Respiratory system part 1

Respiratory System

• Presented By – Prof.Dr.R.R.Deshpande

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05/02/23 Prof.Dr.R.R.Deshpande 1

05/02/23 Prof.Dr.R.R.Deshpande 205/02/23 Prof.Dr.R.R.Deshpande 2

Sharir Kriya -- Paper I –Part B –Point 3

• Presented By – • Prof.Dr.R.R.Deshpande (M.D in Ayurvdic

Medicine & M.D. in Ayurvedic Physiology)• www.ayurvedicfriend.com• Mobile – 922 68 10 630• [email protected]

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Sharir Kriya Paper 1-Part B –Set 3

• Presented By –

• Dr.R.R.Deshpande

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Respiration

• Every organism requires a constant supply of energy.

• It is obtained from the oxidation of food molecules in every cell.

• In animals, the oxygen is supplied by a specialized system called as Respiratory System


Functional anatomy of respiratory system

• Respiration in man occurs by lungs. So the process is termed as Pulmonary Respiration.

• Respiratory system consists of the following organs.


Conducting organs

• 1) Nostrils & nasal chamber

• 2) Nasopharynx

• 3) Larynx

• 4) Trachea


Main organs

• 5) Bronchi & bronchioles

• 6) Lungs & alveoli (air sacs)


1) Nostrils & Nasal Chamber

• A pair of nostrils leads to nasal chamber / cavities.

• It is divided into right & left halves by a cartilage.

• It is differentiated in 3 parts as follows• Vestibular• Respiratory• Olfactory


Vestibular Part

• It is the anterior most region of the nasal chamber lined by mucus & hairs.

• So dust particles are filtered & settled or caught in the mucus


Respiratory Part

• It is the middle air conducting chamber with rich supply of blood capillaries

• This provides moisture by which air is made warm or cool & moist


Sensory or Olfactory Part

• It is internally lined by olfactory epithelium for detection of smell.

• Vibrating cilia also push dust particles towards pharynx where it is swallowed into esophagus.


Respiratory System


2) Nasopharynx

• Nasal chamber opens into ---

• Nasopharynx where respiratory opening (glottis) & oesophageal opening (gullet) cross each other forming pharyngeal chisma.


3) Larynx (Sound Box / Adams Apple)

• It is located in the neck region ventral to oesophagus.

• It contains vocal cords for producing sound of different pitch.

• Its anterior opening (glottis) is guarded by a cartilaginous flap epiglottis, which prevents the entry of food particles while swallowing.


4) Trachea (Wind Pipe)

• It is about 11 cm long & 2. 5 cm broad tube supported by 16 - 20 complete C shaped cartilage rings which avoid the collapsing of trachea.

• It is internally lined by ciliated mucus membrane which propel dust particles towards larynx to oesophagus where they are swallowed.


5) Bronchi & Bronchioles

• The distal end of trachea bifurcates into 2 bronchi. • Each bronchus is supported by complete

cartilaginous rings.• Each bronchus divide & re divide to form branching

system of bronchioles. • Cartilage rings are absent in bronchioles.• Each bronchiole terminates in alveolar duct.

Bronchial Asthama


Bronchial Asthama


Bronchiectasis


Bronchiectasis



6) Lungs with Alveoli

• A pair of conical brownish gray, highly elastic & spongy organs situated in thoracic cavity by the side of the heart.

• Lungs are protected by rib - cage & intercostals muscles of thorax on lateral side & dome shaped muscular partition diaphragm on posterior side


6) Lungs with Alveoli

• Lungs are covered by double pleural membranes - outer parietal & inner visceral pleural membranes.

• Inter pleural cavity filled by Pleural fluid.


Lungs

• Right lung is divided into anterior, middle & posterior lobes

• Left lung is divided into 2 lobes - ant. & post. lobes


Bronchus – Bronchiole - Alveoli


Alveoli / Air - Sacs

• The spongy nature of lungs is due to alveoli or air - sacs.

• Lungs contain about 30 millions of air sacs arranged like bunches of grapes.


• The walls of alveoli are very thin & composed of one cell thick layer.

• The alveoli are surrounded by fine network of capillaries to ensure an easy exchange of oxygen & carbon dioxide.




• Pulmonary artery brings deoxygenated blood from the right ventricle of the heart to lungs

• Pulmonary vein carries oxygenated blood from the lungs to the left auricle of the heart



• Inflation & deflation of the lungs ensures that regular exchange of gases takes place between the alveoli & the external air.

• This is dependent upon the arrangement of the pleura, the contraction & relaxation of the muscles of respiration & the elastic connective tissue.

Emphysema



Muscles of Respiration

• The expansion of the chest during inspiration occurs as a result of muscular activity, partly voluntary & partly involuntary.

• The main muscles of respiration in normal quiet breathing are the intercostal muscles & the diaphragm.

• During difficult or deep breathing they are assisted by the muscles of the neck, shoulders & abdomen


1) Intercostal Muscles

• There are eleven pairs of intercostal muscles that occupy the space between the twelve pairs of ribs.

• They are arranged in 2 layers, the external & Internal intercostal muscles.



• The first rib is fixed.

• Therefore, when the inter costal muscles contract, they pull all the other ribs towards the first rib.

• Because of the shape of the rib they move outwards when pulled upwards.


• In this way the thoracic cavity is enlarged anterio - posterior & laterally.

• The inter costal muscles are stimulated to contract by the inter costal nerves



2) Diaphragm

• The Diaphragm is a dome shaped structure separating the thoracic & abdominal cavities.

• It forms the floor of the thoracic cavity & roof of the abdominal cavity

• Consists of a central tendon from which muscle fibers radiate to be attached to the lower ribs & sternum & to the vertebral column by 2 cura


2) Diaphragm• When the muscle of the Diaphragm is relaxed, the central

tendon is at the level of the 8th thoracic vertebra.

• When it contracts, its muscle fibres shorten & the central tendon is pulled downward enlarging the thoracic cavity in length.

• This decreases the pressure in the thoracic cavity & increases it in the abdominal & pelvic cavities.

• • The Diaphragm is supplied by the phrenic nerves.

Costo Phrenic angle



Muscles of Respiration

• The intercostal muscles & the Diaphragm contract simultaneously

• This ensures the enlargement of the thoracic cavity in all direction.

• From back to front, side to side & up to bottom.


Cycle of Respiration

• This occurs 16 to 18 times / min. & consists of 3 phases.

• 1) Inspiration, 2) Expiration, 3) Pause

• As described previously, the visceral pleura is adherent to the lungs & the parietal pleura to the inner wall of the thorax & to the diaphragm.

• Between them there is a thin film of serous fluid.


Important steps in Respiration Process

• 1) Ventilation

• 2) Diffusion

• 3) Perfusion


Ventilation

• This is the rate at which air enters or leaves the lungs• It is of 2 types --Pulmonary ventilation - This is the

volume of air, moving in & out of respiratory tract in a given unit of time during quite breathing.

• This is also called as minute ventilation or Respiratory Minute Volume (RMV). Pulmonary ventilation is a cyclic process


Pulmonary Ventilation


Alveolar ventilation

• This is the amount of air utilized for gaseous exchange every minute.


Inspiration

• When the capacity of the thoracic cavity is increased by simultaneous contraction of the intercostal muscles & the diaphragm, the parietal pleura moves with the wall of the thorax.


Inspiration

• This reduces the pressure in the pleural cavity to a level considerably lower than atmospheric pressure.

• The visceral pleura follows the parietal pleura. • During this process, the lungs are stretched & the

pressure within the alveoli & in the air passages is reduced, drawing air into the lungs in an attempt to equalize the atmospheric & alveolar air pressures.


Inspiration

• This process of inspiration is active because it requires expenditure of energy for muscle contraction

• The negative pressure created in the thoracic cavity

• This helps venous return to the heart • This is known as the respiratory pump


Expiration

• Relaxation of the intercostal muscles & Diaphragm results in downwards & inward movement of the rib cage & elastic recoil of the lungs.


Expiration

• As this occurs, the pressure of gases inside the thorax exceeds that in the atmosphere & therefore air is expelled from the respiratory tract.

• The lungs still contain some air & are prevented from complete collapse by the intact pleura.

• This process is passive as it does not require the expenditure of energy.


Pause

• After expiration there is a pause before the next cycle begins.


Physiological Variables Affecting Respiration

• Elasticity

• Loss of elasticity of the connective tissue in the lungs necessitates forced expiration & increased effort on inspiration


Physiological Variables Affecting Respiration

• Compliance• This is a measure of the distensibility of the lungs i.e.

the effort required to inflate the alveoli.

• When compliance is low, the effort needed to inflate the lungs is greater than normal. eg. in some diseases where elasticity is reduced or when insufficient surfactant is present


Changes in Thoracic Cavity


Airflow Resistance

• When this is increased eg. in broncho constriction, more respiratory effort is required to inflate the lungs.

• Lung function tests are carried out to determine respiratory function & are based on the parameters outlined above.


Composition of Air

• Atmospheric pressure at sea level is 760 mmHg.

• With the increase in height above sea level, atmospheric pressure is progressively reduced & at 18, 000 ft it is about half that at sea level.

• Under water, pressure increases by approximately 1 atmosphere per 10 m below sea level.


Composition of Air

• Air is a mixture of gases, nitrogen, oxygen, carbon dioxide, water vapour & small quantities inert gases


The Composition ofInspired & Expired Air


Parietal Pressure of Gases

• Each gas in the mixture exerts a part of the total pressure proportional to its concentration, i.e. the partial pressure.

• This is denoted as PO2, PCO2.


Parietal Pressure of Gases


Alveolar air

• The composition of alveolar air remains fairly constant & is different from atmospheric air.

• It is saturated with water vapor & contains more carbon dioxide & less oxygen


Alveolar air

• Saturation with water vapor provides 47 mmHg thus reducing the partial pressure of all the other gases present.

• Gaseous exchange between the alveoli & the blood stream (external respiration) is a continuous process as the alveoli are never empty so it is independent of the respiratory cycle.

• During each inspiration only some of the alveolar gases are exchanged.


Expired Air

• This is a mixture of alveolar air & atmospheric air in the dead space.

• Its composition is shown in the table above.


Diffusion of Gases

• Exchange of gases occurs when a difference in partial pressure exists across semi permeable membranes.

• Gases move by diffusion from the higher concentration to the lower concentration until equilibrium is established


Diffusion of Gases

• Atmospheric nitrogen is not used by the body so its partial pressure remains unchanged & is the same in inspired & expired air, alveolar air & in the blood


External Respiration

• This is exchange of gases by diffusion between the alveoli & the blood.

• Each alveolar wall is one cell thick & is surrounded by a network of tiny capillaries.

• The total area for gas exchange in the lungs is 70 to 80 sq. meters.



• Carbon dioxide diffuses from venous blood along its concentration gradient into the alveoli until equilibrium with alveolar air is reached



• When blood leaves the alveolar capillaries, the processed oxygen diffuses from the alveoli into the blood.

• The slow flow of blood through the capillaries increases the time available for diffusion & carbon dioxide concentrations are in equilibrium with those of alveolar air.


External respiration – the entire change of gases between air & the

alveoli & the blood capillaries


Internal Respiration

• This is exchange of gases between blood in the capillaries & the body cells.

• When there is a difference in partial pressures oxygen diffuses outwards from the arterial end of capillaries into the surrounding extracellular fluid then through cell walls


Internal Respiration

• The process involved is that of diffusion from a higher concentration of oxygen in the blood to a lower concentration in the cells, i.e. the concentration gradient.

• Carbon dioxide diffuses from the cells into the extracellular fluid then the bloodstream towards the venous end of the capillary.


Internal respiration – Exchange of gases between capillaries &

the tissues.


O2 & CO2 carriage by blood

• Transport of Gases• 1) Transport of oxygen• O2 is transported from lungs to the tissues,

through arterial blood.• Transport occurs by 2 methods.• a) Oxyhaemoglobin Form• 98% of O2 is transported by binding with

Haemoglobin & forming Oxyhaemoglobin.


Formation of oxyhaemoglobin


Clinical Application

• In Anaemia / Co poisoning, O2 transport becomes less. This is called as 'Anaemic Hypoxia'.

• Hb4O8 → Oxyhemoglobin• Oxyhemoglobin is formed at lungs, then

transported to tissues.• At the tissue, O2 is liberated & Hb is made

free.


O2 Dissociation curve

• It is S - shaped curve. At PO2 - 40 mm Hg. Curve is very sharp, indicating maximum dissociation of O2 from Hb at tissue level.

• Curve shift to the right (Bohr’s effect) when PCO2 increases, H+ ion increases & temperature increases.

• Shift to the left occurs, when PCO2 ↓, H+ ions ↓ & temperature ↓.


b) Dissolved form

• Very little quantity of oxygen (2 %) is transported in dissolved form.

• The reason for this is solubility of O2 is very poor.


2) Transport of CO2

• CO2 is transported from tissues to lungs, through venous blood.

• CO2 transport occurs in the following 3 ways.• a) Bicarbonate form• Major quantity of CO2 (93%) is transported by this

method. • Near tissue CO2 combines with the H2CO3, which

dissociated to form H+ & HCO3 -


2) Transport of CO2

• These bicarbonates are transported to lungs. Near lungs opposite

• reaction occurs & CO2 & water vapour is liberated, which is thrown

• out through expiration. These bicarbonates These Bicarbonates are transported to lungs. Near lungs opposite reaction occurs & CO2 & water vapour is liberated, which is thrown out through expiration.


2) Transport of CO2

• b) Carbamino compound• CO2 combines with plasma proteins to form

carbamino proteins (plasma)• CO2 also combines with Hb to form

carbamino - hemoglobin (in RBC’s)• These compounds are brought to the lung &

CO2 is liberated from them


2) Transport of CO2

• c) Dissolved form• Less quantity of CO2 is dissolved in plasma &

red cell & is transported to the lungs through venous blood.

• Near lung CO2 is given out.


Clinical Application

• When acidic metabolites accumulate, condition is called as ‘acidosis’ this may be due metabolic or respiratory or renal causes.

• Inj. Sodibicarb is used in this situation


Regulation of Respiration

• 1) Nervous Control

• 2) Chemical Control

Control of Respiration



Nervous Regulation


Functions of centers

• 1) DRGN - inspiratory centre• Main centre to regulate the respiration. They

produce action potential.

• Centre is connected to spinal cord, phrenic nerves, intercostal nerves & to inspiratory muscles.


DRGN - inspiratory centre

• When signals are sent to inspiratory muscles they contract & inspiration occurs when centre stops functioning expiration occurs passively.

• In quite respiration, only this centre is active.


2) VRGN - Expiratory centre

• Centre is connected to expiratory muscles (internal intercostal & abdominal muscles)

• It works only during exercise, reciprocal to DRGN (during exercise CO2 ↑, H+ ion ↑, formation of lactic acid & it is expelled out)


Functions of centers

• 3) Apneustic centre• It is connected to inspiratory centre &

pneumotaxic centre.• 4) Pneumotaxic centre• It is also connected to inspiratory & apneustic

centre.• Last 2 centres maintain rhythmic function of

DRGN


Different reflexes to control the process of Respiration

• 1) Herring, Breuer’s reflex (inflation reflex)• In the wall of Bronchi & pleura, stretch receptors are

present.• When inspiration takes place & chest expands, these

receptors are stimulated afferent impulses via vagus nerve go to DRGN which causes its inhibition. This reflex requires tidal volume of 1. 5 lit.

• So this reflex has no role in quiet respiration. It works only during exercise.


2) Role of ‘J’ receptors

• Special Nerve endings are located between alveolus & pulmonary capillary.

• They are stimulated by pulmonary oedema & send afferent impulses through vagus to the Respiration


Respiration Control

• 3) Lung irritant receptors • Located in bronchi irritant substances

stimulates these receptors & R. R.

• 4) Coughing reflex - Foreign particles in respiratory tract cause cough reflex.


Respiration Control

• 5) Sneezing reflex - Irritation of nasal mucosa causes sneezing reflex.

• 6) Deglutition reflex - at the time of pharyngeal stage of deglutition, respiration stops temporarily (epiglottis )


Control of cerebral cortex

• Higher centers can alter the act of respiration (Voluntary Control)


Chemical regulation of Respiration

• 1) Role of CO2• Accumulation of CO2 increases R. R. • Peripheral chemoreceptors are located in carotid

body & aortic bodies. • These are sensitive for CO2, H+ ions & lack of O2 • CO2 stimulates the chemoreceptors afferent

impulses go via 9th & 10th cranial N. which stimulates DRGN & R. R.


Chemical regulation of Respiration

• 2) Role of H+ ions• Excess H+ ions in the blood also stimulate the

respiration.• 3) Role of lack of O2• When PO2 is less than 60 mm of Hg. Afferent

impulses go to DRGN & R. R.

• Important note - CO2 is more potent stimulus for respiration than lack of O2.


Functions of Respiration

• 1) To supply O2 & remove CO2 from the body.• 2) To regulate hydrogen ion concentration of

the blood.• 3) To increase arterial O2 tension.• 4) To help in the regulation of the body

temperature

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Respiratory system part 1