gas exchange Flashcards
(23 cards)
what are the components of an insects tracheal system
spiracles
trachea
tracheoles
what are spiracles
round valve like openings that run along the lenght of the abdomen
what is the function of the spiracles
they open and close to allow gases such as oxygen and carbon dioxide into and out of the body, as well as have little hairs to further reduce water loss
explain the structure of the trachea
lined with rings of chitin that reinforce the trachea to keep them open and prevent collapsing, providing spaces so filled with air, fast diffusion takes place
explain the function of tracheoles
smaller tubes which extend through all tissues in the insect to deliver oxygen to respiring cells. the tracheal fluid is important in maintaining water potential in the cells and creating air pressure so air moves down into tracheoles
how does diffusion occur in insects
in respiring tissues the release of CO2 and use of O2 creates a gradient. O2 moves into the trachea down the gradient and CO2 moves out along the gradient
How does mass transport occur in insects
As the muscles in their abdomen contracts the spaces inside the tracheae and tracheoles squeezes. This decreases volume and increases pressure, forcing gas out of the insects body
Explain how the movement of fluid at the end of the tracheoles is a method of gas exchange
During flight cells begin to respire anaerobically due to lack of oxygen, producing lactate in the cells which lowers the cells water potential. The fluid in the tracheoles moves down a water potential gradient by osmosis into the cells. This loss of water reduces the pressure of tracheoles drawing air in.
Why is gas exchange essential in insects
Oxygen is essential for respiration
Carbon dioxide changes the acidity of tracheal fluid if dissolved
What are issues with the tracheal system
Water can be lost as spiracles open resulting in dehydration
Mostly relies on the passive movement of gases along their concentration gradient
Diffusion pathway must be short (why insects are small)
How do insects and the tracheal system reduce water loss
Small surface area to volume ratio reducing the area from which water could evaporate
Waterproofing the chitin exoskeleton with a waterproof cuticle
Voluntary closing of the spiracles
What do fish use energy from respiration for
Catabolism
Anabolism
Movement
Explain the inhalation of water in fish
Floor of mouth is lowered as operculum is shut, and water enters buchal cavity due to increased volume and decreased pressure. Operculum opens and floor of mouth is raised, water is forced out of buchal cavity due to decreased volume and increased pressure.
Explain the full structure of the gills
Consist of branches called gill filaments which branch off of a gill bar (held open by water pressure), filaments contain blood vessels which branch into capillaries in the lamellae for gas exchange. At right angles to gill filaments are gill lamellae, which are one cell thick and increase the surface area of gills.
Explain the principle of counter current flow
Water flows in opposite direction to the flow of blood so water with high oxygen concentrations always meets blood with slightly lower oxygen concentrations. Therefore diffusion gradient is maintained along the length of the lamellae
explain the adaptations of a dicotyledonous leaf
-The waxy cuticle is transparent allowing blue/red light to pass through to the palisade mesophyll
-Lots of chloroplasts in the palisade mesophyll, with tightly packed palisade cells to trap sunlight
-Spongy mesophyll has high surface area due to air spaces allowing rapid diffusion
-Many stomata on underside of leaf to reduce transpiration rate and water loss
-Cells are not far from external air
how do the stomata open
-Guard cells have phototropin channels that detect light stimuli and allow K+ ions to flow into the cytoplasm of the cell
-This increases concentration gradient and decreases water potential, causing water to move by osmosis into cells
-This makes cells turgid, and open stomata
how to work out the surface area of a leaf
draw around leaf on both sides on graph paper and count the squares
what do adaptations of a xerophytic plant aim to do
-Reduce water potential gradient
-Slower diffusion
-Less water loss from air spaces
-Reduced evaporation of water
what are the adaptations of a xerophytic plant
-Thick waterproof cuticle to reduce water loss
-Rolled leaves create an area for evaporated water to accumulate, creating high water potential, reducing the movement of water out of the leaf via transpiration
-Hairy leaves trap a layer of air and water molecules arounf the leaf creating a shallower water potential gradient reducing water loss
Why do we need lungs
We have a small surface area to volume ratio and long diffusion pathway so lungs allow substances to get to the inner cells of the body
We have a high rate of respiration and therefore metabolism so need mass amounts of oxygen for aerobic respiration
Explain the structure of the lungs
Air enters through the mouth into the trachea (an open tube supported by rings of c shaped cartilage, and lined with ciliated epithelial cells and goblet cells)
The trachea divides into bronchi, each bronchus goes to each lung
Each bronchus divides into bronchioles (surrounded by smooth muscle which contracts and relaxes to control the flow of air in the alveoli)
At the end of the bronchioles are the alveoli where gas exchange occurs (surrounded by elastic fibres to assist with recall and have a lining of a single cell thick)
