1736890
Descripción
Fichas por Megan Vann, actualizado hace más de 1 año
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Creado por Megan Vann
hace casi 10 años
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| Pregunta | Respuesta |
| Why do multicellular organisms need specialised exchange surfaces? | 1)Small SA:V ratio 2) diffusion would not supply them with enough oxygen and nutrients to survive 3) high demand 4) often have transport system to compensate for this |
| why don't unicellular organisms need special exchange surfaces? | 1)gases, nutrients and wastes can be exchanged across the outer surface. 2) Their cells are surrounded by the environment in which they live where diffusion can happen enough to supply enough 02 and nutrients to survive. |
| What are the features of an efficient exchange surface? | 1) SA increases with folds in membrane 2) Thin barrier to reduce the diffusion distance 3) fresh supply of molecules on one side to keep a high conc gradient.(02) 4) removal of required molecules on the other side to keep the low conc gradient(C02) |
| What is an exchange surface? | It is a specialised area that is adapted to make it easier for molecules to cross from one side of the surface to the other. |
| give 3 examples of specialised exchange surfaces. | 1) The small intestines- for nutrients 2) The liver- blood sugar levels 3)root hair cells- minerals |
| What are the features of a efficient exchange surface? | 1) Large surface area 2) A barrier permeable to 02 and C02 3) Thin barrier to reduce diffusion distance 4) Maintaining diffusion gradient (fresh supply) |
| What are the features of a mammalian lung that adapt it to efficient gas exchange? | 1) Loads of alveoli create a large surface area. 2) The plasma membranes that surround the thin cytoplasm of the cells form the barrier to exchange. - A barrier permeable to oxygen and carbon dioxide. 3) Thin barrier to reduce diffusion distance 4) Maintaining diffusion gradient ( Higher conc of oxygen inside alveoli than in the blood and higher concentration of carbon dioxide inside the blood than in the alveoli) |
| How is a thin barrier in the lungs created? | 1) The alveolus and capillary walls are one cell thick. 2) both walls have flattened squamous cells. 3) capillary and alveolus walls are in close contact. 4) Very narrow capillary walls so red blood cells have to squeeze through making them closer to the air in the alveoli. 5) Total barrier of diffusion is only to flattened cells thick. |
| Outline the mechanism of inspiration. | Diaphragm contracts and moves down. Intercostal muscles contract and move rib cage upwards. Volume of thorax increases. Pressure of thorax decreases below atmospheric pressure. |
| Outline the mechanism of expiration. | Diaphragm relaxes and is pushed up by organs underneath. Intercostal muscles relax and ribs fall. Volume of thorax decreases. Pressure in thorax increases. |
| Where can cartilage be found? | In the wall of the trachea and bronchi and the LARGER bronchioles. |
| Where can ciliated epithelium be found? | The inner lining of the trachea and bronchi. |
| Where are goblet cells found? | Among the ciliated cells in the trachea and bronchi. |
| Where is smooth muscle and elastic fibres found? | on the inside surface of the cartilage in the trachea and bronchi. and most of the bronchiole wall is made of smooth muscle and elastic fibres. |
| What are the functions of cartilage? | Plays a structural role. Supports the trachea and bronchi, holding them open and prevents collapse during low pressure in inspiration. Allows some flexibility because is in incomplete C rings. Allows to move neck without restricting airways and allows the oesophagus to expand during swallowing. |
| What are the roles of smooth muscle? | Contract when harmful substances in the air try to enter the airways. Restrict the airways- reducing the size of the lumen to stop the harmful substances entering. Most obvious in the bronchioles to restrict the flow of air to and from the alveoli. |
| What is the roles of elastic fibres? | The smooth muscles can not reverse the effects of the narrowing of the lumen. When the airways constricts, it deforms the elastic fibres in the loose tissue. When the smooth muscles relax the elastic fibres recoil to their original shape, helping to dilate the lumen again. |
| What is the role of the goblet cells (glandular tissue)? | Under the epithelium and secrete mucus that trap tiny particulates to reduce the risk of infection. |
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