1. The Heart

2. Tricuspid Bicuspid Right SV Left SV
Valves of the Heart
A-V valves Semilunar valves
Tricuspid Bicuspid Right SV Left SV
bw RA bw LA bw RV bw LV
and RV and LV and and
pulmonary aorta
artery

4. The Structure of the Heart

7. The Heartbeat Cycle DIASTOLE SYSTOLE 2. Atria contract.
3.Ventricles contract. Semilunar valves are open.
1. Heart is relaxed. AV valves are open.

8. Systole: Contraction period
The Heartbeat Cycle
The pumping action of the heart has two periods:
Systole: Contraction period
Diastole: Relaxation period
During diastole the heart muscle is relaxed and A-V valves are open.
Blood flows from the atria into ventricles . (This fills the ventricles %70 not fully.)

9. The Heartbeat Cycle Systole begins with the contraction of atria.
When atria contract they can pass all blood inside to the ventricles, so ventricles are full of blood.
Then ventricles contract and the pressure of contraction closes A-V valves.
The pressure also opens the semilunar valves.
As a result blood flows from right ventricle to pulmonary artery and transported to lungs;
blood in the left ventricle flows into the aorta to be carried throughout the body.

10. Heart Sounds
Heart sounds are formed as a result of opening and closing of A-V and semilunar valves. They are called the lub-dup sounds.
lub-dup sound
closing of closing of
A-V valves semilunar valves

11. Heart Sounds Lub sound: Dup sound:
Ventricles contract Pressure increases
Mitral and tricuspid valves close
Dup sound:
At the beginning of diastole pressure in the relaxed ventricles drops below that in the arteries
Semilunar valves close

12. Heart Sounds
Lub hiss dup When A-V valves don’t close completely (blood flows back into atria causes this sound)
Lub dup hiss When semilunar valves don’t close completely (blood flowing back into ventricle causes this sound)

13. The Coronary Arteries
They are the first arteries to branch off from the aorta. They nourish the heart muscle.
If there is blood clot or accumulation of materials in coronary arteries this may cause heart attack.

14. The Coronary Arteries

15. Heart Rate
The number of times the heart contracts each minute is the heart rate or pulse rate. (The pulse is the expansion and relaxation that can be felt in an artery each time the left ventricle contracts and relaxes.)
It is measured by feeling the impact of blood on the wall of an artery.
Pulse can be felt in wrist
on each side of throat
Normal heart rate (beats) times in a minute
In vigorous exercise times a minute

16. Control of the Heartbeat
Heart is made up of the cardiac muscle. Although the nervous system controls the contraction of other types of muscle, cardiac muscle has a built-in ability to contract.
Even when it is removed ftom the body, the heart will keep beating for a while in a special solution called Ringer solution.
Ringer solution contains NaCl, KCl and CaCl.

17. Control of the Heartbeat
There are structures in the heart muscle which are called nodes.
Sinoatrial node (SA node = pacemaker): is located in the wall of the right atrium near the opening of superior vena cava.
Atrioventricular node (AV node): is located in the wall of right atrium near the septum (behind the tricuspid valve)

18. Control of the Heartbeat

19. Control of the Heartbeat
SA node generates impulses, specialized fibers carry impulses throughout the atria and stimulates AV node.
The group of fibers called bundle of His distribute the impulses through the ventricles from AV node.

20. Control of the Heartbeat
Contraction of the heart begins when,
the heart receives electrical impulses from the SA node
atria contract the impulse reaches the AV node
the AV node triggers an impulse that causes the ventricles to contract
Bundle of His conducts the impulses through the ventricles.

21. Control of the Heartbeat
SA node . .
The electrical current produced by heart can be recorded by a machine that produces an electrocardiogram (ECG). .
AV node
Bundle of His

23. The Rate of Heart Beat is Regulated by
Vagus nerve Slow down the pacemaker
Cardioaccelerator nerve Speed up the pacemaker
Acetylcholine
Vagus nerve
[CO2] in blood
High temperature
Anxiety
Adrenalin
Cardiovascular nerve
decreases the
heartbeat rate
increases the
heartbeat rate

24. Cardiac Output
The amount of blood pumped by the left ventricle each minute is called cardiac output.
Resting: the heart pumps about 5 lt. of blood each minute.
Exercise: cardiac output may increase up to 37 lt. per minute.