Presentation on theme: "Exchange Systems F211. Explain, in terms of surface-area-to-volume ratio, why multicellular organisms need specialised exchange surfaces and single-celled."— Presentation transcript:
Exchange surfaces What do cells need to keep them alive? What do cells need to keep them alive? Oxygen for aerobic respiration Glucose for energy Proteins Fats to make membranes Minerals- to maintain water potential and help action
Exchange surfaces What waste do cells need to get rid of? What waste do cells need to get rid of? Carbon dioxide Oxygen Other wastes such as ammonia or urea which contain excess nitrogen
What makes an exchange surface efficient? FeatureHow it helps Large surface areaLarger area for molecules to diffuse Thin barrierShorter distance for diffusion Permeable membraneAllow molecules through Good supply/removal of molecules required Maintain diffusion gradient
Examples Small intestine Liver Lungs Root hairs Hyphae of fungi
Label as many parts as you can. Lungs and breathing
Label as many parts as you can. Lungs and breathing Larynx Trachea Right lung Left lung Left bronchus Right bronchus Bronchioles Intercostal Muscles Heart Alveoli Ribs Diaphragm Pleural cavity Pleural Membrane
The steep concentration gradient across the respiratory surface is maintained in two ways: 1) by blood flow on one side 2)by air flow on the other side. This means oxygen can always diffuse down its concentration gradient from the air to the blood, while at the same time carbon dioxide can diffuse down its concentration gradient from the blood to the air.
The flow of air in and out of the alveoli is called ventilation and has two stages: inspiration (or inhalation) and expiration (or exhalation). Lungs are not muscular and cannot ventilate themselves, but instead the whole thorax moves and changes size, due to the action of two sets of muscles: the intercostal muscles and the diaphragm.
Describe the stages of Inhalation and exhalation Must give reference to Diaphragm Intercostal muscles Volume of chest cavity pressure Exhalation is a passive process, We breathe out when our muscles relax
Breathing is a passive process InhalationExhalation Diaphragm Contracts, moving downwards increasing the volume of the chest cavity and displacing the organs beneath The diaphragm relaxes, the organs below move back into place The intercostal muscles contract moving the ribcage up and out The intercostal muscles relax, the ribcage moves down and in The volume of the chest cavity increases decreasing the pressure in the thorax below atmospheric pressure The volume of the chest cavity decreases causing air pressure in the lungs to increase above atmospheric pressure Air is sucked into the lungs as a result Air is forced out of the lungs as a result
Total Lung Capacity- The maximum amount of air that the lungs can hold Residual Volume- The volume of air that remains in the lungs after breathing approx 1.5dm 3 Vital Capacity- The maximum usable lung volume (total lung capacity minus the residual volume). The average vital capacity is dm 3 for men and for women. Tidal Volume- The volume of air that moves in and out of the lungs in each breath (during normal breathing). In a normal adult this is about 0.5 dm 3. Inspiratory Reserve Volume- The amount of air that the lungs will hold after a normal expiration (i.e. inspiratory reserve + tidal volume). Expiratory Reserve Volume- The amount of air remaining in the lungs after a normal quiet expiration (i.e. expiratory reserve volume + residual volume).
Exam questions..\cells and enzymes\Spirometer traces.rtf