Physiological anatomy of respiratory system

Physiological
Anatomy of
Respiratory system
D.A. Asir John Samuel, BSc (Psy), MPT (Neuro Paed),
MAc, DYScEd, C/BLS, FAGE
Lecturer, Alva’s college of Physiotherapy,
Moodbidri
Dr.Asir John Samuel (PT)

Respiration

• Exchange of gases between an organism and
its environment

• Physiological processes that contribute to
uptake of oxygen and elimination of carbon
dioxide


Anatomical structures

• Respiratory passages

• Lungs

• Respiratory muscles operating on body
structures of thoracic cage


Respiratory passages
• Nasal cavity

• Pharynx

• Larynx

• Trachea

• Bronchi

• bronchioles

Nose (nasal cavity)

• Both olfactory and respiratory functions

• Inspired air is warmed or cooled

• Brought close to body temperature

• Also moistened by fluid derived from
transudation through epithelium and
secretions of glands and goblet cells

Nose (nasal cavity)
• Warming and humidification of inspired air
• Moist air is necessary for integrity and proper
functioning of ciliated epithelium
• Secretions have bactericidal actions
• Stiff hairs trap dust and foreign particles
• Resonator in voice and speech


Pharynx
• Nasal cavity opens posteriorly into
nasopharynx

• During swallowing, respiration is temporarily
inhibited permitting food to enter oropharynx

• Elevation of larynx and closure of vocal cords
prevents entry of food into larynx


Larynx
• Lower part of pharynx and at upper end of
trachea
• Cartilagenous, cartilages being held together
ligaments
• Production of voice
• Achieved by forcible expulsion of air from
lungs, causing production of sound
• Contraction of adductor muscles and glottis

Trachea and main bronchi

• Tubular structure about 10cm long and 1cm in
diameter

• Begins at lower end of larynx

• Lumen of trachea is kept patent by a number
of C-shaped fibro cartilaginous ring

• Divides into right and left bronchus

Lungs

• One on either side

• Large cone-shaped spongy structures which
occupy most of thoracic cavity

• Left lung is divided into 2 lobes and right into 3

• Lined by pleura (visceral and parietal)


Lung lobes


Bronchioles


Terminal branches

• Bronchioles branch further and the smallest
subdivisions being terminal bronchiole

• It is estimated, no. of divisions from tracheal
bifurcation to terminal bronchiole is 16

• Total no. of divisions till alveoli is 23


Dead space

• The bronchiole tree upto and including
terminal bronchiole is purely conducting
pathway for passage of air

• Respiratory gas exchange does not occur in
this region

• Referred to as anatomical dead space

Gas exchange apparatus
• Terminal bronchiole divides into respiratory
bronchioles

• Respiratory bronchioles give rise to a number of
short passages called alveolar ducts

• These open into wider alveolar sacs

• On the walls located pulmonary alveoli

• Some alveoli present in respiratory bronchioles

Alveolus


Pulmonary alveoli
• Alveoli are lined by a single layer of flat epithelial
cells
• Alveolar type I cells are principal lining
• Type II are cuboidal cells, secrete surfactant
• Average width is 0.3 mm
• 300 million alveoli in human lung


Surfactant

• Formed from fatty acids by alveolar type II cells

• Complex mixture of several phospholipids,
proteins and ions

• Most important components are phospholipid,
dipalmitoyl phosphatidyl choline (DDPC),
surfactant appoproteins and calcium ions

RD (Respiratory Distress)
• Deficiency of surfactant at birth causes a serious
pulmonary disease of new born called Neonatal
Respiratory Distress Syndrome (NRDS) or hyaline
membrane disease
• Lung shows several areas of collapse
• Reduced compliance
• Poor expansion
• Presence of fluid in alveoli

Muscles of respiration

• Downward and upward movement of
diaphragm

• Elevation and depression of ribs


Pleural pressure
• Pressure of fluid in the narrow space b/w
visceral pleura and parietal pleura

• Normally a slight suction, which means a slightly
negative pressure

• At beginning of inspiration is about -5 cm of H2O

• Required to hold lungs open to their resting level


Pleural pressure
• During normal inspiration, the expansion of
chest cage pulls outward on lungs with still
greater force
• Creates still more negative pressure to an
average of about -7.5 cm of H2O
• Increasing negativity of pleural pressure from -
5 to -7.5 cm of H2O
• During expiration, events are reversed

Alveolar pressure

• Pressure of air inside the lung alveoli

• Pressure in all parts of respiratory tree are
equal to atmospheric pressure

• 760 mm of Hg/0 cm of H2O

• During normal inspiration, alveolar pressure
decreases to about -1 cm of H2O

Alveolar pressure

• Slight negative pressure is enough to pull 0.5
liter of air into lungs in 2 seconds

• During expiration, opposite changes occur

• Alveolar pressure rises to about +1 cm of H2O

• This forces 0.5 liter of inspired air out of lungs
during 2-3 seconds of expiration

Transpulmonary pressure
• Pressure difference b/w alveolar pressure and
pleural pressure

• Pressure difference between that in alveoli
and that on outer surfaces of lungs

• Measure of elastic forces in lungs that tend to
collapse at each instant respiration

• Recoil pressure Dr.Asir John Samuel (PT)

Compliance of lungs
• Extent to which lungs expand for each unit
increase in transpulmonary pressure

• Total compliance of both lungs together in
normal human being averages about 200 ml
of air/1 cm of H2O

• Every time transpulmonary pressure increases
by 1 cm of H2O, lung volume expands 200 ml

Compliance diagram

• Inspiratory compliance curve and expiratory
compliance curve

• Determined by, elastic forces of lungs

- Elastic forces of lung tissue itself

- Elastic forces caused by surface tension of
fluid that lines inside walls of alveoli

Pressure-volume curve


Spirometry

• The process by which pulmonary ventilation is
recorded by the volume movement of air into
and out of lungs

• Consists of drum inverted over a chamber of
water, with drum counterbalanced by weight

• Drum rises and falls. Recorded on paper

Spirometry


Physiological anatomy of respiratory system

Recomendados

Recomendados

Mais conteúdo relacionado

Mais procurados

Mais procurados (20)

Semelhante a Physiological anatomy of respiratory system

Semelhante a Physiological anatomy of respiratory system (20)

Mais de Asir John Samuel

Mais de Asir John Samuel (20)

Physiological anatomy of respiratory system