3.1.1 Exchange Surfaces Flashcards
What is the surface area?
The amount of tissue of an organism in contact with the environment
Why is diffusion efficient for unicellular organisms?
- due to their metabolic rate being slower
- they have a large surface area to volume ratio
- short diffusion distance
Why is diffusion not suitable for multicellular organisms?
Due to have a small surface area to volume ratio, they rely on specialised adaptations for gas exchange, to receive nutrients and excrete waste
What is mass flow?
movement of large volumes of substances within a transport system
Why do mammals rely on an adapted respiratory system?
Large volume of cells
high metabolic rate
they require a lot of oxygen
and a quick removal of co2 as when combined with water decreases bodys pH
How is the nasal cavity adapted?
Large surface area with a good blood supply ( so this warms the air that is inhaled so it is the same temperature of the body before it reaches the lungs)
Hairy lining with mucus
moist surface to increase humidity to reduce evaporation
How is the trachea adapted?
Make of incomplete rings of cartilage which prevents it from collapsing
the lining made up of epithelium cells and goblet cells which produce mucus
how are the bronchioles adapted?
no cartilage just smooth muscle
with thin flattened epithelium cells
How are the alveoli adapted?
made of thin flattened epithelium cells which contained collagen and elastic fibres (allowing the alveoli to expand with air)
large suface area
rich blood supply
good ventilation
The linings are made up of surfactant water and salts this keeps the alveoli inflated and reduces water evaporation
define the tidal volume?
the volume of air that moves in and out of the lung at resting breath
define the inspiratory volume
is the maximum volume of air that you breath in above normal inhalation
define the expiratory reserve volume
is the extra amount of air you can force out of your lungs over the normal tidal volume of air you breathe out
vital capacity definition
the volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest possible intake of breath
Define Residual volume
the volume of air that is left in your lungs when you have exhaled as a hard as possible
what is the calculation for ventilation rate?
ventilation rate = tidal volume x breathing rate
define peak flow
measurement for the rate at which air is expelled from the lungs
When a woman was exercising her breaths per minute increased her ventilation rate did not. Why?
the breaths become very short which decreases tidal volume, but will maintain at a short and rapid pace due to when the ventilation rate increases so does oxygen uptake.
Explain the process of inspiration and the changes that occur throughout the thorax
external intercostal muscles contract this pulls the ribs up and out
Diagraphm contracts and flattens
Volume of the thorax increases
air pressure outside the lungs is therefore higher than the air pressure inside so air moves in to rebalance
Explain the process of expiration and the changes that occur in the thorax
External muscles relax
Diaphragm relaxes and comes outwards
volume of thorax decreases
The air pressure outside of the lungs is lower
so air will rush out of the thorax
Name and describe the two features of a fish’s transport system
Gills- supported by gill arches which gill filaments stacked up in piles
The end of gills are connected to make the water flow over the gills for longer
Lamellae - To give the gill filaments more surface area
and make a counter current exchange system
explain the process of gas exchange in a fish
Buccal cavity volume increases when the fish opens its mouth
water is pumped over the lamellae by the operculum and oxygen will diffuses into the blood stream
waste carbon dioxide diffuses into the water and flows back out of the gills
Name and describe the 3 main features of an insects gas transport systems
spiracles= holes on the body’s surface which can be opened and closed by sphincters for gas exchnage or water
Tracheae = large tubes extending all throughout the body tissues made up of chitin
Tracheoles= smaller branches will tracheal fluid.
Explain the process of gas exchange in insects.
Gases move in through the spiracles
a diffusion gradient allows oxygen to diffuse into the muscle tissue,while co2 diffuses out
contraction of the abdomen and the trachea allows mass movement (ventilation) of air in and out
How do insects ventilate themselves?
Pumping of the abdomen draws air in and out of the tracheae
so when air enters through the spiracle will enter the muscle tissue faster
How do insects limit water loss when spiracles are open?
closing spiracles minimises water loss
Hairs around the spiracle trap humid air
Bigger insects - have air sacs along the tracheae to store oxygen when the spiracles are closed
describe the 3 states of the spiracles
open - removes co2 and lets o2 enter through
closed- co2 is dissolved in bodily fluid waiting to be diffused out (to maintain insect pH)
fluttering- moves/retreat O2 and minimises water loss
Explain how the structure of the gas exchange system of a bony fish maximises the amount of oxygen that can be taken from water.
Tips of gills are stuck together this makes water flow over the gills for longer, so more gas exchange can occur
The flow of the water and the oxygen is counter current to maintain concentration gradient
Also has secondary filaments called lamella to further increase surface area
Good blood supply to maintain concentration gradient
Thin layers to allow for rapid gas exchange
How does ventilation occur in larger insects?
Their tracheoles will contain collapsible air sacs
mechanical ventilation through the thoracic cavity and stomach movements which causes body volumes changes
Leading to a pressure change in the tracheoles for more oxygen to be diffused into the muscle tissue
Why do multicellular organisms require transport systems?
Large size (they have a small surface area to volume ratio) and a larger diffusion distance
so demand for oxygen is high , so need a specialised system to ensure supply for cells
