7.2 & 7.3 Flashcards
Why do mammals require a transport system
small SA:V ratio & large volume of cells
- high metabolic rate (humans are active and maintain body temperature)
Important features of NASAL CAVITY
- large surface area with good blood supply which warms the air to body temperature
- hairy lining: secretes mucus to trap dust and bacteria, protecting delicate lung tissue from irritation and infection
- moist surface: increase humidity of incoming air to reduce water loss via evaporation at exchange surfaces
What is the laryx
organ located at top of neck, above trachea and in front of the gullet (oesophagus)
–> responsible for producing speech
Key structure of the trachea
main airway carrying clean, warm, moist air from nose down into chest
–> wide tube supported by incomplete ring of cartilage that stops trachea from collapsing
–> incomplete to allow food to travel down oesophagus easily
–> lined with ciliated epithelial and goblet cells
Key structure of the trachea
main airway carrying clean, warm, moist air from nose down into chest
–> wide tube supported by incomplete ring of cartilage that stops trachea from collapsing
–> incomplete to allow food to travel down oesophagus easily
–> lined with ciliated epithelial and goblet cells
How do ciliated epithelium and goblet cells work in trachea
Goblet cells secrete mucus onto lining of trachea, trapping dust and microorganisms
–> cilia beat in rhythm and move the mucus along away from the lungs
key structure of the bronchus
divisions of the trachea that split into two for left and two for right lung
(primary -> secondary)
–> very similar to trachea structurally but smaller (still has cartilage ring)
key structure of Bronchioles
no cartilage but contain smooth muscle
- smooth muscle contract= bronchioles constrict
-relaxed smooth muscle= bronchioles dilate
–> lined with thin layer of flattened epithelium (some gas exchange can occur here)
key structure of alveoli
tiny air sacs where most of gas exchange occurs
–> each alveolus is 200-300 micrometres in diameter
–> made up of think layer of flattened epithelium + some collagen and elastic fibres
- alveoli can stretch when air is drawn in, then recoil to help air move out (elastic recoil)
Adaptions of alveoli 4
- large surface area
- one cell thick= short diffusion distance
- Rich blood supply= maintains steep conc gradient for both CO2 & O2 between air in alveoli and blood
- Good ventilation
What is the inner surface of alveoli covered with?
thin layer of a solution of water, salts and lung surfactant
–> surfactant allows alveoli to remain inflated
What is ventilation
movement of air in and out of the lungs as a result of pressure changes in the thorax
What is Inspiration
taking air in, which is energy-using process
- Diagram contracts, moving down
- Intercostal muscles contract, moving ribs upwards & outwards
- Thoracic volume increases
- As a result, thoracic pressure decreases( now lower than pressure of atmospheric air
- Air is drawn into lungs (to equalise the pressure difference)
Expiration
breathing out which is passive
- Diaphragm relaxes, moving down
- Intercostal muscles relax, moving ribs down and inwards
- Thoracic volume decreases
- Thoracic pressure increases (pressure in thorax is greater than atmospheric air)
- Air flows out of lungs (to equalise pressure difference)
Tidal volume
volume of air breathed in or out in a single breath
–> 0.5L in lungs, normally the smallest wave on a graph
