Blood and organs

• Blood has 4 main components: plasma, platelets, red blood cells and white blood cells.
• Plasma is a pale yellow liquid that carries just about everything that needs transporting around your body. Eg. digested food products, carbon dioxide , urea , hormones and heat energy.
• When you damage a blood vessel, platelets clump together to "plug" the damages area (blood clotting). Blood clotting stops you losing too much blood and prevent microorganisms from entering the wound. In a clot, platelets are held together by a mesh of a protein called fibrin.
• Red blood cells transport oxygen from the lungs to all the cells in the body. It has specialised adaption for this purpose.
• 1. Red blood cells are small and have a biconcave shape to give a large surface area for absorbing oxygen
  2. they contain haemoglobin which reacts with blood to form oxyhaemoglobin and the reverse happens in body cells.
  3. they don't have a nucleus so it frees up space for more haemoglobin so they can carry more oxygen.
• Your immune system and white blood cells have a job of destroying pathogens before they reproduce rapidly. There are two types of white blood cells ( phagocytes and lymphocytes).
• Phagocytes detect things that are "foreign" to the body, they engulf the pathogens and digest them. They are non specific so they attack anything that's not meant to be there.
• Every pathogen has unique molecules called antigens on its surface.
• When lymphocytes come across a foreign body, they produce antibodies, that lock on the invading pathogens and mark them out for destruction by other white blood cells. The antibodies are then also produced rapidly and flow round the body to mark all the similar pathogens.
• 2. Memory cells are also produced in response to a forge in antigen. They then reproduce very fast if the same antigen enters the body again.
• Vaccination involves injecting dead or inactive pathogens into the body. These carry antigens so even though they are harmless they still trigger an immune response (lymphocytes produce antibodies to attack them). Memory cells will be produced and will remain in the blood so if live pathogens of the same type ever appear the antibodies to kill them will be produced much faster and in greater number.
• there are 3 types of blood vessel: arteries, capillaries and veins
• Arteries carry blood under pressure. Heart pumps out blood at high pressure so the artery walls are strong and elastic. The elastic fibres allow arteries to expand. They walls are thick compared to the lumen(middle part). They contain thick layers of muscle to keep them strong.
• The largest artery is the aorta.
• Capillaries are really tiny and they carry blood really close to every cell in the body to exchange substances. They have permeable walls, substance can diffuse in and out easily. Supply food and oxygen and takes wastes away (CO2). Walls are only one cell thick and have a small lumen.
• Veins transport blood which is at a lower pressure in the veins so the walls don't need to be as thick. They have a bigger lumen - helps the blood flow faster. They also have valves to keep the blood flowing in the right direction.
• The diagrams of the heart have the sides of the person whose heart it is (opposite of your hands)
• The right atrium receives deoxygenated blood from the body through the vena cave. The deoxygenated blood moves through the right ventricle which pumps it the lungs via the pulmonary artery.
• The left atrium receives oxygenated blood from the lungs through the pulmonary vein, the oxygenated blood then moves through to the left ventricle which pumps it out around the whole body via the aorta.
• The left ventricles has a much thicker wall than the right ventricle. It needs more muscle because it has to pump blood around the whole body whereas the right ventricle only has to pump blood to the lungs. The blood in the left ventricle is under high pressure than the blood in the right ventricle.
• Valves prevent the back flow of blood. Tricuspid valve is between the right atrium and right ventricle. Bicuspid valve is between the left atrium and left ventricle.
• When you exercise, your muscles need more energy so you respire more. You need to get more oxygen into the cells and remove CO2. Blood flows faster so your heart rate increases.
• Excersice increases the amount of CO2 in the blood. High levels of CO2 are detected by the receptors in the aorta and carotid artery. Receptors send signals to the brain. Brain sends signals to the heart causing it to contract more frequently and with more force.
• When an organism is threatened the adrenal glands release adrenaline. Adrenaline binds to the receptors in the heart causing cardiac muscles to contract more frequently and with force, so heart rate increases and the heart pumps more blood. This increases oxygen supply to the tissues, getting the Boyd ready for action.
• Arteries carry out oxygenated blood and veins carry out deoxygenated blood but the pulmonary veins and arteries are the exception to the rule.
• pulmonary means to do with the lungs
• hepatic means to do with the liver
• renal means to do with the kidneys.
• Hepatic portal veins goes from the gut to the liver.
• Coronary heart disease is when the coronary arteries that supply blood to the muscles of the heart get blocked by layers of fatty material building up.
• The build up of fatty materials cause the arteries to become narrow so blood flow is restricted and there's a lack of oxygen to the heart muscles leading to a heart attack.
• Having a diet hight in saturated fat can lead to fatty deposits forming inside the arteries which can lead to coronary heart disease.
• Smoking increases blood pressure which causes damage inside the the coronary arteries which makes it more likely that fatty deposits will form, narrowing the coronary arteries.
• If you are inactive, it can lead to high blood pressure which can cause damage to the lining of the arteries which makes it more likely that fatty deposits will form.
• The kidneys preform three main roles: removal of urea from the blood, adjustments of ion levels in the blood + adjustment of water content of the blood.
• They do this by filtering stuff out go the blood under high pressure and then reabsorbing the useful things. The end product is urine.
• Each kidneys contain thousands of nephrons which are the filtering units of the kidney.
• 1.Ultrafiltration

  • blood from the renal artery flows through the glomerulus.
  • a high pressure is built up which squeezes the water , urea, ions and glucose out of the blood and into the Bowman's capsule.
  • the membranes between the blood vessels in the glomerulus and the Bowmans capsule act like filters so big molecules like proteins and blood cells are not squeezed out. They stay in the blood.
• 2. Reabsorption

  • all the glucose is reabsorbed from the proximal convoluted tubule so that it can be used in respiration. This involves active transport against the concentration gradient.
  • sufficient ions are reabsorbed, excess ions aren't
  • sufficient water is reabsorbed by the collecting duct into the bloodstream by osmosis.
• 3. release of wastes

  • remaining substance( water, urea and ions) form urine. continues out of the nephron, through the ureter and down to the bladder where it is stored before being released via the urethra.