Respiration : Inspiration , expiration

1. Respiratory Anatomy and
physiology

2. anatomy
The respiratory system is made up of
the organs involved in breathing and
consists of the:
nose
pharynx
larynx
trachea
bronchi
lungs

3. The upper respiratory tract includes
the:
nose
nasal cavity
ethmoidal air cells
frontal sinuses
maxillary sinus
larynx
trachea

4. The lower respiratory tract includes
the:
lungs
bronchi
alveoli

6. Respiration
Breathing
External respiration
Gas transport by blood
Internal respiration

7. Process of breathing

8. Breathing
Inspiration:
Contraction of diaphragm / intercostal muscles

Expansion of thorax  expansion of lungs 
Pressure in lungs ↓ 
Air inflow
Expiration:
Relaxation of muscles 
Thorax / lung recoil back 
Pressure in lungs ↑ 
Air outflow

9. Forceful breathing
Inspiration:
Contraction of accessory muscles 
extra expansion of thorax  extra air
inflow
Expiration:
Contraction abdominal muscles  abdominal
contents move up  diaphragm moves up
Abdominal muscles retract rib cage
Internal intercostal muscles retract rib cage

10. Lung volumes and capacities

11. TIDAL VOLUME (TV): Volume
inspired or expired with each
normal breath.
INSPIRATORY RESERVE
VOLUME (IRV): Maximum volume
that can be inspired over the
inspiration of a tidal volume/normal
breath. Used during
exercise/exertion.

12. EXPIRATRY RESERVE VOLUME (ERV):
Maximal volume that can be expired after the
expiration of a tidal volume/normal breath.
RESIDUAL VOLUME (RV): Volume that
remains in the lungs after a maximal expiration.
CANNOT be measured by spirometry.
INSPIRATORY CAPACITY ( IC): Volume of
maximal inspiration:
RV + TV

13. FUNCTIONAL RESIDUAL
CAPACITY (FRC): Volume of gas
remaining in lung after normal
expiration, cannot be measured by
spirometry because it includes
residual volume:
ERV + RV
VITAL CAPACITY (VC): Volume of
maximal inspiration and expiration:
IRV + TV + ERV = IC + ERV

14. TOTAL LUNG CAPACITY (TLC):
The volume of the lung after maximal
inspiration. The sum of all four lung
volumes, cannot be measured by
spirometry because it includes
residual volume:
IRV+ TV + ERV + RV = IC + FRC

15. DEAD SPACE: Volume of the respiratory
apparatus that does not participate in gas
exchange, approximately 300 ml in normal
lungs.
--ANATOMIC DEAD SPACE: Volume of the
conducting airways, approximately 150 ml
--PHYSIOLOGIC DEAD SPACE: The volume
of the lung that does not participate in gas
exchange. In normal lungs, is equal to the
anatomic dead space (150 ml). May be greater
in lung disease.

16. FORCED EXPIRATORY VOLUME in 1
SECOND (FEV1): The volume of air that
can be expired in 1 second after a maximal
inspiration. Is normally 80% of the forced
vital capacity, expressed as FEV1/FVC. In
restrictive lung disease both FEV1 and
FVC decrease , thus the ratio remains
greater than or equal to 0.8. In obstructive
lung disease, FEV1 is reduced more than
the FVC, thus the FEV1/FVC ratio is less
than 0.8.

17. Atmospheric pressure
Free molecules
Gravity of earth
Dependent on
location (height)
Normal atmospheric
pressure (sea level) =
760 mm Hg

18. Partial pressure
Atm Pressure: 760 mm Hg
Dalton’s law
Nitrogen= 597 mm Hg
Oxygen= 159 mm Hg
Carbondioxide:
Water:

19. Partial pressure
Henry’s law: when a mixture of gases
is in contact with a liquid, each gas
will dissolve in the liquid in proportion
to its partial pressure gradient
H2O H2O

20. Gas solubility
CO2 20 times more soluble in water
than O2
N2 almost insoluble
H2O H2O H2O
Carbondioxide Oxygen Nitrogen

21. External respiration (in lungs)
pO2= 104
mm Hg
pCO2= 40
mm Hg
Alveoli Capillaries
pO2= 40
mm Hg
pCO2= 45
mm Hg
pO2= 104
mm Hg
pCO2= 40
mm Hg
pO2= 104
mm Hg
pCO2= 40
mm Hg

22. Internal respiration (in tissue)
pO2= 100
mm Hg
pCO2= 40
mm Hg
Capillaries Tissue
pO2< 40
mm Hg
pCO2> 45
mm Hg
pO2= 40
mm Hg
pCO2= 45
mm Hg
pO2= 40
mm Hg
pCO2= 45
mm Hg

23. Oxygen transport
1.5 % dissolved
98.5 % bound to
haemoglobin
Iron in Hb binds
to oxygen
4 O2 molecules
per Hb molecule

24. Carbondioxide transport
7-10 % dissolved in plasma
22 % bound to Hb
70 % transported as HCO3
-
COCO22 + H+ H22OO HH22COCO33 HH++
+ HCO+ HCO33
--

25. Regulation of breathing
DRG stimulates
inspiratory
muscles, 12-15
times / minute
VRG active in
forced breathing
Pontine respiration
centre: finetuning
of breathing /
inhibits DRG

26. Factors that influence
respiration
Hypothalamus (emotions / pain)
Cortex (voluntary control)
Chemoreceptors:
Central (in medulla oblongata): responds to CO2
↑
CO2 passes blood brain barrier
CO2 + H2O H2CO3 H+
+ HCO3
-
H+
stimulates receptors  breathing depth ↑ + rate ↑
Peripheral (in aortic / carotid bodies):
responds when O2 < 60 mm Hg  increase ventilation
Responds to pH ↓  increase ventilation

27. Factors that influence
respiration
Marieb, Human Anatomy & Physiology, 7th
edition

28. Overview
Breathing:
Inspiration: contraction muscles  thorax expansion  air
inflow
Expiration: relaxation  recoil lungs  air outflow
Different lung volumes and capacities
External respiration:
Gas exchange following partial pressure gradient
Internal respiration
Gas exchange following partial pressure gradient
Gas transport
O2 mainly bound to Hb
CO2 mainly transported as HCO3
-
Regulation of breathing
Respiratory centres
Chemoreceptors

29. THANK YOU