The Lungs
- Created by: Nicola Carter
- Created on: 14-12-12 09:32
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- The Lungs
- Air can pass into the lungs through the nose and along the trachea, bronchi and bronchioles
- All features adapted for their function in gas exchange
- Reach the alveoli, wall of the alveoli are the surface where the exchange of gases takes place
- All features adapted for their function in gas exchange
- Lungs are protected by they ribs
- Gas exchange in the lungs
- Gases can pass both ways through the thin alveoli walls
- Oxygen passes from the air in the alveoli to the blood in the capillaries
- Carbon dioxide passes from the blood to the alveoli
- Gases can pass both ways through the thin alveoli walls
- Adaptions for gas exchange
- Large surface area - provides more space for molecules to pass through, small alveoli but there **** so many creating the large surface area
- Barrier permeable to O2 and CO2 - the plasma membranes that surround the thin cytoplasm of the cell form the barrier exchange. These readily allwo diffusion of O2 and CO2
- Thin barrier to reduce diffusion distance:
- Alveolus wall is one cell thick
- Capillary wall is one cell thick
- Consist of squamous cells
- Capillaries are narrow so the RBC are squeezed against the capillary wall making them closer to alveoli
- Capillaries are in close contact with the alveolus wall
- Maintains the diffusion graident
- Requirments of airways:
- Must be large enough to allow sufficient air to flow without obstruction
- Strong enough to prevent collapsing when the air pressure is low.
- Must be flexible to allow movement
- Must be able to stretch and recoil
- Trachea and bronchi
- Have releatively thick walls, several layers of tissure
- Much of walls is made of cartilage in the form of C-rings
- Less regular in the bronchi
- Layer of 'loose tissue' - glandular tissue, connective tissue, elastic fibres, smooth muscle and blood vessels
- Inner lining is an epithelium layer that has two types of cell, cilia (ciliated epithelium) and among them are goblet cells
- Much of walls is made of cartilage in the form of C-rings
- Have releatively thick walls, several layers of tissure
- Bronchioles
- Narrower than the bronchi
- Larger bronchioles may have some cartilage, but somaller ones have no cartilage
- The wall is made mostly of smooth muscle and elatsic fibres
- The smallest bronchioles have clusters of alveoli at their ends
- Role of tissue
- Smooth muscle - can contract, constricting the airways
- Cartilage - structural role, supports trachea and bronchi holding them open prevents collapse when the air pressure is low during inhalation.
- Doesn't form a complete ring so there is flexibility in the airways
- Elastic fibres - as the smooth muscle relaxes the elastic fibres recoil to their original shape
- Goblet cells and glandular tissue - secrete mucus to trap tiny air particles
- Ciliated epithelium - Cilia move in a synchronized pattern to waft the mucus up the airway to the back of the throat
- Air can pass into the lungs through the nose and along the trachea, bronchi and bronchioles
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