Transport In Animals Flashcards
Need for specialised exchange surfaces
- metabolic activity is higher than single felled organisms
- distance between the cells and where oxygen is needed and the supply of oxygen is too far for effective diffusion
Sa:Vol ratio is too small for efficient gas exchange
Specialised exchange surfaces properties
- increased sa
- thin layers - quick diffusion
- good blood supply
- ventilation to maintain diffusion gradient
Human gaseous exchange system
Nasal cavity
Trachea
Bronchus
Bronchioles
Alveoli
Nasal cavity
Good blood supply warms air to body temp
Hairy mucus lined to trap bacteria
Moist reduces evaporation
Trachea
Wide tube of C shaped cartilage (incomplete for food to move)
Goblet cells secrete mucus trapping dust/unwanted shit
Ciliated Epithelium- waft away mucus and dust etc from lungs
Bronchus
Trachea divides to form bronchi
Similar structure to trachea but smaller
Bronchioles
No cartilage
Walls contain smooth muscle which constricts and dilated controlling air flow
Thin flattened epithelium where some exchange can occur
Alveoli
Tiny air sacs where main exchange occurs
Contain flattened epithelial cells with some collagen and elastic fibres to allow elastic recoil depending on air drawn in/out
Alveoli adaptations
- large sa :vol ratio
- thin layers
-good blood supply - good ventilation- breathing in and out
- lung surfactant makes it possible for alveoli to remain inflated
Inspiration
-diaphragm contracts flattens and lowers
- ex intercostal muscles contract - ribs up and out
- thorax pressure reduced lower pressure
Expiration
Diaphragm relax
Ex intercostal muscles relax ribs down+ in
Alveoli elastic fibres relax
Thorax pressure increase moves air out
Forced- in intercostal muscles contract forcing diaphragm up
Measuring lung capacity
Peak flow meter
Spirometer
Vilatographs
Tidal vol
Vol air and out resting
Vital capacity
Vol air strongest inhale and exhale
Inspiratory and expiratory reserve
Max ins/exp reserve- tidal
Residual volume
Air left in lungs after strongest exhalation
Ventilation rate
Tidal vol x breathing rate
Why do insects have an exchange system
Have a tough exoskeleton so no exchange occurs on surface so require specialised exchange system
Spiracles
Air enter and leaves
Water is also lost here
Minimised by sphincters
Located in thorax and abdomen
Tracheae
Largest tubes
Leading away from spiracles
Lined w chitin - impermeable and strong
Lead to tracheoles
Tracheoles
No chitin so permeable for gas exchange
Tracheol fluid at ends of tracheoles which limits diffusion
V large sa
Tracheal fluid
Seeps into tracheoles at rest
Muscles draw up fluid when active
Lowers pressure in tracheoles and incr sa for direct gas exchange
Larger insect adaptations
Pump using thorax / abdomen incr decr pressure forcing air in and out
Air sac reserves