C7- Exchange surfaces and Breathing Flashcards
2 reasons why simple diffusion alone is enough to supply the needs of a single celled organism
The metabolic activity of a single celled organism is usually low, so oxygen demands and CO2 production of the cell are usually low
The surface area to volume ratio of the organism is large
4 common features of specialised exchange surfaces
Increased surface area
Thin layers
Good blood supply
Ventilation to maintain diffusion gradient
Why do specialised exchange surfaces have an increased surface area?
Provides area needed for exchanges
Overcome limitations provided by lowered SA:V in larger organisms
Why do specialised exchange surfaces have thin layers
Shortens the diffusion pathway
This makes the process fast and efficient
Why do specialised exchanged surfaces have a good blood supply and ventialtion
Maintains concentration gradient for diffusion
Makes the process of exchange more efficient
Adaptations of the nasal cavity
Moist – reduces evaporation from
exchange surfaces
Good blood supply – warms the air
Hairs – traps bacteria and dust
Mucus – traps bacteria and dust
Adaptations of the trachea
Carries warm moist air
- Greater kinetic energy of particles in air then increases rate of diffusion
C-shaped rings of cartilage
– prevents collapse
Lined with:
Ciliated epithelial cells
Goblet cells
Adaptations of Bronchus
Rings of cartilage in the walls of the bronchi provide support
It is strong but flexible
It stops the trachea and bronchi collapsing when pressure drops
Adaptations of bronchioles
Small (1mm)
No cartilage
Thin layer of epithelial cells – some
gaseous exchange
Walls contain smooth muscle so can
constrict and dilate
Adaptations of alveoli
Good ventilation- Oxygen and carbon dioxide are moved efficiently into and out of the alveoli so that concentration gradients are maintained
Thin layers –single cell thick Less distance for oxygen to diffuse across
Large surface area- Greater efficiency of diffusion
Good blood supply –Takes oxygen away quickly so maintains a high concentration gradient
Ventilation
definition
Breathing
where air is constantly moving in and out of the lungs
Inspiration
Inhalation
occurs when air pressure in the atmosphere is greater than that of the lungs
forcing air into the alveoli
Expiration
exhalation
occurs when air pressure in the lungs is greater than the air pressure in the atmosphere
Forcing air out of the alveoli
2 sets of muscles involved in ventialltion
Diaphragm
Intercostal muscles
2 types of intercostal muscles
effects of contraction
internal = contraction leads to expiration
external= contraction leads to inspiration
antagonistic pair of muscles
definition
One muscle of the pair contracts to move the body part, the other muscle in the pair then contracts to return the body part back to the original position
Boyles law
P1V1= P2V2
Decreasing volume increases collisions, increasing pressure
Inspiration process
External intercostal muscles contract, internal relax
diaphragm contracts
Air pressure in thorax decreases
lung volume increases
air moves in
Expiration process
Internal intercostal muscles contract, external relax
Diaphragm relaxes
Air pressure in thorax increases
Lung volume decreases
Air moves out
Adaptation of gills
Large surface area
Gill filaments overlap – so resist water
flow (slows water down for more
efficient oxygen uptake)
Counter-current exchange – allows 80%
of oxygen to be taken up (cartilaginous
fish have a parallel system which only
allows 50% uptake)
Fish gills
Operculum
Skin flap over the gills
Protects gills
Directs flow of water
Fish Gills
Counter current system
Water flows against the direction of blood
Means there is always a concentration gradient
Blood can be more oxygenated at the gills than parallel system
The water with the lowest oxygen concentration is found adjacent to the most deoxygenated blood
Why will fish die if left for a long time out of the water
In air gill filaments all stick together
SA for gas exchange is greatly reduced and so fish dies from lack of oxygen
Structure of gills in fish
Series of gills on each side of the head
Each gill arch is attached to two stacks of filaments
On the surface of each filament, there are rows of lamellae
The lamellae surface consists of a single layer of flattened cells that cover a vast network of capillaries
Ventilation mechanism in fish
Inspiration of water
The ventilation mechanism in fish constantly pushes water over the surface of the gills and ensures they are constantly supplied with water rich in oxygen (maintaining the concentration gradient)
When the fish open their mouth they lower the floor of the buccal cavity. This causes the volume inside the buccal cavity to increase, which causes a decrease in pressure within the cavity
The pressure is higher outside the mouth of the fish and so water flows into the buccal cavity
Ventilation mechanism in fish
expiration of water
The fish then raises the floor of the buccal cavity to close its mouth, increasing the pressure within the buccal cavity
Water flows from the buccal cavity (high pressure) into the gill cavity (low pressure)
As water enters pressure begins to build up in the gill cavity and causes the operculum (a flap of tissue covering the gills) to be forced open and water to exit the fish
The operculum is pulled shut when the floor of the buccal cavity is lowered at the start of the next cycle
Function of gill rakers in fish
Gill rakers’ primary function is to guard the fragile respiratory surfaces of the gill filaments from potential damage by particulates within the water taken into the buccal cavity during respiration
Gas exchange in insects
spiracles
There are tiny holes called spiracles along the side of the insect.
The spiracles are the openings of larger tubes called tracheae.
The spiracles allow oxygen to diffuse in and carbon dioxide to diffuse out of the tracheae.
Gas exchange in insects
tracheae and tracheoles
The spiracles are the openings of larger tubes called tracheae.
The finest branches of the tubes are called tracheoles, these extend to the surface of nearly every cell
At the cell surface gas is exchanged by diffusion across the moist epithelium that lines the terminal ends of the tracheal system.
Gas exchange in insects
Mechanism of tracheal fluid
when oxygen demand build up, lactic acid concentrations increase in the tissues
Water moves out of tracheoles to the tissues by osmosis
Exposing more surface area for gas exchange
Extra adaptations for gas exchange in large insects
Mechanical ventilation of the tracheal system
–> air is mechanically pumped in by muscles in abdomen and thorax,
creates volume and pressure changes forcing air in and out
collapsible trachea which act as air reservoirs
–> increase volume of air moved through the gas exchange system
ventilation rate
tidal volume x breathes per minute
Methods to test capacity of lungs
3
peak flow meter
vitalograph
spirometer
Tidal volume
volume of air that moves in and out of lungs with each resting breath
Vital capacity
volume of air that can be breathed in with largest possible exhalation followed by largest possible inhalation
residual volume
volume of air left in lungs after you have exhaled as hard as possible
inspiratory and expiratory reserve volumes
maximum volume of air you can breathe in or out over and above normal inhalation or exhalation
total lung capacity
sum of vital capacity and residual volume
What is insect exoskeleton made out of
Chitin
Spirometer
measure lung volume and breathing pattern
Peak flow meter and vitalograph
peak flow meter- rate of expulsion of air form lungs
fastest rate of air flow from lungs–> indication of lung
function
vitalograph- digital peak flow
Why is inhalation an active process but exhalation passive
for inhalation diaphragm contracts
requires, ATP / energy
for exhalation elastic recoil of lungs;
