Respiratory

• Respiration


  The main function of the respiratory system
• Respiration


  1. Pulmonary ventilation

  2. External respiration

  3. Internal respiration
• Pulmonary ventilation


  The mechanical flow of air in and out of the lungs
• External respiration


  Gaseous exchange in the lungs
• Internal respiration


  Gaseous exchange in the tissues
• Functions of the respiratory system


  • Regulates blood pH
  • Contains receptors for the sense of smell
  • Filters, warms, and moistens inspired air
  • Produces sounds
  • Rids the body of some water and heat in exhaled air
• Structural anatomy of the respiratory system


  • Nose
  • Nasal cavity
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Lungs
• Functional anatomy of the respiratory system


  • Conducting zone
  • Respiratory zone
• Nose


  Performs specialist functions in the respiratory system, including warming, moistening and filtering air, olfaction and acting as a resonating chamber
• Pharynx


  A funnel shaped tube that starts at the internal nares and extends a short way down the neck, acts as a resonating chamber for sounds, contains the nasopharynx and oropharynx
• Larynx


  Connects the pharynx and the trachea, contains the thyroid cartilage, epiglottis, cricoid cartilage, and vocal cords
• Trachea


  Joins the larynx to the primary bronchi, made up of smooth muscle and C-shaped rings of cartilage, divides into the right and left main bronchi
• Lungs


  Paired organs contained within the thoracic cavity, each lung is enclosed by the pleural membrane, the right lung has three lobes and the left lung has two lobes and a cardiac notch, gaseous exchange occurs across the respiratory membrane
• Pulmonary ventilation


  Contraction and relaxation of skeletal muscles causes changes in air pressure inside the lungs, leading to inhalation and exhalation
• Diaphragm

  Contracts when it receives nerve impulses from the phrenic nerves, contributing to forced inhalation
• Muscles involved in forced inhalation


  • Sternocleidomastoid
  • Scalenes
  • Pectoralis minor
• Muscles involved in forced exhalation


  • Internal intercostals
  • External oblique
  • Internal oblique
  • Transverse abdominis
  • Rectus abdominis
• Partial pressure


  The pressure of a specific gas in a mixture
• External respiration


  The exchange of gases between alveolar air and pulmonary blood capillaries
• Internal respiration


  The exchange of gases between systemic tissue capillaries and systemic tissue cells
• Haemoglobin


  About 98.5% of O2 in the blood is bound to haemoglobin
• Ways CO2 is transported in the blood


  • 70% is converted to bicarbonate ions
  • 23% combines with haemoglobin
  • 7% is dissolved in plasma
• Respiratory center


  Can be divided into the medullary respiratory center in the medulla oblongata and the pontine respiratory group in the pons
• Inspiratory area


  Sets the basic rhythm of respiration
• Factors that may modify respiration


  • Cortical influences
  • Chemoreceptors
  • Limbic system stimulation
  • Proprioceptor stimulation
  • Temperature
  • Pain
  • Irritation of airways
  • Inflation reflex (stretch receptors)
• Normal quiet breathing


  1. Diaphragm contracts and external intercostal muscles contract

  2. Diaphragm relaxes and external intercostal muscles relax, elastic recoil of lungs
• Forceful breathing


  1. Diaphragm contracts and external intercostal muscles contract

  2. Accessory muscles of inhalation (SCM, scalene and pectoralis minor) contract

  3. Accessory muscles of exhalation (internal intercostal, external oblique, internal oblique, transversus and rectus abdominis) contract
• Breathing and homeostasis