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1. -RESPIRATORY
SYSTEM
-Dr Nisar Ahmed Arain
Assistant Professor
Anesthesia/Critical care/ER

2. -RESPIRATORY SYSTEM
-Respiration:-It is the process of exchanging gases
between the atmosphere and body cells,
This consist of following events
--a-Ventilation – Air in and out of lungs
--b-External respiration:-
--c-Transport of gases:-
--d-Internal respiration:-Blood and tissues
--e-Cellular respiration:-Oxygen and carbon dioxide

3. -RESPIRATORY SYSTEM
-STRUCTURES
--1-NOSE
(nares)
--Nasal cavity separated from
a-cranial cavity
b-oral cavity
c-ethmoid
d-maxilla
--Nasal septum
a-meatus
b-superior, middle and inferior cilia (They moves
mucus
and arrested particles towards pharynx
--2-PHARYNX
smell, conducts air, entraps particles, moistens
and heats air

4. -RESPIRATORY SYSTEM
-STRUCTURES contd.
--3-LARYNX
--Vocal cords, Epiglottis, and cartilage
-4-TRACHEA
-Cartilage, Muscles, and elastic Rings
--5-BRONCHIAL TREE
a-RIGHT AND LEFT main stem bronchi
b-Secondary Lobar:-Three on right and Two on the
left
c-Tertiary:-Ten on the Right and Eight on the Left
d-Terminal:-50 to 80 with in each lobe of lung
e-Respiratory:- 2 to 3 branches from each terminal
alveolar ducts---These branches terminates into
Sacs---Ultimately hey terminate into Alveoli

5. -RESPIRATORY SYSTEM ORGANS OF THE RESPIRATORY SYSTEM

6. -RESPIRATORY SYSTEM -UPPER RESPIRTORY TRACT

7. -RESPIRATORY SYSTEM -MUCOUS IN RESPIRATORY TRACT
--Cilia move mucous and trapped particles from the nasal cavity to the pharynx
--Trachea—Bronchi—Bronchioles—Ciliated Pseudo columnar Epithelium
--Goblet cells here secretes Mucous

8. -RESPIRATORY SYSTEM -SINUSES
--Air Filed spaces in Maxillary, Frontal, Ethmoid and Sphenoid bones. Functions are to reduce
the weight of the skull and serve as a resonant chambers that affect the quality of the voice

9. -RESPIRATORY SYSTEM -LARYNX

10. -RESPIRATORY SYSTEM
-LARYNX contd.
--LARYNX:- This part is superior to the
Trachea and inferior to the pharynx
--It is composed of Muscles and Cartilage
--Cartilages are Thyroid, Cricoid, and Epiglottic
--Thyroid cartilage is superior to the Thyroid Gland
--Cricoid Cartilage is inferior to the Thyroid Gland
--Epiglottis is attached to the upper border of the
Thyroid Cartilage
-Anterior view
-Posterior view

11. -RESPIRATORY SYSTEM
-TRACHEA
--1-It lies anterior to the esophagus, located in the
thoracic cavity (Mediastinum)
--2-Trachea and Bronchi are supported with C-shaped
hyaline cartilage
--3-Posteriorly – incomplete rings contain Muscle and
connective tissue
--4-Carina – projection of the last tracheal ring, located
in the sagittal plane
(It is associated with the cough reflex)
--5-Splits into Right and Left main stem Bronchus

12. -RESPIRATORY SYSTEM
-TRACHEA AND BRONCHI
--1-Right main Bronchus is wider, shorter and runs
more vertically then the left
--2-Left main Bronchus passes inferiorly to the arch
of the aorta and anterior to the esophagus
--3-Lobar Bronchi – secondary branches two on the
left and three on the right.
--4-Tertiary Bronchi – several segments that branch
into 20 to 25 terminal Bronchioles
--5-Respiratory Bronchioles – contain 11 – alveolar
ducts and five to six alveolar sacs. Fully developed
by age 8 years, with 300 million alveoli

13. -RESPIRATORY SYSTEM
-TRACHEA
-CROSS SECTION OF TRACHEA -WALL OF TRACHEA

14. -RESPIRATORY SYSTEM
-BRONCHEAL TREE

15. -RESPIRATORY SYSTEM -ALVEOLI

16. -RESPIRATORY SYSTEM -LOCATION OF LUNGS

17. -RESPIRATORY SYSTEM
-MUSCLES OF THE THORACIC WALL
--1-PECTORAL MUSCLE:- Major and minor
--2-SUBCLAVIUS
--3-SERRATUS ANTERIOR:-Rotates the scapula and holds the
scapula against the thoracic wall.
--4-SCALENE MUSCLES:-From the neck to the1st and 2nd Ribs
They elevate the ribs during forced inspiration
--5-INTER COSTAL MUSCLES:-
a-EXTERNAL INTERCOSTAL MUSCLES:- These are muscles of
inspiration and they elevate the ribs during forced
inspiration
b-INTERNAL INTERCOSTAL MUSCLES:-These are muscles of
expiration
--6-INNERMOST INTERCOSTALS:-They lie deep and separated
from internal intercostals by nerves and vessels
--7-SUBCOSTAL MUSCLES:-They aid in elevation of ribs

18. -RESPIRATORY SYSTEM -TRANSVERSE SECTION OF LUNGS

19. -RESPIRATORY SYSTEM
-BREATHING MECHENISM
--Breathing or ventilation is the movement of air
from outside of the body into the bronchial
tree and the alveoli
-The actions responsible for these air movements
are inspiration, or inhalation, and expiration, or
exhalation

20. -RESPIRATORY SYSTEM -INSPIRATION
--Atmospheric pressure due to
the weight of the air is the
force that moves air into the
lungs
--At sea level
a-Atmospheric pressure is
760 millimeters of
mercury (mm Hg)
b-Moving the plunger of a
syringe causes air to
move in and out.
c-Air movements in and out
of the lungs occur in much
the same way
-Diaphragm
-Atmospheric pressure
of 760 mm Hg on the
inside
Air passage way
-Atmospheric
pressure of
760 mm Hg
on the outside

21. -RESPIRATORY SYSTEM -INSPIRATION
--Intra-alveolar pressure decreases to about 758 mm Hg as the
thoracic cavity enlarges due to the downward movement of
diaphragm caused by impulses carried by Phrenic Nerve
--Atmospheric pressure then forces air into the airways
-Atmospheric pressure
760 mm Hg
-Intra-alveolar
pressure
758 mm Hg
-Intra-alveolar
pressure
760 mm Hg
Diaphragm

22. -RESPIRATORY SYSTEM -MUSCLES OF INSPIRATION
Sternocleidomastoid
elevates sternum
Pectoralis minor
elevates ribs
Diaphragm
contracts more
Sternum moves
Up and out
External
intercostal
muscles pull
ribs up and out
-Diaphragm
contracts
Sternum
moves
Up and out
--Diaphragm
contracts
External
intercostal
muscles pull
ribs up and out

23. -RESPIRATORY SYSTEM -MAJOR EVENTS IN INSPIRATION

24. -RESPIRATORY SYSTEM
-EXPIRATION
--The forces responsible for normal resting expiration come
from elastic recoil of lung tissues and from surface tension
--These factors increase the intra-alveolar pressure about
1 mm Hg above atmospheric pressure forcing air out of the
lungs

25. -RESPIRATORY SYSTEM
-MUSCLES OF EXPIRATION
Posterior internal
intercostal muscles
pull ribs down and
inward
Diaphragm
Abdominal organs
force diaphragm
higher
Abdominal wall
muscles contract
and compress
abdominal organs
Diaphragm
Abdominal organs
recoil and press
diaphragm upward

26. -RESPIRATORY SYSTEM -MAJOR EVENTS IN EXPIRATION

27. -RESPIRATORY SYSTEM
-RESPIRATORY AIR
-Volumes and Capacities
--Different degrees of effort in breathing move
different volumes of air in and out of the lungs
--This measurement and process of calculation
of volumes of the lungs is called spirometry

28. -RESPIRATORY SYSTEM -RESPIRATORY VOLUMES
--TV—(Tidal volume) – Volume moved in or out during a normal breath
--IRV—(Inspiratory reserve volume) – Volume that can be inhaled during forced
breathing in addition to Tidal volume
--ERV—(Expiratory Reserve volume) – volume that can be exhaled during forced
breathing in addition to Tidal volume
--RV—(Residual volume) – volume that remains in lungs at all times
--FRV—(Functional residual capacity) = ERV + RV
--IC---(Inspiratory capacity) = TV + IRV
--VC—(Vital capacity) = TV + IRV + ERV
--TLC—(Total lung capacity) = VC + RV

29. -RESPIRATORY SYSTEM -RESPIRATORY VOLUMES

30. -RESPIRATORY SYSTEM -RESPIRATORY VOLUMES and CAPACITIES

31. -RESPIRATORY SYSTEM
-ALVEOLAR VENTILATION
-MINUTE VENTILATION
--Tidal volume multiplied by breathing
rate is called Minute ventilation
-ALVEOLAR VENTILATION
--Major factor affecting concentrations
of oxygen and carbon di oxide in the
alveoli
--It is volume of air that reaches alveoli
--Tidal volume minus physiological dead
space then multiplied by breathing rate

32. -RESPIRATORY SYSTEM
-NON RESPIRATORY AIR MOVEMENTS
--Air movements other than breathing are called
non respiratory movements
--They clear air passages, as in coughing and sneezing
or express emotions, as in laughing and crying

33. -RESPIRATORY SYSTEM
-CONTROL OF BREATHING
--Normal breathing is a rhythmic
involuntary act that continues
when a person is unconscious
--Respiratory muscles can be
controlled as well voluntary
muscles

34. -RESPIRATORY SYSTEM
-RESPIRATORY AREAS
--Groups of neurons in the brain stem
comprise the respiratory areas that
control breathing
--Impulses travel on cranial nerves and
spinal nerves causing inspiration and
expiration
--Respiratory areas also adjust the rate
and depth of breathing
--The respiratory areas include:-
a-Respiratory center of the Medulla
b-Respiratory group of the pons
Midbrain
Fourth
ventricle
Medullary
respiratory
center
Internal (expiratory)
intercostal muscles
External (inspiratory)
intercostal muscles
Diaphragm
Dorsal respiratory group
Ventral respiratory group
Medulla oblongata
Pons
Pontine respiratory
group

35. Pontine respiratory
group
Respiratory areas
Medullary respiratory center
Ventral
respiratory
group
Dorsal
respiratory
group
Nerve impulses Nerve impulses
Respiratory muscles
Basic rhythm
of breathing
Forceful breathing
-RESPIRATORY SYSTEM -RESPIRATORY AREAS

36. -RESPIRATORY SYSTEM -FACTORS AFFECTING BREATHING
--1-A number of factors affect breathing
rate and depth including
a-Partial pressure of oxygen(Pao2)
b-Partial pressure of carbon
dioxide(Pco2)
c-Degree of stretch of lung tissue
d-Emotional state
e-Level of physical activity
--2-Receptors involved are
f-Mecheno receptors and
g-Chemoreceptors
(1)-Central and
(2)-Peripheral
Medulla oblongata
Sensory nerve
(branch of
glossopharyngeal
nerve)
Carotid bodies
Common carotid
artery
Aortic bodies
Sensory nerve
(branch of vagus nerve)
Aorta
Heart

37. -RESPIRATORY SYSTEM
-FACTORS AFFECTING BREATHING
--Changes in blood pH, O2 and CO2
concentration stimulates chemo-
receptors
--Motor impulses can travel from the
respiratory center to the diaphragm
and external inter-costal muscles and
the contraction of these muscles
causes the lungs to expend by
stimulating Mecheno receptors
in the lungs
--Inhibitory impulses from the
mechanoreceptors pass back to the
respiratory center and prevent over
inflation of the lungs
Spinal cord
Motor pathways
Intercostal nerve
External intercostal
muscles
Rib
Diaphragm
Respiratory center
Sensory pathway
Vagus nerve
Phrenic nerve
Stretch receptors
Lung

38. -RESPIRATORY SYSTEM -FACTORS AFFECTING BREATHING

39. -RESPIRATORY SYSTEM
-ALVEOLAR GAS EXCHANGE
--The alveoli are the sites of the
vital process of Gas exchange
between air and the Blood

40. -RESPIRATORY SYSTEM -DIFFUSION ACROSS THE
RESPIRATORY MEMBRANE

41. -RESPIRATORY SYSTEM -THE DEAD SPACE
--It is that part of respiratory system through which inspiration and expiration occurs, But it does not
participate in gas exchange
IT IS FORMED AS:-
--1-ANATOMICAL DEAD SPACE:-
--It includes the airway passage from the Nasopharynx down to the respiratory bronchioles. It also includes
a-EQUIPMENT DEAD SPACE:--such as endotracheal tube and tubing distal to the Y – connector of the
anesthesia breathing circuits. It normally equals 150 ml of the respiratory passage in an average
adult i.e 2.2 ml/ Kg
b-ALVEOLAR DEAD SPACE:-It is the alveoli that are ventilated, but not Perfused.
it normally equals Zero
--2-PHYSIOLOGICAL DEAD SPACE:-
--Physiological = anatomical + alveolar
--Normally, the alveolar dead space = Zero
--so, Physiological dead space = anatomical dead space.
--The ratio of dead space (Vd) to tidal volume (V1) is more useful. Normally it is 0.3

42. -RESPIRATORY SYSTEM -FACTORS AFFECTING THE DEAD SPACE
--A-FACTORS INCREASING THE DEAD SPACE
--1-Upright posture
--2-Neck Extension
--3-Advanced age
--4-Positive pressure ventilation, PEEP, and increased airway pressure
--5-Anticholinergics which cause Broncho-dilatation
--6-Decreased Pulmonary perfusion e.g Pulmonary emboli or Hypotension
--7-Lung diseases such as emphysema or cystic fibrosa
--B-FACTORS DECREASING THE DEAD SPACE
--8-Supine posture
--9-Neck Flexion
--10-Intubation

43. -RESPIRATORY SYSTEM
-SHUNT
--DEFINATION:-
--It is the process where the desaturated mixed venous blood from the right
heart returns to the left heart without being Re-Saturated with Oxygen
in the lungs (i.e Right-to-Left-Shunt)
It dilutes and decreases arterial Oxygen content resulting in Hypoxemia
--TYPES
--Intrapulmonary shunts are either
--1-AN ABSOLUTE SHUNT:-It refers to anatomical shunts where V/Q is Zero
(i.e No Ventilation) This produces Hypoxemia which cannot be corrected
--2-A RELATIVE SHUNT:-It refers to areas of lung where there is less circulation
where V/Q ratio again is low.
This produces Hypoxemia which can be partially corrected by increasing
inspired oxygen concentration