Gas Exchange and Transport Flashcards
Alveoli
are air sacs in the lungs and are a place where gas exchange occurs. They are very thin, so that oxygen and carbon dioxide can easily move through them, into or out of the blood. They are also moist and have transport systems which maintain the concentration gradient. High SA to Vol ratio. Linked with a thick layer of flattened cells, allowing for easy diffusion.
Gill
the gas exchange surface of aquatic animals. In fish, these are highly vascularised. A constant stream of water must be passed over the gills to maintain an oxygen supply to the body and maintain a concentration gradient. Oxygen diffuses from the water into the filament capillaries along a concentration gradient, and carbon dioxide diffuses into the opposite direction.
What three fluids are involved in the transportation of materials in the liquid medium?
Tissue fluid, blood and lymph.
Tissue fluid
The tissue fluid surrounds the individual cells. It is the primary source of nutrients and gases from the blood and takes up wastes from the cell to the blood.
Blood
Blood moves through a series of tubular vessels. These vessels, the artieries, veins and capillaries, vary in size. Lymph is carried in lymphatic vessels
Lymph
Lymph is carried in lymphatic vessels. It picks up tissue fluid and particles and returns these to the blood system. The lymph is important in the body’s immune response.
Red and white blood cells
Human blood is composed of red cells (erythrocytes), white cells (leucocytes), plasma proteins and platelets suspended in a straw- coloured fluid called plasma. Plasma also carries proteins, vitamins, carbon dioxide, nitrogenous wastes, etc.
The main function of the red blood cells is to transport oxygen from the respiratory surfaces to the tissues. Mature red blood cells have no nucleus so must be produced in the bone marrow.
The inside of a red blood cell is packed with the red pigment haemoglobin.
Capillaries
narrow blood vessels. A network of them surround each alveolus to speed up gas exchange.
Blood circulatory system
The vessels involved in the blood circulatory system are arteries (carry blood away from the heart), veins, and capillaries. Blood under pressure enters the capillaries. The blood pressure forces the fluid, ions, gases and nutrients through the spaces between the cells of the capillary wall. These form the extracellular fluid that surrounds the cells and exchange of material between the cells and blood is made in this tissue fluid.
Carbon dioxide and exchange of materials
Carbon dioxide is a waste product or aerobic and anaerobic respiration in the cells. It must be transported away from the cells to a gas exchange area to be released into the external environment. It can be carried in the blood through plasma.
Is the lymphatic system an open circulatory system?
Yes. Not all of the tissue fluid returns to the capillaries as some is taken up by these lacteals that drains into lymphatic vessels. The fluid in these is lymph. A major role of lymph is the carriage of lipids from the digestive system to the cells, particularly those of the liver.
