Blood

• Blood is made up of various types of blood cells and a liquid called blood plasma.
• The four main components of blood are red blood cells, white blood cells, blood plasma and platelets
• White blood cells (leukocytes) have a nucleus. All white blood cells have a defensive function. They protect the body from infection by producing antibodiesor phagocytosing foreign particles.
• Platelets are fragments of cells made in the red bone marrow. They play an essential role in blood clotting.
• Blood plasma is a yellowish fluid.
• Red blood cells (erythrocytes) are flat, biconcave cells without a nucleus. They are red because they contain haemoglobin, a protein containing iron that transports oxygen to cells.
• Blood types are characterised by the presence or absence of certain proteins on the surface of red blood cells. The ABO system consists of four blood types: A, B, AB and 0.
• Everyone can donate you blood except for the people that have antigens that you DON'T have.
• Noise that makes the heart: Loop Doop.
• The heart acts as a pump. Its rhythmic contractions (the heartbeat) suck blood out of the veins and push it into the arteries.
• The heart normally beats between 70 and 100 times per minute. Stress or exercise can increase the heart rate.
• Atrial systole: The atria, which are full of blood, contract and push blood into the ventricles via the mitral and tricuspid valves. These valves then close to stop blood flowing backwards from the ventricles.
• Ventricular systole: The ventricles contract and push blood through the semilunar valves into the aorta and pulmonary artery. The valves then close.
• Diastole: The cardiac muscle relaxes and the atria fill with blood. The mitral and tricuspid valves open and the ventricles start to fill. A new cycle begins.
• 1. Atrial systole 2. Ventricular systole 3. Diastole
• The hartbeat indicates that the heart is working.
• There are two heart sounds: the first is prolonged, deep sound. This is when the atrioventricular valves close; the second sound is shorter. This is when the semilunar valves close. When one of the heart valves does not close properly, other sounds can be heard. These are called heart murmurs.
• Human circulation is: Closed. The blood always circulates through the blood vessels and never leaves them.
• Human blood circulation is: Double. The blood must flow through the heart twice to complete a circuit.
• Human blood circulation is: Complete. Oxygenated and desoxygenated blood never mix. They circulate through different cicuits.
• The lymphatic system has three functions.
• Function 1. Absorption of fats from digested foods: after foods have been digested, fats are absorbed by the mucosa of the small intestine. They are then absorbed in the intestinal villi by the lymphatic vessels.
• Function 2. Interstitial fluid drainage: blood capillaries filter out substances and pass them into the interstitial fluid that bathes cells. The filtered fluid mainly contains water, glucose, fatty acids, amino acids, vitamins and hormones need to return to the general blood circulation. Most of the proteins and fluids are collected by the lymph capillaries. These capillaries collect lymph and take it to the lymph veins. These veins reach the subclavian veins of the cardiovascular system, near the heart.
• Function 3. Formation of immune system cells: the lymph nodes store infectious organisms collected by the lymph. These nodes also produce cells involved in protecting the body.