Scientific Illustration

leaves-that-are-green:

Anatomy of the neck from the Swedish “Every Home’s Illustrated Book of Medicine” (Illustrerad läkarebok för hemmet), 1920.

biomedicalephemera:

Sweat glands in the human epidermis:

Diagrammatically represented (top)
Isolated vertical cross-section (Right)
Isolated horizontal cross-section (left)

Staying cool this ridiculous summer, fellow North Americans? Even if you’re hot and miserable and sweaty, your body knows how to keep its organs at the optimal temperature - that’s why you sweat in the heat in the first place!

Unlike other mammals that sweat for thermoregulation (such as oxen and horses), humans largely sweat from their eccrine sweat glands, which are not directly connected to hair follicles. Eccrine sweat glands secrete mostly water, with a few electrolytes (mostly NaCl, which is why sweat tastes salty). The amount we sweat is regulated by the hypothalamus and the contraction of cells surrounding the eccrine glands, and is influenced by hormone release and internal body temperature.

The water secreted by the eccrine sweat glands utilizes a process called evaporative cooling to reduce the surface temperature of the skin, which in turn reduces the temperature of the blood flowing through the expanded arterioles near the skin surface, and that blood flows through the body and keeps the organs and muscles at a relatively constant temperature. Sweat glands are coil-shaped, with a bulbous sac at the bottom that filters blood plasma to produce sweat. When the cells surrounding the sac and coil are triggered, they contract, pushing that sweat to the surface of the skin.

We also have apocrine sweat glands (the only functional thermoregulatory glands in horses and other sweaty mammals), but they’re largely restricted to the armpits, areola, and perianal region. Their secretions are not as simple as eccrine sweat glands - they’re typically milky-white and contain hormones and additional components of blood plasma that bacteria *love* to chow down. Those bacteria produce stinky excretions of their own, and that’s what causes smelly armpits!

When you use deodorant, the substance you apply works by breaking down the components excreted by bacteria that cause the smell, and masking any residual stink that can’t be broken down. Antiperspirants function by plugging the openings of the sweat pores, so that sweat can’t escape. This is usually done with small particles of aluminum. Despite misconceptions, blocking the sweat glands does not cause breast cancer, though some people experience adverse effects due to allergies to aluminum or other ingredients.

Images:

Top: Anatomy, Descriptive and Applied. Henry Gray et al, 1910.
Bottom: Diseases of the skin; a text-book for students and practitioners. J.M.H. Macleod, 1920.

atelierentomologica:

EA Seguy, born 1920 France, Pl. 18 from the portfolio Insects c.1925

biomedicalephemera:

The Life-Cycle of Spirochaeta duttoni, as elucidated by William Boog Leishman

Fig 1-6. General character of organism
Fig 6-8. Transverse division
Fig 9. Longitudinal division
Fig 10-11. Unknown method reproduction, thought to be conjugation
Fig 12. Coiled form in peripheral blood
Fig 13. Swollen form in liver
Fig 14-15. Skein-like forms in the spleen
Fig 16. Encysted form

Spirochetes such as Spirochaeta duttoni and Trepanoma pallidum pallidum (syphilis) were originally grouped with other eukaryotic parasitic organisms such as protozoa, because their methods of reproduction (both longitudinal and transverse division) made discerning their true nature confusing at first.

All spirochetes are now known to be Gram-negative helically-coiled bacteria. The species “Spirochaeta duttoni” (now Borrelia duttoni) causes African tick fever, which causes general muscle pain, fever, chills, nausea, and a generalized rash. The bacteria has the ability to change its surface proteins to evade the immune system for some time, and as such often relapses after initial treatment. 

[Human Parasitology. Damaso Rivas, 1920.]

biomedicalephemera:

Right lung with surface hemorrhages

Lung moderately enlarged due to influenza. Note the consolidation of infectious activity in the blue area.

The Pathology of Influenza. M. C. Winternitz, Isabel M. Wason, and Frank P. McNamara, 1920.

biomedicalephemera:

Lungs from Autopsy - Cause of Death: Pulmonary Embolism 

You can see the massive thrombus in the main artery of the lung, which led to a sudden death with no preceding symptoms. 

Most pulmonary embolisms are caused by blood clots in the deep veins of the legs, but can sometimes be caused by introduction of air into the blood stream, embolization of fat, or amniotic fluid.

The Pathology of Influenza. M. C. Winternitz, Isabel Wason, and Frank McNamara, 1920.

biomedicalephemera:

Showy Lady’s Slipper - Cypripedium spectabile

How to Know the Wild Flowers: A Guide to the Names, Haunts, and Habits of our Common Wild Flowers. Mrs. William Starr Dana, 1920.

biomedicalephemera:

Layers of the human hand.

Principles of Anatomy, as Shown in the Hand. Frederic James Wood, 1920.

biomedicalephemera:

Hipitty hop, hipitty hop…

Jerboas can hop faster than a human can run! They don’t walk around like normal gerbils or mice, but walk upright or hop. They’re like little kangaroos!