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The Lungs

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									             The Lungs

•Lung Basics
•System Structure
•Lung Cell Structure
•Control of Breathing
                     Lung Basics
• The lungs are situated in the upper thorax and are an
  essential part of respiration.
• It’s main function is to transport oxygen into the
  bloodstream and to remove waste gases such as carbon
  dioxide (via gaseous exchange).
• The lungs also have non-respiratory functions such as
  filtering out small blood clots in the veins and serve as a
  physical layer of soft shock-absorbent protection for the
  heart.
• The lungs receive de-oxygenated blood from the heart via
  the pulmonary artery. Oxygenated blood is then sent back
  to the heart via the pulmonary vein (the only vein the
  human body to carry oxygenated blood).
              System Structure
• Human lungs are located in two cavities on
  either side of the heart, the thoracic cavity.
• They are similar in appearance but not
  identical as the left lung is slightly smaller in
  size.
• Both are separated into lobes, with three
  lobes on the right (Superior, middle, and
  inferior) and two on the left (Superior and
  inferior)
        Right And Left Lungs




Right Lung             Left Lung
          System Structure (cont.)
• They are connected to the mouth and nasal cavity via the
  trachea (made of C shaped cartilage rings). The trachea splits
  into 2 branches called the bronchi.
• The lungs are lined with pleural membrane.
• The space between the lungs and the thorax is called the
  pleural cavity and is filled with pleural liquid.
• This prevents friction and helps the outside of lungs to adhere
  to inside of cavity when breathing.
• The lungs are protected by the ribcage.
• The inter and outer costal muscles on the ribcage help move
  the lungs. As you inspire and expire, the muscles contract and
  expand.
• The lungs contain alveoli which are branched from the
  bronchiole (branched from the bronchi).
             Lung Cell Structure
• The alveoli are made of 300million squamous epithelial
  cells. They are 100-300 micro meters in diameter and
  has a large surface area about 40-60 meters square
  (can be stretched to the size of a tennis court).
• There are 2 types of epithelial cells involved in the
  lungs:
• Type 1 pneumocytes – Form alveolar walls
• Type 2 pneumocytes – Produce surfactant which is
                          made of lipids and proteins
                        - Prevents collapse of the alveoli
                        - Lowers surface tension to allow
                          easy diffusion of gases
                                Epithelial Cells
• Epithelium is a tissue formed by a layer of cells
• Squamous cells are flat cells with an irregular flattened shape. A one-cell
  layer of simple squamous epithelium forms the alveoli of the respiratory
  membrane.
• Because they are so thin and have a large surface area, it is easier for
  gases to diffuse across them which is an important part of breathing.

                                      Squamous Epithelial cells
Epithelial cells in the lungs
             Control of Breathing
• The central controlling area for breathing, called the
  respiratory centre, is in the lower part of the brain stem, in
  the medulla oblongata.
• There are 2 groups of neurones that maintain rhythmic
  breathing called the inspiratory neurons and expiratory
  neurons.
• Cells in the brain called chemoreceptors are sensitive to
  chemical change. They measure the concentration of
  carbon dioxide of the blood by monitoring hydrogen ions. If
  CO2 levels are too high, the pH of the blood decreases and
  in response to this, the inspiratory neurons send nervous
  impulses to the intercostal muscles and the diaphragm to
  increase breathing rate.
             The End



By Taz and Stacey

								
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