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Physiology Of Respiratory System
Physiology Of Respiratory System
1. The Respiratory System
2. Mechanics of Breathing
3. Gas exchange in the lungs
4. O2
transport in blood
5. CO2
transport in blood
6. Gas exchange in the tissues
7. Control of breathing
1. THE RESPIRATORY SYSTEM
Respiratory system is divided into two parts: airways and lungs. In the lungs there
is exchange of gases, in Airways it isn’t.
AIRWAY
As air is drawn into the lungs, it is
distributed through a highly branched
airway. The first 16–17 generations of
division comprise the conducting zone (i.e.,
from the trachea through the various
bronchi and bronchioles to the terminal
bronchioles). Gas exchange occurs in the
respiratory zone and begins distal to the
terminal bronchioles.
Lungs
The lung is specialized for gas diffusion and has an internal surface area of 50–100 m2
.
The large surface of the Lungs area is produced by repeated branching of the airways,
which begins at the trachea and terminates in over 300 million closed air sacs called
alveoli.
Acinus
A lung acinus is a functional
unit formed by the division of a
terminal bronchiole into the
respiratory bronchioles, the
alveolar ducts, and the terminal
alveoli. Gas moves by diffusion
within lung acini.
Pleural cavity
Pleural cavity is the thin fluid-filled space between the two pulmonary
pleurae (visceral and parietal) of each lung.
Functions of the respiratory (pulmonary) system:
1. Gas exchange
Is extraction of oxygen from the atmosphere and transfer it into
the bloodstream, and to release carbon dioxide from the bloodstream into
the atmosphere. Generally it is maintenance of systemic arterial blood gas
(O2 and CO2
) levels within normal range.
2. Olfaction ( Sense of smell )
Is the sense of smell. This sense is mediated by specialized sensory cells,
called olfactory receptors, in the nasal cavity.
Olfaction occurs when odorants bind to specific sites on olfactory receptors located in the nasal cavity.
3. Voicing
The movement of gas through the larynx, pharynx and mouth allows
humans to speak, or phonate.
4. Protective function
Includes mucocilliary clearance and immune protection
5. Temperature control
During the breath, water evaporates from the surface of the airway. This
process helps to cool the body.
6. Excretion
Daily from the surface of the respiratory tract evaporates about 600 ml of
fluid containing metabolites and toxins.
Voicing
The mechanism for generating the human voice can be
subdivided into three parts; the lungs, the vocal folds within
the larynx, and the articulators. The lung, the "pump" must
produce adequate airflow and air pressure to vibrate vocal folds.
The vocal folds then vibrate to use airflow from the lungs to
create audible pulses that form the laryngeal sound source. The
articulators (the parts of the vocal tract above the larynx
consisting of tongue, palate, cheek, lips,
etc.) articulate and filter the sound emanating from the larynx.
Protective function of the respiratory system
1. The respiratory tract is lined by epithelia with hairlike projections called cilia that beat rhythmically and
carry mucus. This mucocilliary clearance is an
important defence system against air-borne
infection. The dust particles and bacteria in the
inhaled air are caught in the mucosal surface of the
airways, and are moved up towards the pharynx by
the rhythmic upward beating action of the cilia.
PULMONARY PHYSIOLOGY
Shutova S.V.
Protective function of the respiratory system
2. There is an immune protection – the lining of the aivays and of the lung
secretes immunoglobulines, antibacterial enzymes and antioxidates, the lining
of the lung and tonsils also contain macrophages.
