Human breathing

• Respiratory system


  • Located in the chest (thoracic) cavity
  • Function is breathing

  
• Breathing


  Taking in oxygen from the air and letting out carbon dioxide and water vapour
• Respiration


  Release of energy from food, takes place in the cells of the body

  
• Lungs (and heart)


  • Protected by the ribs and the breast bone
  • Surrounded by 2 pleural membranes filled with pleural fluid to lubricate and reduce friction
• Nose and mouth


  • The human breathing system starts here
  • Breathing in through the nose traps dirt, pollen and bacteria, and warms and moistens the air

  
• Epiglottis


  Small flap of cartilage that stops food from entering the trachea
• Larynx


  Contains the vocal cords that vibrate to produce sound
• Trachea


  Also called the windpipe, surrounded by C-shaped rings of cartilage to prevent airway collapsing, carries air from nose to lungs
• Bronchi and bronchioles


  Bronchi carry air from trachea into lungs, bronchioles carry air from bronchi to alveoli
• Alveoli


  Tiny air-sacs in the lungs where gas exchange occurs, have a very large total surface area

  
• Alveoli


  • Wall and capillaries are only one cell thick to aid diffusion
  • Surrounded by dense network of capillaries
  • Moist for rapid diffusion of gases
• Gas exchange


  1. Oxygen passes from alveoli into capillaries and binds to haemoglobin

  2. Carbon dioxide and water pass from capillaries into alveoli
• Breathing


  Normal resting rate is 12-18 breaths per minute
• Inhaling


  Intercostal muscles contract, diaphragm contracts, chest cavity volume increases, air pressure decreases, air is sucked in

  
• Exhaling


  Intercostal muscles relax, diaphragm relaxes, chest cavity volume decreases, air pressure increases, air is forced out
• Inhaled and exhaled air have different compositions
• Effect of exercise on breathing rate

  Fitter people have slower resting breathing rate and recover more quickly after exercise
• Control of breathing rate

  Medulla oblongata detects changes in blood CO2 levels and sends messages to adjust breathing rate
• Asthma


  Common breathing disorder with symptoms of coughing, wheezing, breathlessness and chest tightness
• Cause of asthma


  Narrowing and inflammation of bronchi and bronchioles, triggered by allergens
• Asthma prevention and treatment

  Removing triggers, using bronchodilator inhalers to open airways
• Smoking affects many parts of the body and can lead to serious diseases like cancer, emphysema and heart disease
• Substances in cigarette smoke

  Nicotine (addictive), tar (carcinogenic), carbon monoxide (toxic)
• Respiratory diseases


  • Asthma
  • Bronchitis
  • Pneumonia
  • Emphysema
  • Cystic Fibrosis
  • Lung Cancer
  • Tuberculosis
• Bronchitis


  Inflammation of bronchiole tubes, causes coughing, difficulty breathing and heavy chest
• Pneumonia


  Inflammation of lungs due to infection, alveoli fill with fluid making it difficult to breathe
• Emphysema


  Chronic breathlessness caused by breakdown of alveoli walls, decreasing surface area for gas exchange
• Cystic Fibrosis


  Genetic disorder causing excess mucus production that clogs bronchial tubes and obstructs breathing
• What are the main components of the upper respiratory tract?

  • Nose
  • Nasal cavity
  • Sinuses
  • Pharynx
• What are the primary functions of the respiratory system?

  To take in oxygen and remove carbon dioxide
• What is the role of the trachea in the respiratory system?

  To conduct air from the larynx to the bronchi
• What is the function of the epiglottis?

  To prevent food and liquids from entering the trachea
• What is the primary function of the alveoli?

  They are the primary sites of gas exchange
• Name the main respiratory muscles involved in breathing.

  • Diaphragm
  • Intercostal muscles
• What are the defense mechanisms of the respiratory system?

  • Mucus and cilia
  • Sneezing
  • Coughing
  • Alveolar macrophages
  • Inflammatory response
• How do macrophages contribute to the respiratory defense system?

  They engulf and digest foreign particles
• What are the common treatment options for asthma?

  • Inhaled corticosteroids to reduce inflammation
  • Inhaled beta-agonists to relax bronchial muscles
  • Leukotriene modifiers to decrease inflammation and mucus production
  • Immunomodulators such as biologics
  • Long-acting beta-agonists for long-term bronchodilation
• What is the primary function of the respiratory system?

  Breathing, including inhaling and exhaling
• Why is a large surface area of the alveolar-capillary membrane important for gas exchange?

  It increases the contact area for diffusion
• How is cellular respiration related to the energy needs of a cell?

  Cellular respiration provides ATP, which is the main energy currency used by cells to power various cellular processes.