biomedicalephemera:

Effects of influenza on the respiratory system

Left: Acute hemorrhagic and ulcerative laryngotracheitis
Right: Right lung - showing consolidation, grey hepatization (lower lobe), and congestive edema (upper lobe). There is a large hemorrhage in the center of the hepatized lobe.

Happy Flu Season!

I’ve said it before, and I’ll say it again - even if the flu is just a few days of misery for you, it’s often far more serious than you might think for many others out there. It’s worth making sure you get the vaccine every year so you don’t spread infection, and, if you do get infected, stay the hell at home.

Hepatization is the conversion of a tissue or organ to a “liver-like” substance. In the lungs, this occurs when they become engorged with effused matter, such as red blood cells, neutrophils, and fibrin, which clog up the alveoli to the point that the lungs are impervious to air, where this has occurred. Grey hepatization is the second stage in lung hepatization - at this point, the red blood cells have broken down, leaving only the fibrinogen exudate and dead tissue behind.

Laryngotracheitis is an inflammatory response in the larynx and trachea. The trachea is lined with the same epithelial cells as much of the bronchial tree, and all influenza strains are able to infect those cells. This is why, whether you have a “light” case of the flu or a deathly-serious case, coughing and throat pain still occur. When the infection is bad enough, the coughing can lead to ulceration of the tissue below the epithelium, which can lead to bleeding into the lungs, or coughing up blood.

In cases involving “consolidation”, there is generally an opportunistic pneumonia taking hold. The bacterial exotoxins and sometimes the patient’s own immune system, break down epithelial cells that separate and define the alveolar sacs. The surface area given by these epithelial layers is what allows a high volume of oxygen to be absorbed with each breath we take. When those cell layers are destroyed, the oxygenation of blood is severely decreased.

Pathology of Influenza. Charles Winternitz, Isabel Wason, and Frank McNamara, 1920.

biomedicalephemera:

Anatomical Teaching Models

It’s believed that anatomical models have been used for teaching purposes (as opposed to ritualistic or religious purposes) since some point between 100 BCE - 300 CE, since dissection of the dead was a taboo and crime in the Late Greek and  Roman empire, and paper or vellum for illustration was much more fragile than, say, carved wooden figures.

However, most of our evidence for anatomical models comes from the late Medieval era and later, when materials such as ivory and sealed papier-mâché were used for many anatomical carvings. Later, especially in the 18th and 19th centuries, wax sculptures were common in medical schools, as much finer detail was attainable with such a pliable substance.

Today, most models used for teaching both lay persons and students are made from thermoplastics and texturing agents, and can range from highly detailed micro-premature babies, to fully-removable models of life-sized animals with every layer of tissue and organs, to huge versions of virions not normally visible except under an electron microscope. Given that the majority of students show greatly increased memory of a subject when able to physically manipulate a representation of it, the use of anatomical teaching models is here to stay.

For more on anatomical models and tons more on the history of medicine, visit the Science Museum: Brought to Life!

Images:

Top: Anatomical structure of reclining woman in early pregnancy. Florence, Italy, ca. 1770.
Center left: Wax model of the human brain, with skin, skull, and meninges removed. Intended for medical students. Western Europe, ca. 1700-1900. Date uncertain.
Center right: Papier-mache model of acupuncture meridians. Japan, ca. 1601-1700.
Bottom left: Sculpture of male black infant, 22-23 weeks development. Created for exhibit on how micro-preemies are kept alive in the modern era. England, 1998.
Bottom right: Model of an adenovirus, magnified 3,000,000x, from electron microscope images. London, England, 1985.