Animal Gas Exchange Flashcards
Define diffusion
The movement of a substance down the concentration gradient
Describe and explain the mechanism that causes forced expiration.
- Contraction of internal intercostal muscles;
- Relaxation of diaphragm muscles / of external intercostal muscles;
- Causes decrease in volume of chest / thoracic cavity;
- Air pushed down pressure gradient.
Order of labeling mammalian gas exchange system
- Larynx
- Trachea
- Lung
- Bronchus
- Bronchioles
- Diaphragm
- Ribs and Intercostal muscles (if required)
Why is the mammalian gas exchange system efficient? (3 points)
1) Large SA
2) Short diffusion pathways
3) Large conc. gradient
Why are alveoli adapted for efficient exchange?
1) Cloud-like structure- high SA
2) Thin epithelium- short diffusion pathway
3) High concentration of CO2 in blood- faster difffusion rate
Describe how oxygen in the air reaches capillaries surrounding alveoli in the lungs. [5 point]
- Trachea and bronchi and bronchioles;
- Down pressure gradient;
- Down diffusion gradient;
- Across alveolar epithelium.
- Across capillary endothelium / epithelium.
List the steps in inspiration
- Internal intercostal muscles RELAX
- External intercostal muscles CONTRACT
- Ribs pulled up & out
- Diaphragm contracts (flattens)
- Vol. of thorax increases
- Press. of thorax decreases
List steps in expiration
- Internal ic muscles CONTRACT
- External ic muscles RELAX
- Ribs pulled back down and in
- Diaphragm relaxed ((dome shape)
- Vol. of thorax decreases
- Press. of thorax increases
What are the main features of an insect gas exchange system?
- large SA- extensive network of tracheoles which penetrate deep into tissues
- small bodies which enable gases to get in and out of tissues by diffusion , sometimes helped by rhythmical body movements
- thin, fluid filled tracheoles which allow gases to dissolve and diffuse into tissues efficiently
What is the function of a spiracle in a locust?
An opening in the exoskeleton that connects to the tracheal system
How do insects control the rate of their gas exchange?
- Respiration increases, conc. of lactic acid increases
- Sets up osmotic pressure, so fluid diffuses from tracheoles to tissues via osmosis
- Gas exchange happens faster, gases can diffuse through gaseous medium (residual air in tracheoles).
What is haemolymph?
Tissue where gases can diffuse from tracheoles into muscle cells.
Describe ‘counter-current flow’
- Blood flows opposite to direction of current
- Conc. gradient is maintained
- Oxygen diffuses across entire length of gill
- Simple current flow reaches equilibrium quicker
Explain the advantage to the fish of the change in its rate of ventilation s water temp changes.
- As concentration of oxygen falls less oxygen flows over gills
- Blood oxygen is lower;
- An increase in ventilation rate increases
- Maintains diffusion and conc. gradients in gills
- To maintain oxygen supply to cells
What features of a fish gill make gas exchange more efficient?
- Filaments have many lamellae which increase SA and contain capillary networks
- Lamellae also have thin epithelium- short diffusion pathway
- Operculum protects gill and opens to force water through gills (moisture)
