Circulatory System
Heart (cont.) chambers
- 2 upper called atria and 2 lower are called the ventricles - RIGHT ATRIUM: receives blood as it returns from the body cells - RIGHT VENTRICLE: receives blood from the right atrium and pumps the blood into the pulmonary artery, which carries the blood to the lungs for oxygen - LEFT ATRIUM: receives oxygenated blood from the lungs - LEFT VENTRICLE: receives blood from the left atrium and pumps the blood into the aorta for transport to the body cells
Arteries 4
- Additional branches of the aorta carry blood to the head, neck, arms, chest, back, abdomen, and legs.
Conductive Pathway 2
- After the electrical impulse passes through the atria, it reaches the atrioventricular (AV) node, a group of nerve cells located between the atria and ventricles.
Cardiac (Heartbeat) Cycle (cont.) 2
- As the atria are filling, systole begins, and the ventricles contract. The right ventricle pushes blood into the pulmonary artery, sending the blood to the lungs for oxygen.
Cardiac (Heartbeat) Cycle (cont.) 1
- At the start of the cycle, the atria contract and push blood into the ventricles. The atria then relax, and blood returning from the body enters the right atrium, while blood returning from the lungs enters the left atrium.
pacemaker
- At times it is necessary to use external or internal artificial pacemakers to regulate the heart's rhythm. The pacemaker is a small, battery-powered device with electrodes.
Conductive Pathway
- Electrical impulses originating in the heart cause the cyclic contraction of the muscles - A group of nerve cells located in the right atrium and called the sinoatrial (SA) node, or the "pacemaker," sends out an electrical impulse that spreads out over the muscles in the atria. The atrial muscles then contract and push blood into the ventricles.
pacemaker 5
- Even though modern pacemakers are protected from electromagnetic forces, such as microwave ovens, most manufacturers still recommend that people with pacemakers avoid close contact with digital cellular telephones. - For example, the cellular telephone should not be stored in a shirt pocket close to the pacemaker.
pacemaker 4
- Fixed pacemakers deliver electrical impulses at a predetermined rate. Demand pacemakers, the most common type, deliver electrical impulses only when the heart's own conduction system is not responding correctly.
Arrhythmias 2
- For example, an early contraction of the atria, or premature atrial contraction (PAC), can occur in anyone and usually goes unnoticed.
Arrhythmias
- If something interferes with the normal electrical conduction pattern of the heart, arrhythmias occur. Arrhythmias are abnormal heart rhythms and can be mild to life-threatening.
Conductive Pathway 6
- In this way, the electrical impulse reaches all the muscle tissue in the ventricles, and the ventricles contract.
Heart (cont.) valves one-way valves in the chamber of the heart keep the blood flowing in the right direction
- TRICUSPID VALVE: located between the right atrium and the right ventricle. it closes when the right ventricle contracts, allowing blood to flow to the lungs and preventing blood from flowing back into the right atrium. - PULMONARY VALVE: located between the right ventricle and the pulmonary artery, a blood vessel that carries blood to the lungs. it closes when the right ventricle has finished contracting, preventing blood from flowing back into the right ventricle. - MITRAL VALVE: located between the left atrium and left ventricle. it closes when the left ventricle is contracting, allowing blood to flow into the aorta (4 transport the the body) and preventing blood from flowing back into he left atrium. - AORTIC VALVE: located between the left ventricle and the aorta, the largest artery in the body. it closes when the left ventricle is finished contracting, allowing blood to flow into the aorta and preventing blood from flowing back into the left ventricles
Conductive Pathway 3
- The AV node sends the electrical impulse through the bundle of His, which are nerve fibers in the septum.
Arteries 2
- The aorta branches into all of the other arteries that supply blood to the body.
Conductive Pathway 5
- The bundle branches further subdivide into the Purkinje fibers, a network of nerve fibers throughout the ventricles.
Conductive Pathway 4
- The bundle of His divides into a right bundle branch and a left bundle branch, which carry the impulse down through the ventricles.
pacemaker 2
- The electrodes are threaded through a vein and positioned in the right atrium and in the apex of the right ventricle.
Arteries 3
- The first branch of the aorta is the coronary artery, which divides into a right and left coronary artery to carry blood to the myocardium of the heart.
Cardiac (Heartbeat) Cycle (cont.) 3
- The left ventricle pushes blood into the aorta, sending the blood to all other parts of the body. The blood in the right side of the heart is low in oxygen and high in carbon dioxide.
pacemaker 3
- The pacemaker monitors the heart's activity and delivers an electrical impulse through the electrodes to stimulate contraction.
Arteries 5
- The smallest branches of arteries are called arterioles. They join with capillaries. - Arteries are more muscular and elastic than are the other blood vessels because they receive the blood as it is pumped from the heart.
Cardiac (Heartbeat) Cycle (cont.) 5
- This blood in the left side of the heart, high in oxygen and low in carbon dioxide, is ready for transport to the body cells.
Conductive Pathway 7
- This electrical conduction pattern occurs approximately every 0.8 seconds. The movement of the electrical impulse can be recorded on an electrocardiogram (ECG) and used to detect abnormal activity or disease.
Arrhythmias 4
- Treatment depends on the type and severity of the arrhythmia. - Life-threatening fibrillations are treated with a defibrillator, a device that shocks the heart with an electrical current to stop the uncoordinated contraction and allow the SA node to regain control.
Arrhythmias 3
- Ventricular fibrillation, in which the ventricles contract at random without coordination, decreases or eliminates blood output and causes death if not treated. - Cardiac monitors and electrocardiograms are used to diagnose arrhythmias.
Blood vessels
- When the blood leaves the heart, it is carried throughout the body in blood vessels. - The heart and blood vessels form a closed system for the flow of blood. - There are three main types of blood vessels: arteries, capillaries, and veins.
Cardiac (Heartbeat) Cycle (cont.) 4
- When this blood arrives in the lungs, the carbon dioxide is released into the lungs, and oxygen is taken into the blood. This oxygenated blood is then carried to the left side of the heart by the pulmonary veins.
Circulatory system
- a.k.a. cardiovascular system - referred to as the "transportation" system of the body - consisting of the heart, blood vessels, and blood. - transports oxygen and nutrients to the body cells, and carbon dioxide and metabolic materials away from the body cells
Arteries
- carry blood away from the heart. The aorta is the largest artery in the body; it receives the blood from the left ventricle of the heart
The Heart 1st
- muscular hollow organ often called the "pump" of the body - weighs less than 1 pound - contracts about 100,000 times each day to pump the equivalent of 2,000 gallons of blood through the body - located in the mediastinal cavity, between the lungs, behind the sternum, and above the diaphragm
Heart (cont.) SEPTUM
- muscular wall that separates the heart into right and left sides. - prevents blood from moving between the right and left side of the heart - UPPER part of the SEPTUM is called the INTERATRIAL SEPTUM - LOWER part of the septum is called the INTERVENTRICULAR SEPTUM
Cardiac (Heartbeat) Cycle
- right and left side of the heart is separated by the septum - right and left work together in a cyclic manner - Diastole: brief period of rest involved in the cycle followed by Systole - Systole: period of ventricular contractions
Heart (cont.) 3 layers of tissues
3 layers of tissue forms the heart: ENDOCARDIUM- smooth layer of cells that lines the inside of the heart and is continuous with the inside of blood vessels (allows for the smooth flow of blood) MYOCARDIUM- (thickest layer, muscular middle layer) PERICARDIUM- double-layered membrane, or sac, that covers the outside of the heart a lubricating fluid, pericardial fluid, fills the space between the two layers to prevent friction and damage to the membranes as the heart beats or contracts
