Anatomy and Physiology of Respiration

8/6/2019 Anatomy and Physiology of Respiration

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Anatomy and Physiology of

Respiration


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RESPIRATORY SYSTEM

Consists of - Nose

- Nasal Cavity

- Pharynx

- Larynx- Trachea

- Bronchi

- Lungs

the lungs have the terminal air sacs (or)alveoli


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RESPIRATION is the sum of processess by which an organnism meetsits requirement of oxygen and eliminates carbondioxide

Multicellular organs needs 2 systems to get enough O2

1.blood circulatory system - to carry O2 & CO22.respiratory system to load the blood with O2

- to remove excess CO2

TYPES OF RESPIRATION

1. External respiration (pulmonary ventilation) exchange of air

between the external environment and the pulmonary alveoli

2. Internal respiration (cell respiration, enzymatic oxidation)

- consumption of O2 by cells and the formation and liberation ofCO2

RESPIRATORY RATE

Varies with age at birth : 40-60/min

1st year : 25-35/min

2-4yrs : 20-30/min

5-14 yrs : 20-25/min

normal adult : 10-18 times/min


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RESPIRATORY SYSTEM

1.Lungs

the gas exchanging organs2.A pump that ventilates the lungs

i .chest wall & respiratory muscles

ii .respiratory centres in the brain stem

that control the respiratory muscles

-nerves that connect the brain to the

muscles


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FUNCTIONALLY the system consists of

two zones

1.Conducting zone

2.Respiratory zone

Conducting zone- trachea to terminal bronchioles

- nose to terminal bronchioles is known as dead

space

- no gaseous exchange take place

Respiratory zone

- the actual site of gas exchange take place

- composed of respiratory bronchioles

- alveolar ducts and alveoli


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THORACIC WALL(CHEST WALL) AND

RESPIRATORY MUSCLES

Consists ofposteriorly = 12 thoracic vertetbraelaterally = 12 pairs of ribs

anteriorly = sterum and costal cartilages

superiorly = supra pleural membrane

inferiorly = diaphragm

INTERCOSTAL SPACES

spaces between adjacent ribs and each contain 3

intrinsic muscles1.external intercostal muscles

2.internal intercostal muscles

3. inner most intercostal muscles (intercostalis)


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MUSCLES OF CHEST WALL

arranged in 3 layers for each intercostal space:

1.external intercostal muscle external layer

2.internal intercostal muscles middle layer3. inner most intercostal, subcostal, transversus thoracic

internal layer

Other muscles sub costalis

- sternocostalis

- levatores costarum


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1.External internal muscle directed forward and downward

- extends from the tubercle of the ribs posteriorly to the

costochondral junction anteriorly where the muscles isreplaced by an aponeurosis called anterior intercostalmenbrane

Action elevation of the ribs (inspiratory mscles)

Nerve supply corresponding intercostal nerves orthoracoabdominal nerves

2.Internal intercostal muscles directed downward and backward

from the subcostal groove of rib above to the upper border ofrib below

-extends from the medial end of the intercostal spaces to theangles of the ribs where the muscles is replaced by theposterior or internal internal costal membrane

Action muscles of expiration

Nerve supply - corresponding intercostal nerves or thoraco -abdominal nerves


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INNERMOST INTERCOSTAL MUSCLES (INTERCOSTALISINTIMI)

Directed downward and backward

Lies within the lateral wall of thorax

Arises from the inner lip of the costal groove above to the uppermargin of the rib below

Nerve supply and action same as internal intercostal muscle

OTHER MUSCLES

1.SUBCOSTALIS- arises from the lower margin of the ribs near their angles

- Inserted to the upper margins of 2nd or 3rd rib below

Action elevates the ribs

Nerve corresponding intercostal nerve

2.STERNOCOSTALIS (TRANSVERSUS THORACIC)

Arises from posterior surface of xiphoid process, body of sternum

Inserted into the internal surface of the 2nd to 6th costal cartilages

Action expiratory function.

Nerve corresponding intercostal nerves


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3.LEVATORES COSTARUM

- arises from the transverse processes of the 7th cervical to 11th

thoracic vertebeae

Each is inserted into the external surface of the subajacent rib,between the tubercle and angle

Action elevates the ribs

Nerve supply dorsal rami of 8th cervical,1st to 11th thoracicnerves

BLOOD SUPPLY

ARTERIAL SUPPLY - intercostal arteries anterior andposterior intercostal arteries

VENOUS DRAINAGE

intercostal veins

LYMPHATIC DRAINAGE

- anterior intercostal,

- posterior intercostal,

- phrenic (diaphragmatic nodes)


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RESPIRATORY MUSCLES

INSPIRATORY MUSCLES- QUIET INSPIRATION

1.diaphragm (most important m/s)

2.Internal intercostal muscle3.External intercostal muscle

DEEPER INSPIRATION

1.above muscles

2.Scalena muscles raise the 1st and 2nd ribs

3.Sternal head of sternomastioid4.Levatores costarum

5.Serratus posterior superior and serratus posterior inferior

6.Quadratus lumborum

FORCED INSPIRATION (Shortnessofbreath fromexertionordisease)

1.Above muscles plus 2.pectoralis major & minor3.trapezius, levator scapulae, rhomboideus

4.Erector spinae , deep muscles of back

5.Nostrils and glottis dilate rhythmically to easier entrance of air


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EXPIRATORY MUSCLES

QUIET EXPIRATION recoil of lungs and costal cartilages

DEEP EXPIRATION contraction of internal intercostal

muscles

DEEPER EXPIRATION aided by abdominalmuscles

- oblique and transverse abdominal muscles

- iliocostalis and latissimus dorsi


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DIAPHRAGM

Principle muscle of respiration

dome shaped, fibro-muscular partation between the thorax and

abdomen

Right dome overlies the liver ,at the level of 5th rib Slightly higher than the left

Pierced by structures passing between the thorax and abdomen

Composed of 2 parts muscular part and central part

muscular part is again divided into 3parts

a. sternal

b. costal part

c. lumbar or vertebral part


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Centralpart

-Muscular fibres converge radially to a strong, sheet like tendons

or aponeurosis called central tendon which is fused to fibrouspericardium

- No bony attachment

- Divides into 3 leaves-right, anteromedial and left

- Openings 3 major openings 1.vena caval opening (T8)

2.oesophageal (T10)

3.aortic opening(T12)

- 6 small openings

NERVE SUPPLY 1.phrenic nerve (C345)

2.lower 6 intercostal nerves


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TRACHEA

Trachea

Rt: bronchus

(p bronchus) Lt: bronchus


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Primary (Main/Principal) Bronchus

Rt.Primary bronchus

Wider, Shorter & moreVertical

gives off 3

i. Superiorlobar(secondary)

bronchusbefore entering the hilum oflung

ii. Middle

iii. Inferiorlobar

Lt.Primary bronchus

gives off 2


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Clinical application

Inhaled Foreign body

- tends to enter the

right primary bronchus

Carina

In case of Ca. involvolving

tracheobronchial lymphnode

Widening ofCarina can beseen during Bronchoscopy


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Secondary (Lobar) bronchus

Right

3 lobar bronchi

i.Superior lobar

( b/f entering the hilum)

On entering the hilum ii.Middle

iii.Inferior

Left 2 lobar bronchi

(on entering hilum)

i. Superior

ii.Inferior


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Tertiary (Segmental) bronchi and

Broncho pulmonary segments

Right side

Upperlobe

-3 Segmental or

Tertiary bronchi

Middlelobe

- 2 Segmental bronchi

Inferiorlobe

- 5 Segmental bronchi

Left side

Upperlobe

- 3 Seg. bronchi

- +Lingular

- 2 seg. bronchi

Inf.lobe- 5 segmental bronchi


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Bronchopulmonary segments Right

Upper lobe i. apical

ii. post.

iii. ant.

Middle lobe

i. lat.

ii. medial

Lower lobe

i. superior

(apical) ii. ant.basal

iii.medial basal

iv.lat.basal

v.post.basal

Left upper lobe

superior

inferior

Lingular

Apical

Lower lobe

postanterior


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Clinical applications

1.Knowledge of branching of bronchial tree is needed i. for appropriate posture of patient to promote the

postural drainage

ii. to locate the segment involved by radiography &

bronchoscopy

2.Bronchopulmonary segment is the smallest segment

which can be removed surgically


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Clinical

application

3. Aspiration pneumonia

4. Lung abscess

(In comatose or anaesthetized

patient) more common in

apical segment ofright

lowerlobe


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LUNGS

pair of respiratory organs situated in the pleural cavities separated by

mediastinum

conical in shape

each lung has an apex at the upper end

each lung has an apex at the upper end

right lungs weigh 625 gms

left lungs weigh 575 gms

3 borders - anterior- posterior

- inferior

2 surfaces costal fits the parts of thoracic wall

- medial a ) vertebral part applied on each side of the vertebral

bodies b ) mediastinal related to mediastinum


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Right lung

(hilum)

Vertebral surface

Mediastinal

surface


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Left lung

(hilum)

Vertebral

surface

Mediastinal

surface


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apex

Inferior border

Diaphragmatic surface

Ant. border


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Oblique fissure

Superior pul vein

Pulmonary artery

Main bronchus

Inferior pul. vein

Pulmonary ligament


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Transverse fissure

Oblique fissure

upper

mid

lower

Oblique

fissure

upper

lower


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FISSURES AND LOBES OF THE LUNGS

right lung is divided into 3 lobes superior, middle,inferior by 2 fissures oblique and horizontal

left lung is divided into 2 lobes by oblique fissure

BRONCHIAL TREE

trachea bifurcates at the level of T4 into right and left

main (primary) bronchi

main bronchus gives off a branch to each lobe of the lung,known as lobar or secondary bronchi 3 for the right and 2

for the left

each lobar bronchus subdivides into segmental or tertiary

bronchi, which supply the broncho pulmonary segments


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BLOOD SUPPLY

Bronchial arteries

2 on Lt. originate from Aorta

1 on RT. from .3rd right posterior intercostal artery

Run along bronchi Supply

- the bronchial tree from Carina to Respiratory bronchiole

- visceral pleura

Bronchial veins

drain from hilar region & visceral pleura

Into Azygos (Rt.) & Accessory hemiazygos (Lt.)


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Lymphatic drainage From superficial part

1.Superficial plexus (beneath visceralpleura)

to Bronchopulmonary nodes (at the hilum)

& Tracheobronchial nodes (at bifurcation)

From deeper part 2.Deep plexus (in submucosa)

drain along the bronchi & pulmon vessels

to Bronchopulmon.nodes

From .Bronchopulmonary to

-i. Tracheobronchial

-ii.Bronchomediastinal lymph trunks

Finally into junction of subclavian.& internaljugular veins at root of the neck

- Rt.lymph.trunk or Thoracic duct

Clinical application-Bronchogenic CA.

most common CA. in men

may metastasize to pleura,hilum of lung &

mediastinum via Lymph.

Common sites of metastasis

Brain, Bone,Lung &Adrenal

Supraclavicular Node- often becomes enlarged

in CA.bronchus


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NERVES SUPPLY OF THE LUNGS

Sympathetic

From T1 T5 segment of spinal cord

relay in upper thoracic ganglia

bronchodilator & vasoconstrictor

Parasympathetic

From vagus nerve bronchoconstrictor, secretomotor & vasodilator

afferent fibres are responsible for cough reflex


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PLEURA

-serous membrane covering the lungs

- two pleural sacs (one on each side)

- each pleural sac is invaginated by the lung

-2 layers - outer parietal

- inner visceral pleura-in between two layers is the potential space called

pleural cavity, contains a film of serous fluid

-parietal layer lines the thoracic wall and mediastinum

- visceral pleural applied to the lung substance, covers the

surfaces and lines the fissures


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PARIETAL PLEURA costal pleura

- mediastinal pleura

- diaphragmatic pleura

- cervical pleura

COSTAL PLEURA lines the sternum, ribs, intercostal spaces and sides of

the bodies of the vertebrae

Anteriorly and posteriorly continous with the mediastinal pleura

Inferiorly - with the diaphragmatic pleura

MEDIASTINAL PLEURA lines the mediastinal surface of the lungs

DIAPHRAGMATIC PLEURA covers most of the diaphragm except the

central tendons

CERVICAL PLEURA rounded extension of the parietal pleura which passes

through the superior of the thorax into the root of the

neck


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PLEURAL RECESS parts of the pleura cavity which are not occupied bylung tissue except in inspiration

1.costo mediastinal recess : along the anterior margin of pleura

2. costo diaphragmatic recess : along the inferior margin of pleura3.retro oesophageal recess : the reflexion of mediastinal pleura behind the

oesophagus

4. infra pericardial recess : behind the inferior venacava

BLOOD SUPPLY AND NERVE SUPPLY

Parietalpleura - branches from posterior intercostal, internal thoracic,musculophrenic and superior phrenic arteries

its veins join the systemic veins in the neighbouring parts of chest wall

Nervesupply costal and peripheral parts of diaphragmatic pleura aresupplied by intercostal nerves

- mediastinal and central part of diaphragmatic pleura phrenic nerves

Visceralpleura bronchial artery

- venous drainage is by pulmonary vein

Nervesupply sympathetic through pulmonary pleuxus


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PLEURA


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a.

b.

c.

d.

cevical

mediastinal

Costal

diaphragmatic


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VISCERAL PLEURAL

Covers the lung closely except around the hilum

It extends into the depth of fissures of the lung

Where does the parietal and viscera meet ?

Two layers b/c continuous with one another at the hilum

What is the Pulmonary ligament ?

Extension of pleural reflexion like a cuff below the hilum


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Clinical Applications When the Pleural cavity is filled with

Fluid - Hydrothorax

Air- Pneumothorax; Blood - Haemothorax

Pus - Empyema

Irritation of parietal pleura - painful

From Costal & peripheral diaphragmatic pleura

Chest or Abdominal wall (intercost.n)

Fr.Mediasti.& central diaphragmatic pleura (phrenic)-Neck & shoulder

Costo diaphragmatic recess may get involved in

surgical operation around kidney (esp.left upper pole)


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MECHANICS OF RESPIRATION

Study of mechanicals factors involved in ventilation

Study of movements of diaphragm and thoracic cage during respiration

When chest cavity expands the air pressure inside is lowered, the greaterpressure outside causes a flow of air into the lungs

When the chest cavity shrinks the increased pressure inside

causes some contained air to flow out

RESPIRATION

Is the sum of processes by which an organism meets its requirement ofoxygen and eliminates carbon dioxide

PULMONARY VENTILATION

movement of gases in and out of lungs.


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The lungs and chest wall are elastic structures and have a

tendency to recoil

There is a thin layer of fluid between the lungs and chest wall,

the pressure in that space is known as intrapleural pressure

subatmospheric

Intra pulmonary pressure pressure inside the lungs


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INSPIRATION

- active process

- When the inspiratory neurones discharge,

- the nerve to inspiratory muscles are excited

- Contraction of the inspiratory muscles (diaphragm & external intercostal)

causes an increase in the intrathoracic volume

- The intrapleural pressure which is about -2.5mm Hg at the start of

inspiration decreases to -6mm Hg

- The lungs are expanded so that the intrapulmonary pressure decreases

- When intrapulmonary pressure becomes lower than the atmospheric

pressure, air enters the lungs causing a rise in intrapulmonary pressure

- Intrapulmonary volume increases during inspiration

- When the inspiration neurone discharge stops, it is the end of inspiration


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EXPIRATION

When the inspiratory neurone discharge stops, it is the end of inspiration

The lung recoil pulls the chest back to expiratory position ,where the recoil

pressures of lungs and chest wall balance each other

Expiration is a passive process, that no expiratory muscles are working

There is some contraction of the inspiratory muscles in the early part ofexpiration

This contraction exerts a braking action on the recoil forces slows

expiration

During expiration, intrapleural pressure rises from -6mmHg to-2.5 mmHg

Intrapulmonary pressure also rises ,as the lungs recoil

When it exceeds the atmospheric pressure ,air moves out of the lungs

causing a fall in intrapulmonary volume and intrapulmonary pressure

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Anatomy and Physiology of Respiration

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