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Invitation to Submit Questions for Respiratory Unit

As I’ve been doing lately, I wanted to offer the opportunity to my students (and anyone else who would like to) to submit questions for the Respiratory Unit Exam of my Pathophysiology class. Topics covered on this exam will focus primarily on the outline below. However, I wish to remind students that they are responsible for all the material covered in chapters 21-23 of Porth’s Essentials of Pathophysiology.

Airways preserved in the right lung, airways and pulmonary circulation in the left lung.

Airways preserved in the right lung, airways and pulmonary circulation in the left lung.

To submit questions, please provide a fully worked out multiple choice question in the comments section below. Also indicate the correct answer.

Respiratory Pathophysiology Outline (Please, forgive the formatting below, I’m having trouble fixing this appropriately in the browser):

  1. Control of Respiratory Function
    1. Conducting Airways
      1. Nasopharynx
      2. Larynx
  • Trachea
  1. Bronchial Tree (Primary -> Terminal)
  1. Respiratory Tissue (Acini)
    1. Respiratory Bronchiole
    2. Alveoli
      1. Type I, Type II Alveolar Cells and Alveolar macrophages
    3. Pulmonary (And Bronchial) Circulation
    4. Pleura
    5. Ventilation and the Mechanics of Breathing
      1. Chest Cage and Respiratory Muscles
      2. Lung Compliance
    6. Lung Volumes and Capacities
      1. Total Lung Capacity
      2. Tidal Volume
  • Etc.
  1. Diffusion according to Fick’s Law
  2. Oxygen Delivery
    1. Oxygen / Globin Dissociation Curves
  3. Infections
    1. The Common Cold
      1. Caused by a number of different viruses
      2. A number of different serotypes
    2. Influenza
      1. One of the most deadly uncontrolled human infections
      2. Three types of influenza (A,B, and C – A is most diverse)
        1. Influenza A
          1. Distinguished by serotypes based on H&N genes
  • Three types of infections
    1. Uncomplicated upper respiratory disease
    2. Viral Pneumonia
    3. Viral Pneumonia + Bacterial Pneumonia
  1. Pneumonia
    1. Typical*
      1. Bacterial ( pneumoniae)
    2. Atypical*
      1. Viral (Influenza, Chickenpox), Fungal, protozoan
  • Legionnaire’s Disease
    1. (I find that pneumonia caused by Legionella is placed as either typical or atypical depending on the source)
  1. Fungal Infections
  2. Tuberculosis
    1. Diagnosis
    2. Treatment
  3. Congenital and Acquired Obstructive Disorders
    1. CF
    2. Asthma
    3. COPD
    4. Pulmonary Hypertension – causes and outcomes

*The distinction between Typical and Atypical pneumonia appears to be more historic than clinically valuable. For this reason, on our exam we will continue to call S. pneumoniae the most common form of ‘Typical’ pneumonia, but otherwise not use these terms.

 
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Posted by on March 4, 2015 in Uncategorized

 

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Aside
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Substrate Level Phosphorylation

Several processes occur during normal eukaryotic metabolism to create ATP. During glycolysis (the breaking of sugar) both prokaryotes and eukaryotes use energy from the chemical bonds in the sugar to make ATP by directly transferring phosphates from the substrate molecule to ADP, resulting in ATP. Predictably, this process became known as ‘substrate-level phosphorylation. Both Cell Respiration, occurring in the mitochondria, and the light reactions of photosynthesis, occurring in the chloroplasts, also made ATP, however, no one understood how this occurred as no intermediate substrate molecule bearing the phosphates groups was known.

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1978 Nobel Prize in Chemistry winner

The Peter Mitchell, working at his own, privately funded research foundation, tackled this problem and determined that the power to make ATP came from two processes linked indirectly. For his work in this area, Mitchell won the 1978 Nobel Prize in Chemistry “for his contribution to the understanding of biological energy transfer through the formulation of the chemiosmotic theory”.

Model diagram of electron transport and H+ translocation across the membrane

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Electron flow carries H+ across the membrane

Process#1: One of these processes is the electron transport chain (E.T.C.) during which a high-energy, excited electron is passed down a series of membrane proteins. As the electron is passed, it sometimes pulls hydrogen ions (H+) along and passes them across the membrane (see the cartoon illustration of this model by Mitchell). As a result, this process creates an electrochemical gradient across the membrane with more H+ on one side compared to very few on the other.

Process #2: As we know, these gradients will ‘want’ to resolve themselves and move towards equilibrium (by diffusion). There exists a special channel protein that H+ may pass through from the side of the membrane with a high concentration of these ions to the other.

“Each chemical species (for example, “water molecules”, “sodium ions”, “electrons”, etc.) has an electrochemical potential (a quantity with units of energy) at any given location, which represents how easy or difficult it is to add more of that species to that location. If possible, a species will move from areas with higher electrochemical potential to areas with lower electrochemical potential; in equilibrium, the electrochemical potential will be constant everywhere for each species”

                         -from the wiki page on electrochemical potential

I prefer to imagine the membrane and ions as a hydroelectric dam with water building up on one side and a relief passage through the dam.Image

Just as energy is captured when water rushes through the dam, H+ ions coming through the channel protein are used to power an enzymatic subunit that synthesizes ATP.

Sigma-Aldrich provides an excellent animation illustrating how ATP Synthase operates as both a H+ channel and an enzyme making ATP.

http://www.sigmaaldrich.com/life-science/metabolomics/learning-center/metabolic-pathways/atp-synthase/atp-animation.html

A conceptually simple set of experiments provides the evidence supporting this model. Here, an artificial membrane is made incorporating ATP synthase and bacteriorhodopsin. The rhodopsin molecule is capable of transporting H+s across the cell membrane when it is struck by light. Given sufficient supplies of H+ ions, ADP and Pi, ATP will be formed when a light source is present. In the absence of light, no H+ is transported and no ATP is made.

When a H+ carrier molecule that can diffuse through the membrane is introduced, this carrier maintains equal amounts of H+ on both sides of the membrane. Further, even when light is present, H+ is pumped across the membrane and then re diffuses back creating little or no ATP. This is illustrated in a cartoon from Albert’s Essential Cell Biology:

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Chemiosmosis defined experimentally

Chemiosmosis and the work of Peter Mitchell

 
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Posted by on October 5, 2013 in Uncategorized

 

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Getting Oxygen Where It’s Needed

Getting Oxygen Where It’s Needed.

This is an older post of mine that I thought I should point back to because my general biology class is now covering cellular respiration.

 
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Posted by on October 3, 2013 in Education

 

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