The Cardiovascular System
Functions of the cardiovascular system. Blood Blood vessels. The heart. The spleen The haemoglobin then returns carbon dioxide waste to the lungs. Erythrocytes are Simplified diagram of the circulatory system. Image Source: . There is an association with Myelodysplastic syndromes and acute myeloid leukaemia. This image of the heart and lungs is taken from a middle school health textbook. or diagrams where the physical relationships between elements of the image are important. The circulatory and respiratory systems work together to transport. The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to.
Map of the Human Heart: PBS shows how the heart functions to pump blood throughout the body with an animated interactive and an overview of heart anatomy and heart facts. Explore the differences between arteries and veins in this lesson plan designed to teach students about the circulatory system.
This article explains the relationships between the heart, the blood stream, and How the Body Works: Watch a video that shows how the circulatory system works, including information about the relationship between the heart and the vast network of blood vessels, veins, and arteries. How the Normal Heart Works: The Children's Hospital of Philadelphia explains how a healthy heart works, and you can watch a video that shows how a healthy heart pumps blood.
The Texas Heart Institute offers a collection of anatomy animations to show how the heart supplies blood to the body. Study Guide to Systems of the Body: Maintaining a Healthy System Just like other muscles in your body, the heart needs continual use and exercise to keep it strong and healthy. Aerobic exercise involves activities that increase the heart rate and breathing rate.
Activities such as swimming, running, and biking are examples of aerobic exercise. Engaging in regular aerobic exercise helps make the heart stronger. This helps the heart work more efficiently with the lungs, and it helps it pump blood more efficiently throughout the body. Anaerobic exercise involves strengthening activities, such as lifting weights.
Anaerobic exercise does not directly benefit the cardiovascular system. However, it can contribute to overall health because it can help you build muscle and become stronger. Healthy Kids Become Healthy Adults: Image from Purves et al. Multicellular animals do not have most of their cells in contact with the external environment and so have developed circulatory systems to transport nutrients, oxygen, carbon dioxide and metabolic wastes. Components of the circulatory system include blood: The open circulatory systemexamples of which are diagrammed in Figure 2, is common to molluscs and arthropods.
Open circulatory systems evolved in insects, mollusks and other invertebrates pump blood into a hemocoel with the blood diffusing back to the circulatory system between cells. Blood is pumped by a heart into the body cavities, where tissues are surrounded by the blood.
The resulting blood flow is sluggish. Circulatory systems of an insect top and mollusc middle. Images from Purves et al.
Circulatory system - Wikipedia
Vertebrates, and a few invertebrates, have a closed circulatory systemshown in Figure 2. Closed circulatory systems evolved in echinoderms and vertebrates have the blood closed at all times within vessels of different size and wall thickness. In this type of system, blood is pumped by a heart through vessels, and does not normally fill body cavities.
Blood flow is not sluggish. Hemoglobin causes vertebrate blood to turn red in the presence of oxygen; but more importantly hemoglobin molecules in blood cells transport oxygen. The human closed circulatory system is sometimes called the cardiovascular system. A secondary circulatory system, the lymphatic circulationcollects fluid and cells and returns them to the cardiovascular system.
Vertebrate Cardiovascular System Back to Top The vertebrate cardiovascular system includes a heart, which is a muscular pump that contracts to propel blood out to the body through arteries, and a series of blood vessels.
The upper chamber of the heart, the atrium pl. Passing through a valve, blood enters the lower chamber, the ventricle. Contraction of the ventricle forces blood from the heart through an artery.
The heart muscle is composed of cardiac muscle cells. Arteries are blood vessels that carry blood away from heart. Arterial walls are able to expand and contract. Arteries have three layers of thick walls. Smooth muscle fibers contract, another layer of connective tissue is quite elastic, allowing the arteries to carry blood under high pressure. A diagram of arterial structure is shown in Figure 3. Structure of an artery.
The aorta is the main artery leaving the heart.
The pulmonary artery is the only artery that carries oxygen-poor blood. The pulmonary artery carries deoxygenated blood to the lungs.
In the lungs, gas exchange occurs, carbon dioxide diffuses out, oxygen diffuses in. Arterioles are small arteries that connect larger arteries with capillaries.
Small arterioles branch into collections of capillaries known as capillary beds, an exampe of one is shown in Figure 4. Structure and blood flow through a vein. The above illustration is from http: This image is copyright Dennis Kunkel at www. Capillaries, shown in Figures 4 and 5, are thin-walled blood vessels in which gas exchange occurs.
In the capillary, the wall is only one cell layer thick. Capillaries are concentrated into capillary beds. Some capillaries have small pores between the cells of the capillary wall, allowing materials to flow in and out of capillaries as well as the passage of white blood cells.
Changes in blood pressure also occur in the various vessels of the circulatory system, as shown in Figure 6. Nutrients, wastes, and hormones are exchanged across the thin walls of capillaries. Capillaries are microscopic in size, although blushing is one manifestation of blood flow into capillaries.
Control of blood flow into capillary beds is done by nerve-controlled sphincters. Changes in blood pressure, velocity, and the area of the arteries, capillaries, and veins of the circulatory system. The circulatory system functions in the delivery of oxygen, nutrient molecules, and hormones and the removal of carbon dioxide, ammonia and other metabolic wastes.
Capillaries are the points of exchange between the blood and surrounding tissues.
Materials cross in and out of the capillaries by passing through or between the cells that line the capillary, as shown in Figure 7. Capillary structure, and relationships of capillaries to arteries and veins. The extensive network of capillaries in the human body is estimated at between 50, and 60, miles long. Thoroughfare channels allow blood to bypass a capillary bed.
These channels can open and close by the action of muscles that control blood flow through the channels, as shown in Figure 8. Capillary beds and their feeder vessels. Blood leaving the capillary beds flows into a progressively larger series of venules that in turn join to form veins. Veins carry blood from capillaries to the heart. With the exception of the pulmonary veinsblood in veins is oxygen-poor. The pulmonary veins carry oxygenated blood from lungs back to the heart. Venules are smaller veins that gather blood from capillary beds into veins.
Pressure in veins is low, so veins depend on nearby muscular contractions to move blood along. The veins have valves that prevent back-flow of blood, as shown in Figure 9. Structure of a vein top and the actions of muscles to propel blood through the veins.
Ventricular contraction propels blood into arteries under great pressure. Blood pressure is measured in mm of mercury; healthy young adults should have pressure of ventricular systole of mm, and 80 mm at ventricular diastole. As blood gets farther from the heart, the pressure likewise decreases. Each contraction of the ventricles sends pressure through the arteries. Elasticity of lungs helps keep pulmonary pressures low. Systemic pressure is sensed by receptors in the arteries and atria.
Nerve messages from these sensors communicate conditions to the medulla in the brain. This allows a second possible route of blood flow. Instead of blood flowing through the pulmonary artery to the lungs, the sphincter may be contracted to divert this blood flow through the incomplete ventricular septum into the left ventricle and out through the aorta.
This means the blood flows from the capillaries to the heart and back to the capillaries instead of to the lungs. This process is useful to ectothermic cold-blooded animals in the regulation of their body temperature. Birds, mammals, and crocodilians show complete separation of the heart into two pumps, for a total of four heart chambers; it is thought that the four-chambered heart of birds and crocodilians evolved independently from that of mammals.
Their body cavity has no lining or enclosed fluid. Instead a muscular pharynx leads to an extensively branched digestive system that facilitates direct diffusion of nutrients to all cells.
The flatworm's dorso-ventrally flattened body shape also restricts the distance of any cell from the digestive system or the exterior of the organism. Oxygen can diffuse from the surrounding water into the cells, and carbon dioxide can diffuse out. Consequently, every cell is able to obtain nutrients, water and oxygen without the need of a transport system.
Some animals, such as jellyfishhave more extensive branching from their gastrovascular cavity which functions as both a place of digestion and a form of circulationthis branching allows for bodily fluids to reach the outer layers, since the digestion begins in the inner layers.
History Human anatomical chart of blood vessels, with heart, lungs, liver and kidneys included. Other organs are numbered and arranged around it. Before cutting out the figures on this page, Vesalius suggests that readers glue the page onto parchment and gives instructions on how to assemble the pieces and paste the multilayered figure onto a base "muscle man" illustration.
The earliest known writings on the circulatory system are found in the Ebers Papyrus 16th century BCEan ancient Egyptian medical papyrus containing over prescriptions and remedies, both physical and spiritual. In the papyrusit acknowledges the connection of the heart to the arteries.
The Egyptians thought air came in through the mouth and into the lungs and heart. From the heart, the air travelled to every member through the arteries. Although this concept of the circulatory system is only partially correct, it represents one of the earliest accounts of scientific thought.
In the 6th century BCE, the knowledge of circulation of vital fluids through the body was known to the Ayurvedic physician Sushruta in ancient India. However their function was not properly understood then.