Blood, the heart and the vessels through which blood is pumped around the body, together make up the cardiovascular system. They are vital for carrying nutrients, oxygen and waste around the body. Show Blood is made up of cells and plasma. An average adult has about 5 litres of blood in their body. As well as carrying cells, nutrients, oxygen and waste, blood also helps to regulate body temperature. Blood cellsMost blood cells are made in the bone marrow. There are 3 main types of blood cells:
Red blood cellsRed blood cells transport oxygen from the lungs to the rest of the body, and carry waste products to the lungs or kidneys for release. Red blood cells contain haemoglobin, which is the protein that enables them to carry oxygen. White blood cellsWhite blood cells are part of the immune system. They detect and fight infections or foreign substances that enter the body. There are 5 main types of white blood cell — neutrophils, lymphocytes, monocytes, eosinophils and basophils. PlateletsPlatelets are small cell fragments that help the blood clot. They circulate in the blood until there is an injury to a blood vessel. Then they clump together and help a clot form at the injury site. PlasmaPlasma is the straw-coloured fluid that carries the blood cells. It makes up around half of your blood. It also carries the nutrients from our diet such as sugars, fats, proteins, vitamins and minerals. Blood testsYour blood can give useful information on how well your body is working and help doctors test for some diseases and conditions. Some common blood tests are:
Blood typesEveryone has a particular blood type (blood group), which is determined by the genes inherited from their parents. The main blood types are A, B, AB, and O. Doctors check a person’s blood type before a blood transfusion or organ transplant, to ensure compatibility with the donor’s blood type. Blood type is also important in pregnant women to work out which Rhesus type they are and whether the mother’s blood and baby’s blood are compatible. What are blood vessels?Blood vessels are the network of tubes through which blood is pumped around the body. Along with the heart and the blood, the blood vessels form the cardiovascular system. The 3 main types of blood vessels are:
Blood leaves the heart in large arteries, then moves through progressively smaller ones to reach the capillaries in the tissues. Oxygen and nutrients pass through the thin capillary walls into the tissues, and waste products from the tissues pass into the capillary blood. The blood then leaves the capillaries and moves into veins that progressively get larger as they get closer to the heart. Once at the heart, this de-oxygenated blood (blood that needs oxygen) enters the right-hand side of the heart. From there it is sent to the lungs where the carbon dioxide is removed and replaced with oxygen. Some of the waste products that were picked up by the capillaries from the tissues are filtered out from the blood as it flows through the kidneys. The walls of arteries are strong and elastic and can expand and contract to lower or increase blood pressure, according to your needs. Blood pressure is the pressure of your blood on the walls of the arteries as your heart pumps blood around the body. Veins have thinner walls, and some veins (for example in the legs) have valves to prevent the backflow of blood due to gravity. Diseases of blood and blood vesselsThe blood and blood vessels can be affected by physical injury (trauma) or disease, such as cancer. Problems that can happen with the blood include:
Problems that may happen to blood vessels include:
What is a condition of insufficient blood flow?This condition is known as coronary artery disease. Insufficient blood flow to the heart muscle can lead to symptoms of chest pain (angina). If the coronary artery becomes completely blocked, it will cause a heart attack. During a heart attack, some of the heart muscle can die from a lack of oxygen. Risk factors.
Which medical condition is when there is insufficient blood supply to the heart?Myocardial ischemia occurs when the blood flow through one or more of your coronary arteries is decreased. The low blood flow decreases the amount of oxygen your heart muscle receives. Myocardial ischemia can develop slowly as arteries become blocked over time.
What is lack of blood flow called?Eventually, the narrowed artery causes less blood to flow, which may lead to ischemia, or inadequate blood flow to your body's tissue.
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