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Structure and functions of the cardiovascular system

There are several major components of the cardiovascular system
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The next component which makes up the heart are the atria, these are the two upper chambers of
the heart
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The left
atrium receives the oxygenated blood from the left and right pulmonary veins, which it then pumps
to the left ventricle for pumping through the aorta for systemic circulation
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The right atrium receives blood returning to the heart from the superior and
inferior venae cavae
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The inferior vena cava returns de-oxygenated
blood from the lower body regions (legs, back, abdomen and pelvis) to the right atrium
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The lower two chambers
of the heart are called ventricles
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The left ventricle differs to the right ventricle, this is because the right ventricle Receives
blood from the right atrium and pumps it to the main pulmonary artery
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Here deoxygenated blood picks up oxygen and is returned to the heart via the pulmonary
veins
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The aorta
carries and distributes oxygen-rich blood to the rest of the body
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Deoxygenated blood enters the right side of the heart via the inferior and
superior vena cava
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The next valve is the bicuspid valve, also known as this a
structure in the left side of the heart that controls the flow of oxygenated blood
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This same structure also is what prevents blood in the left ventricle from backing up into the left
atrium
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The pulmonary vein delivers
oxygenated blood to the heart's left atrium
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With each of the heart's contract actions, oxygenated blood exits the left ventricle
through the aortic valve
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It is a one-way
valve
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The valve is opened by the increased blood
pressure of pushing blood out of the heart and into the artery
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It is located in the right ventricle of the heart
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There are several structures which are in place in order to keep the heart healthy and protected,
such as the Chordae tendineae
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The aorta is the largest artery in the body
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The aorta arises from the left ventricle of the heart, forms an arch, and then extends down to the
abdomen, where it branches off into two smaller arteries
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This vein is short in length; however, it is
very wide in diameter
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Pulmonary veins are responsible for carrying oxygenated blood from the lungs to the left atrium of
the heart
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There are two right
pulmonary veins, known as the right superior and right inferior veins
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The fact that these veins carry oxygenated blood makes them different from all other
human veins, as they are used to carry deoxygenated blood
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The main artery splits into the left pulmonary artery and the right pulmonary, each of
which directs the blood to the corresponding lung
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The main artery leaving the
heart is the aorta; it quickly splits up into smaller vessels
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Arterioles are the small branches of arteries
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These are found in all parts of the body especially muscles
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These tiny spaces allow oxygen
and other nutrients to diffuse into one another
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In capillaries the blood will also pick up the waste products of
metabolism, such as carbon dioxide and lactic acid
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The
walls of these veins are thinner and less muscular than arteries
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Veins are generally acting against gravity so they contain non-return valves to
prevent the blood flowing back once the smooth muscle has relaxed
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Veins predominantly carry deoxygenated blood, with the exception of the
pulmonary vein, which carries oxygenated blood to the heart from the lungs
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This could happen because of a number of reasons such as heat
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Components of Blood –

The main components of blood are plasma, erythrocytes, leucocytes, thrombocytes
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Red blood cells – erythrocytes, these Red blood cells are small and biconcave in shape as they lack
nucleus and other organelles
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The red blood cells are also flexible so they can squeeze through the small
capillaries
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White blood cells – leucocytes, these play a pivotal role in your immune system
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Platelets / thrombocytes aren’t complete cells; they stop blood loss through blood clotting
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There are approximately
15,000 – 40,000 of platelets per micro-litre of blood
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The main function of the nasal cavity is to
warm, moisturise and filter air entering the body before it reaches the lungs
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The Pharynx connects the nasal cavity and mouth to the larynx (air) and oesophagus (food)
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The muscular pharynx wall is made of skeletal muscle
throughout its length
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The larynx is about 5 cm
(2 in
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It is part of the respiratory system and is located between the pharynx and the trachea
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Its outer wall of cartilage forms the area of the
front of the neck referred to as the Adam's apple
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The trachea is 12cm long and 2cm wide and is flexible and mobile
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One entering the left and one entering the
right lung, the left bronchi are narrower, longer and more horizontal than the right
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Bronchioles- once inside the lungs each bronchus subdivides into lobar bronchi; three on the right
and two on the left
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There are roughly 23 orders of branching bronchial airways in the lungs
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The left lung contains two lobes, the right lung has three
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Each lung is enclosed in a pleural membrane that helps keep the two lungs away from each other
and airtight
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Pleural Cavity is an area which surrounds the lung
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This space inside the body is formed
between the parietal and visceral pleura which line the lungs and body cavity
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Parietal pleura- outermost of the two pleural membranes, it covers the thoracic wall and the top of
the diaphragm
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Thoracic cavity- is protected by the thoracic wall
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The thoracic cavity protects and holds the lungs, heart, trachea, oesophagus, endocrine
glands, thoracic aorta and the pulmonary artery
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It is a thin serous membrane tissue layer that sticks to the lung
surface
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Pleural fluid- Pleural fluid is a thin, transparent fluid produced in the area around the lungs that
helps them expand and contract effortlessly
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When breathing the pleural
cavity experiences a negative pressure which helps adhere the lungs to the chest wall
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Alveoli- bronchioles end within alveolar sacs (or ducts)
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They are surrounded by a network of capillaries, into
which the inspired gases pass
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The Diaphragm is the main muscle used in the process of inspiration or breathing in
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Lying at the base of the thorax, it
separates the abdominal cavity from the thoracic cavity
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There are two sets of intercostal muscles the first is the external intercostal muscles which pull the
ribs upwards and outwards, increasing the volume of the chest cavity and drawing air into lungs
during inspiration
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