respiratory system and mechanisms

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Respiratory system and its mechanisms : 

presentation Respiratory system and its mechanisms

Respiratory system and mechanism contents : 

Respiratory system and mechanism contents Introduction on respiratory system Upper respiratory tract Bronchial tree Bronchopulmonary segments Muscles of respiration Movement of chest wall Surface anatomy of the lungs Mechanics of rspiation Lung volumes Compliance of the lungs and chest wall Work of breathing Postural relationship Applied part

Introduction respiratory system : 

Introduction respiratory system Respiratory system extracts oxygen from the atmosphere , and the body utilizes the oxygen and produce CO2as a result of metabolism

The Respiratory System : 

The Respiratory System Basic functions of the respiratory system Breathing (Pulmonary Ventilation) – movement of air in and out of the lungs Inhalation (inspiration) draws gases into the lungs. Exhalation (expiration) forces gases out of the lungs. Non –pulmonary functions: Gas Conditioning – as gases pass through the nasal cavity and paransal sinuses, inhaled air becomes turbulent. The gases in the air are • warmed to body temperature • humidified • cleaned of particulate matter Protects respiratory surfaces Site for olfactory sensation Secretes pulmonary alveolar macrophages Functions of pulmonary circulation Endocrine functions .

Respiration processes : 

Respiration processes Respiration – four distinct processes must happen Pulmonary ventilation – moving air into and out of the lungs External respiration – gas exchange between the lungs and the blood Transport – transport of oxygen and carbon dioxide between the lungs and tissues Internal respiration – gas exchange between systemic blood vessels and tissues

Respiratory organ : 

Respiratory organ Respiratory organs Nose, nasal cavity, and paranasal sinuses Pharynx, larynx, and trachea Bronchi and smaller branches Lungs and alveoli

Organ of the respiratory system : 

Organ of the respiratory system

The Nose : 

The Nose Provides an airway for respiration Moistens and warms air Filters inhaled air Resonating chamber for speech Houses olfactory receptors Skin is thin – contains many sebaceous glands

The Nasal Cavity : 

The Nasal Cavity External nares – nostrils Divided by – nasal septum Vestibule - anterior opening Continuous with nasopharynx Two types of mucous membrane Olfactory mucosa - Near roof of nasal cavity, houses olfactory (smell) receptors Respiratory mucosa - Lines nasal cavity

Nasal Conchae : 

Nasal Conchae 3 paired bony projections along the lateral walls of the nasal cavity Superior and middle nasal conchae - part of the ethmoid bone Inferior nasal conchae - separate bone Function - Particulate matter deflected to mucus-coated surfaces

The Paranasal Sinuses : 

The Paranasal Sinuses Figure 7.11a, b

The Pharynx : 

The Pharynx Funnel-shaped passageway Connects nasal cavity and mouth Shared by the digestive and respiratory systems Divided into three sections by location Nasopharynx – superior portion, Oropharynx – continuous with the oral cavity Laryngopharynx – between the hyoid bone and the esophagus

The Nasopharynx : 

The Nasopharynx Superior to the point where food enters Only an air passageway Closed off during swallowing Epithelium consists of ciliated pseudostratified epithelium that moves mucus

The Oropharynx : 

The Oropharynx Arch-like entranceway – fauces Extends from soft palate to the epiglottis Epithelium - stratified squamous epithelium Two types of tonsils in the oropharynx Palatine tonsils – in the lateral walls of the fauces Lingual tonsils – covers the posterior surface of the tongue

The Laryngopharynx : 

The Laryngopharynx Passageway for both food and air Epithelium - stratified squamous epithelium Continuous with the esophagus and larynx

The Larynx : 

The Larynx Prevent food and drink from entering the trachea Passageway for air Produces Sound It connects the pharynx to the trachea Epithelium of the larynx Stratified squamous – superior portion Pseudostratified ciliated columnar – inferior portion

Nine Cartilages of the Larynx : 

Nine Cartilages of the Larynx Thyroid cartilage - shield-shaped, forms laryngeal prominence (Adam’s apple) Three pairs of small cartilages Arytenoid cartilages Corniculate cartilages Cuneiform cartilages Epiglottis - tips inferiorly during swallowing

The Larynx : 

The Larynx Vocal ligaments of the larynx Vocal folds (true vocal cords) - act in sound production Vestibular folds (false vocal cords) - no role in sound production Voice production Length of the vocal folds changes with pitch Loudness depends on the force of air across the vocal folds

The Trachea : 

The Trachea Descends into the mediastinum C-shaped cartilage rings keep airway open Carina - marks where trachea divides into two primary bronchi Epithelium - pseudostratified ciliated columnar

The Trachea : 

The Trachea Figure 21.7a, b

Bronchi in the Conducting Zone : 

Bronchi in the Conducting Zone Bronchial tree - extensively branching respiratory passageways Primary bronchi (main bronchi) Largest bronchi Right main bronchi - wider and shorter than the left Secondary (lobar) bronchi Three on the right Two on the left Tertiary (segmental) bronchi - branch into each lung segment Bronchioles - little bronchi, less than 1 mm in diameter Terminal bronchioles - less than 0.5 mm in diameter

Lobes and Surfaces of the lungs : 

Lobes and Surfaces of the lungs Right lung has three lobes Left lung has two lobes Concavity on medial surface = cardiac notch Bronchi enter the lungs at the hilus

The Pleurae : 

The Pleurae A double-layered sac surrounding each lung Parietal pleura Visceral pleura Pleural cavity - potential space between the visceral and parietal pleurae Pleurae help divide the thoracic cavity Central mediastinum Two lateral pleural compartments

Mediastinal surface of the lungs : 

Mediastinal surface of the lungs

Slide 26: 

Alveolar walls Capillary walls

Bronchopulmonary segments : 

Bronchopulmonary segments

Mechanics of breathing : 

Mechanics of breathing The physical movement of air into and out of the lungs consisting of inspiration and expiration processess

Inhalation or inspiration : 

Inhalation or inspiration inspiration is an active process,thoracic cavity changes in size- how? Phrenic nerve stimulation causes diaphragm to contract (and drop) Thoracic cavity enlarges, air pressure drops and atmospheric pressure forces air in External intercostals may contract, elevate sternum Pleural membranes moves out (and together)

movement of inspiration : 

movement of inspiration 1.Rib movements – consists of pump handle movement buckle handle movement 2.Diaphragmatic movements

Pump handle movement : 

Pump handle movement Quiet respiration- only first pair of ribs moves but little . On hypernoea .the 2nd and 6th ribs which slopes obliquely downwards and forwards from their joints with the spinal column , moves upwards to assume a more horizontal position due to contraction of the external internal costal muscles Increases in the anterior- posterior diameter of the thorax Also the curves of the ribs increases in transverse diameter

Bucket handle movement : 

Bucket handle movement This movements brings about the increase in transverse diameter of the thorax by the movement of the lower 7th to 10 rib which swings outward and upwards

Diaphragmatic movements : 

Diaphragmatic movements During inspiration , diaphragm contracts and draw the central tendon part downwards by 1.5cm in eupnoe and 7cm in deep respiration … Cause an increase in transverse diameter of the thorax Accounts for 75% of the tidal volume

Expiration or exalation : 

Expiration or exalation Lots of elastic tissue in lungs and thoracic wall It’s a passive process Recoil helps return tissues to original configuration Alveoli enlarge during inspiration, contract during expiration

Muscles work in expiration : 

Muscles work in expiration Anterior abdominal muscles contracts – increases intrabdominal pressure – pulls the lower ribs downwards and medially – push the diaphragm upwards internal intercostal muscles - passess obliquely downward and posteriorly from ribs to ribs – contracts – pull the upper ribs downward

Here is an experiment : 

Here is an experiment

Mechanism of pulmonary ventilation : 

Mechanism of pulmonary ventilation

The respiratory muscles : 

The respiratory muscles

Biomechanics of breathing : 

Biomechanics of breathing During tidal breathing , if unopposed by the scalenes and the parasternals , the negative pleural pressure and the rsultant decreased intrapulmonary pressure are strong enpugh to cause the upper chest to collapse inward during inspiration . During diaphragmatic contraction , the abdomen becomes the fulcrum to lift the lower rib cage and rotate it outward .

Mechanisms of breathing : 

Mechanisms of breathing Quiet breathing (eupnea) Diaphragm and external and internal intercostals muscles Forced breathing (hyperpnea) Accessory muscles

Air movement : 

Air movement Movement of air depends upon Boyle’s Law Pressure and volume inverse relationship Volume depends on movement of diaphragm and ribs Pressure and airflow to the lungs

Pressure changes during inhalation and exhalation : 

Pressure changes during inhalation and exhalation Relationship between intrapulmonary pressure and atmospheric pressure determines direction of air flow In quiet breathing , at end expiration and at end inspiration .no air is going in and out of the lungs as the intrapulmonary pressure and atmospjeric pressure are equal. Intrapleural pressure maintains pull on lungs Pressure in the space between parietal and visceral pleura. Causes a slight change in the subatmospheric pressure i.e. -2mmhg at the start of inspiration . This is proportuonal to the thorarcic expasion

Pressure changes during inhalation and exalation : 

Pressure changes during inhalation and exalation


APPLIED EMPHYSEMA- loss and decrease in the lung elasticity , increases the intra- pleural pressure , therefore , chest expands and becomes barrel – shaped Pneumothorax- injury to yhe thoracic wall causes air to enter between the layes of the pluera till intraplueral pressure equalises atmospheric pressure – leads to collapse of the lungs as no opposing forces.

Respiratory volumes : 

Respiratory volumes Alveolar volume Amount of air reaching the alveoli each minute Tidal Volume (VT) Amount of air inhaled or exhaled with each breath Vital capacity Tidal volume plus expiratory and inspiratory reserve volumes Residual volume Air left in lungs after maximum exhalation

Respiratory volumes and capacities : 

Respiratory volumes and capacities

Diffusion and respiratory function : 

Diffusion and respiratory function Gas exchange across respiratory membrane is efficient due to: Differences in partial pressure Small diffusion distance Lipid-soluble gases Large surface area of all alveoli Coordination of blood flow and airflow

An overview of respiratory process and partial pressure : 

An overview of respiratory process and partial pressure

Compliance : 

Compliance compliance is the change in lung volume per unit change in airway pressure , which gives the distensibility or stechability of the lungs and chest wall. Expressed as litre/cm h2o Studied in two ways – compliance of the lungs and chest wall and compliance of the lungs only

Compliance of the lungs and chest : 

Compliance of the lungs and chest It is o.13cm/H2O .i.e. when there is increase of pressure by 1cm H2O the volume of the lungs inside the thoracic wall increases by 0.13 cm/H2O


COMPLIANCE OF THE LUNGS ALONE ie lungs outside the chest wall Compliance 0.22 litre cm/ when the airway is increase by 1cm H2O,then the lungs expand by 0.22 lt Therefore compliance of the lungs alone is approx 2times the compliance of the lung and chest wall.this is so because inside the thorax some energy is required to expand the thorax also.

Respiratory centres and the brain : 

Respiratory centres and the brain Medullary centers Respiratory rhythmicity centers set pace Pons Apneustic and pneumotaxic centers

Respiratory Centers and Reflex Controls : 

Figure 23.27 Respiratory Centers and Reflex Controls

Slide 59: 

Effects of Posture Abdominal Pressure Breathing

Postural relationship : 

Postural relationship The height of the diaphragm varies in the thorax to the position of the body and tone of the abdominal muscles . Sitting – here the diaphragm is the lowest , due to gravity and not press on the abdominal contents ,so less effort in inspiration,and RV is increase .most comfortable . Standing- the diaphragm is mid-way Supine – the diaphragm lies in the highest position , uncomfortable position

In dysponea : 

In dysponea So the comfortable position is sitting up which allows maximum ventilation, by leaning forwards and fixing the arms ,this fixes the scapulae, so that the serratus anterior and pectoralis minor may act on the ribs ,thus aidind for respiration.

Transection of the spinal cord : 

Transection of the spinal cord Above the 3rd cervical segment – fatal without artificial respiration Below the 5th not fatal as the phrenic nerves(c3,4,5) is intact. Paralysis of the laryngeal nerve supplying the intrinsic muscles of the larynx cause inspiratory stridor .

applied : 

applied During pregnancy at the second half of the pregnancy there is progressive uterine distension repositioning the diaphragm cephalad with a resultant increased in in chest circumferance. Scoliosis affects the chest wall biomechanics causing limititation to ventilation-how? on side of the convexity the along with the transverse process the ribs moves – causing posterior rib hump- the intercostal space are widened up , wheras on the concavity side the intercostal spaces are narrowed. This leads to insufficiency of the intercostal muscles and other ventilatory muscles – reduces chest wall compluance – decrease lung functions

Chronic obstructive pulmonary disease : 

Chronic obstructive pulmonary disease Hyperinflation of the lungs due to destruction of the alveolar walls -_so elastic coiling of the lung is lessened_so at the end of tyche exalation more air is housed_ assumes position of end inspiratory cycle – thorax becomes barrel shaped _also diaphragm gets flattened(expiration diaphragm dome shaped)_pulls the lower ribs inwards working against inflation In copd inspiration is carried out by acessory parasternals ansd scalenes

Paradoxical breathing in copd : 

Paradoxical breathing in copd So in COPD the upper ribs is pulled upward and outward and as the diaphragm has limited efficiency to push the abdominal contents downward , so the abdominal and diaphragm moves upward , under the rib cage .this is paradoxical thoracoabdominal breathing (the abdomen is pulled inward and upward during inspiration and is pushed outward and downward during expiration).

Bibliography : 


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