Posts tagged blood
Top: Uterine lining at 5 1/2 months, displaying thin maternal separation from fetus, and high level of placental implantation
Center: Relation of placenta to uterus at 5 weeks and 8.5 months
Bottom: Major arteries and veins of the placenta
Did you know that the placenta is a temporary organ that’s actually created by the fetus, and not the woman?
The human female is a curious creature; like our close great ape cousins, but unlike almost all other mammals, they build up a thick barrier in the uterine wall, to protect against any potential embryo that might implant itself. When there’s no embryo implantation, the thickened wall is shed, in the process known as menstruation.
The thing is, most mammals don’t menstruate. They go into heat, and occasionally shed uterine lining (if the uterus is scratched, or an egg tries to implant but fails, for example), but there’s no regular cycle of bloody discharge relating to breeding. This is because other mammals go through triggered decidualization (developing a uterine lining only when a fertilized egg begins to implant itself), while the great apes (and a couple other convergently evolved families, including bats) experience spontaneous decidualization, where they develop a thick uterine lining during every ovulation, before an egg can even attempt to implant itself.
Why the different linings? Well, it turns out that there are three types of mammal placentas (remember, placentas are developed by the embryo/fetus, not the mother):
- Epitheliochordal, which is completely superficial, and does not connect in any significant way to the mother’s body. The endometrial epithelium, connective tissue, and uterine epithelium are all preserved and undisturbed in the mother. The fetus is separated from the mother by three layers of tissue. Nutrients and waste are delivered and eliminated through diffusion, rather than direct connection. This group includes equids, swine, and ruminants.
- Endotheliochordal, which is slightly more invasive to the mother, only preserves the uterine epithelium. Nutrients and waste are not exchanged through direct connection to the mother, but the placenta only leaves one layer of tissue between it and the mother. This group includes cats and dogs.
- Hemochorial is the most invasive form of placenta in the animal kingdom. The embryo directly hooks itself up to the host (mother’s) blood flow, and leaves no tissue layers between the female and the placenta. This allows much more efficient nutrient transfer to the embryo or fetus, but is also potentially the most harmful to the female since the embryo attaches itself so securely to the uterine wall. The female must develop preemptive measures (a thickened uterine lining) to protect herself from a life-form that is literally driven to take all of the nutrients it needs to develop, and which has adapted to connect itself directly to the host. This group includes elephant shrews, most bats, and most primates.
Interested in more about the science behind reproduction and how amazingly efficient the human embryo is at sucking its host clean, just to obtain its needed resources for development?
PZ Meyers at Pharyngula has an understandable explanation of the article I referenced for this post.
There is also a great site by R. Bowen about the pathophysiology of the reproductive system.
An American Text-Book of Obstetrics for Practitioners and Students. Edited by Richard C. Norris, 1895.
Plaster model of executed Chinese pirate
The neck stump of this executed Yangzee River pirate is surprisingly accurate for what was probably a sideshow prop. The cervical spine, blood vessels, muscles, trachea, and esophagus are all visible.
The muscular nature of the esophagus is highly visible here. You can also see the hardness of the trachea.
The donation of this model to the Science Museum London came with little accompanying information, but it is known that it was produced in England, between 1910 and 1922. The braid is real human hair, and the plaster and finish is of a high quality. Given its “blood-splattered” carrying case, it was most likely a prop in a traveling sideshow.
Dyspholidus typus - The Boomslang
Though it belongs to the same family as king snakes and the most common “grass snakes”, the boomslang is one of the few members of Colubridae to possess a venom that’s legitimately dangerous to humans, and the fangs that are able to inject it (some members of the family have venom, but weak fangs). In fact, the fangs of the boomslang are some of the broadest and most deeply-grooved in the snake world.
The venom of the boomslang is hemotoxic. That means that the proteins in the venom affect the blood of the victim, and in the case of the most common hemotoxin in boomslang venom (phospholipase A2, if you’re wondering), it causes red blood cells to rupture. Given enough time with this toxin floating around in the bloodstream, the significant thinning of the blood allows it to flow out of the capillary walls, and can flow out of any part of the body where capillaries are particularly close to the exposed surface.
In other words, if you’re bitten by a boomslang and don’t seek help right after being bitten, you’ll likely end up bleeding out from your nose, eyes, mouth, ears, and genital orifices. Because of the significant blood loss associated with a wait of more than 48 hours between bite and antivenin administration (phospholipases are fairly slow-working, compared to neurotoxins and cardiotoxins), full blood transfusions are sometimes needed, to replenish the plasma, red blood cells, and platelets that were lost in the bleed-out.
Illustrations of the Zoology of South Africa. Andrew Smith, 1888.
Median Section of Skull
Showing middle meningeal artery and significant planes of skull. Dura mater that would be visible in typical median section not depicted.
Anatomy of the Brain and Spinal Cord. Harris E. Santee, 1907.
Underside and circulatory system of the Atlantic Horseshoe Crab (Limulus polyphemus)
The curious horseshoe crab (or king crab) is not actually a crab at all. It is an ancient member of the Chelicerata - more closely related to scorpions and spiders than any crustacean.
Note that the colors on the bottom illustrations only indicate a state of oxygenation and deoxygenation (red and blue, respectively), not the true color of the blood. Since horseshoe crabs utilize the copper-based hemocyanin to transport oxygen (as opposed to hemoglobin, in vertebrates), their blood is colorless or a light yellow when oxygenated, and a deep blue color when deoxygenated.
Of note - the mouth of the horseshoe crab is a jawless opening leading to a gizzard, between the legs on the underside of the body, and the book gills are located directly below them. The book gills, in addition to being used for blood gas exchange, are occasionally used for increased motility.
Images:
Top: Anatomy of underside and tail. From the John Reeves Collection, via scientificillustration. 1827.
Bottom: Circulatory system. Recherches sur l’Anatomie Limulus. M. Alphred Milne Edwards, 1873.
Posterior view of arteries and veins of the heart and lungs
The coronary sinus is clearly visible, as the largest vein on the body of the heart. “Coronary” means “crown”, so if one thinks of the heart as a head, anything labeled “coronary” likely goes around it in a somewhat-encircling fashion.
The anterior cardiac veins drain directly into the right atrium, but the majority of the other cardiac veins (excluding some of the smallest), including the great cardiac vein, drain into the coronary sinus. The junction between the right atrium and the coronary sinus is marked by the Thesbian valve.
Traité complet de l’anatomie de l’homme comprenant la medecine operatoire, par le docteur Marc Jean Bourgery. Illustration by Nicolas Henri Jacob, 1831.
*skee!* I love questions like this…you know, ones that I can actually answer well and give diagrams for and that force me to rack my brain for old anatomy/biology/zoology information.
ANYWAY. There are coronary veins (when referred to as a set, at least), but the major ones are the coronary sinus and the great cardiac vein, which both empty into the right atrium of the heart, like most deoxygenated blood does. However, the little veins known as the smallest coronary veins (imaginative, I know) will drain directly into any chamber of the heart. The blood from these veins is not significant enough to warrant necessary reoxygenation, and some of the smallest coronary veins are scarcely larger than capillaries.
Non-pathological heart and great vessels, viewed from front and behind.
Note the significant number of vessels that cover the heart itself - though it moves blood around the entire body, it doesn’t just run on its own. The short loop of the coronary circulatory system is distinct from both the systemic circulation (where oxygenated blood travels to the rest of the body) and the pulmonary circulation (where deoxygenated blood travels from the right ventricle to the lungs, and back to the left ventricle of the heart).
When the coronary circulation is hindered or halted, the myocardium (heart muscle) is killed off. This can cause a myocardial infarction, or heart attack. Coronary bypass surgery takes blood vessels from other parts of the body and grafts them to parts of the coronary circulatory system that are clogged up or otherwise non-functional.
Diseases of the Heart and Aorta. Arthur Douglass Hirschfelder, 1912.
Angeiographie
Vascularization of the organs and muscles. The viscera requires an amazing amount of oxygenated blood to do its job properly, which is one of the many reasons you don’t want to get shot in the gut.
Note the inclusion of the veins that go from the intestines to the liver in the top right quadrant of this plate (the image with the blue vessels) - the hepatic portal vein is not a “true” vein, in that it does not take deoxygenated blood back to the heart and lungs, but it takes nutrient-rich blood from the GI tract into the capillary beds of the liver for processing.
Anatomie Methodique, ou, Organographie Humaine. Jean-Baptiste Sarlandière, 1829.
The First Practical Transfusion Method
The citrate method of transfusion as shown in Lewisohn’s illustrations (from Boston Med. & Surg. J., 190:733, 1924). This was the first method for transfusion that was simple enough to be practical.
Fagged?
“All tired out. Can’t hardly take another step. Don’t seem to have any ambition. Can’t do half my regular work. I’m weak, nervous, depressed, discouraged.” Is that your story? If so, you tell it well, for it’s the story of impure blood. There’s only one remedy that will make you change this story —
Ayers Sarsaparilla
What a record it has! 50 years of cures! It can’t be said of any other sarsaparilla.
Daily Mail and Empire. Toronto, Canada. Nov. 3, 1900.
Hemorrhage from eclampsia
Despite knowing enough about pre-eclampsia and eclampsia to realize that they only occur in the presence of a placenta, and can only be cured by the removal of the placenta, the pathophysiology and origin of the condition(s) is still relatively poorly understood.
We do know that the seizures that characterize eclampsia are due to hypertensive encephalopathy resultant of pre-eclampsia. While brain damage due to eclampsia seizures is uncommon, hemorrhage (fatal or occasionally non-fatal) was considered a “typical” outcome.
The Toxemias of Pregnancy. George William Kosmak, 1922.
Liver Vasculature and Ducts
On top, the small vessels shown are are the branches of the vena cava in the liver. The large vein behind those vessels is the vena cava ascendens.
On bottom, the pouch labeled “4” is what Cheselden called the “cystis hepaticus” - the gall bladder. You can see the ductus cysticus coming off of the gall bladder, and the ductus hepaticus underneath it (this duct is actually posterior to the gall bladder in most cases, not underneath). The small vessels shown are the ductus pancreaticus, and the area labeled “8” is the entrance of the ductus communis into the duodenum.
The Anatomy of the Human Body. William Cheselden, 1750.
the unit “one human” is the same in metric AND imperial
-one modern bathtub holds approximately 80 gallons of water when completely full
-a human displaces one gallon of water for every ~8.3 lbs of weight at 4 C/39.2 F
-at 150 lbs, one human would displace ~18 gallons
-assuming you don’t want to cause the tub to overflow but to be near the top, you need about 60 gallons of liquid
——-
-one human contains ~5 quarts of blood (1.25 gallons)
Assuming full exsanguination (optimistic, I know), you would need 48 humans in order to bathe in blood.
You’d probably want 50, just to be certain you have enough blood. Up that amount to 75 or so if you’re looking to bathe in the blood of virgins or you have one of those old-style claw tubs.
I TEACH YOU ALL VALUABLE LESSONS
Báthory Erzsébet (the Countess of Bathory) tortured and exsanguinated between 200 and 650 girls and young women between the years of 1585 and 1610, in an effort to preserve her youth, with virginal blood.
Effects of the Crotalus adamanteus venom on mesentery of rabbit (top), and pectoralis of pigeon (bottom).
Many venomous snakes have hemotoxic venom, or a hemotoxic component within their venom. These toxins are able to break down red blood cells, disrupt clotting, and cause hemorrhaging due to the blood being thin enough to slip through capillary and tissue walls. Unlike a neurotoxic venom, which kills by paralyzing the diaphragm and suffocating the victim or prey, hemotoxic venom does not kill quickly. The internal bleeding and hemorrhaging of organs and major vessels is extremely painful.
When snakes kill with hemotoxins, they tend to follow their prey until it collapses, before attempting to eat it. However, the majority of the time, it turns out that the prey isn’t dead yet. It’s simply in shock and unable to continue - it would end up dying soon enough, but if the snake isn’t too far behind it, the prey does get eaten alive.
Snake Venoms: An Investigation of Venomous Snakes, with Special Reference to the Phenomena of Their Venoms. By Hideyo Noguchi M. D., 1909.
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