Exchange surfaces Flashcards
(102 cards)
Why do multicellular organisms need specialised exchange surfaces?
Diffusion doesn’t have a fast enough rate
Why does diffusion not work in multicellular organisms?
Small surface area to volume ratio, high metabolic rate, large distance between where the oxygen and carbon dioxide is and where it needs to be
Features of efficient exchange surfaces
Increased surface area, thin layer, good blood supply or ventilation to maintain gradient
Example of thing with increased surface area
Root hair cells
Example of thing with a thin layer
Alveoli
Example of thing with good blood supply/ventilation
Gills, alveoli
Components of the mammalian gaseous exchange system (Muscles etc)
Cartilage, ciliated epithelium, goblet cells, smooth muscle, elastic fibres
Parts of the mammalian gaseous exchange system
Nasal cavity, trachea, bronchus, bronchioles, alveoli
Important features of the nasal cavity
Large surface area, good blood supply which warms the blood to body temperature, hairy lining to secrete mucus to trap dust, moist surfaces which increase the humidity to reduce evaporation from the exchange surfaces
What does the trachea do?
Main airway carrying clean, warm and moist air from the nose down into the chest
Things in the trachea
Cartilage, ciliated epithelium
What does cartilage do in the trachea?
Stops the trachea from collapsing, incomplete rings to allow food to move down the oesophagus behind the trachea
What does the ciliated epithelium do in the trachea?
Goblet cells secrete mucus on the lining of the trachea to trap dust and microorganisms, cilia waft the mucus away from the lungs towards the throat
Things in the bronchi
Cartilage, ciliated epithelium
Things in the bronchioles
Smooth muscle, thin layer of flattened epithelium
What does the smooth muscle do in the bronchioles?
When the smooth muscle contracts, the bronchioles constrict. When it relaxes, the bronchioles dilate. This changes the amount of air reaching the lungs.
What does the thin layer of flattened epithelium do in the bronchioles?
Makes some gaseous exchange possible
What does the alveoli do?
Main gas exchange surfaces of the body
Adaptations of alveoli
200-300 micrometres, large surface area so high surface area to volume ratio, good blood supply, good ventilation, thin layers, lung surfactant
Features of the alveoli
Collagen, elastin fibres
What do the elastin fibres do in the alveoli?
Allow alveoli to expand when inhaling, can recoil to original size when exhaling, helps expel air
Role of lung surfactant
It makes it possible for the alveoli to remain inflated
Parts of the body involved in mammal ventilation
Rib cage, internal and external intercostal muscles, diaphragm
What moves air in and out f the lungs?
Pressure changes in the thorax due to breathing movements