Features of exchange surfaces
Exchange surface-Is a specialised area that is adapted to make it easier for molecules to cross from one side of the surface to the other
Large surface area for molecules to pass through usually via folding.
Thin barrier to reduce diffusion distance.
Fresh supply of molecules on one side to keep concentration high and maintain a steep diffusion gradient.
Removal of required molecules on the other side to keep the concentration low.
Features of lungs for efficient gas exchange
Large SA - Alveoli are folded and in large numbers.
Thin barrier-Alveoli are made of squamous epithelium and one cell thick
-Capillary touches alveoli
-Capillary is one cell thick and made of squamous epithelium
High supply-lungs high conc of oxygen by breathing constantly.
Demand side-capillary - low conc of carbon dioxide by pumping blood around body - deoxygenated blood brought to the lungs.
Functions of parts of the lungs
Cartilage-supports trachea and bronchi/ lumen
Cillia-wafts mucus up the lumen to the throat
Smooth muscle-Contracts to constict the lumen , relaxes to dilate.
Elastic fibres-Stretches during inhalation and recoils during exhalation
Goblet cells-Secrete mucus to trap bacteria smokers secrete more mucus
Inhaling and exhaling
Inhaling Diaphragm contracts to become flatter and pushes digestive organs down.
External intercostal muscles contract to raise ribs
Volume of chest cavity increases.
Pressure in chest cavity drops below atmospheric pressure.
Air moves into lungs.
Exhaling Diaphragm relaxes and is pushed up by displaced organs underneath
External intercostal muscles relax and ribs fall.
Volume of chest cavity decreases.
Pressure in lungs increases and rises above atmospheric pressure
Air moves into lungs
All terms associated with spirometers
Tidal volume-the volume of air moved in and out of the lungs with each breath when you're at rest.
Ventilation rate-The amount of air going in and out of your lungs per minute - tidal volume x breaths per minute
Vital capacity-the larger volume of air that can be moved in and out of lungs in any one breath
Oxygen uptake-the volume of air extracted from the lungs in 1 minute
Residual volume-The volume of air that always remains in the lungs
Inspiratory reserve volume-how much air can be breathed in above and beyond the tidal volume
Expiratory-how much more air can be breathed out and over and above the amount that is breathed ina tidal volume breath.