Respiration Ventilation

1. RESPIRATION
. .
Dr VictoriaG Giango
Chair, Dept. of Physiology

2. GOALS OF RESPIRATION
1. To provide oxygen to the tissues
2. To remove carbon dioxide
MAJOR FUNCTIONAL EVENTS
OF RESPIRATION
1. Pulmonary Ventilation – inflow and
outflow of air between the atmosphere and
lung alveoli

3. 2. Diffusion of oxygen and carbon
dioxide between the alveoli and the
blood
3. Transport of oxygen and carbon
dioxide in the blood and body fluids
to and from the cells.
4. Regulation of Ventilation

6. RESPIRATORY SYSTEM – made up of:
1. Gas exchanging organ – Lungs
2. Pump that ventilates the lungs – consists of:
a. Chest wall
b. Respiratory Muscles – increase and
decrease the size of the thoracic cavity
c. Areas in the Brain – control the
muscles
d. Tracts and Nerves – connect the brain
to the muscles

7. MUSCLES OF INSPIRATION
1.Diaphragm – 75%
2.External intercostals
3.Sternocleidomastoid
4.Serratus (anterior)
5.Scaleni
MUSCLES OF EXPIRATION
1. Internal intercostals
2. Abdominal recti

8. COMPLIANCE
The extent to which the lungs expand
for each unit increase in
transpulmonary pressure
Both lungs – 200 ml of air per cm of
water transpulmonary pressure
Thorax and lungs together – 110 ml per
cm of water transpulmonary pressure

9. FACTORS THAT DETERMINE
COMPLIANCE:
1. Elastic forces of the lung tissue itself (elastin
and collagen fibers interwoven among the
lung parenchyma
2. Elastic forces caused by surface tension of
the fluid that lines the inside walls of the
alveoli and other lung spaces
Surface Tension accounts for 2/3 of total
elastic forces in normal lung

12. SURFACTANT
- Surface active agent, when it spreads over the
surface of a fluid, it reduces the surface
tension
- Secreted by type II alveolar epithelial cells
- Complex mixture of phospholipids, proteins
and ions
- dipalmitoylphosphatidylcholine
- surfactant apoproteins
- calcium ions

13. SURFACTANT
1.Lowers surface tension
2.Stabilizes the size of the alveoli
3.Prevents the accumulation of fluid

14. Surface Tension of Different
watery fluids:
72 dynes/cm – pure water
50 dynes/cm – normal fluids lining the
alveoli but without surfactant
5 to 30 dynes/cm – fluids lining the
alveoli with surfactant included.

15. -Stabilize the sizes of the alveoli
- inversely affected by radius of
the alveolus
- begin to be secreted between
the 6
th
and 7
th
month of gestation

16. Collapse Pressure of Occluded Alveoli
Caused by Surface Tension
Pressure = 2 x surface tension
Radius
Respiratory Distress Syndrome of the
Newborn - caused by little or no
surfactant. The lungs of babies have
extreme collapse tendencies, 30 mmHg
or more

17. “WORK” OF BREATHING
(work of inspiration)
1. Compliance work or Elastic work –
that required to expand the
lungs against the lung and
chest elastic forces

18. 2. Tissue resistance work – required
to overcome the viscosity of the
lung and chest wall structures
3. Airway resistance work –
required to overcome airway
resistance to movement of air
into the lungs

19. Compliance and Tissue resistance work –
increased by diseases that cause fibrosis of the
lungs as in tuberculosis
Airway resistance work – increased by
diseases that obstruct the airways as in
asthma
3 to 5% of the total energy expended by
the body is required to energize the
pulmonary ventilatory process

20. LUNG VOLUMES
Tidal Volume (Vt) – is the volume of air
inspired or expired with each normal
breath - 500 ml
Inspiratory Reserve Volume (IRV) – the
extra volume of air that can be
inspired over and above the normal
tidal volume when the person inspires
with full force – 3000ml

21. 3. Expiratory Reserve Volume (ERV)–
is the maximum extra volume of air
that can be expired by forceful
expiration after the end of the
normal tidal expiration - 1100 ml
4. Residual Volume (RV) – the
volume of air remaining in the lungs
after the most forceful expiration –
1200ml

24. CAPACITIES
1.Inspiratory Capacity (IC)
IC = Vt + IRV = 3, 500 ml
2. Functional Residual Capacity (FRC) = 2,300 ml
FRC = ERV + RV
3. Vital Capacity (VC)
VC = IRV + Vt + ERV
= IC + ERV
4. Total Lung Capacity (TLC) = 5, 800ml
TLC = Vt + IRV + ERV + RV
= IC + FRC
= VC + RV

25. HELIUM DILUTION METHOD –
determination Functional Residual capacity,
Residual volume, Total Lung Capacity
FRC = Initial conc. Of Helium in spirometer
Final conc. Of Helium
FRC = Ci
He __ - 1
Vi
Spir
Cf
He
RV = FRC – REV
TLC = FRC + IC

26. FACTORS AFFECTING LUNG
VOLUMES AND VITAL CAPACITY
1.Body build or physique
2.Position of the body
3.Strength of respiratory muscles
4.Pulmonary compliance

27. Minute Respiratory Volume
is the total amount of new moved into the
respiratory passages each minute
= Tidal volume x Respiratory rate/minute
= 500 x 12
Alveolar Ventilation
Total volume of new air entering the the
alveoli and adjacent gas exchange areas each
minute
V
A
= Freq . (V
T
– V
D
)

28. Respiratory Dead Space – space in the
conducting zone of the airways occupied by gas
that does not exchange with the blood in the
pulmonary vessels
Vital Capacity – the largest volume of air that can be
expired after a maximal inspiratory effort. It is
frequently measured clinically as an index of
pulmonary function. It gives useful information about
the strength of the respiratory muscles and other
pulmonary functions.
Maximal Voluntary Ventilation –(MVV) or Maximal
breathing Capacity – largest volume of gas that can
be moved into and out of the lungs in 1 minute by
voluntary effort – 125 – 170 L/min.

29. ANATOMIC DEAD SPACE – space of the
respiratory system besides the alveoli and other
gas exchange areas
Dead space air = 15 0 m
PHYSIOLOGIC DEAD SPACE – alveolar dead
space and anatomic dead space
In normal person the Anatomic and Physiologic
dead spaces are nearly equal
In person with partially functional or
nonfunctional alveoli the Physiologic dead
space is much as 10 x the volume of
Anatomic dead space

31. FUNCTIONS OF THE
RESPIRATORY PASSAGEWAYS
ANATOMY:
Trachea, Bronchi, Bronchioles
between trachea and alveolar sacs
airways divide 23 times – first 16 generations
made up of bronchi, bronchioles, and
terminal bronchioles.
Last 7 generations are made up of respiratory
bronchioles, alveolar ducts, and alveoli

32. Muscular Wall of the Bronchi and
Bronchioles and its Control
Resistance to Airflow in the Bronchial Tree
Nervous and Local Control of the Bronchiolar
Musculature – “Sympathetic” Dilatation of the
Bronchioles
Parasympathetic constriction of the Bronchioles
Local Secretory Factors Often Cause Bronchiolar
Constriction
- Histamine
- Slow Reacting Substance of Anaphylaxis

33. FUNCTIONS:
1.Mucous Lining of the Respiratory Passageways and
Action of Cilia to Clear the Passageways
2.Cough Reflex – Vagus Nerve
a. Irritation
b. Inspiration – 2.5 liters of air are rapidly inspired.
Epiglottis closes and the vocal cords shut tightly to
entrap the air within the lungs.
c. Compression – abdominal muscles contract
forcefully. Pushing against the diaphragm. Pressure
rises to 100 mmHg or more.
d. Expulsion – air under high pressure in the lungs
explude outward

35. 3. Sneeze Reflex – Trigeminal Nerve
Uvula is depressed so large amounts of
air pass directly through the nose helping
to clear the nasal passages of foreign matter,
4. Normal Respiratory Functions of the
Nose – Air Conditioning Function of the
Upper Respiratory Passages
a. Air is warmed
b. Air is Humidified
c. Air is Filtered
- turbulent precipitation
- gravitational precipitation

36. 5. Vocalization
Phonation – larynx is adapted to act
as vibrator (vibrating element is the
vocal cord)
Vocalization and resonance – organs
of articulation are the lips, tongue,
and soft palate