The Respiratory System         (IB Topic B3.1)

Essential Idea(s): Adaptations in multicellular organisms efficiently perform gas exchange. Structural adaptations of mammalian lungs make this system efficient and effective.

Unit Length: 3 Lessons (+2 AHL)

  Guiding Questions

◊ How are multicellular organisms adapted to carry out gas exchange?

◊ What are the similarities and differences in gas exchange between a flowering plant and a mammal?

IB Statement(s) and Objective(s)

 

B3.1.1: Gas exchange as a vital function in all organisms

  • Define gas exchange
  • Explain the need for gas exchange in living organisms
  • Explain the impact of surface area: volume ratios (SA:Vol) on the size of organisms
  • Give 3 unique examples of mechanisms of gas exchange found in living organisms

 

B3.1.2: Properties of gas-exchange surfaces

  • Define gas exchange surface
  • Outline the role of permeability in the adaptive properties of gas exchange surfaces
  • Outline the role of tissue thickness in the adaptive properties of gas exchange surfaces
  • Outline the role of moisture in the adaptive properties of gas exchange surfaces
  • Outline the role of large surface area in the adaptive properties of gas exchange surfaces

 

B3.1.3: Maintenance of concentration gradients at exchange surfaces in animals

  • Explain the need for concentration gradients at gas exchange surfaces
  • Outline the function of dense blood vessel networks in maintaining gas concentration gradients
  • Define ventilation
  • Outline the function of ventilation in the lungs in maintaining gas concentration gradients
  • Outline the function of water movement in gills in maintaining gas concentration gradients
  • Outline the function of the countercurrent exchange system in fish

 

B3.1.4: Adaptations of mammalian lungs for gas exchange

  • Outline the key adaptations for gas exchange found in mammalian lungs
  • Outline the flow of air into the lungs
  • Outline the function of surfactant in the lungs
  • Outline the structural features that enhance surface area in the lungs
  • Outline the function of the primary respiratory muscles
  • Outline the function of the thin respiratory membrane of the lungs

 

B3.1.5: Ventilation of the lungs

  • State the relationship between gas pressure and volume
  • Explain the physiology of ventilation in the lungs
  • Explain the contraction and relaxation of muscles through the use of antagonistic muscle pairs
  • Explain the contraction and relaxation of muscles through the use of antagonistic muscle pairs

 

B3.1.6: Measurement of lung volumes

  • Skill: make measurements to determine tidal volume, vital capacity, and inspiratory and expiratory reserves
  • Define ventilation rate and tidal volume
  • Define vital capacity and expiratory reserve
  • Outline techniques for measuring ventilation rate or lung tidal volume
  • Explain the effects of exercise on ventilation

Additional Higher Level Topics

B3.1.11: Adaptations of foetal and adult haemoglobin for the transport of oxygen

  • Define affinity
  • Describe hemoglobin’s affinity for oxygen
  • Describe the saturation of hemoglobin at different oxygen partial pressures
  • Define allosteric binding
  • Outline the differences between adult and fetal hemoglobin
  • State the reason why it is adaptive for fetal hemoglobin to have a higher oxygen affinity than adult hemoglobin

 

B3.1.12: Bohr shift

  • Explain the mechanism and benefit of the Bohr shift

 

B3.1.13: Oxygen dissociation curves as a means of representing the affinity of haemoglobin for oxygen at different oxygen concentrations

  • Define partial pressure
  • State the relative partial pressures of oxygen  in the atmosphere at sea level, in the alveoli, in alveoli blood capillaries, and in respiring tissue
  • Draw the oxygen dissociation curve to show affinity of hemoglobin for O2 at different partial pressures of oxygen
Activities: = podcast / = inquiry 5 / = Write it Ӕ = The academy  / = Read it

Lung labs – Choose 1 of the following 3 lab options:

/: Engineer a Lung (💁/ 👭 max 2)

Grab a few basic supplies (clay is the only item on here that isn’t in most AHs…see me for some) and create a functional model of lungs. This is a very open-ended task that requires some trial + error to pull off – try to do it without any help from Google! See me if you hit a dead end.

 

/: Lung Capacity Lab (using a spirometer) (💁/ 👭 max 2)

Can your lungs tell us how fit you are? This lab will help you determine if you’re above – or below – where you should be. Grab one of the school’s spirometers and use it to calculate the tidal volume, vital capacity, and residual volume of your lungs. Then compare your results to the expected results for your gender + fitness level.

 

/: Observing Breathing and Heart Rates (💁/ 👭 max 2)

How does exercise affect your breathing rate and heart rate? With a partner, measure both your pulse and your breathing rate, then push yourself with some moderate exercise (a quick walk and a quick jog) to see how that affects your body. 

 

Ӕ: 3D Tour of the trachea

Use this 3D model to screencast a tour of the trachea, larynx, and bronchi — explaining the key features that allow breathing to take place. Make sure you give an overview of the mechanism that allows air to flow into the lungs.

 

: “Inquiry 5″: Q&A on Respiratory Anatomy (💁/ 👭max 2)

Create a list of 5 inquiry questions related to the anatomy and physiology of the trachea and lungs. Remember that good inquiry questions are conceptual / open-ended…such as: “What would happen if a person’s lungs could no longer produce surfactant?; NOT: “What do alveoli look like?” If working solo, write out answers to your own questions; if working in pairs, record yourselves asking each other your 5 questions.

*Try to write questions that cover as many topics from 6.4 as possible! 

 

: From Genes to Latrines: The Curious Connection Between Vikings and Emphysema (💁)

Scientific curiosity leads to some interesting places – archeological excavations of Viking latrine pits in Denmark have revealed that these populations suffered massive worm infestations. Adaptations that protected the Vikings from these worms had a negative effect – they made their lungs more susceptible to emphysema, a harsh lung disease. Read up about this strange history, and how evolution might have kept Vikings a little bit safer from worms, but also a bit more susceptible to lung disorders. Respond by answering: 1) What is emphysema, and what causes it?;  2) Why are Nordic genes more susceptible to lung disorders; and 3) Discuss how the randomness of evolution can sometimes provide both problems and solutions into one package.   

Extras: Old School Worksheet on Gas Exchange