Unit 5 Study Guide—This is only a guide and not to be considered an exhaustive list.

Acid Base Balance –Yes! Do this again for the next lecture and lab exam.

  1. Define pH. Describe the pH scale. What is normal blood pH and what is the normal pH range of urine?
  2. Why is it that even small changes in a pH value represent large changes in hydrogen ion concentration of a solution, and large changes in acidity or basicity?
  3. What is a buffer? What is the effect of a buffer in a solution? What are some of the chemical and physiological buffers we possess in the body?
  4. Why are large changes in pH dangerous? What is the effect of this on protein structure? On plasma electrolytes?
  5. The kidney and lung play a large role in acid base balance because they each regulate the components of the bicarbonate-carbonic acid buffer system. Explain this statement.
  6. Know the Henderson-Hasselbach equation. Be able to work with it. How do changes in the ratio of bicarbonate/carbonic acid affect pH?
  7. What is the source of carbonic acid in the body? How do we eliminate it?
  8. What is the source of bicarbonate in the body? How do we eliminate it?
  9. Define acidosis and alkalosis
  10. Define metabolic and respiratory forms of acidosis and alkalosis.
  11. In each of these 4 conditions, explain how the body compensates for (corrects for) changes in pH.
  12. What are some ways that each of these conditions can be produced?
  13. What is meant by the terms hyper- and hypoventilation? Does it just mean a speeding up or slowing down in the rate of breathing? If not, what does it mean?

The Respiratory Cycle

  1. What is meant by respiration? Differentiate between ventilation and internal/external and cellular respiration.
  2. Review the anatomy of the respiratory system, the microscopic structure of bronchi and alveoli, and path of blood to lung. Make the anatomic distinction between conductive and respiratory airways.
  3. What is the respiratory membrane?
  4. Describe the natural elastic recoil of the chest wall (in lecture.) How come the chest wall doesn’t simply recoil according to this tendency? Why doesn’t the lung simply recoil according to its tendency? (hint: what anatomical structure keeps them balanced? Pleural cavity and membranes)
  5. Describe the anatomy of the pleural space. Identify the pleural membranes (visceral and parietal.) What is the function of these membranes? Why is the pleural space called a “potential” space?
  6. Remember that the pleural cavity and the fluid there reduces friction as the lungs move, but also helps keep the chest wall and lungs in contact with each other.
  7. Describe the musculature used to produce “normal” and “forced” inspiration and expirations. Identify which processes require active muscle contraction and which are simply “passive” (i.e., they rely on releasing the energy of recoil)
  8. Define Boyle’s Law. Be able to apply it with respect to alveolar pressures and thoracic cage volume.
  9. Define the terms elasticity, elastic recoil, compliance. How is recoil related to compliance?
  10. Describe the natural elastic recoil of the lung. List the factors responsible for producing these elastic forces on the lung.
  11. Understand the four pressures involved in the lung: Patm and Palv create the pressure gradient that drives ventilation, But Ptrans= Palv-Pip and Ptrans provides the force for expansion of the lungs.
  12. Explain the flow rule with respect to air made to move through a tube (airway.) What can you say about the flow through an airway if the resistance changes? What kinds of pressure differences must you produce across the airway to get the same fluid flow when resistance increases or decreases?
  13. What is compliance? Be able to give the equation for it. Rearrange the equation to state the two ways to change lung volume. Lung compliance and transpulmonary pressure are critical for influencing changes in lung volume. Understand that there are 2 factors responsible for lung compliance: elastic fibers, but more importantly surfactant.
  14. Where is surfactant made? By what cells? What is its chemical nature?
  15. What is LaPlace’s law? What is surface tension of a fluid? How does surface tension act in a bubble structure (like an alveolus?) What role does it play in the alveolus?
  16. How is surfactant important in the lung? What is the LS ratio? Define RDS (respiratory distress syndrome).
  17. Go back to the flow rule and now incorporate Poiseuille’s law of resistance. What factor is most responsible for generating resistance? Describe how, in the lung, this factor of resistance can change with changes in tractive forces, and neural/hormonal and local changes in bronchiole dilation.
  18. What is a respiratory cycle?
  19. How do you compute “total” minute ventilation? What two factors determine this value?
  20. What is meant by “alveolar” ventilation? How is it different from total ventilation? What is anatomical dead space?
  21. Know the lung volumes (TV, IRV, ERV, RV) and lung capacities It’s best to learn these by actually experiencing them. Recognize them from their starting and ending points. Name the instrument used to test lung function in the lab and the importance of static vs. dynamic lung tests

ex. name the volume . . .from a forced inhalation to a forced exhalation.

ex. name the volume . . .from a normal exhalation to a forced exhalation, etc.

  1. What is FRC? How does it change in COPD? What does FEV1/VC tell you?
  2. Describe the “work” of breathing (Ventilation = rate x depth of breathing). How will patients with different respiratory problems change these factors? That is, how will a person with COPD alter their breathing? What will a person with a restrictive disorder do?
  3. What are the three classic disorders involved in COPD? Describe each one and the work of breathing for each.
  4. What are restrictive disorders? What is pneumothorax? How can they occur? What is the effect of this on lung and chest wall position? What is atelectasis?
  5. Why is emphysema classified as both obstructive and restrictive? What happens to lung recoil in this disease, and why? Why do these lungs “trap” air? What happens to IRV, ERV, FEV1?

Internal and External Respiration

  1. What is Fick’s law and how does it apply to the alveolus and gas exchange? What anatomical structure in the alveolus would be factored into Fick’s Law.
  2. Review Boyle’s ideal gas law again. If one mole of helium has a pressure of 100mmHg, what pressure will 2 moles have (assuming volume and temperature remain constant, of course!).
  3. What is Dalton’s law? Understand what is meant by terms like atmospheric pressure and partial pressure. What is the composition of the air around us?
  4. Understand Henry’s Law and gas solubility. What is equilibrium with respect to a gas entering and leaving an aqueous phase?
  5. Are partial pressures equal to the concentration of a gas in liquid? Are partial pressures and concentrations proportional?
  6. According to Henry’s law, what two factors determine the concentration of a gas in a liquid? Of the two factors, which one is the most important for driving gases across the respiratory membrane and capillary membrane (internal respiration).
  7. How are sodas and scuba diving perfect examples of Henry’s law?
  8. What four partial pressures are you most concerned with when dealing with Henry’s law and what do they represent?
  9. What are the partial pressures of oxygen and CO2 in alveolar air, venous and arterialized blood?
  10. Alveolar gas partial pressure values result from the steady exchange of gases with blood and steady introduction of fresh air by ventilation. What will happen to each value if one hyper- or hypoventilates? How will these changes in alveolar partial pressure of O2 and CO2 affect arterial partial pressures?
  11. What is the rate of diffusion in the lung vs. lung transit time? Is there any reserve time? How much? When would this reserve time be needed?
  12. How many oxygen molecules does the myocardium need? What do exercise stress tests do?
  13. What is the oxygen consumption in an average person? Can plasma alone deliver this amount of oxygen?
  14. How is oxygen carrying capacity dependent on hemoglobin concentration (gm %). For each gm of hemoglobin how many ml of oxygen can be transported?
  15. What two ways can oxygen be transported?
  16. Review the hemoglobin molecule—what are its components? What are globin chains? What is heme? Why not use heme alone to carry oxygen? What form of iron carries oxygen? What is methemoglobin?
  17. What is affinity? What is allosterism? What allosteric binding sites does hemoglobin have? Understand the nature of these allosteric binding sites and how they can alter the loading and unloading of oxygen (i.e., changing from deoxyhemoglobin to oxyhemoglobin).
  18. If a normal person were placed on pure oxygen (100% vs 20%), would the oxygen carrying capacity of their blood significantly improve? Why?
  19. Walk yourself through the oxyhemoglobin dissociation curve. Be able to interpret it with respect to hemoglobin’s allosteric binding sites. How are the axes labeled (understand what each label expresses), and be familiar with the shape of the curve, i.e., in what range is it fairly flat or fairly steep? What is the slope of the curve in each region (look specifically at venous and arterial pO2’s)
  20. Relate the ease or difficulty with which Hb will release its bound oxygen to the change in slope of the curve. How much of a pressure change is required for Hb to release its first, second, third and fourth oxygen molecule?
  21. How can this sigmoidal curve be shifted? What four (plus one) things can change oxyhemoglobin affinity?
  22. What is a shift to the left vs. a shift to the right? Why is this a description of the affinity of Hb for oxygen? If you have difficulty with this concept, Examine the dissociation curve, and determine the partial pressure of oxygen necessary to saturate Hb to 50%, for example. Now shift the curve either to the left or right, and determine what partial pressure is required to saturate the Hb to 50% under each of these conditions. Hb that loads more easily (higher affinity) requires a lower partial pressure (smaller driving force.)
  23. If fetal and adult hemoglobin have the same affinity for oxygen, then why is the adult hemoglobin’s dissociation curve shifted to the right?
  24. Why is it that carbon monoxide alters the carrying capacity for oxygen AND shifts the dissociation curve for hemoglobin to the left? Why could the blood still be red and the patient exposed to CO not appear cyanotic? Where does CO bind, how great is the affinity of Hb for CO and how does this affect Hb’s loading with oxygen? How does it affect Hb’s unloading of any oxygen it already has bound?
  25. What three things alter the carrying capacity of blood?

Hemoglobin Transport of Oxygen and Carbon Dioxide

  1. Why aren't pCO2 and pH changes independent of each other? The effect of CO2 and hydrogen ion on oxygen affinity is known as the Bohr effect. What is the enzyme that is responsible for the hydration of CO2 and where is it found?
  2. Consider each of the variables listed in the previous answer, and explain how they change in concentration in the RBC as it moves from pulmonary capillary to metabolically active tissue capillaries.
  3. Examine carbon dioxide transport in plasma and on Hb. List the ways in which this gas is transported in both plasma and then in the RBC. Which of these modes of CO2 transport is quantitatively the most significant?
  4. Be familiar with the movement of bicarbonate across the RBC membrane (the “chloride shift”,) as it occurs while in the pulmonary capillaries and then in metabolically active tissue capillaries.
  5. Hydrogen ions produced by the hydration of CO2 must be buffered, or plasma pH will certainly change. Explain how these ions are buffered by Hb.
  6. Hb’s affinity for binding hydrogen ions and CO2 is affected by its binding of oxygen. Explain this. This is known as the Haldane effect.

Control of Respiration

  1. What is the effect of depolarizing cells of the Dorsal Respiratory Group (DRG)?
  2. What is the action of the pneumotaxic centers on the DRG?
  3. What are chemoreceptors? What is their role?
  4. Where are the peripheral chemoreceptors located? By what nerves do they relay information to the medulla? What substances do they monitor? What fluid do they monitor?
  5. Where are the central chemoreceptors located? What fluid are they bathed with? What substances do they monitor? How is this related to changes in plasma chemistry?
  6. What other factors can influence respiration.
  7. What is Ondine’s curse? Central Sleep Apnea? Cheyne-Stokes breathing?
  8. What receptors do we have in our lungs that may alter breathing?
  9. Is hypoxemia ALWAYS associated with hypercapnia?
  10. How do the lungs control ventilation and perfusion when there is increased/decreased pCO2 or pO2?
  11. Definethe terms: atelectasis, hyper/hypoxia, hyper/hypocapnia, dyspnea.

Ventilation vs. Perfusion Ratio

  1. What is the difference between “negative” and “positive” pressure breathing?
  2. What is anatomic deadspace? About how large is it in the normal person? Define physiologic deadspace. Why does this vary from person to person?
  3. Are all regions of the lung ventilated evenly? Are all regions of the lung perfused equally?

Metabolism

  1. Define metabolism, catabolism and anabolism
  2. The process, substrates, products and location of events during glycolysis.
  3. The process, substrates, products and location of the Kreb’s cycle.
  4. The process, substrates, products and location of oxidative phosphorylation
  5. The process of using fat and protein as energy sources: where they feed into the metabolic pathways listed in the above questions, how they are broken down, what waste products are generated (ketone bodies).
  6. What happens in a patient who is starving or has diabetes “starving in the face of plenty.” Be able to discuss how fatty acid and protein catabolism shunt to less desirable products (again, you should understand why acetyl-coA can’t feed into the Kreb cycle and why it is turned into ketone bodies).
  7. Be able to recognize monomers and polymers and answer questions regarding them (see next page).

Digestive Physiology

  1. Review the anatomy of the digestive system and the general function of each of the regions.
  2. Describe the regulation of stomach function by Gastrin: how it leads to stimulate HCl secretion, pepsinogen secretion.
  3. Describe how bile helps in digestion and how it is stimulated to be secreted. What do bile salts do for the body when they emulsify fats?
  4. What enzymes are released from the pancreas and what is the trigger for their release. Also, what is their function?
  5. How does the small intestine control digestion? (Hint: this would be the hormones released by the duodenum that feed back to the pancreas, gallbladder, and stomach).
  6. How does the parasympathetic nervous system augment the digestive process?
  7. How is fatcatabolized, absorbed and carried in the blood?
  8. How are carbohydrates catabolized and transported across the mucosa?
  9. How are amino acids catabolized and transported across the mucosa?