B3 exchange and transport

• the bronchioles and these structures are lined by ciliated epithelial cells which contain goblet cells and these cells help to maintain a concentration gradient and remove any pathogens from the air that flows through the bronchi and the bronchioles.
• Exchange surfaces in organisms are adapted to ensure that substances like oxygen and carbon dioxide can exchange across their surfaces as efficiently as possible.
• Small organisms like amoeba have a large surface area compared to their volume, allowing for efficient transport of substances and simple diffusion to meet their metabolic needs.
• Larger organisms have a smaller surface area compared to their volume, requiring adaptations to increase the efficiency of exchange across their surface.
• Fish, insects, and humans have adaptations such as gills, alveoli, and trachea respectively, to increase surface area and maintain a concentration gradient.
• To increase surface area, structures like root hair cells and folded membranes are used.
• Concentration gradients can be maintained through ventilation or a good blood supply.
• In fish, the counter current flow mechanism and the length of the diffusion pathway can be reduced by having only a single layer of cells, normally squamous epithelial cells.
• Oxyhemoglobin dissociation curve is a way to view the percentage saturation of hemoglobin with oxygen, shown against different partial pressures of oxygen.
• At high partial pressures of oxygen, hemoglobin is at about 100% saturation, fully loaded with oxygen.
• At low partial pressures of oxygen, hemoglobin has lower percentage saturations, indicating that oxygen is being unloaded.
• The changes in affinity of hemoglobin for oxygen are due to the hemoglobin changing shape when oxygen binds, causing further binding sites to become exposed.
• The bore effect is when high carbon dioxide concentration causes the oxyhemoglobin curve to shift to the right.
• The pH of the blood affects the oxyhemoglobin dissociation curve, with a decrease in pH causing the curve to shift to the right.
• Hemoglobin from different organisms, such as humans, llamas, and doves, have different affinities for oxygen, linked to their environments.
• Fetal hemoglobin, which is the hemoglobin that fetus has, has a curve that has shifted to the left, indicating that it is more saturated with oxygen even at the same partial pressure of oxygen.
• Llamas have a higher affinity for oxygen due to living at high altitudes.
• The hemoglobin of a dove has a lower affinity for oxygen, as indicated by the curve shifted to the right.
• The mammalian gas exchange system consists of the trachea, bronchium, bronchioles, and alveoli.
• The trachea, also known as the windpipe, is lined by ciliated epithelial cells which contain goblet cells and is supported by c-shaped rings of cartilage to ensure it stays permanently open.
• The trachea also has smooth muscle within its walls which can contract if there are any harmful substances within the air, resulting in the Lumen constricting and reducing the airflow to the lungs.
• When the smooth muscle relaxes, the Lumen dilates, and the stretch and recoil of the Lumen is possible because there are also elastic fibers within the tracheal walls.
• The bronchioles and alveoli have cartilage within their walls to provide structural support and keep the tubes open.
• The large surface area for gas exchange is provided by the large number of alveoli in both sets of lungs.
• The short diffusion distance is due to the walls of the alveoli and capillary walls being made up of a single layer of squamous epithelial cells.
• The concentration gradient is maintained because each alveolus is surrounded by a capillary network.
• Ventilation involves the diaphragm muscle and antagonistic interactions between the external and internal intercostal muscles, which change the volume of the thorax and maintain the concentration gradient in the alveoli.
• When you inhale, the diaphragm contracts, causing it to move down and become flatter, while the external intercostal muscles contract and the internal intercostal muscles relax, pulling the rib cage up and out, increasing the volume of the thorax.
• When you exhale, the diaphragm relaxes, causing it to dome upwards, while the external intercostal muscles relax and the internal intercostal muscles contract, pulling the rib cage inwards and down, reducing the volume of the thorax.
• The volume of air inhaled and exhaled can be measured using a spirometer, and this can be plotted on a graph to show normal respiration, forced respiration, and residual volume.
• Vital capacity is the maximum volume of air an individual can inhale and exhale during a deep breath.
• Tidal volume is the air inhaled and exhaled when at rest.
• Residual volume is the volume of air that always remains in the lungs, so the lungs don't ever fully empty and collapse inwards.
• Ventilation rates can be calculated by counting repeating patterns on a graph of breathing rates.
• Uptake of oxygen will increase when the ventilation rate increases, for example, during exercise.
• Fish face challenges in maintaining the concentration gradient due to less oxygen dissolved in water than is present in the atmosphere.
• The bronchi and bronchioles are neck structures that are part of the mammalian gas exchange system and are lined by ciliated epithelial cells which contain goblet cells, helping to maintain a concentration gradient and remove any pathogens from the air that flows through them.
• Tension in the water column of the xylem is caused by the continuous column of water being pulled upwards and the walls of the xylem inwards, making the walls of the xylem closer together and therefore the Lumen narrower.
• The transport of organic substances in photosynthesizing cells is known as the transport of organic substances produced in photosynthesis.
• Translocation is the transport of organic substances in plants, an active process that requires energy and involves the mass flow from the source to the sink.