Breathing and exchange of gases

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Breathing and exchange of gases by Mind Map: Breathing and exchange of gases

1. Respiratory organ

1.1. Lower invertebrates = sponges , coelenterates,flatworms Earthworm = moist cuticle Insect = network of tubules ( tracheal tubes) Fishes= gills (brachial rapiration) Amphibian, reptile, bird, mammals = lungs (pulmonary respiration) In amphibian frog also respire through moist skin ( cutaneous respiration)

1.1.1. Human respiratory system

1.1.1.1. Nostril ↓ Nasal passage ↓ Nasal chamber ↓ Pharynx ( common passage for food and air) ↓ Larynx ( sound box ) ↓ Trachea( straight tube extend upto the mid thoracic.) cavity) ↓ Divides at the level of 5 th thoracic vertebra into ↓ Right and left primary bronchi ↓ Bronchioles ↓ Alveoli

1.1.1.1.1. Network of Bronchi ↓ Bronchioles ↓ Alveoli ( Comprises lungs)

2. Mechanism of breathing

2.1. Two stages of breathing

2.1.1. Inspiration ( it is a process by which fresh air enters the lungs

2.1.1.1. Expiration : it is the process by which the foul air containing CO2 is expelled out of the lungs

2.2. Respiratory movement in man are carried out with the help of intercostal muscles and diaphragm 1. Diaphragm : Elastic , dome shaped , plate like structure with its convex side towards thoracic cavity It is pulled by pherenic muscles 2. Intercostal muscles (ICM) Space between two ribs is called intercostal space Two types of intercostal muscle: 1.EICM (external) The Contraction in these muscles, ribs and sternum shift upward and outward they help in inspiration 2.IICM (internal) Contraction in this muscles, ribs and sternum shift downward and inward Helps in forceful expiration which is a voluntary activity Contraction of IICM is under control of cerebrum Volume of thoracic cavity is changed by : 1. Shifting of ribs or sternum 2. The flatting of diaphragm

2.2.1. Route followed by air during inspiration Outside →nostril →nasal chamber →pharynx →glottis →larynx →trachea→bronchi→bronchioles →alveolar ducts→alveoli

2.2.1.1. Route followed by air during expiration Alveoli→alveolarduct→bronchioles →bronchi→trachea→larynx→glottis→pharynx →nasal chamber→nostril→outside

3. Respiratory volumes and capacity

3.1. The volume of air involved in breathing movement can be estimated by using a spirometer which is clinical assessment of pulmonary function

3.2. Pulmonary volume

3.2.1. 1.Tidal volume (TV) Volume of inspired or expired during normal breathing It's value approximetely 500ml A healthy man can inspire or expired approximately 6000 to 8000 ml of air 2. inspiratory reserve volume (Irv) Additional volume of air , a person Can inspire by forcible inspiration This averages 2500ml to 3000ml 3.expiratory reserve volume ( ERV) Additional volume of air , a person can expire by forcible experiation . This averages 1000ml to 1100ml 4. Residual volume( RV) Volume of air remaining in the lungs even after forcible expiration . This averages 1100ml to 1200ml

4. Exchange of gases

4.1. It takes place in alveoli by simple diffusion mainly based on pressure concentration gradient of co2 and o2 in the alveoli The pressure contributed by an individual gas in a mixture of gases is called partial pressure Represented as po2 for oxygen Pco3 for carbon dioxide O2 moves from atmospheric air to alveoli and then finally blood where as the CO2 movement is in Opposite direction

4.1.1. Factors that affect diffusion

4.1.1.1. Solubility of gases Partial pressure Thickness of membrane

5. Pulmonary capacities 1. Inspiratory capacity (IC) Total volume of air a person can inspire by maximum distension of his lungs after a normal expiration IC= TV + IRV 2. Expiratory capacity (EC) Total volume of air a person can expire forcefully after a normal inspiration . EV=TV + ERV 3.functional resdiual capacity (FRC) The amount of air that normally remain inside lungs after normal expiration FRC=ERV+RV 4. Vital capacity (VC) The maximum volume of air a person can breathe in after a forced expiration VC= TV+ IRV+ERV 5. Total lung capacity (TLC) Total volume of air accommodated in the lungs at the lungs at the of forced inspiration TLC =IRV +TV + ERV+RV

6. Transport of gases

6.1. Transport of O2 Hb+ O2 gives Hbo2( oxyhaemoglobin) Each haemoglobin molecule can carry a maximum four molecules of O2 100ml of blood carries 15×1.34ml =20ml O2 So 5L of blood has 1L of oxygen Normal person hb level is 15g

6.1.1. A sigmoid curve is contained when percentage saturation of haemoglobin with o2 is plotted against the po2 this curve is called the oxygen dissociation curve

6.1.1.1. Factors that affect oxygen dissociation curve 1. Shift to left 2. Shift to right

6.1.2. Transport of carbon dioxide Approximately 75% carbon dioxide Is transport in red cell and 25%in plasma

6.1.2.1. Factors that affect binding of co2 with hb In tissue = High pco2 and low po2 in tissue are responsible for binding more co2 with hb In alveoli = low pco2 and high po2 in alveoli are responsible for dissociation of co2 from carbamino hemoglobin Co2 +H20in presence of carbonic anhydrase gives h2co3 gives in the presence of carbonic anhydrase hco३- + h+

7. Regulation of respiration

7.1. New Topic

7.1.1. A specialized center located in the medulla region of the brain is called respiratory rhythm center Primarily responsible for this regulation Another center present in the pons Region of the brain called pneumotoxic center Neural signal from this center can reduce the duration of inspiration

8. Disorder of respiratory system 1.asthma 2. Emphysema 3.hyponea (slow breathing) 4. Hypoxia 5.rhinitis (acute chronic inflammation of mucus membrane Of nose 6. Narcosis (narcotic or deprssent drug causes depression of respiration center that fails to respond to chemotactic stimulation 7.pneumonia (bacterial infection of Lungs the surface area of diffusion Decreases 8. Sillicosis and asbestosis are the common example and caused due to continuous exposure to silica and asbestos dust at place of work