Download Mechanism of breathing

Learning Objectives
 Explain, with the use of diagrams, the process of
breathing
 Examine Respiratory Tissue slides under the
microscope and Identify tissue types within them
Mechanism of breathing …
 Movement of the ribcage and diaphragm ventilate the
lungs.
 This is important:
 Inspiration (inhalation) brings fresh supplies of O2 to
maintain the O2 concentration gradient.
 Expiration (exhalation) removes waste air with its cargo
of CO2 to maintain the CO2 gradient.
 Movement of respiratory gases is by diffusion so it is
driven by concentration differences.
Inspiration
 External intercostal
muscles contract, pulling
the ribcage upwards and
outwards.
 Diaphragm contracts,
pulling it from a domed to
a flattened shape.
 Combined effect is:
 volume of the thorax and
lungs increase
 pressure is reduced
 air enters, goes down the
pressure gradient.
Expiration - relaxed
 External intercostal
muscles relax and the
ribcage falls under its own
weight.
 Diaphragm relaxes and
gut pressure pushes it
back into its domed shape.
 Elastic recoil of lung
tissue.
 Combined effect is:
 volume of the thorax and
lungs decrease
 pressure is increased
 air is forced out.
Expiration - forced
 Internal intercostal
muscles contract, pulling
the ribcage down and in.
 Abdominal muscle
contracts pushing the
diaphragm upwards.
 Combined effect is:
 volume of the thorax and
lungs decrease
 pressure is increased
 air is forced out.
 Exercise, singing, playing
a wind instrument.
To Do:
 Draw diagrams to explain the process of
breathing.
 Help yourself to a Microscope and examine slide
of lung tissue under high magnification – What
tissues do you expect to see? Can you identify
some of these tissues?
bronchiole and alveolar tissue
Alveolar space
Lumen
or airway
Alveolar wall cell
(nucleus purplish
stain)
Smooth muscle
Capillary – blood vessels
have been injected with
dye
Epithelium – ciliated
in bronchiole but not
respiratory
Trachea
Ciliated
epithelium
Cilia
Elastic tissue
Goblet
cell
Blood vessel with
numerous blood
cells clearly visible
Smooth muscle
Cartilage –
chondrocytes clearly
visible
PREP
 The content of today’s lesson (found on page 46
– 49) to be written up, in the format of your
choice, in your Prep Books
 To be completed and checked by next lesson
(Monday)