Biking To Cape May Day 1 - Correlation Does Sometimes Imply Causation

 

 Photo by Dr. Haus

 

Well, I decided to do something crazy and take a week off work to bike around 200 miles to Cape May.  As with most of my ingenious plans, I decided to do this on a whim and thought to myself, I am sure I can make it.

Photo by Dr. Haus

Day 1 consisted of getting myself out of the "city" area and to the coast.  For this trip, I wanted to follow the ocean as much as possible for the views and honestly mostly for the flatness/emptiness I would find there.  That experience would come more the second and third days as I worked my way down the Jersey coast.

Photo by Dr. Haus

For this first leg of the journey, I used my GPS until I caught up with my coastal route.  A friend of mine's friend created a route for me that started in Sandy Hook and went all the way down to Cape May.  I didn't want to ride my bike to Sandy Hook to start the ride there out of sheer laziness.  I wanted to decrease the amount of miles so decided to cut diagonally to the coast to pick up the route further south.  It was about 42 miles of some nice trails and road riding to get to the coast.

Photo by Dr. Haus

 

I was able to take the Henry Hudson Trail for part of the journey which is a trail I absolutely want to get back to on a day that I am not grinding out a huge amount of miles.  I would have enjoyed taking more time on this trail and enjoying all the sights and sounds.  Thankfully my road bike did okay on the trail given that it had minimum gravel.  I did have to cut through an orchard prior to the Henry Hudson trail which was tough because my road bike wasn't made for that.  At one point I had to walk my bike a few yards due to sandy conditions and my bike sliding around like my Corolla on ice.

 

 Photo by Dr. Haus

The other highlight of this first day was riding on the Capital to Coast Trail which was a beautiful ride where I got to see an old fashioned train slowly moving down the train tracks.  This part of the journey was one of my favorites and I want to do this trail again when I am not on a crazy mission.

Photo by Dr. Haus

I stopped for lunch in Manasquan (lovely diner with lovely staff) and then hopped on my bike to get another 20-30 miles completed before the end of the day.  This is where I realized that correlation does sometimes imply causation as my mood on the ride was directly correlated to whether I was climbing or riding on a flat road.  I can now say with absolute certainty I made the correct choice in taking a slightly longer route to Cape May by taking the shore due to the general flat nature of the ride (minus the bridges from hell but don't worry, I will be complaining about them in every subsequent post as well).  Let's just say the bridge into Tom's River from Seaside Heights is offensive and it can fall into the ocean and I wouldn't even care (of course with no one on the bridge, obviously).

 

🌉

The most interest aspect of the final part of this first leg was that once I got to the coast I entered the Jersey Shore ghost towns of the Fall/Winter season.  It was a combination of amazing (for my introvert soul coupled with not wanting to get hit by a car) and eerie (for the part of me that watches too many crime-based shows).  Being in a tourist town is not new to me, I lived in one for 1.5 years straight out of school and I was reminded of how much I love these towns in the off-season (and some of the annoyances that come with being in a tourist town off-season).  This made for an excellently solitary ride to end my day that started in the bustle of the city and city drivers (aka, gross).  I completed the night in Tom's River, quite a bit sore but very proud as I made it significantly further than I thought I would on Day 1 of the Biking to Cape May adventure.  Catch you in the next one!

Photo by Dr. Haus

 

 

Liver Anatomy

 

Photo by Dr. Haus

Liver Anatomy

The anatomy of the liver must be understood to truly understand the functioning of this vital organ.  Of course this is required for all organs but, as usual, I digress...  

🪅

The liver sits in the upper-abdominal region of most mammalian organisms situated beneath the diaphragm.  The diaphragm is the muscle that separates the thoracic (chest) cavity from the abdominal (belly) cavity as well as assisting an organism with breathing.  

❓

Thought provoking question (based on the above paragraph) - what might happen in a patient whose liver is severely enlarged?  I saw this in my clinical rotations and this patient stumped the docs for a brief time as this clinical sign/symptom is not immediately thought of as being caused from liver enlargement. 

🐳

Check out the image of the liver, gallbladder, stomach, spleen, pancreas, and small intestines of a human with its associated blood vessels/biliary ducts:

   

Photo from: https://www.hopkinsmedicine.org/-/media/images/health/1_-conditions/liver-gallbladder-and-pancreas/liver-anatomy.png 

 

Liver Lobes

Liver lobes are macroscopic (visible with the naked eye) sections of the liver that can be seen when looking at a liver.  The number and names of the liver lobes is dependent on species.  Some examples are below:

Dogs - 6 lobes

Cats- 6 lobes

Horses - 5 lobes

Cattle - 4 lobes

Whales - 2 lobes

Pigs - 5 lobes

Humans - 4 lobes

Image of a Pig Liver with 5 Liver Lobes:

 

Photo from:  https://www.researchgate.net/figure/Anatomic-features-of-pig-liver-a-Pig-liver-showing-relative-position-of-each-of-the_fig4_23803968

 

Liver Lobules

The liver is often discussed in microscopic (cannot be seen with the naked eye) terms as liver lobules.  A liver lobule is a small grouping of liver tissues that make up the functional unit of the liver.  A functional unit of an organ is the smallest categorization of an organ that can perform all of the organ's function.  The liver lobule is the smallest categorization of the liver that can perform every basic function the liver needs to keep an organism healthy. 

💾

 

There are three (3) major parts of a liver lobule: 

 

1. Portal Triad (five (5) parts)

    1. Proper hepatic artery (portal arteriole) - Supplies oxygen to the liver, this vessel is an arteriole off the hepatic artery

    2. Hepatic portal vein (portal venule) - High in nutrients and low in oxygen, this vessel is a venule off the portal vein

    3. Bile ductules (bile duct) - Branches of the biliary system, these ducts move bile through the liver

    4. Lymphatic vessels - Vessels which move lymph through the liver (not pictured in image below)

    5. Branch of the vagus nerve - Nerve innervation from the vagus nerve, autonomic nervous system (not pictured in image below)

2. Central vein - Venule that drains deoxygenated hepatic blood into the hepatic vein

3. Hepatocytes - Liver cells

 

Photo from:  https://upload.wikimedia.org/wikipedia/commons/b/b7/2423_Microscopic_Anatomy_of_Liver.jpg

 

Portal Vein Anatomy

The portal vein is arguably the most important vessel to understand within the liver because it collects all of the blood that comes from the gastrointestinal system (large intestines, small intestines, stomach, etc.), gallbladder, pancreas, and spleen.  Now, think about what the previous statement means - what does the portal vein carry?

🍛

You guessed it - the portal vein carries EVERYTHING the gastrointestinal tract absorbs and brings it to the liver.  This means the portal vein carries a HUGE amount of nutrients from food, water, microorganisms, toxins, bile salts, etc.  The large amount of microscopic materials present in the portal vein explains the major functions of the liver due to its need to process all of the different contents of the portal vein upon its arrival to the liver.  

🌟

*In a normal, healthy organism, the portal vein will arrive to the liver and the blood will be processed by the liver PRIOR TO returning to the right side of the heart.* (thought provoking question - why is this important?)

🛼

Below is an image that illustrates how all the blood from the gastrointestinal tract flows into the portal vein.  This blood then arrives to and is processed by the liver prior to returning to the heart.

 

 

Photo from:  https://projects.cos.ncsu.edu/bio370/wrap/TopicsFolder/circulatory3/text_images/portal_vein.jpg 

 

Now that we understand the basic anatomy of the liver, we will continue to explore the different functions of the liver to allow us to work through some upcoming liver-related cases.  Keep up the great work and catch you all in the next post (which will hopefully happen in a quicker time frame)!

 

The Liver

 

Photo by Dr. Haus

The Liver

The liver is an organ that always fascinated me but was never a large focus in any of the courses I taught as there was never enough time.  This bothered me as as the liver affects every other organ in the body and affects the ability of an organism to function and survive.  The liver is an often neglected organ in the study of body systems, especially for undergraduate students.  The liver only took up about one-third of a lecture in my Pathophysiology course though it was not nearly enough time to dive into the amazing world of the liver.  I always dreamed of offering a course that was entirely based on the liver and this is what I am going to try to do here in this blog through this post and many more.

🤓

Liver = Love

A previous student once spoke to me after the liver lecture and mentioned that in their culture the liver is the organ representing love.  They explained to me that you tell someone they are your liver as the strongest way to express your love for another person.  This fascinated me as it was new information and I have an odd interest in the history of language, the root of different words, and understanding other cultures.  As I have read more and more, I see that the liver is used in numerous languages and phrases from African nations to Middle Eastern nations to Eastern nations to express unconditional love and emotion.  

🫶

From a completely scientific standpoint, it makes sense that the liver is associated with love in many cultures as the liver is a vital organ in the body that processes all of the blood flowing throughout the body.  After diving into this information more deeply, I learned most Eastern and Middle Eastern cultures view the liver as the organ of love, not the heart like the Western world.  In the spirit of creating a liver-focused post, I knew I needed to do some digging into the history of the liver in different cultures, and its focus on symbolizing love.

😻

Liver Etymology

Etymology is the study of words, their history, and how words change over time.  This is a great starting point for the word liver because historically it was considered the organ of love, life, emotions, pleasure, and passion.  In Western languages, the liver's historical origins are that it is the organ of emotions, the organ of life, and the organ of courage.  It is interesting that even during ancient times the recognition of the liver's importance for survival was well understood.  To learn more about the etymology of the liver check out the sources links below [1].

🫰

Digging deeper into the history of the liver further increases my fascination with this organ as multiple different ancient cultures viewed the liver as central to the functioning of humans.  Hepatocentrism was the focus of medicine in most ancient populations of humans.  The ancient civilizations in Mesopotamia considered the liver central in the functioning of a human body and the Western world did not move away from this mindset until the 1600s.  The liver was thought to be where a human's soul was housed with some even believing there was a fire (soul) burning in each person's liver [2].

❤️‍🔥

Ancient religious texts, pieces of famous literary works, Greek mythology, and medical writings all focus on the liver being the center of human life in ancient times.  Some of the famous works that demonstrate the reverence felt for the liver are listed below [2]:

• The Quran
• Moby Dick
• The myth of Prometheus
  
• The Bible
• The Tale of Hind bint ‘Utbah
  
• Snow White
• The Torah
• The God of death in ancient Aztec mythology
• The myth of Tityus
• The Iliad
• Ancient Chinese, Persian, and Urdu medical texts
• The crucifixion of Jesus Christ
  

🧑‍🎨

It is interesting to note that the ancient Egyptians did NOT see the liver as the location the soul - the ancient Egyptians saw the heart as the location a soul resides.  This is the reason why the heart was left in a mummified corpse while the liver was not.  The heart remaining in the corpse was thought to allow the person to move into the afterlife to live on forever [2].

🇪🇬

In the 1600s, medical knowledge started to change and scientists of that time discovered that many of the functions they associated with the liver were actually associated with the heart.  It was during this time Western culture started moving away from its reverence for the liver.  There is a work of art in the Museo Storico Nazionale dell'Arte Sanitaria in Rome, Italy called "Il Fegato" that depicts the heart and liver fighting over being the king of organs through the production of blood (interestingly enough, the heart does not produce blood as you all know, but I guess talking about the bone marrow isn't as cute as the heart).  Moral of this story?  I need to get to Rome to check out this painting [2]! 

🇮🇹

Above is a very brief outline of the history of the liver and helps explain common phrases related to the liver in many cultures.  What is most interesting is the strong correlation of the liver and love in most non-Western cultures that seems to have been lost to the Western world in the seventeenth century.  I highly encourage you all to check out the two sources below [1 and 2] as they are good reads and can jump start you on the fun nerd journey of entomology and the intersection of science, medicine, the arts, and language.  To end, I must say, I love my two little livers (my cats).

😎

Liver Education (To be updated as I complete blog posts)

Anatomy

Liver Lobules

 

Basic Liver Functions

Accessory Organ of Digestion

Organ of Metabolism

Organ of Hematology

Organ of Endocrinology

Organ of Detoxification

Organ of Storage

Organ of Immunity

Organ of Synthesis

 

Liver Dysfunction

Icterus/Jaundice

 

 Sources

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3747976/pdf/nihms493154.pdf
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6078213/
   
   
   
   
   
   
   
   
   
   
   

Conclusion Caturday: Vince Vomits Valiantly (Case 7)

Photo of TA Douglas (Left) and Professor Pocky (Right) taken by Dr. Haus

 

Click For Explanation of Case Flow

 

Click for Test Case Tuesday:  Vince Vomits Valiantly

 

Click for Thoughtful Thursday:  Vince Vomits Valiantly

 

Quick Review

Diagnosis:

🦴Myasthenia Gravis🦴

 

Pathophysiological Point:

Myasthenia gravis is a disease where the acetylcholine receptors between nerves and muscles are destroyed or blocked.  Simply, nerves cannot conduct their signals to muscles.  Muscles are unable to contract (move) without the signals from the nerves.

 

 Questions, Answers, and Further Information:

 

Level 1 Questions, Answers, and Further Information:

1. Vince's communication between his nerves and muscles is disrupted, how does that affect the muscles of his body?  Why?
   
   If Vince's nerves cannot communicate with his muscles, his muscles will not be able to move.  The nerves tell the muscles to move and without this signaling he will not be able to contract his muscles easily leading to difficulty moving.
   
   
2. What part of Vince's history and physical exam findings support the diagnosis of a disease that affects communication between the nerves and muscles of his body?
   
   The history and physical exam findings that support his diagnosis are the generalized weakness and muscle loss.  These findings support the fact that Vince's nerves are not able to send their normal signals to the muscles.
   
   
3. Challenge question, why does Vince have megaesophagus?  How does this cause regurgitation after meals?  (HINT:  Think about Vince's disease and how it would affect the muscles of the esophagus)
   
   The esophagus is a muscle much like the other muscles of the body.  In order for food and fluid to get to the stomach, the esophagus must be able to contract.  With Vince's disease, he cannot use his esophageal muscles to push the food/fluid down to his stomach so the food and fluid accumulates in the esophagus causing it to expand and stretch causing megaesophagus.  As this food/fluid builds up in the esophagus it will comes out the mouth because the muscle contractions are not there to get the food and fluid to his stomach efficiently.
   
   

   Helpful Links:

   • VCA (dogs):  https://vcahospitals.com/know-your-pet/megaesophagus
     
     
   • Mayo Clinic (humans):    https://www.mayoclinic.org/diseases-conditions/myasthenia-gravis/symptoms-causes/syc-20352036
     
     
   • Cornell Vet School:  https://www.vet.cornell.edu/departments/riney-canine-health-center/canine-health-information/myasthenia-gravis
     

 

Level 2 Questions, Answers, and Further Information:

1. How does myasthenia gravis cause disease (i.e., megaesophagus) in a patient?  Be sure to mention the “normal” esophageal physiology in your answer and explain physiologically where the miscommunication is occurring.  (HINT:  Review normal neuromuscular junction physiology)
   
   Myasthenia gravis destroys/blocks the acetylcholine receptors on the muscle cells.  Neurons release acetylcholine into the synaptic cleft at the neuromuscular junctions.  This allows the muscle cell to begin to undergo the process of depolarization which will eventually lead to the muscle contracting.  The esophagus is a muscle that must contract to move food/fluid towards the stomach.  With the acetylcholine receptors of the esophageal muscles destroyed/blocked, the esophagus cannot move the food/fluid and the esophagus will expand to accommodate all the stuck food/fluid material.
   
   
2. How does megaesophagus lead to Vince’s major clinical sign (regurgitation)?  (HINT:  Think about what keeps us from floating away into space)
   
   Since Vince cannot contract his esophagus, the food/fluid will sit in the esophagus unable to move aborally.  This leads to the material falling back out the mouth especially when Vince puts his head down as gravity will cause the food/fluid to fall out of the mouth.
   
   
3. Challenge question, explain why Vince has pneumonia.  Be sure to explain how his underlying disease predisposed him to this condition.  Be sure to mention the anatomy involved.  (HINT:  Think about what structure sits right next to the esophagus)  
   
   Vince's pneumonia is likely due to his regurgitation from the megaesophagus.  Each time Vince regurgitates his food, he risks some of the food/fluid accidentally falling into the trachea which sits next to the esophagus.  When food/fluid enters the esophagus there is a risk that the material gets into the deeper lung tissues leading to pneumonia (inflammation of the alveoli).
   
   

   Helpful Links:
   

   • Merck Vet Manual:   https://www.merckvetmanual.com/nervous-system/congenital-and-inherited-anomalies-of-the-nervous-system/neuromuscular-disorders-in-animals 
     
     
   • Cornell Vet School:  https://www.vet.cornell.edu/departments/riney-canine-health-center/canine-health-information/myasthenia-gravis
     
     
   •  Merck Vet Megaesophagus:  https://www.merckvetmanual.com/digestive-system/diseases-of-the-esophagus-in-small-animals/dilatation-of-the-esophagus-in-small-animals
     
     

Level 3 Questions, Answers, and Further Information:

1. Describe the treatment plan you would recommend Vince and why you are recommending each part of your treatment plan.  Please answer this question as if you are speaking to a professional colleague.  .
   
   Vince's treatment plan will depend on the etiology of his disease.  If Vince's disease is due to a thymoma the thymoma needs to be surgically removed.  Otherwise, anti-acetylcholinesterase medications can be used to treat these patients.  Vince will also need to be treated for his pneumonia with antibiotics and other supportive care as needed.
   
   
2. Describe your recommended treatment plan and why you are recommending each part of your treatment plan.  Please answer this question as if you are explaining it to a client/patient without a scientific background.
   
   Vince has a disease that causes his nerves and muscles to not communicate correctly.  We will be starting Vince on a medication that will help his nerves and muscle communicate better while also starting him on antibiotics to treat his pneumonia.
   
   
3. Please describe the different ways Vince's owners could help manage his condition with environmental changes.
   
   There are a few ways Vince's owners can help increase Vince's quality of life at home.  Firstly, Vince should be fed and watered from dishes that are elevated off the floor (less gravitational effects).  The owners can also hold Vince up vertically after meals to help gravity "push" the food/fluid down to his stomach.  His owners should also feed him smaller, more nutrient dense meals to decrease his risk for regurgitation.
   
   

   Helpful Links:

   • Journal of Internal Veterinary Medicine:   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8478050/  
     
     
   • Journal of Clinical Medicine:    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8196750/
   
   

Day 3 Conclusion

I hope you enjoyed the Vince's case!  Don't forget to...

📚 Review material related to the goats' case 

🤩 Get excited for upcoming cases

 

Thoughtful Thursday: Vince Vomits Valiantly (Case 7)

  

Photo of Professor Pocky taken by Dr. Haus

Click For Explanation of Case Flow

 

Click for Test Case Tuesday:  Vince Vomits Valiantly (Case 7)

 Vomiting or Regurgitation?

The MOST important determination to make in a vomiting patient's case is to make sure the patient is actually vomiting.  Vomiting is NOT the same as regurgitation.  Regurgitation is when food/fluid comes out of the mouth from any structure before the stomach (mouth, pharynx (throat), esophagus (food tube), etc.)  Vomiting is when food/fluid come out the mouth from the stomach or upper small intestines.

🤢

This distinction is extremely important because the causes of vomiting and regurgitation are different and the way we work up the two types of cases are completely different.  It is important to remember that an owner can say their pet is vomiting when they are in fact regurgitating food.  The ways you can differentiate vomiting and regurgitation are noted below:

Vomiting

• Abdominal push (abdominal muscles contract to push the vomitus out of the mouth)
  
• Bile present (green substance)
  
• Active process (you can see the whole body put in an effort to vomit)
  

🤮

Regurgitation

• No abdominal push
• No bile present
• Passive process (the mouth opens and the food/fluid comes out, no pushing seen)

 😵

An important aspect of any veterinary professional is to have your acting skills on point as it is common to see us acting out vomiting versus regurgitation.  The things that happen in an exam room are sometimes bananas (ask your vet med friends to act out reverse sneezing, you won't regret it).

 🎭

The owners describe Vince's "vomiting" as him eating his food and then immediately it "falls" back out of his mouth.  The owners do not see Vince actively retching or "pushing" when he has the "vomiting".  It is determined Vince is regurgitating, not vomiting!

 

Diagnostic Testing Results:

 

Radiographs: Severe megaesophagus (enlarged esophagus, food tube), signs of pneumonia 🩻

 

Specific Disease Testing - Acetylcholine Receptor Antibody Test: Positive ➕

 

🧪

Diagnosis:

🦴Myasthenia Gravis🦴

 

Pathophysiological Point:

Myasthenia gravis is a disease where the acetylcholine receptors between nerves and muscles are destroyed or blocked.  Simply, nerves cannot conduct their signals to muscles.  Muscles are unable to contract (move) without the signals from the nerves.

 

 Questions:

Level 1 Questions:

1. Vince's communication between his nerves and muscles is disrupted, how does that affect the muscles of his body?  Why?
   
   
2. What part of Vince's history and physical exam findings support the diagnosis of a disease that affects communication between the nerves and muscles of his body?
   
   
3. Challenge question, why does Vince have megaesophagus?  How does this cause regurgitation after meals?  (HINT:  Think about Vince's disease and how it would affect the muscles of the esophagus)
   

 

Level 2 Questions:

1. How does myasthenia gravis cause disease (i.e., megaesophagus) in a patient?  Be sure to mention the “normal” esophageal physiology in your answer and explain physiologically where the miscommunication is occurring.  (HINT:  Review normal neuromuscular junction physiology)
   
   
2. How does megaesophagus lead to Vince’s major clinical sign (regurgitation)?  (HINT:  Think about what keeps us from floating away into space)
   
   
3. Challenge question, explain why Vince has pneumonia.  Be sure to explain how his underlying disease predisposed him to this condition.  Be sure to mention the anatomy involved.  (HINT:  Think about what structure sits right next to the esophagus) 
   

    
   

Level 3 Questions:

1. Describe the treatment plan you would recommend Vince and why you are recommending each part of your treatment plan.  Please answer this question as if you are speaking to a professional colleague. 
   
   
2. Describe your recommended treatment plan and why you are recommending each part of your treatment plan.  Please answer this question as if you are explaining it to a client/patient without a scientific background.
   
   
3. Please describe the different ways Vince's owners could help manage his condition with environmental changes.
   

  

Day 2 Conclusion

Before Conclusion Caturday think about your...

❓Answers to the above questions

📚 Review Material Related to Vince's case

 

Conclusion Caturday: Vince Vomits Valiantly (link will go live Saturday, 02/17/2024)

 

Test Case Tuesday: Vince Vomits Valiantly (Case 7)

 

Picture of Professor Pocky taken by Dr. Haus

Click For Explanation of Case Flow

 

Signalment:

Vince is a 4-year-old male neutered Labrador Retriever Dog

🐶

History:

Vince is presenting for vomiting his food after every meal, generalized weakness, and lethargy.  His owners note that for the past few meals (even small ones) Vince will vomit immediately after he eats any food.  ​

Vince has a 2-year-old Labrador Retriever female spayed sister named Vanessa.  Vanessa is showing no signs of illness.

🤮

Physical Exam Findings:

Respiratory:  Raspy lung sounds​ 🫁

Musculoskeletal:  Generalized muscle weakness/atrophy (muscle wasting)​ 🏋️

 

🩺

 

🛑STOP and brainstorm what diagnostic tests you would like to perform on Vince 🛑

 

 

We will be stopping here today.  Before Thursday, think about what question(s) you need to ask Vince's owners to fully understand his history (Hint: Think about vomiting).  We will review an important distinction veterinarians need to make with vomiting patients and what diagnostic testing will be done based on that knowledge.

🧪

Day 1 Conclusion

Before Thoughtful Thursday think about your...

📋 Differentials List

🧪 Further Diagnostic Testing

📚 Review Material Related to Vince's case (i.e. what questions to ask owners of a vomiting patient, questions to ask a vomiting patient (if patient is a human that can communicate), specific diseases of interest, causes of vomiting, types of vomiting, personal interests, confusing points, etc.)

 

Thoughtful Thursday: Vince Vomits Valiantly (link will go live Thursday, 02/15/2024)