The Cardiovascular System is a dynamic system that serves as a machinery and pathway of the circulatory system. This system consists of three essential components: the heart, the blood, and the blood vessels.
The heart works as the pump that propels the blood throughout the body while the blood carries gases and nutrients that replenish the metabolic needs of the tissues and organs. the blood vessels run as channels that deliver blood where it is needed.
The adult heart is shaped like a blunt cone and is approximately the size of a closed fist. Its functions of the heart are:
- Generation of blood pressure
- Routing blood
- Ensuring one-way blood flow
- Regulating blood supply
- Epicardium (outer surface of heart)
- Myocardium (responsible for contraction of heart chambers)
- Endocardium (allows easy blood movement through the heart)
The surfaces of the interior walls of the ventricles are modified by ridges and columns of cardiac muscle called trabeculae carneae.
Contraction of the atria and ventricles is coordinated by specialized cardiac muscle cells in the heart wall that form the conduction system of the heart.
Electrodes place on the body surface and attached to a recording device can detect the small electrical changes resulting from the action potentials in all of the cardiac muscle cells. The record of these electrical events is an electrocardiogram (ECG or EKG).
The two main heart sounds:
- lubb
- duff
Abnormal heart sounds called murmurs are usually a result of faulty valves.
Here are the locations of the heart valves in the thorax.
Large, elastic arteries have many elastic fibers but little smooth muscle in their walls. They carry blood from the heart to smaller arteries with little decrease in pressure. The walls of muscular arteries have much smooth muscle and some elastic fibers. They undergo vasodilation and vasoconstriction to control blood flow to different regions of the body. Arterioles, the small arteries, have smooth muscle cells and a few elastic fibers. They undergo vasodilation and vasoconstriction to control blood flow to local areas.
Venules are composed of endothelium surrounded by a basement membrane. Small veins are venules covered with a layer of smooth muscle and a layer of connective tissue. Medium-sized and large veins contain less smooth muscle and fewer elastic fibers than arteries of the same size. Valves prevent backflow of blood in the veins.
They consist of only endothelium and are surrounded by a basement membrane and loose connective tissue. Nutrients and waste exchange is its principle function. Blood is supplied to capillaries by arterioles. Precapillary sphincters regulate blood flow through capillary networks.
The Circulatory System can be divided into the pulmonary vessels and the systemic vessels. The system and the heart maintain sufficient blood flow to tissues. The system also carries blood; exchanges nutrients, waste products, and gases; transports hormones; regulates blood pressure; and directs blood flow.
Below is the summary of the blood flow through the circulatory system.
Systemic circulation is the system of blood vessels that carries blood from the left ventricle of the heart to the tissues of the body back to the right atrium.
Blood pressure is a measure of the force of blood exerts against the blood vessel walls.
When the ventricles contract, blood is forced into the arteries, and the pressure reaches a maximum value called the systolic pressure. When the ventricle relax,blood pressure in the arteries falls to a minimum value called diastolic pressure.
A sphygmomanometer is used to measure blood pressure together with a stethoscope. The turbulence that produces vibrations in the blood and surrounding tissues that can be heard through the stethoscope are called Korotkoff sounds.