Exchange and transport
- Created by: Freja
- Created on: 08-04-21 21:50
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- Water vs Gas Exchange
- Land animals face a constant battle between ventilation and gas exchange and retaining water
- Gas exchange surfaces are moist to aid diffusion by oxygen dissolving
- Ventilation causes water to readily evaporate
- The gas exchange system is adapted to efficiently exchange gas without loosing too much water
- Mammalian Gaseous Exchange System
- Structures
- Elastic Fibres
- Stretch when inhaling and recoil when exhaling
- Controlling the flow of air
- Stretch when inhaling and recoil when exhaling
- Smooth Muscle
- Their ability to contract enables them to play a role in constricting the airway
- Thus controls its diameter and so controls the flow of air to and from the alveoli
- Their ability to contract enables them to play a role in constricting the airway
- Goblet Cells
- Involved in mucus secretion to trap bacteria and dust to reduce the risk of infection with the help of lysozyme which traps bacteria
- Cells present in the trachea, bronchi and bronchioles
- Involved in mucus secretion to trap bacteria and dust to reduce the risk of infection with the help of lysozyme which traps bacteria
- Ciliated Epithelium
- It is involved in moving mucus along to prevent lung infection, by moving it towards the throat
- Cartilage
- Plays an important role in preventing the lungs from collapsing in the event of pressure drop during exhalation
- Involved in supporting the trachea and bronchi
- Plays an important role in preventing the lungs from collapsing in the event of pressure drop during exhalation
- Elastic Fibres
- Lungs and Gas Exchange
- Nasal Cavity
- Has a large surface area and good blood supply, which warms the air as it passes through the body
- It has a hairy lining that traps dust and bacteria in mucus and prevents them from reaching the lungs, which could cause infection
- It has moist surfaces, which increases the humidity of the incoming air, to reduce the evaporation of water in the lungs
- Trachea
- Contains goblet cells, which trap micro-organisms and debris to keep the airways clear
- The pipe is supported by a layer of cartilage that holds the trachea open and prevents it from collapsing
- The rings are incomplete to allow it to bend when food is swallowed down the oesophogus
- Bronchus
- Thee bronchus are extensions of the trachea that split into two
- For the left and right lung
- Has a similar structure to the trachea but smaller cartilage rings to hold the pipe open
- Thee bronchus are extensions of the trachea that split into two
- Bronchioles
- The bronchus splits into much smaller bronchioles
- Are 1mm or less in diameter
- Does not contain cartilage and is instead held open by smooth muscle
- They are lined with a thin layer of epithelial tissue, making some gas exchange possible
- When the smooth muscle contracts the bronchioles contract and this is dependent on air flow
- Alveoli
- Little air sacs, where most of the gas exchange occurs
- About 200-300um in diameter
- Made up of a thin layer of flattened epithelial cells, as well as collagen and elastic fibres
- The elastic fibres recoil, which helps air move out
- Pleural Membrane
- The space in between is called the pleural cavity and is filled with a small amount of pleural fluid
- Pleural fluid lubricates the lungs
- It also adheres to the outer walls of the lungs to the thoracic cavity by water cohesion, so the lungs expand with the chest while breathing
- Nasal Cavity
- Structures
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