = Out of Shape, Unhealthy
Low stroke volume results in a high resting heart rate
Individual C = Exceptionally fit
very high stroke volume results in a low resting heart rate
can maintain the same level of oxygen delivery at a much lower heart rate than the less fit individual B.
Why is a low resting heart rate healthier?
When the heart is forced to work harder, it will break down sooner

24. ECGs Activity: Research 1 of 3 other conditions on www.ecglibrary.com
left ventricular stenosis
atrioventricular block
Wolf-Parkinson White
Draw a normal ECG
Draw the abnormal ECG for the condition
Identify where the major differences are (which sections of the ECG) between the two ECGs
Explain the pattern and cause of the abnormal ECG

25. Blood Pressure

26. Blood Pressure