Presentation on theme: "The Heart. Valves of the Heart A-V valves Semilunar valves Tricuspid Bicuspid Right SV Left SV -bw RA - bw LA - bw RV - bw LV and RVand LVand and pulmonary."— Presentation transcript:
Valves of the Heart A-V valves Semilunar valves Tricuspid Bicuspid Right SV Left SV -bw RA - bw LA - bw RV - bw LV and RVand LVand and pulmonary aorta artery
The Structure of the Heart
The Heartbeat Cycle 1. Heart is relaxed. AV valves are open. DIASTOLE SYSTOLE 2. Atria contract. 3.Ventricles contract. Semilunar valves are open.
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.) 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.
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 A-V valves semilunar valves
Heart Sounds Lub 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
Heart Sounds Lub hiss dup When A-V valves dont close completely (blood flows back into atria causes this sound) Lub dup hiss When semilunar valves dont close completely (blood flowing back into ventricle causes this sound)
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.
The Coronary Arteries
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 200 times a minute
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. 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)
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.
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. Control of the Heartbeat
... SA node AV node Bundle of His The electrical current produced by heart can be recorded by a machine that produces an electrocardiogram (ECG).
The Rate of Heart Beat is Regulated by Cardioaccelerator nerve Speed up the pacemaker Vagus nerve Slow down the pacemaker [CO 2 ] in blood High temperature Anxiety Adrenalin Cardiovascular nerve Acetylcholine Vagus nerve increases the heartbeat rate decreases the heartbeat rate
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.