Post on 18-Dec-2014
description
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
Dr.Asir John Samuel (PT)
Anatomical structures
• Respiratory passages
• Lungs
• Respiratory muscles operating on body
structures of thoracic cage
Dr.Asir John Samuel (PT)
Respiratory passages
• Nasal cavity
• Pharynx
• Larynx
• Trachea
• Bronchi
• bronchioles
Dr.Asir John Samuel (PT)
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 Dr.Asir John Samuel (PT)
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
Dr.Asir John Samuel (PT)
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
Dr.Asir John Samuel (PT)
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 Dr.Asir John Samuel (PT)
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 Dr.Asir John Samuel (PT)
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)
Dr.Asir John Samuel (PT)
Lung lobes
Dr.Asir John Samuel (PT)
Bronchioles
Dr.Asir John Samuel (PT)
Dr.Asir John Samuel (PT)
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
Dr.Asir John Samuel (PT)
Dr.Asir John Samuel (PT)
Dr.Asir John Samuel (PT)
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
Dr.Asir John Samuel (PT)
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 Dr.Asir John Samuel (PT)
Dr.Asir John Samuel (PT)
Alveolus
Dr.Asir John Samuel (PT)
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
Dr.Asir John Samuel (PT)
Dr.Asir John Samuel (PT)
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
Dr.Asir John Samuel (PT)
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 Dr.Asir John Samuel (PT)
Muscles of respiration
• Downward and upward movement of
diaphragm
• Elevation and depression of ribs
Dr.Asir John Samuel (PT)
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
Dr.Asir John Samuel (PT)
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 Dr.Asir John Samuel (PT)
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 Dr.Asir John Samuel (PT)
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
Dr.Asir John Samuel (PT)
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 Dr.Asir John Samuel (PT)
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 Dr.Asir John Samuel (PT)
Pressure-volume curve
Dr.Asir John Samuel (PT)
Pressure-volume curve
Dr.Asir John Samuel (PT)
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
Dr.Asir John Samuel (PT)
Dr.Asir John Samuel (PT)
Spirometry
Dr.Asir John Samuel (PT)
Dr.Asir John Samuel (PT)
Dr.Asir John Samuel (PT)