3.1.1 Flashcards
Why is only diffusion needed to supply single celled organisms with what it needs?
- Low metabolic activity (low oxygen demand, low carbon dioxide production)
- large surface area to volume ratio
What are the features for effective exchange surfaces in multicellular organisms? Mention four
-Increased surface area (overcomes SA:V limitations)
E.g. root hair cells, villi
-thin layers (diffusion distance is shorter-fast and efficient)
E.g. alveoli, Villi
-Good blood supply (steeper concentration = faster diffusion)
E.g. alveoli, gills, Villi
-Ventilation to maintain diffusion gradient
E.g. alveoli, gills (flow of water carrying dissolved gases)
Name five key structures in the Mammilian gas exchange system.
Nasal cavity Trachea Bronchus Bronchioles Alveoli
What are the adaptations to the nasal cavity and why?
- Large surface area, good blood supply that warms to body temp
- hairy lining/mucus secretion-traps dust and bacteria to protect the lung tissue from irritation and infection
- moist surfaces-increased humidity reduce evaporation
What are the adaptations of the trachea and why?
-Incomplete rings of strong flexible cartilage-stop trachea from collapsing
-ciliated epithelium (goblet cells and Celia)
Days stop dust at the micro organisms from entering the lungs and music to the throat to be digested
What is the bronchus ?
Trachea divides into left and right bronchus (supporting rings of cartilage to a smaller)
Describe the adaptations of the bronchioles and why?
Smooth-muscle walls (contract and relax causing construction or dilation) changes amount of air entering
-Lined with flattened epithelium making gaseous exchange possible
What are alveoli made of?
Thin flattened epithelial cells with collagen and elastin fibres that allow it to stretch
What is meant by elastic recoil and where does this happen?
In the alveoli
When alveoli returns to resting size to help squeeze air out
What are the adaptations of alveoli and why?
- Large surface area
- single cell thick
- good blood supply
- good ventilation
- in a surface is covered in thin layer of water salts and lung surfactant (allows alveoli be allowed to remain inflated)
What is ventilation and what does it cause?
Movement of air
It causes pressure changes in the thorax
Where are external and internal intercostal muscles found?
Between ribs
Describe the thorax
It’s lined with pleural membranes that surround the lungs and pleural cavity (in between)
Filled with thin layer of lubricating fluid so membranes slide easily over each other
What happens during inspiration (inhalation)?
Diaphragm contracts (flattening and lowering) External intercostal muscles contract (ribs move up and out) Thorax volume increases, pressure gets reduced Atmospheric pressure is lower so Air gets drawn in to equalise internal and external pressure
What happens in expiration (Exhalation)?
Diaphragm relaxes
External intercostal muscles relax (ribs move down in)
Elastic fibres in alveoli and lungs go back to normal
Thorax volume decreases
What are the three ways of measuring capacity of lungs?
- Peak flow meter
- Vitalographs
- Spirometer
What does a peak flow meter do?
Measures the rate at which air can be expelled
What do vitalographs do?
A more sophisticated version of PFM.
Patient breathes out as fast as possible, graph is produced (how much are they and how fast)
Forced expiratory volume in one second
What does a spirometer measure?
Different aspects of lung volume
Investigate breathing patterns
What is tidal volume?
Volume of air that moves in and out
What is vital capacity?
Volume of air breathed in when strongest possible exhalation is followed by deepest possible inhalation
What is inspiratory reserve volume?
Maximum air breathed in
What is expiratory reserve volume?
Extra air you can force out of the lungs over and above normal tidal volume
What is residual volume?
Volume of air left in lungs when you have exhaled as hard as possible
(can’t be measured directly)
