Basic anatomy and physiology of respirationBasic anatomy and physiology of respiration Basic anatomy and physiology of respirationBasic anatomy and physiology of respiration
Due to adhesion between the visceral and parietal
pleura, this expansion of the thoracic cage leads to
an expansion of the thoracic space that is filled by
the lungs. Through this expansion the pressure in
the thoracic cavity is decreased in relation to the
abdominal cavity and the outside. This increases
venous return to the right atrium of the heart.
Therefore more blood is supplied to the lungs for
gas exchange. More air is sucked into the lungs, to
supply oxygen for gas exchange. In normal exhala-
tion these movements are reversed passively; during
forced exhalation they are enhanced using the acces-
sory respiratory muscles. Due to the attachments
of the serratus anterior muscles the shoulder blades
are closely related to the ribs as well. Therefore
good mobility of the shoulder blades is important
for breathing.The spine
The spine needs a good balance between stability
and flexibility. Activating the abdominal muscles
sufficiently during inhalation stabilizes the lumbar
spine. Due to contraction of the pelvic floor mus-
cles the sacrum moves into counternutation, which
lengthens the spine.
The thoracic spine bends backwards slightly. B K S
Iyengar (2009) gives an elegant description that
the ninth thoracic vertebra and the sternum move
slightly towards the chin. As a result the physiolog-
ical curves of the spine become flatter (Hartman
2001 ). Good mobility of the costovertebral joints is
important for breathing. Good mobility of this area
also improves the blood supply and drainage of the
sympathetic chain that is close to the costovertebral
joints.The sternum
During inhalation the sternum moves forwards
and upwards. Anterior movement of the upper
sternum is more than that of the lower sternum
(Kapandji 2008). This also involves various move-
ments of the costal cartilages, the sternocos-
tal joints, and the costochondral junction and is
important for rib movement. In connection with
sternal mobility the transverse thoracic muscle is
particularly relevant and should be stretched and
mobilized.The exchange of oxygen and carbon
dioxide between the alveoli and the
blood vesselsThe alveoli are the terminal air saccules of the lungs.
Fine pulmonary capillaries surround them. Both are
lined by layers of extremely thin epithelium and sepa-
rated by membranes. In the alveoli the concentration
of oxygen is higher than in the capillaries. Therefore
oxygen moves passively by diffusion into the capillar-
ies. In contrast the concentration of carbon dioxide is
higher in the capillaries and moves passively by diffu-
sion into the alveoli. Air containing less oxygen and
more carbon dioxide is removed by exhalation. The
fresh oxygen diffused into the capillaries is carried
into all tissues and organs of the body by red blood
cells for absorption by the cells of the body.
In conclusion, a basic understanding of these pro-
cesses shows how important a good pattern of res-
piration is for sufficient oxygen supply, to maintain
the acid/alkaline balance, and to support the func-
tioning of all systems of the body. Breathing is also
important for the musculoskeletal system and its
functions, including exercise. By the same token,
practicing breathing techniques contributes to good
lung function. The supply of the alveoli with air
and the capillaries with blood can be significantly
improved through good posture and practicing.The rhythm and volume of respiration
There is a significant difference between the normal
respiratory volume of 500 ml and the maximum
capacity of respiration of up to 5 litres (Martini
& Nath 200 8 ). In quiet breathing the main respi-
ratory muscles are used for inhalation; exhalation
is passive, by elastic rebound. The emphasis can
either be on the contraction of the diaphragm or
on raising the ribs through contraction of the exter-
nal intercostal muscles to increase thoracic volume
so that air can be drawn into the lungs. Normally
diaphragmatic breathing is deeper – 75% of total
volume – whereas costal breathing is shallower- 25% of total volume. It can be further differ-
entiated between high, clavicular breathing, inter-
costal mid breathing, and diaphragmatic breathing
(Iyengar 2009). In full breathing in yoga all areas
can be integrated. Capacity is greatest if the ribs