Transport & Exchange Flashcards
What are exchange systems used for
For the transport of molecules from one area across a cell to a new area e.g. Alveoli
What do alveoli exchange
Oxygen and carbon dioxide
How are alveoli adapted and how do these adaptations help
Having moist linings (to help make diffusion better), thin walls (less distance for gases to travel), large network of capillaries and good blood flow (to increase the concentration gradient so diffusion can be quicker), large surface area (make diffusion and gas exchange happen quicker as there is more space for gases to exchange from)
What do most organisms need to take in to survive
Oxygen - from breathing in the air and glucose - from food we eat (for respiration). As well as this, other dissolved food molecules, water, minerals (for metabolism)
What does metabolism produce as waste products
Carbon dioxide (from respiration), urea (from the breakdown of amino acids), water. These are all excreted as they are toxic
Surface area to volume ratio
SA/V (how big a surface area is compared to its volume). There are no units or ratio signs
With small SA:Vol, rate of diffusion is… (so exchange organs have…)
Slower. Large SA:Vol ratio
What SA:Vol do small organisms have? What does this mean?
Large SA:Vol meaning substances such as oxygen can diffuse quickly across their surface
What SA:Vol do big organisms have? What does this mean?
Smaller SA:Vol so it can lose less heat. Diffusion across their surface would be too slow to supply enough oxygen for aerobic respiration in all their cells. Hence, they need exchange organs and transport systems to transport all the substances to the many cells
Composition of the blood
Plasma, rbc, white blood cells and platelets
Red blood cells/erythrocytes (structure and function)
Transport oxygen - haemoglobin binds oxygen to become oxyhaemoglobin
biconcave disc - large surface area to volume ratio for more oxygen to diffuse in per second
no nucleus - more space for haemoglobin to carry more oxygen
White blood cells - phagocytes structure and function)
Engulf (surround) and digest pathogens
White blood cells - lymphocytes (structure and function)
Make antibodies that stick to antigens on pathogens to destroy them
Platelets (structure and function)
Fragment of cells which make chemicals that help blood clot when cut (make scars and scabs to heal your cut and protect it from further infection)
Plasma (structure and function)
Straw coloured liquid part of the blood, carries rbc, wbc, platelets, dissolved glucose, carbon dioxide and hormones
