mammalian gas exchange

• the trachea is a c shaped ring of cartilage that provides support
• the trachea is lined with ciliated epithelium cells and goblet cells
• cilliated epithelial cells move mucous away from the lungs
• goblet cells produce the mucous to trap pathogens and other substances
• smooth muscle is contained within the tracheas walls
• the smooth muscle will contract if there is harmful substances within the air resulting in the lumen of trachea constricting and reducing airflow to lung
• when the smooth muscle relaxes the lumen dilates
• the stretch and recoil of trachea is possible due to elastin fibres within walls of trachea
• cartilage rings prevent collapse of trachea during expiration
• elastic tissue allows the trachea to return to its original shape when it has been stretched
• the trachea splits into a tube called the bronchi which connects the left and right lungs
• the bronchi splits further into bronchioles which are smaller tubes that carry air to the alveoli
• Both bronchi and bronchioles have cartilage within the walls which provide structural support and keep the tubes open
• alveoli is located at the end of the bronchioles and is the site of gas exchange
• oxygen from the alveoli will diffuse into the blood and carbon dioxide within the capillaries will then diffuse into the alveoli and then be exhaled
• alveoli have a large surface area this is provided by the large number of alveoli in both sets of lungs
• alveoli provide a short diffusion distance due to the very thin cell walls which are made up of a single layer of squamous epithelial cells
• each alveoli is surrounded by a capillary network to remove exchange gases maintaining the concentration gradient
• Ventilation is a mechanism of breathing and involves the diaphragm muscle and antagonistic interactions between external and internal intercostal muscles changing the pressure off thoracic cavity
• ventilation maintains the concentration gradient in alveoli for gas exchange
• inspiration increases the volume of the thorax meaning the pressure will decrease and causes airflow into lungs
• exploration decreases volume of thorax and there is an increase in air pressure forcing air out of lungs
• Process of inhalation

  • When you inhale the diaphragm contracts causing the diaphragm to come down and become flatter
  • the external intercostal muscle contract and the internal intercostal muscle relax pulling the rib cage up and out
  • provides a large volume in the thorax
• process of exhalation

  • When you exhale the diaphragm relaxes causing the diaphragm to going upwards
  • the external intercostal muscles relax and the internal intercostal muscles will contract pulling the rib cage inwards and down
  • reduces the volume of thorax
• Inspiring me to measure the inhaled and exhaled
• vital capacity is the maximum volume of air an individual can inhale and exhale during the deep breath
• Tidal volume is the air inhaled and exhaled when at rest
• Residual volume is the volume of air that is always remained in the lungs to prevent them from collapsing and emptying out