7.2 Flashcards
Nasal Cavity
- Large surface area
- good blood supply
- warms air to body temp
hairy lining
secretes mucus to trap dust and bacteria.
protects lung tissue from irritation and infection
Moist surfaces
increases humidity of incoming air
reduces evaporation
Trachea
Main airway carrying air from nose to chest
wide tube
supported by incomplete rings of strong flexible cartilage
stops tube from collapsing
incomplete rings so food moves easily down oesophagus behind trachea
lined with ciliated epithelium and goblet cells which secrete mucus to trap dust and microorganisms
cilia beat and waft mucus away from lungs to throat to be swallowed and digested.
(effect of cigarette smoke is that cilia stop beating)
Bronchus
trachea divides to form
left bronchus leading to left lung
right bronchus leading to right lung
smaller rings of cartilage
Bronchioles
small tubes spreading into both lungs
smaller bronchioles have no cartilage rings
walls contain smooth muscles with
- contract to close up bronchioles
- relax to dilate them
changing amount of air entering the lungs
lined with thin layer of flattened epithelium
making some gaseous exchange possible
Alveoli
Tiny air sacs
200 - 300 micrometres in diameter
layer of thin flattened epithelial cells
some collagen and elastic fibres
elastic tissues allow alveoli to stretch as air is drawn in
when they return to their resting size, air is squeezed out.
(elastic recoil)
- Large surface area: allows more gases to exchange in and out
- Thin layers: short diffusion distance
alveoli + capillaries have walls that are a single epithelial cell thick - Good blood supply
Maintains steep concentration between air in alveoli and blood in capillaries. - Ventilation as breathing moves air in and out of alveoli
inner surface of alveoli is covered in a thin layer of solution of water, salts and lung surfactants
keeps alveoli inflated.
Inspiration
Taking air in
energy using process
- Diaphragm contracts, flattening and lowering
- external intercostal muscles contact
moving ribs upwards and outwards - volume of thorax increases
pressure decreases - air is drawn in
Expiration
passive process
- diaphragm relaxes
domed and rising - external intercostal muscles relax
down and inwards - volume of thorax decreases
increased pressure - air is drawn out
Composition of cartilage
provides support
strong + flexible
stop collapsing
Trachea
Bronchi
Composition of ciliated epithelium
lines the airways of cells
cilia beat the mucus towards the throat to be swallowed
trachea
bronchi
bronchioles (large and medium)
Composition of Goblet cells
line airways
secrete mucus to transport and trap microorganism
preventing reaching alveoli
destroyed by acid in stomach
Trachea
Bronchi
Bronchioles (only in large)
Smooth muscle composition
control diameter
relax during exercise to expand the tubes, giving less resistance to air flow
regulate flow of air
trachea
bronchi
bronchioles
elastic fibres composition
stretch and recoil
Trachea
bronchi
bronchioles
alveoli
Trachea composition
cartilage
ciliated epithelim
goblet cells
smooth muscle
elastic fibres
Bronchi composition
cartilage
ciliated epithelium
goblet cells
smooth muscle
elastic fibres
Bronchioles composition
NO cartilage
ciliated epithelium
goblet cells
smooth muscle
elastic fibres
