This essay The Circulatory System has a total of 6655 words and 25 pages.
The Circulatory System
Forwards and backwards to the right and are at the same level of the fifth to eight dorsal vertebrae. The apex of the heart points downwards and forwards to the left and corresponds to the space between the fifth and sixth ribs. However, in thin people, the hearts apex may be pointing more downwards than to the left. Its atrial border corresponds to a line drawn across the sternum on a level with the upper border of the third costal cartilage. Its apex corresponds to a line drawn across the lower end of the same bone. Its upper surface is rounded and convex, directed upwards and forwards, which is formed mainly by the right ventricle and a part of the left ventricle. The back surface of the heart is flattened and rests upon the diaphragm. Of its two borders, the right is the longest and thinnest, the left is shorter but thicker and round. The muscles that make up the heart are known as cardiac muscles. Cardiac muscle only exists in the heart, not like skeletel muscle which is found in many parts of the body. Cardiac muscle fibers possess striations that are typical of skeletel muscle. However, they only respond to the autonomic nervous system and electrical commands that are generated from the heart. Skeletel muscle may have many nuclei, but cardiac muscle only has one nucleus. As well, cardiac muscle is very small compared to the larger skeletel muscle. As fitting with its duty, cardiac muscle has many mitochondria to convert food into energy faster than other muscles. Cardiac muscles communicate between junctions that are laid down between the muscles. They are called intercalated disks. Along certain points of the disks, cell membranes fuse together. The electrical current required to cause the muscles to contract pass through the cells easily and the adjoining cells will respond as well due to the intercalated disks. The cardiac muscle is really a large number of cells working together that function to act as a single cell.
There are many proteins that give cardiac, as well as other muscles, to contract. Thin bundles of protein called myofibrils run the length of each fiber. Within the myofibrils are filaments (tiny threads of protein) that are arranged in a repeating pattern called a sarcomere. The filaments in each sacromere are made up of the proteins actin and myosin. Two clusters of actin are set in each end of the sacromere stretch towards the centre but do not touch. There are continuos threads of myosin located at the end of the sarcomere. The contraction can occur because of the region where the actin and myosin over lap each other. Small hooks on the myosin binds to the actin filaments and pull towards the centre of the sarcomere. This happens through the rapid ratchet-like actions of the myosin and actin pulling together. When the sarcomere pulls together, the fiber contracts and so does the muscle. In order for this to occur again, the sarcomere must be stretched out, which is caused by the blood re-entering the heart, expanding it.
In an adult, the heart measures about five inches in length, three and a half inches in the broadest part of its horizontal diameter, and two and a half inches in its posterior. The average weight in the males is from ten to twelve ounces. In the female, the average weight is eight to ten ounces. The heart will continue to grow in size up to old age. This growth is more obvious in men than in women.
The heart is subdivided by a muscle called the septum into two halves, which are named right and left according to their position. A muscle divides each half into two cavities. The upper cavity on each side is called the atria or auricle, and the lower side is called the ventricle. The right atrium and ventricle form the venous side of the heart. Dark venous blood is pumped into the right atrium from the entire body by the superior vena cava(SVC) and inferior vena cava (IVC), and the coronary sinus. From the right atrium, the blood passes into the right ventricle and from the right ventricle, through the pulmonary artery into the lÜ¥e #À ñ Ð " ß ,º l
Earth WormsEarth Worms Earth Worm Disection Parts Function Digestive System - Prostomium - a small fleshy lobe that extends over the mouth, used to help dig through the soil - Mouth - the entrance for food into the digestive system, located under the prostomium - Pharynx - A tube at the beginning of the digestive tract that creates a sucking action to remove food particles from the soil, located just behind the mouth - Esophagus - a narrow passage in the digestive track that connects the pharynex to the cr
Roman ArtRoman Art Romans were collectors and admirers of Greek art. Art from Greece was brought to Rome, copied, and also changed by the Romans. As a result, Roman art is somewhat based on Greek art. However, Roman art is not merely a continuation of Greek art. For an amateur it is difficult to determine between the two art forms because neither the Romans nor the Greeks wrote down the history of their own art. The characteristics pertaining to each particular type of art are known to some extent, so th
The Circulatory SystemThe Circulatory System Forwards and backwards to the right and are at the same level of the fifth to eight dorsal vertebrae. The apex of the heart points downwards and forwards to the left and corresponds to the space between the fifth and sixth ribs. However, in thin people, the hearts apex may be pointing more downwards than to the left. Its atrial border corresponds to a line drawn across the sternum on a level with the upper border of the third costal cartilage. Its apex corresponds to a lin
ANGINA PECTORISANGINA PECTORIS ANGINA PECTORIS Submitted by: Course: SBI OAO To: Date: CONTENTS 3 Introduction 4 The Human Heart 5 Symptoms of Coronary Heart Disease 5 Heart Attack 5 Sudden Death 5 Angina 6 Angina Pectoris 6 Signs and Symptoms 7 Different Forms of Angina 8 Causes of Angina 9 Atherosclerosis 9 Plaque 10 Lipoproteins 10 Lipoproteins and Atheroma 11 Risk Factors 11 Family History 11 Diabetes 11 Hypertension 11 Cholesterol 12 Smoking 12 Multiple Risk Factors 13 Diagnosis 14 Drug Treatment 14 Nitra
The Human HeartThe Human Heart Biology - Histology The Human Heart. Abstract: Dorland\'s Illustrated Medical Dictionary defines the heart as the viscus of cardiac muscle that maintains the circulation of the blood. It is divided into four cavities; two atria and two ventricles. The left atrium receives oxygenated blood from the lungs. From there the blood passes to the left ventricle, which forces it via the aorta, through the arteries to supply the tissues of the body. The right atrium receives the blood af
The BrainThe Brain A.M.D.G 27th October 1996 The Brain By Manuel Socarrás In the central nervous system of animals, the brain is a segregated group of nerve cells, or neurones, within the cranium, or skull, in vertebrates, and within the head segment in lower forms of animals. The brain varies in size and complexity from rudimentary ganglia (a group of nerve-cell bodies) in the central nervous systems of primitive worms to the large and complex human brain. As the central control organ of the body, the b
Biology InstinctBiology Instinct subject = biology title = Biology Instinct Insects are neumerout invertebrate animals that belong in the Phylum Arthropoda and Class Insecta. The class Insecta is divided into 2 subclasses: Apterygota, or wingless insects, and Pterygota, or winged insects. Subclass Pterygota is futher divided on basis of metamorphosis. Insects that have undergone incomplete metamorphosis are the Exopterygota. Insects that undergo complete metamorphosis are the Endopterygota. Insects have an oute
RhododendronRhododendron Rhododendron The plant rhododendron belongs to the family Ericaceae which also includes the Heath, and there are about eight-hundred fifty species which grow worldwide (Turner and Szczawinski, 171-2). The Heath family is a large one with so many species, all of the poisonous species fall into two of its subfamilies, one of which is the rhododendron. These cultivated plants occur naturally in temperate regions of the northern hemisphere and in the mountains of Southeast Asia. They ar
ReflexologyReflexology The origins of Reflexology evidently reach back to ancient Egypt as evidenced by inscriptions found in the physicians tomb at Saqqara in Egypt. The translation of the hieroglyphics are as follows: Dont hurt me. The practitioners reply:- I shall act so you praise me. We cannot determine the exact relationship between the ancient art as practiced by the early Egyptians and Reflexology as we know it today. Different forms of working the feet to effect health have been used all over t
AidsAids Aids by sean ross How is HIV Diagnosed? You can get tested for HIV in a number of locations -- including public clinics, AIDS organizations, physicians\' offices, and hospitals. Many locations give the test for free. You can choose between anonymous tests, in which you do not give your name to the HealthCare provider, or confidential tests, in which you do give your name. Test sites should provide trained counselors who can offer you support and guidance, no matter what the test result.(Bal
The Physical Development Of A Human BeingThe Physical Development Of A Human Being Catherine The Physical Development of a Human Being As defined in Berk\'s, Development Through the Lifespan, physical development is changes in body size, proportions, appearance, and the functioning of various body systems; brain development; perceptual and motor capacities; and physical health. The physical development of a human being is the unique because of all of the visible changes that every human being goes through. Physical growth results from
Human BodyHuman Body In the Beginning Within a month of conception, the cluster of cells that will, in the course of time, become a human being begins throbbing, signaling the development of a primitive heart. Scarcely four weeks more pass before an intricate network of veins and arteries the size of a pea forms and subdivides into a tiny replica of the four chambers that will one day make up the adult heart. As the fetus grows, so does its vitally important circulatory system. Although most of the functi
Television: Sending The Wtong MessageTelevision: Sending The Wtong Message Television: Sending the Wrong Message Everyday, human beings make assumptions by what they can see physically. Even in the supermarkets, they distinguish good products from bad products based on how those products look. Being a human, I would say we are apt to choose good-looking products because they don\'t have flaws, cracks, and bruises. Those good products are shaped nicely, colored and look great. Moreover, we assume those products to have good qualitie
Physical FitnessPhysical Fitness My report is on what it takes to become physically fit. Physical fitness is the ability of the human body to function with vigor and alertness, without undue fatigue, and with ample energy to engage in leisure activities, and to meet physical stresses. Muscular strength and endurance, cardiorespiratory integrity, and general alertness are the overt signs of physical fitness. Physical fitness is usually measured in relation to functional expectations-that is, typically, by period