Respiratory system

• Respiratory system


  Takes up oxygen from the air we breathe & expels unwanted CO₂, allowing for cellular respiration to make ATP
• Functions of the respiratory system

  • Provides an area for gas exchange between the blood and air (CO₂ diffuses into the lungs, O₂ diffuses into the blood)
  • When you breathe in, O₂ travels down to the lungs entering the alveoli (tiny air sacs)
  • Gas exchange occurs between alveoli & the blood inside surrounding capillaries (O₂ attaches to the RBC in the capillaries)
  • CO₂ is produced as a by-product of cellular respiration, it travels in the bloodstream back to the lungs, and in the alveoli, CO₂ leaves the blood & enters the air when you breathe out
• Gas exchange in the lungs

  1. Blood enters the lungs

  2. CO2 leaves the bloodstream

  3. O2 enters the bloodstream when it leaves the lungs
• Respiratory tract preparation


  • Warms, moistens, and filters the air we breathe
  • The air is warmed up to a more suitable temperature as it travels down the respiratory tract
  • Mucous membrane lining the nose, throat, and airways contain blood vessels that help transfer heat from the body to the air, warming it up
  • As air travels through the respiratory tract, it passes over moist surfaces lined with mucus, adding moisture to the air and improving the efficiency of gas exchange
  • The nose is the first line of defense for filtering, with tiny hairs called cilia producing mucus to trap particles, and specialized cells called macrophages that engulf and destroy foreign particles and pathogens
• sound production

  When air passes through the larynx (voice box), it causes vocal folds (vocal cords) to vibrate, producing sound
• Nasal and oral cavities

  • Breathing starts in either the nasal or oral cavity, it is divided into 2 sections called the nasal passage
  • The nasal passage filters, moistens, and warms the air
  • The hard palate formally separates the oral and nasal cavities, while the soft palate is made up of muscle and connective tissue covered by a mucous membrane (cartilage)
• Nasal cavity features


  • The entrance of the nasal cavity is lined with small hairs called vibrissae that trap larger particles
  • The lining of the nasal cavity contains specialized cells that produce mucus to trap foreign particles
  • The nasal conchae are long curved shelves of bone that force air flow over the largest area of cilia as possible
• Paranasal sinuses


  Air-filled cavities located within the bones of the skull that can produce extra mucous, lined with a mucous membrane similar to that found in the nasal cavity
• Epiglottis


  A flap of tissue just above the larynx that prevents food and drinks from entering the trachea
• Larynx


  The area of the throat containing vocal cords, known as the voice box
• Thyroid cartilage


  The tough, flexible tissue that forms the front part of the larynx, forming the Adam's apple and supporting and protecting the vocal cords
• Hyoid bone


  A V-shaped bone situated at the root of the tongue, serving as an attachment structure for the tongue and muscles in the floor of the oral cavity
• Tonsils


  Lymph nodes that help filter out bacteria and other germs, situated at the back of the mouth
• Thyroid gland


  A small butterfly-shaped gland located below the Adam's apple that produces hormones regulating the body's metabolism rate, growth, and development
• Trachea


  The airway (windpipe) that leads from the larynx to the bronchi, delivering air to the bronchi
• Esophagus


  A tubular elongated organ that connects the pharynx to the stomach
• Pharynx


  A muscular tube that helps you breathe and digest food, in the middle of the neck and connects the mouth, nasal passage with the trachea and esophagus
• Uvula


  A fleshy extension at the back of the soft palate hanging above the throat
• Vocal folds


  Two bands of smooth muscle tissues found in the larynx, also known as vocal cords
• Thoracic cavity


  Contains the lower respiratory organs, the heart, and the thymus gland
• Diaphragm


  Separates the thoracic cavity from the abdominopelvic cavity
• Tracheal cartilage


  Maintains the mechanical stability of the trachea, keeping it open and preventing its collapse from negative pressure of the respiratory cycle
• Lungs


  • Pair of organs in the chest that supply the body with oxygen and remove CO₂ from the body
  • The lungs inflate and deflate within the pleural space of the thoracic cavity every time you breathe
  • The right lung has 3 lobes (superior, middle, inferior) and the left lung has 2 lobes (superior, inferior) to accommodate the heart
• Bronchi


  The passage ways that connect the windpipe (trachea) to the lungs, formed by the division of the trachea and becoming more narrow
• Serous membrane


  Smooth muscle tissue membrane that lines the contents and inner walls of the body cavity
• Visceral pleura


  Serous membrane that covers the surface of the lungs
• Pleural space


  The space enclosed by the pleura, a thin layer of tissue that covers the lungs & lines the interior walls of the chest cavity
• Right lung


  • Has 3 lobes: superior lobe, middle lobe, inferior lobe
• Left lung


  • Has 2 lobes to accommodate the heart: superior lobe & inferior lobe
• Division of the trachea

  1. Forms the bronchi

  2. Bronchi continue to subdivide, becoming more narrow

  3. Primary bronchi

  4. Secondary bronchi

  5. Tertiary bronchi then bronchioles
• Bronchioles


  Smallest bronchi/airway in the lungs
• Parietal pleura


  Serous membrane that covers the walls of cavities
• Pleural cavity


  Also known as pleural space, found between the two pleurae
• Mechanics of breathing - Inhale


  1. Diaphragm contracts, moving down

  2. Intercostal muscles contract, expanding the rib cage

  3. Increases volume in the lungs, lowers air pressure, drawing air inside
• Mechanics of breathing - Exhale


  1. Diaphragm relaxes & moves upward

  2. Intercostal muscles relax

  3. Lung volume decreases, air pressure increases, forcing air out
• Pathway of breathing

  1. Diaphragm contracts, pulling air into the nasal/oral cavity

  2. Air is moistened, warmed, filtered by mucus

  3. Air passes through pharynx from the nasal/oral cavity to larynx

  4. the esophagus will remain open when breathing

  5. the larynx contains vocal folds that produce sound when exhaling
• Mitochondria in body cells use O2 & glucose in cellular respiration to produce ATP, releasing CO2 as a waste product
• Intercostal muscles


  • Muscles found between the ribs
• Cough


  Clears the larynx & lower bronchi, expels irritants & mucus
• Sneeze


  Clears the pharynx & upper nasal passage, caused by irritation in the upper respiratory tract