mass transport in animals

• Haemoglobin is a water soluble globular protein
• haemoglobin has 2 polypeptide chains, each with 4 polypeptide subunits. 2 beta polypeptide chains and 2 alpha helices
• haemoglobin carries oxygen through the blood and forms an iron group which can hold 4 oxygen molecules
• The greater the concentration of dissolved oxygen in cells the greater the partial pressure.
• as partial pressure increases, the affinity of haemoglobin for oxygen increases. oxygen binds to haemoglobin tightly.
• during respiration, partial pressure decreases and oxygen affinity has decreased as well. because of this oxygen is released in respiring tissues when needed. haemoglobin returns to the lungs and binds to oxygen
• Dissociation curves illustrate the change in haemoglobin saturation as partial pressure changes.
• haemoglobin is highly saturated as it has high partial pressure and high oxygen affinity
• carbon dioxide causes oxygen affinity to decrease because carbon dioxide creates slightly acidic conditions which change the shape of the haemoglobin protein, thus making it easier for the oxygen to be released
• the bohr effect is when carbon dioxide decreases the oxygen affinity in haemoglobin which releases oxygen in respiration
• blood leaves the lungs through the pulmonary vein and goes to the heart
• blood leaves the heart in arteries which are under very high pressure. when our hearts contract, the pressure increases
• blood travels from the heart to the lungs through the pulmonary artery
• oxygenated blood travel from the heart to other organs through the aorta
• before blood reaches the organs, it passes through arterioles (blood vessle)
• once through the capillaries, the blood passes into the venules and into the veins
• oxygenated blood travels from the lungs to the heart. deoxygenated blood travels from the heart to the lungs
• properties of arteries?

  1. thick walls (helps to withstand high pressure) 2. small elastic fibre 3. smooth muscle layer (when contracted the diameter narrow)
• elastic fibres contain elastin which can stretch and help blood flow more smoothly
• at the centre of the artery, the lumen is present and is summoned by endothelium cells (which can give smooth surface to reduce friction with blood flow)
• arterioles have the same structure as arteries but have a less thicker collagen layer and elastic layer.
• vasoconstriction - when smooth muscle in arterioles contract blood flow through capillaries are reduced
• vasodilation - when smooth muscles in arterioles relax and blood flow increases
• capillary bed = a network of capillaries
• substances are exchanged between blood and body cells through the capillary bed
• the extensive branching of capillaries provide a large surface area for the exchange of materials
• capillaries have thin walls so they have a short diffusion rate which increases the rate of diffusion
• the lumen in capillaries is slightly wider than red blood cells so the red blood cells have to travel in a straight line which causes a slower movement
• capillaries have a small gap between the endothelium cells which allow fluids to pass out of the blood and also allows white blood cells to leave the bloodstream
• properties of veins?

  1. have low pressure 2. thinner walls than arteries as they aren't high in pressure 3. larger lumen so they can carry more blood
• when the skeletal muscle contract, they squeeze the veins lying between them. this changes their shape and forces the blood to flow along. if the blood flows forwards then the valves will be open. but if the blood flows backwards then the valves will be closed
• tissue fluid leaves the blood at parts of the capillary that are close to the artery
• hydrostatic pressure - force fluid out of the blood and into the tissue.
• plasma proteins are hydrophilic so they move water back into the blood by osmosis. tissue fluid leaves as the hydrostatic pressure is greater than the oncotic pressure
• near the venous end, oncotic pressure is greater than the hydrostatic pressure so fluid is allowed in
• 10% of tissue fluid that doesn't go into the blood is drained into the lymph capillaries
• lymph capillaries connect into a larger lymph vessels forming the lymphatic system
• lymph fluids move when lymph vessels are squeezed by nearby skeletal muscles
• whats the hearts 4 chambres?

  1. right atrium 2. left atrium 3. right ventricle 4. left ventricle
• the atria and ventricles are separated by the intraventricular valve (AV valves