Gas exchange in Humans
- Created by: Emily Cartwright
- Created on: 28-05-14 15:21
View mindmap
- Human Respiratory System
- Epiglottis
- Covers the opening to airways when food is being swallowed
- Trachea
- Strengthened by rings of cartilage to keep the airway open
- Rib and Intercostal Muscle
- Alter the size of the thoracic cavity to change volume/pressure
- Bronchioles
- Small passageway to alveoli
- Pleural Membranes
- Reduce friction
- Diaphragm
- Alters size of thoracic cavity to change volume/pressure
- Bronchus
- Carry air to and from each lung
- Alveoli
- Respiratory gas exchange surface
- The respiratory system has two functions;
- Ventilation
- The purpose of ventilation is to move gases over the gas exchange surfaces to maintain a concentration gradient between blood in the capillaries and air in the alveoli
- Mammals ventilate their lungs by negative pressure breathing, forcing air down into the lungs
- In order for air to enter the lungs, the pressure inside must be lower than the atmospheric pressure outside
- Mammals ventilate their lungs by negative pressure breathing, forcing air down into the lungs
- The purpose of ventilation is to move gases over the gas exchange surfaces to maintain a concentration gradient between blood in the capillaries and air in the alveoli
- Gaseous Exchange
- Gas exchange takes place in the alveoli
- Features and adaptations;
- Large surface area
- Millions of alveoli
- The extensive capillary network surrounding each alveolus
- Moist Surface
- Tissue fluid lining the alveolus allows gases to dissolve and diffuse across
- Short diffusion pathway
- The alveolar wall is a single layer of flattened epithelial cels
- The capillary wall is a single layer of flattened endothelial cells
- Maintenance of a steep concentration gradient
- Ventilation ensures the O2 concentration in the alveolus is high
- A dense capillary network and blood flow ensure that the oxygen concentration entering the alveolar capillaries is low
- Large surface area
- Ventilation
- Advantages of internal lungs;
- Infolding reduces heat loss
- Infolding reduces water loss
- Protected by ribcage
- Epiglottis
Comments
No comments have yet been made