1. Heart

2. Heart Structure The ________ separates the heart into 2 separate pumps
The right side of the heart pumps blood into the __________ circuit
The left side of the heart pumps blood into the _________ circuit
The muscles in the (atria/ventricles) is thicker
On average, our heart beats over 100,000 times per day, totalling up to nearly 2.5 billion times in a life time

3. Cardiac Cycle
Cardiac cycle: a complete heartbeat, including the contraction and relaxation of heart muscle
Takes 0.8 seconds to complete
Cardiac cycle is divided into two phases
Diastole: Ventricles are relaxed, being filled with blood
Systole: Ventricles contract, blood is ejected
What is the pericardium’s function?

4. Diastole begins when the atria begin to fill with blood, once the pressure and volume has built up in the atria, it causes the atrioventricular valves to open, sending blood into the ventricles
The atria walls contract to send remaining blood into the ventricles
Once the ventricles are filled to capacity, they contract, sending blood to the lungs and body by pushing through the semilunar valves
The ventricles can then open up again (increasing in ’empty’ volume)

5. Heart Sounds
The lubb-dubb sound of the heart is made by the valves closing
Lubb = Atrioventricular valves
Dubb = Semilunar valves
Heard through the use of a stethoscope
Heart murmur: valves fail to close properly, leads to ineffective blood delivery
What was the sound associated with the heart beating?
People with heart murmurs have an increased heart rate, why do you think this is?

6. Experiments have shown that when the heart is removed, it continues to beat for a short time
What could this mean?

7. Cardiac Muscle
Myogenic muscle: cardiac muscle, unusual ability to contract and relax on its own without an external source
Ensures the heart will continue to beat even if the nervous system is damaged
‘Brain Dead’
Coma

8. Cardiac Muscle
Sinoatrial (SA) node: mass of nerve and muscles cells in the right atrium, maintains a normal heartbeat
Pacemaker
Atrioventricular (AV) node: mass of conducting cells in the wall of the right atrium/ right ventricle, transmits signals from SA to ventricles
Purkinje fibers: conducting fibers on the septum and ventricles, transmit signals from AV to muscles
There are three components that allow for the heart to have precise and timely contractions and relaxations

9. Autonomic Nervous System
Sympathetic
Preparation for stress “Fight or Flight”
Parasympathetic
“Rest + Digest”
What does the autonomic nervous system control?
There are two divisions of the autonomic nervous system
Sympathetic and Parasympathetic
What would happen to heart rate when the body is signalling stress?

10. Electrocardiograph
Electrocardiograph (ECG): device that detects the electrical activity of the heart through electrodes placed on the body’s surface
Produces an electrocardiogram
Because the heartbeat is electrically stimulated, it can be indirectly observed by reading those electrical signals
An electrocardiogram is the reading it produces (the graph)

11. Electrocardiograph
A single heartbeat includes the P wave, the ORS complex, and the T wave
P = Contraction of the atria by the signals from the SA node
The space in between (the plateau) is the delay when the SA node signals are reaching the AV node
QRS = contraction of the ventricles (from the tip and moving upwards, think of squeezing a yogurt tube)
Another slight delay as the ventricles recover and get ready for another contraction
T = recovery period,
To look for heart beat problems, you simply compare the normal graph to the one your patient produced, and look for the problem areas
Animation: Figure 7