Module 3.1 Flashcards
Exchange surfaces
Why are specialised exchange surfaces needed
Smaller SA:V means diffusions distance is larger and would be too slow to sustain life also would not be able to diffuse enough to provide a sufficient supply to most cells
Higher metabolic activity means diffusion is not fast enough
single-celled organisms cytoplasm is close to the environment diffusion is enough
Features of an efficient exchange surface
Increased surface area
Thin layers for diffusion
Good blood supply/ventilation to maintain concentration gradient
Mechanism of ventilation in mammals - inhalation
Diaphragm contracts pushing downwards
External intercostal muscles contract
Ribcage moves upwards an outwards
Volume in the thoracic cavity increases
Pressure decreases
Air rushes into the lungs
Mechanism of ventilation in mammals - exhalation
Diaphragm relaxes pushing upwards
Internal intercostal muscles contract
Ribcage moves inwards and downwards
Volume of the thoracic cavity decreases
Pressure increases
Air is forced out of the lungs
What is vital capacity
Maximum volume of air that can be moved into the lungs in one breath
What is tidal volume
The volume of air moved in and out in each breath
Mechanism of ventilation in bony fish
Buccal cavities volume increases to increase water flow through the buccal cavities to the gills
Water flow over the gill filaments and gill lamellae (large surface area and good blood flow)
Gas exchange takes place
Role of the operculum
Protects the gill filaments and lamellae
What is counter current flow
Water flows over the gill lamellae in the opposite direction to the blood flow
Maintains the concentration gradient
Mechanism of ventilation in insects
Spiracles are little holes on the outside of the body
Air enters in the spiracle
Air moves through trachea and tracheoles
At the end of the tracheoles in tracheal fluid in which gas exchange occurs
exchange can also take place across the tracheole walls
thoracic and abdominal movement
Insects like locusts can alter the abdomen volume with breathing like movements
In some insects moving the wings alters the volume of the thorax to pull and push air in/out of the tracheal system
Tracheal fluid
When tissues are active the fluid can be withdrawn to increase the surface area of tracheole wall exposed to air
Distribution and function of tissues - trachea
Cartilage - c shaped rings to prevent collapse c shaped for flexibility and space for food in the oesophagus
Distribution and function of tissues - bronchi
Cartilage - c shaped rings to prevent collapse c shaped for flexibility and space for food in the oesophagus
goblet cell and ciliated epithelium
Smooth muscle
Elastic fibres
Narrower than trachea
Distribution and function of tissues - bronchioles
Narrower than bronchi
Much less cartilage
Mostly smooth muscle and elastic fibres
Goblet cells and ciliated epithelium
