Respiratory (SG)

• Which gases make up the air that we breathe? Which one is most abundant? Why is that good?

  Nitrogen and Oxygen make up the air around us. Nitrogen is the most abundant (79%), which is good because Oxygen (21%) is toxic to us.
• Trace the path that air takes as it travels from your nose to the alveoli

  Nose --> nasopharynx --> oropharynx --> laryngopharynx --> larynx --> trachea --> carina --> primary bronchi --> secondary bronchi --> tertiary bronchi --> bronchioles --> alveoli
• What are the roles of the Pharynx? What are the roles of the Larynx?

  The pharynx (throat) serves as a passageway for air and food and acts as a resonating chamber for speech sounds. The larynx (voice box) allows air, but not food or liquid, to flow into the rest of the airways. 
• What type of tissue lines the trachea and nasal passages?  What type of tissue lines the alveoli? Why does the respiratory system use different tissues for the different areas? 

  The trachea and nasal passages are lined with ciliated pseudostratified columnar epithelium tissue, so that the cilia can move mucus up to the pharynx. The alveoli is lined with simple squamous epithelium tissue, to allow oxygen diffusion into the blood.  
• Explain the mucociliary escalator.  What does it do?  How does it do it? 


  The mucociliary escalator is the movement of mucus along the respiratory tract towards the pharynx to then be swallowed and digested. It does so because of the cilia from the ciliated pseudostratified columnar epithelium tissue. 
• Compare and contrast hypoxia, dyspnea and cyanosis. What is a normal blood oxygen saturation level? 

  Hypoxia is low blood oxygen levels. Dyspnea is air hunger or trouble breathing. Cyanosis is blue color to persons skin or area of skin. A normal blood oxygen saturation level is about 95% or higher.  
• Define pneumothorax and atelectasis.  Name several medical conditions that are likely to cause atelectasis. 

  Pneumothorax is the presence of air in the pleural cavity. Atelectasis is the collapse of the lung or part of the lung. A tumor, blocking of airway, pneumonia, and foreign bodies can cause atelectasis.
• Air moving into the lungs

  1. Thorax expands

  2. Volume increases

  3. Pressure decreases (alveolar pressure<atmospheric pressure)

  4. Diaphragm pulls down

  5. Sucks air in
• Air moving out of the lungs

  1. Thorax relaxes

  2. Volume decreases

  3. Pressure increases (intra-alveolar pressure>atmospheric pressure)

  4. Diaphragm relaxes up

  5. Pushes air out
• Air moves into the lungs to allow oxygen (O2) to enter
• Air moves out of the lungs to allow carbon dioxide (CO2) to leave
• Pneumonia


  An infection that causes inflammation of the air sacs (alveoli)
• Pneumonia causes inflammation of the air sacs

  Not enough oxygen is entering the blood, lowering the blood oxygen levels (hypoxia)
• Respiratory membrane

  A thin barrier in the lungs where gas exchange occurs between the air in the alveoli and the blood in the capillaries
• Pneumonia patients benefit from breathing in extra oxygen because this will allow their blood to receive oxygen that they're lacking
• Name TWO factors that prevent the collapse of alveoli. 

  Surfactant made by type II alveolar cells and substance residual volume.
• What is the most important muscle of respiration?

  The diaphragm  
• What is the carina?  What part of the bronchial tree is the largest tube inside a lung?  In which lung lobe are foreign bodies (like parts of toys) most likely to land and why?

  1. Carina: Point at which the trachea bifurcates into the left and right main bronchi. 2. Main bronchi: Trachea bifurcates into left and right main bronchi. 3. Right bronchus: Straighter and wider than the left, making it easier for foreign bodies to enter.
• What is the difference between a bronchus and a bronchiole?


  Size; bronchi are larger air passages that branch off from the trachea and enter the lungs, while bronchioles are smaller air passages that further divide from the bronchi within the lungs and lack cartilage.
• In healthy individuals, hemoglobin becomes saturated as it passes through the capillary bed.  What effect does exercise have on oxygen saturation of the hemoglobin?  How is this related to equilibration of gasses?


  Exercise increases oxygen saturation of hemoglobin. This is related to gas equilibration as increased exercise leads to higher oxygen demand, causing more oxygen to bind to hemoglobin in the lungs and release it in the tissues.
• How is oxygen transported in the blood? In what part of the blood is O2 transported? Why? How is carbon dioxide transported in the blood? In what part of the blood is CO2 transported?  Why does oxygen need a special carrier?


  Oxygen is transported in the blood by binding to hemoglobin in red blood cells. Carbon dioxide is transported in the blood in three forms: dissolved in plasma, as bicarbonate ions, and bound to hemoglobin. Oxygen needs a special carrier because it is not very soluble in blood and needs to be efficiently transported to tissues.
• What causes asthma?  How is it treated?


  Causes: Inflammation, airway hyperresponsiveness. Treatment: Inhalers, steroids, avoiding triggers.
• How the blood picks up CO2 from the tissues while it delivers oxygen


  1. Oxygen is delivered to tissues in regions of higher oxygen concentration, facilitated by diffusion across the thin walls of capillaries from areas of high oxygen partial pressure to areas of low partial pressure in the tissue cells

  2. Carbon dioxide produced by cellular metabolism diffuses from the tissues, where its concentration is higher, into the bloodstream, where it can be transported back to the lungs for elimination during exhalation
• Diffusion


  • Plays a vital role in the exchange of gases between the bloodstream and tissues during respiration
  • Ensures the continual exchange of oxygen and carbon dioxide to meet the metabolic demands of the body's cells
• How the blood picks up O2 from the alveolus while it drops off CO2


  1. Oxygen diffuses from the air into the blood due to a concentration gradient, moving from an area of higher partial pressure of oxygen in the alveoli to an area of lower partial pressure in the blood

  2. Carbon dioxide, generated by cellular metabolism, diffuses from the blood into the alveoli, driven by its higher concentration in the blood compared to the lower concentration in the alveoli

  3. Exchange is facilitated by the thin walls of the alveoli and the surrounding capillaries, ensuring that oxygen is absorbed into the bloodstream while carbon dioxide is released into the alveoli for exhalation
• What is the relationship between blood CO2 and pH?  What happens to blood pH if carbon dioxide levels are too high?  How does high blood CO2 affect the pH of CSF?

  Inverse. Decreases. Increases.
• How does low blood oxygen affect respiratory rate?  How does low blood pH affect respiratory rate?  Which is the stronger effect on respiratory rate?


  Low blood oxygen: Increases Low blood pH: Increases Low blood oxygen has a stronger effect on respiratory rate.
• How does low tissue oxygen affect the affinity of hemoglobin for oxygen?  How does temperature affect it?  How does pH affect it?  What causes the affinity of hemoglobin for oxygen to increase?  Decrease?


  Low tissue oxygen: Increases Temperature: Decreases pH: Decreases Increase: High oxygen levels Decrease: Low pH, high CO2 levels
• Explain the way muscular effort causes air to move into the lungs.  How does the body exhale quietly?  What is the difference between forced expiration and quiet expiration?


  Inhalation; Diaphragm and intercostal muscles contract; Passive process; Forced expiration uses additional muscles.
• Quiet respiration


  1. Medulla detects high CO2 levels

  2. Chemoreceptors send signals to medulla

  3. Medulla sends signals through motor neurons

  4. Diaphragm and intercostal muscles contract

  5. Chest cavity expands, air rushes into lungs

  6. Diaphragm and intercostal muscles relax

  7. Lungs shrink, air pushed out
• Quiet respiration


  • Natural breathing when not doing strenuous activity
  • Controlled by medulla in brain
  • Involves contraction and relaxation of breathing muscles
  • Lungs have pulmonary compliance to expand and contract easily
• Quiet respiration is the way your body naturally breathes when you're not doing anything too strenuous
• It's all controlled by a part of your brain called the medulla
• When the levels of carbon dioxide in your blood go up, little detectors called chemoreceptors tell the medulla to send signals
• These signals travel through motor neurons to your breathing muscles
• When it's time to breathe in, your diaphragm, a big muscle under your lungs, and some other muscles called intercostal muscles, contract
• This makes your chest cavity bigger, so air rushes into your lungs
• When it's time to breathe out, these muscles relax, and your lungs shrink back down, pushing the air out
• This whole process happens smoothly because your lungs are stretchy enough to expand and contract easily, which is called pulmonary compliance
• Where are the peripheral chemoreceptors of respiratory control located?  Where are the central chemoreceptors? Which type of sensory receptors is found on the medulla oblongata?


  Peripheral chemoreceptors: Carotid bodies and aortic bodies. Central chemoreceptors: Medulla oblongata. Sensory receptors: Central chemoreceptors are primarily sensitive to changes in CO2 levels.