Ventilation- In Mammals And Fish And Insects Flashcards
What are the 2 things ventilation consists of?
- inspiration= breathing in
- exhalation= breathing out
Explain the process of inspiration
- external intercostal and diaphragm muscle contract
- this causes the ribcage to move upwards and outwards and the diaphragm to flatten, increasing the volume of the thorax
- as volume of thorax increases, lung pressure decreases to below atmospheric pressure, creating a pressure gradient to which air flows into the lungs
- this is an active processes which requires energy
Explain the process of expiration
- external intercostal and diaphragm muscles relax
- ribcage moves downwards and inwards, and the diaphragm becomes curved again
- thorax volume decreases, causing the air pressure to increase to above atmospheric pressure, creating a pressure gradient to which air is forced out of the lungs
- normal expiration is a passive process
What’s 1 main difference between expiration and inspiration?
Expiration can be forced (for e.g blowing out candles). During forced expiration, the internal intercostal muscles contract to pull the ribcage down and in
What is vital capacity?
Maximum volume of air that can be breathed in/out in one breath
What is tidal volume?
Volume of air that is breathed in/out during a normal breath (at rest)
What is your breathing rate?
Number of breaths taken in one minute (one breath= taking air in and breathing it back out again)
What is oxygen uptake?
Volume of oxygen used up by someone in a given time
What is a spirometer?
A machine that can give readings of tidal volume, vital capacity, breathing rate and oxygen uptake
Describe how a spirometer works.
- has an oxygen filled chamber with a moveable lid
- the person breaths through a mouth piece connected to the oxygen chamber
- as person breathes in and out, the lid of the chamber moves up and down
- these movements are recorded by a pen attached to the lid of the chamber-it writes on a rotating drum creating a spirometer trace
- the soda lime in the tube the person breathes in and out of absorbs carbon dioxide
Why does the total volume of gas in the chamber decrease over time?
-air breathed out is mix of oxygen and carbon dioxide, and carbon dioxide is absorbed by the soda lime so there’s only oxygen in the chamber the subject breathes from. Decreasing total volume
Explain how gas exchange works in a fish, and explain the importance of them using a counter current system.
- water containing oxygen enters the fish through its mouth (buccal cavity) and passes out through its gills.
- blood flows through the gill plates in one direction through its capillary network, and water flows over in the opposite direction, creating a counter current system.
- this maintains a constant large concentration gradient between the water and the blood, as oxygen concentration is always higher in water then in blood
- this is because the water with some oxygen in has a higher concentration then the blood returning from the fishes body, and the freshest water still has higher oxygen concentration then the blood with some oxygen, allowing diffusion
- this process maximises the efficiency of gas exchange
Explain the adaptations of fish gills
- each gill made of lots of thin branches called gill filaments= increase surface area
- each filament is covered in lots of tiny structures called lamellae= further increases surface area
- each gill is supported by a gill arch
- gill plates have lots of blood capillaries and thin surface layer to speed up diffusion
How are fish gills ventilated in bony fish?
1) fish opens mouth which lowers floor of buccal cavity (space inside mouth). Volume of buccal cavity increases, decreasing pressure inside cavity. Water is then sucked in to the cavity
2) when fish closes its mouth, floor of buccal cavity is raised again, decreasing volume but increasing pressure, and water is forced out of buccal cavity through gill filaments
3) each gill is covered by a bony flap which protects the gill (operculum). The increase in pressure forces the operculum on each side of head to open, allowing water to leave the gills
Explain how insects gas exchange system work.
- Insects have microscopic air-filled pipes (trachea) which they use for gas exchange
- Air moves into the trachea through pores on the insects surface (spiracles)
- Oxygen travels down the concentration gradient towards the cells, and carbon dioxide moves from the cells down its own concentration gradient towards the spiracles to be released
- Trachea branch off into smaller tracheoles which have a thin, permeable wall and go to individual cells. They also contain fluid, which oxygen dissolves in
- The oxygen then diffuses from the fluid into body cells, and carbon dioxide diffuses in the opposite direction
- Insects use rhythmic abdominal movements to change the volume of their bodies and move air in and out of the spiracles. When larger insects are flying they use their wings to pump their thoraxes too.
