Biomedical Engineering Reference
In-Depth Information
9
Protein and Peptide Delivery
through Respiratory Pathway
Hemal Tandel, Kiruba Florence,
Ambikanandan Misra
Pharmacy Department, TIFAC - Centre of Relevance and Excellence in
New Drug Delivery Systems, The Maharaja Sayajirao University of
Baroda, PO Box 51, Kalabhavan, Vadodara 390 001, Gujarat, India
9.1 Introduction
The principal function of the respiratory system is to supply and distribute air to the
body such that the exchange of oxygen and carbon dioxide between alveolar gas and
pulmonary capillary blood is achieved efficiently. In addition to these main processes,
the respiratory system serves to regulate blood pH, which occurs in coordination with
the kidneys as a defense against microbes, and to control body temperature. The upper
respiratory tract acts as a first-line of defense and a filtration system for particles,
microbes, and other environmental pollutants within preferred size ranges. A more
elaborate process for particle removal takes place throughout the tracheobronchial tree.
Although the lung's host defense mechanism eliminates foreign particles continuously
from the lung, excessive intake of particles from polluted air and successive buildup
of particle burden on tissues often causes lung injury, leading ultimately to a variety of
lung diseases. To treat respiratory tract diseases, a complete understanding of the struc-
ture, physiology, and deposition and clearance mechanism of the respiratory system is
essential.
9.2 Respiratory System
9.2.1 Anatomy of the Human Respiratory Tract
The respiratory system is divided into three regions: the nasopharynx, tracheobron-
chia, and pulmonary (alveolar) regions. The upper respiratory tract includes the nose
(nasal cavity, sinuses), mouth, larynx, and trachea (windpipe). The lower respiratory
tract comprises the lungs/pulmonary region with bronchi and alveoli. In the process
of breathing, air enters the nasal cavity through the nostrils and is filtered by coarse
hairs (vibrissae) and mucus. The vibrissae filter macroparticles, which are particles of
large size. Dust, pollen, smoke, and fine particles are trapped in the mucus that lines
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