3.2 Gas exchange Flashcards
do fish have a small or large surface area to volume ratio
small
why can’t gases diffuse through fish skin
they have an impermeable membrane
how do blood and water flow in a fish
counter current system - opposite to eachother
what does the counter current system ensure
ensures that a steep concentration gradient is maintained so maximum amount of oxygen is diffusing into the deoxygenated blood from the water
what is ventilation required for
- maintaining a continuous unidirectional flow
process of ventilation in a fish
- fish opens its mouth by lowering the floor of the buccal cavity which enables water to flow in
- fish closes its mouth, causing buccal cavity floor to raise which increases pressure
- water is forced over gill filaments by the difference in pressure between mouth cavity and opercular cavity
- operculum acts as a valve and pump and lets water out and pumps it in
structure of the gills
- each gill is made of gill filaments (increase surface area)
- filaments are covered in lamellae
> lamellae have lots of a capillaries and a thin surface layer
what does the counter current system ensure
water with a high o2 concentration flows next to blood with a lower o2 concentration so concentration gradient is MAINTAINED ACROSS WHOLE GILL
insect gas exchange system
- have tracheae which air moves into through pores called spiracles
- oxygen moves down concentration gradient towards cells
- tracheae branch off into tracheoles
- ## o2 diffuses directly into respiring cells
how does co2 move out of spiracles in infests
moves down its own concentration gradient towards spiracles to be released into atmosphere
structure of an insect
have an exoskeleton with waxy coating that is impermeable to gasses with spirackes
What is Fick’s Law
what are the holes in leaves called
stomata
why does the large number of stomata mean
no cell is far away from a stomata so short diffusion pathway
pathway of air in human gas exchange
enters through the nose, along the trachea, bronchi and bronchioles, gas exchange takes place in alveoli
how are alveoli adapted for transport
- walls are thin (one cell thick) so short pathway + surrounded by one cell thick capillaries
- constant blood supply from capillaries means steep concentration gradient is maintained
- large number of alveoli so large surface area
process of inspiration
- EXTERNAL intercostal muscles CONTRACT , INTERNAL intercostal muscles RELAX
- ribs move upwards
- diaphragm contracts and flattens
- this causes volume inside thorax to increase, lowering pressure
- difference between lung pressure and atmospheric pressure creates a gradient so air is forced into lungs
process of expiration
- INTERNAL intercostal muscles CONTRACT, EXTERNAL intercostal muscles RELAX
- rib cage is lowered
- diaphragm relaxes and moves upwards
- this decreases volume in thorax which increases the pressure
- forces air out of the lungs due to the concentration gradient
what device is used to measure lung volume
spirometer
what is vital capacity
the maximum amount of air that can be inhaled or exhaled in a single breath
what is tidal volume
the volume of air we breathe in and out at rest
what is the breathing rate
number of breaths per minute
- can be calculated from spirometer using the number of peaks per minute
what is the residual volume
volume of air always present in lungs
what is the expiratory reserve volume
additional volume of air that can be exhaled on top of the tidal volume
