Exchange and Breathing Flashcards
(21 cards)
Why does multi-cellular need specialised exchange surface?
- Small SA: Vol ratio
- High metabolic rate
- Long diffusion distance
- Large organism cannot rely on simple diffusion
What are the general properties of an effective exchange surface?
- Large surface area - increase SA: Vol ratio
- Thin layer - Short diffusion distance
- Good blood supply - maintain conc gradient
- Good ventilation (gas) - maintain diffusion gradient
Describe the pathway of air movement in human gaseous exchange system?
- Nasal cavity
- trachea
- bronchus
- bronchioles
- alveoli
What is the key features of nasal cavity?
- A large surface area with good blood supply, which warms the air to body temperature
- A hairy lining, which secret mucus to traps bacteria and dust, protecting delicate lung tisse from irritation and infection
- Moist surfaces, which increase the humidity of the incoming air,reducing evaporation from the exchange surface
What are the features of trachea?
C-shape cartilage - prevent trachea from collapsing
Ciliated epithelium - move mucus away from the lung (cough out or digest in the stomach)
globlet cells - secret mucus to trap dust and bacteria
What are the features of bronchus?
Similar to trachea but smaller
There are two, each leading to a different lung
What are the features of bronchioles?
Contains smooth muscle which contracts and relaxes to change the amount of air that reaches lungs
Lined with epithelium to make gas exchange possible
What are the features of alveoli?
Elastic tissues – allow alveoli to stretch (to allow air in) and recoil (to squeeze out air)
Inner surface of alveoli is covered with a layer of water, salts and lung surfactant (keeps alveoli inflated)
Oxygen dissolves in to water before diffusing but could also evaporate. Adaptations of the gas exchange system aim to reduce water loss.
Describe the process of inspiration
- The diaphragm contracts and flattens
- The intercostal muscles contract
- The ribcage moves up and out
- The volume inside the chest cavity (thorax) increases
- This decreases the pressure so air moves in (from high to low)
Describe the process of expiration
- The diaphragm relaxes and moves up
- The intercostal muscles relax
- The ribcage moves in and down
- The volume inside the chest cavity decreases
- This increases the pressure so air moves out (from high to low)
What is tidal volume?
the volume of air moved in and out of the lungs with each breath when you are at rest. It is approximately 0.5dm3
What is vital volume?
the largest volume of air that can be moved into and out of the lungs in any one breath. It is approximately 5dm3
What is residual volume?
the volume of air that always remains in the lungs, even after the biggest possible exhalation. It is about 1.5dm3.
What is Inspiratory reserve volume?
how much more air can be breathed in (inspired) over and above the normal tidal volume when you take in a big breath
What is expiratory reserve volume?
how much more air can be breathed out (expired) over and above the amount that is breathed in a tidal volume breath
What is total lung capacity?
the maximum volume of air that the lungs can hold after a complete and maximal inhalation
What is the structure of fish gills?
- Water containing oxygen enters through the fish’s mouth and passes out through the gills
- Each gill is made of primary lamellae (big SA)
- The primary lamellae have lots of tiny structures called secondary lamellae, increasing the SA even more
- Gill plates have lots of capillaries to maintain conc. gradient and a thin layer of cells to keep the blood supply as close to the water as possible
What is a counter-current system?
- Blood flows in the opposite direction to water flow
- This means water with a high oxygen concentration will always flow next to blood with a low oxygen concentration
- Maintains steep conc gradient
How does ventilation work in fish?
- Fish opens its mouth, lowering the floor of the buccal cavity
- Volume of buccal cavity increases, decreases pressure inside cavity
- Water is then sucked in
- The fish closes its mouth, the buccal cavity floor rises
- Volume inside the cavity decreases, pressure increases, opening the operculum
- Water forced out over gills
How does ventialtion work in insects?
- Air is actively pumped into the system by muscular pumping of the thorax and/ or the abdomen
- These movement changes the volume of the body and this changes the pressure of tracheae and tracheoles.
- Air is drawn into or forced out the tracheae and tracheoles as pressure changes
How does gaseous exchange work in insect?
- Air-filled pipes called tracheae are used for gas exchange
- Air moves in through pores on the surface called spiracles (diffusion)
- The tracheae branch in to tracheoles which have thin permeable walls and to individual cells
- The tracheoles also contain fluid which oxygen dissolves in, the oxygen moves from this fluid, in to cells
