Exchange surfaces and breathing Flashcards
SA and V
- organisms exchange material with surroundings
- amount of material is proportional to volume
- amount of material its able to exchange is proportional to SA
why do some organisms need specialised exchange surfaces?
they are multicellular, have a small SA:V ratio and a high metabolic activity
SA definition
amount of tissue in contact with the environment
SA and V of a sphere
SA - 4πr^2
V - 4/3πr^3
features of specialised exchange surfaces
- large SA=overcomes limitations of SA:V in large organisms eg. villi and root hair cells
- thin layers=shortens diffusion distance eg. alveoli
- good blood supply/ventilation=maintans a (steep) conc. gradient for faster diffusion
mass flow definition
movement of large volumes of substance within the transport system
adaptations of the respiratory system in mammals
nasal cavity
- large SA with rich blood supply=keeps blood warm
- hairy lining with mucus (traps bacteria)
- moist surface (↑humidity=↓evaporation=air coming out of lungs loses less moisture)
trachea
- has incomplete rings of cartilage (prevents collapse+eases food passage)
- smooth muscle=contract/relax to constrict/dilate the airway and change airflow
- elastic tissue contains elastic fibres with elastin=allows stretching and recoiling
- ciliated epithelium=wafts mucus backwards towards stomach
goblet cells=secret mucus
bronchi
- reinforced with cartilage to keep the airway open
- smooth muscle can contract/relax to constrict/dilate the airway and change airflow.
- elastic tissue contains elastic fibres with elastin=allow stretching and recoiling
- lined with ciliated epithelial cells and goblet cells
bronchioles
- no cartilage=can change shape
- smooth muscle can contract/relax to constrict/dilate the airway change airflow
- elastic tissue contains elastic fibres with elastin=allow stretching+recoiling
alveoli
- one layer of epithelial cells=short diffusion pathway=rapid diffusion
- large SA=up rate of gas exchange
- partially permeable=only certain gases can diffuse across
- surrounded by dense network of capillaries=good blood supply=maintains conc. gradient
- ventilation=maintains steep diffusion gradient
- elastic fibres=stretching+recoiling
- collagen fibres=prevent alveoli from bursting+limits overstretching
- moist inner surface=gases can dissolve
- lung surfactant helps alveoli remain inflated
ventilation definition
movement of air in and out of lungs
ventilation in mammals
inspiration
- uses energy
- diaphragm contracts, flattens and lowers
- external int. contract - ribs up+out, internal int. relax
- ↑thoracic volume
- inside pressure<atmospheric=air enters
expiration
- x energy used
- diaphragm returns to og position
- external int. relax and internal int. contract - ribs in+down
- ↓thoracic volume
- inside pressure>atmospheric=air comes out
vital capacity definition
the maximum volume of air that can be breathed in or out in one breath
tidal volume definition
this is the volume of air that is breathed in or out during normal breathing (at rest)
inspiratory reserve volume definition
the amount of air a person can inhale forcefully after normal tidal volume inspiration
expiratory reserve volume definition
the amount of air a person can exhale forcefully after a normal exhalation
residual volume definition
the volume of air left in the lungs after as much air has been breathed out as possible
total lung capacity definition
the sum of the vital capacity and residual volume
breathing rate definition
the number of breaths taken in one minute (one breath = taking air in and breathing it back out again)
oxygen uptake
how much oxygen used by someone in a given time
vent. rate definition
the amount of air that moves in and out of the lungs per minute
vent. rate equation
vent rate=tidal vol x breathing rate
characteristics of insects
- exoskeleton
- open circulatory system (body fluid acts as bld & tissue fluid)
- active living
- no bld. pigment (Hb) to carry O2
how do insects breathe?
- air enters through spiracles (small in abdomen/thorax)=allow O2 to travel tracheae=narrow into trachieoles which have fluid over them
why is there fluid over the trachieloe?
- up lactic acid when insect’s active=down water potential=tracheal fluid moves into insect’s body by osmosis=exposes large SA for gas exchange
structure of insect’s ventilation system
- spiracles along abdomen+thorax allow air+water to enter
may have sphincters. - when they’re inactive: low O2 demand = spiracles closed
(opposite when CO2 builds up) - Spiracles lead to tracheae (widest) which carry air to body lined by chitin= keeps them open but impermeable to gases= X gas exchange
- Tracheae lead to tracheoles (elongated cell x chitin) throughout body tissues=allow gas exchange by diffusion
- At end of tracheoles = tracheal fluid limits air penetration