Respiratory system

• Plant exchanges gas in two physiological process which are photosynthesis,respiration 


  Plants have no special organ to breath
• Exchange of gases occurs in stomata of leaves and lenticels on the mature barks of stem


  The amount of gas exchanged is approximately the same
• At night photosynthesis ceases and respiration goes on . Thus Co2 is still in production. So, breathing problem occurs if one sleeps under a big tree at night
• Where does exchange of gases occur?

  Stomata of leaves and lenticels on the mature barks
• In plants, gas exchange occurs through the absorption of carbon dioxide and water by the roots from the soil, leading to the production of oxygen which is released back into the atmosphere
• The exchange of gases in plants involves the absorption of CO2 and water by the roots, resulting in the release of O2 into the atmosphere
• Oxygen is essential for sustaining life in living beings, as it is required for breaking down digested food substances to produce heat and energy
• Animals cannot survive without oxygen, which enters the body through air, travels to the lungs, and is then distributed to all organs via the blood
• Within body cells, oxygen reacts with digested food substances (glucose) to produce carbon dioxide and water, which are carried by the blood to the lungs for exchange
• The process of inhaling oxygen to oxidize digested food substances in body cells, converting potential energy into usable energy and eliminating carbon dioxide, is known as respiration
• Respiration involves the exchange of oxygen and carbon dioxide within the lungs and cells simultaneously
• If the supply of oxygen stops, death is inevitable within 3- 4 minutes, highlighting the critical importance of continuous oxygen supply for survival
• Organs involved in the respiratory system include:

  • Nasal cavity and nasal passage
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Lungs
  • Diaphragm
• Nasal cavity and nasal passage:

  • Beginning of the respiratory system
  • Situated above the buccal cavity
  • Helps to sense the smell of substances
  • Structure prepares inhaled air for the lungs
  • Extends from an aperture in front of the nose to the pharynx behind
  • Divided by a thin partition
  • Front side covered with cilia, back side lined by mucous-producing membrane
• Nasal cavity:

  • Cilia and mucous trap foreign substances like germs and dust
  • Cleans the air before it enters the lungs
  • Makes inhaled air relatively free from dirt
  • Inhaled air becomes warm and moist in the nasal passage, preventing harm from sudden cold air
• How to we get smell through nasal passage?

  A specific nerve in nose stimulates the organ to give us the smell
• Air passing through the nasal passage becomes warm and moist to prevent harm to the lungs from sudden cold air
• The pharynx can be seen at the back of the mouth and extends behind the nasal passage to the upper part of the larynx
• The soft palate, located at the back of the roof of the mouth, closes the backside of the nasal cavity when swallowing food or drink
• The soft palate also produces mucus and may have a link to the evolution of the human oral system
• (3) Larynx:

  • Situated below the pharynx and at the top of the trachea
  • Contains two folds of muscle called the cords
  • The epiglottis, a flap of soft tissue at the back of the tongue, acts as a lid during food intake
  • The epiglottis covers the opening of the larynx to prevent food particles from entering the esophagus while keeping the larynx open for respiration
  • Allows air to enter the lungs during respiration, but has no function in respiration
• (4) Trachea:

  • A hollow tube located in front of the esophagus
  • Extends from the larynx downwards into the thoracic cavity
  • Supported by incomplete rings of cartilage and smooth muscles
  • Inner layer covered with mucous membrane and cilia
  • Allows air to flow through it, and cilia help in expelling trapped dust, germs, and other unwanted particles
• (5) Bronchus:

  • The lower end of the trachea divides into two bronchi leading to the right and left lung lobes
  • Bronchi further divide and subdivide to form bronchioles
  • Bronchi have a similar structure to the trachea
• (6) Lungs:

  • Main organ of the respiratory system
  • Right and left lungs are situated on either side of the heart within the thoracic cavity
• Where does trachea extend to ?

  From larynx to thoracic cavity downwards
• Trachea is supported by ?

  Incomplete rings of cartilage and smooth muscles
• The diaphragm is a muscular sheet that separates the thoracic cavity from the abdominal cavity
• When the diaphragm contracts, it moves downwards, increasing the volume of the thoracic cavity
• When the diaphragm expands, it moves upward, decreasing the volume of the thoracic cavity
• The diaphragm plays an important role in respiration
• Lung is ?

  Spongy, soft, light reddish in color
• Alveoli is composed of?

  Single layer of epithelial tissue
• Alveoli is surrounded by?

  Mesh work of capillaries
• Bronchioles are smaller than bronchus but larger than alveolar ducts.