Persius/hicric huggingface dataset:
Caput medusae
Caput medusae is the appearance of distended and engorged umbilical veins which are seen radiating from the umbilicus across the abdomen to join systemic veins.

# Etymology
The name caput medusae (Latin for "head of Medusa") originates from the apparent similarity to Medusa's hair once Minerva had turned it into snakes.

# Causes
It is a sign of severe portal hypertension that has decompressed by portal-systemic shunting through the umbilical veins.

# Differential diagnosis

## Inferior vena cava obstruction
- Produces abdominal collateral veins develop to bypass the blocked inferior vena cava and permit venous return from the legs.

### How to differentiate
Determine the direction of flow in the veins below the umbilicus.
- Caput Medusae - flow is towards the legs
- Inferior vena cava obstruction - flow is towards the head.
Caraway thyme
Thymus herba-barona is a species of thyme native to Corsica, Sardinia and Mallorca, also known by its common name Caraway Thyme. This thyme has a strong scent similar to Caraway, for which it can be used as a substitute in any recipe. It can be used in cuisine or as an evergreen groundcover for gardens.
Caraway Thyme is a creeping, woody herb growing to 10-25 cm high and spreading out across the ground using runners. The leaves are 4-10 mm long, dark green, and hairy. The flowers are pink, produced in late spring and early summer, and are attractive to bees. It grows best in average soil with light watering and full sunlight.
There are two subspecies:
- Thymus herba-barona subsp. herba-barona. Corsica, Sardinia.
- Thymus herba-barona subsp. bivalens. Mallorca.

# Cultivation and uses
Caraway Thyme was favoured in England as a seasoning for barons of beef; this inspired its scientific name. It is cultivated in gardens across the world. It is difficult to grow Caraway Thyme from seed, so it is usually purchased as young plants 5-10 cm high, in small pots.
Carbamic acid
Carbamic acid is a compound that is unstable under normal circumstances. Its importance is due more to its relevance in identifying the names of larger compounds.
The radical is called "carbamoyl". "Carbamoyltransferases" are transferase enzymes classified under EC number 2.1.3.
Carbamate is an ester of carbamic acid. Methyl carbamate is the simplest ester of carbamic acid.
Some esters have use as muscle relaxants.
Carbenoxolone

# Overview
Carbenoxolone (CBX) is a glycyrrhetinic acid derivative with a steroid-like structure, similar to substances found in the root of the licorice plant. Carbenoxolone is used for the treatment of peptic, esophageal and oral ulceration and inflammation. Electrolyte imbalance is a serious side effect of carbenoxolone when used systemically.
Carbenoxolone reversibly inhibits the conversion of cortisol to the inactive metabolite cortisone by blocking 11-hydroxysteroid dehydrogenase (11-HSD). 11-HSD also reversibly catalyzes the conversion of 7-ketocholesterol to 7-beta-hydroxycholesterol. 
Carbenoxolone is a modestly potent, reasonably effective, water-soluble blocker of gap junctions.

# Nootropic effects
Carbenoxolone has also been investigated for nootropic effects. This research started from an observation that long-term exposure to glucocorticoids may have negative effects on cognition. Carbenoxolone may decrease the amount of active glucocortocoid in the brain, because the drug inhibits 11-HSD, an enzyme which regenerates cortisol, an active glucocorticoid, from inactive cortisone.
In the research trial investigating this use of carbenoloxone, it was shown that the drug improved verbal fluency in elderly healthy men (aged 5575). In type 2 diabetics aged 5270, the drug improved verbal memory. However, potassium-sparing diuretic amiloride was co-administered with carbenoxolone, since carbenoxolone used by itself may cause hypertension by increasing cortisol in the kidneys.
Carbonium ion
A carbonium ion is a carbocation of the penta- or tetracoordinated nonclassical type such as an ion of the type  R5C+.

# Methanium
The parent compound methanium or CH5+ is protonated methane and a superacid. This ion exists as a reactive intermediate in interstellar space and can be produced in the laboratory in low concentrations in the gas phase at low temperatures. This compound is considered a CH3+ carbenium ion with a molecule of hydrogen interacting with the empty orbital in a 3-center-2-electron bond. The two hydrogen atoms in H2 can continuously exchange positions with the three hydrogen atoms in the CH3+ so the methanium ion is considered a fluxional molecule. The energy barrier for the exchange is quite low and occurs even at very low temperatures.
Infrared spectroscopy has been used to obtain information about the conformations of methanium. The IR spectrum of plain methane has two C-H bands from symmetric and asymmetric stretching at around 3000 cm-1 and two bands around 1400 cm-1 from symmetrical and asymmetric bending vibrations. In the spectrum of CH5+ three asymmetric stretching vibrations are present around 2800 - 3000 cm-1, a rocking vibration at 1300 cm-1 and a bending vibration at 1100 1300 cm-1.
Carbonylation
Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates.  Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry.

# Organic chemistry
Several chemicals used significantly in industry are prepared by carbonylation, which can be highly selective reactions.  Carbonylations produce organic carbonyls, i.e., compounds that contain the C=O functional group.  Carbonylations are the basis of two main types of reactions, hydroformylation and Reppe Chemistry.

## Hydroformylation
Hydroformylation entails the addition of both carbon monoxide and hydrogen to unsaturated organic compounds, usually alkenes.  The usual products are aldehydes:
The reaction requires metal catalysts that binds the CO, the H2, and the alkene, allowing these substrates to combine within its coordination sphere.

## Reppe Chemistry
Reppe Chemistry, named after Walter Reppe, entails addition of carbon monoxide and an acidic hydrogen donor to the organic substrate.  The largest-scale application of this type of carbonylation is the Monsanto acetic acid process, which produces acetic acid from methanol. Acetic anhydride is prepared by a related carbonylation of methyl acetate.. In the related hydrocarboxylation and hydroesterification, alkenes and alkynes are the substrates. This method is used in industry to produce propionic acid from ethylene:
These reactions require metal catalysts, which bind and activate the CO.  In the industrial synthesis of Ibuprofin, a benzylic alcohol is converted to the corresponding carboxylic acid via a Pd-catalyzed carbonylation:
Acrylic acid was once prepared by the hydrocarboxylation of acetylene but is now produced by the oxidation of propene.

## Other reactions
The Koch reaction (also the related Koch-Haaf reactions) entail the addition of CO to unsaturated compounds in the presence of strong acids such as sulfuric acid.  This method is less frequently used in industry as are the metal-catalyzed reactions, described above.  The industrial synthesis of glycolic acid is achieved in this way:
The conversion of isobutene to pivalic acid is also illustrative:
Unrelated to the Koch reaction, dimethylcarbonate and dimethyloxalate are also produced in industry from carbon monoxide.  These reactions require oxidants:

# Inorganic chemistry
Metal carbonyls, compounds with the formula M(CO)xLy (M = metal; L =  other ligands) are prepared by carbonylation of transition metals.  Iron and nickel powder react directly with CO to give Fe(CO)5 and Ni(CO)4, respectively.  Most other metals form carbonyls less directly, such as from their oxides or halides.  Metal carbonyls wildly employed as catalysts in the hydroformylation and Reppe processes discussed above.
Carboxylation

# Overview
Carboxylation in chemistry is a chemical reaction in which a carboxylic acid group is introduced in a substrate. The opposite reaction is decarboxylation.

# Carboxylation in organic chemistry
In organic chemistry many different protocols exist for carboxylation. One general approach is by reaction of nucleophiles with dry ice (solid carbon dioxide)  or formic acid  

# Carboxylation in biochemistry
Carboxylation in biochemistry is a posttranslational modification of glutamate residues in proteins.  It occurs primarily in proteins involved in the blood clotting cascade, specifically factors II, VII, IX, and X, protein C, and protein S, and also in some bone proteins.  This modification is required for these proteins to function.  Carboxylation occurs in the liver and is performed by -glutamyl carboxylase.
The carboxylase requires vitamin K as a cofactor and performs the reaction in a processive manner.  -carboxyglutamate binds calcium, which is essential for its activity.  For example, in prothrombin, calcium binding allows the protein to associate with the plasma membrane in platelets, bringing it into close proximity with the proteins that cleave prothrombin to active thrombin after injury.
Contractility

# Overview
Myocardial Contractility is a term used in physiology to describe the performance of cardiac muscle.  It is often defined as: the intrinsic ability of a cardiac muscle fibre to contract at a given fibre length.

# Determinants of Myocardial Contractility
The five determinants of myocardial performance are:
- Heart rate
- Conduction velocity
- Preload
- Afterload
- Contractility
If myocardial performance changes while preload, afterload, heart rate, and conduction velocity are all constant, then the change in performance must be due to the change in contractility.
It might be thought that a better definition would be that Contractility is the property that represents the strength of myocardial contraction. However, this definition does not separate contractility from the other loading factors that affect the strength of myocardial contraction. In particular, an increase in preload results in an increased force of contraction - this is Starling's law of the heart - but this does not require a change in contractility.
Any chemicals that affects contractility is called inotropic agent. 
For example drugs such as catecholamines (norepinephrine and epinephrine) that enhance contractility are considered to have a positive inotropic effect.
The concept of Contractility was necessary to explain why some interventions (e.g. an adrenaline infusion) could cause an increase in myocardial performance even if, as could be shown in experiments, the preload, afterload and heart rate were all held constant. Experimental work controlling the other factors was necessary because a change in contractility is generally not an isolated effect.
For example:
- An increase in sympathetic stimulation to the heart increases contractility AND heart rate.
- An increase in contractility tends to increase stroke volume and thus a secondary increase in preload.
All factors that cause an increase in contractility work by causing an increase in intracellular  during contraction.
Gallop rhythm

# Overview
A gallop rhythm refers to a (usually abnormal) rhythm of the heart on auscultation. It includes three or four sounds, thus resembling the sounds of a gallop.
The normal heart rhythm contains two audible heart sounds called the first heart sound or  (S1) and the second heart sound (S2) that give the well-known "lub-dub" rhythm.  These two heart sounds are caused by the closing of valves in the heart.
A gallop rhythm contains another sound, called S3 or S4, dependent upon where in the cycle this added sound comes.
It can also contain both of these sounds forming a quadruple gallop, and in situations of very fast heart rate can produce a summation gallop where S3 and S4 occur so close as to be indistinguishable.

# Associated conditions
Gallop rhythms may be heard in young or athletic people, but may also be a sign of serious cardiac problems like heart failure.
Cardiac shunt

# Overview
Cardiac shunts refer to the abnormal flow of blood or mixing of blood between anatomic structures that are ordinarily separated. An example would be mixing of blood between the right atrium and the left atrium in a patient with an atrial septal defect.  The direction of flow of the blood may be described as right-to-left, left-to-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemic. The direction may be controlled by left and/or right heart pressure, a biological or artificial valve, or both.

# Congenital shunts
The most common congenital heart defects (CHDs) which cause shunting are the atrial septal defect (ASD), ventricular septal defect (VSD), patent ductus arteriosus (PDA), and patent foramen ovale (PFO). In isolation, these defects may be asymptomatic, or they may produce symptoms which can range from mild to severe, and which can either be acute or have delayed onset. However, these shunts are often present in combination with other defects; in these cases, they may still be asymptomatic, mild or severe, acute or delayed, but they may also work to counteract the negative symptoms caused by another defect (as with d-Transposition of the great arteries).

# Acquired shunts

### Biological
Some acquired shunts are modifications of congenital ones: a balloon septostomy can enlarge a foramen ovale (if performed on a newborn), PFO or ASD; or prostaglandin can be administered to a newborn to prevent the ductus arteriosus from closing. Biological tissues may also be used to construct artificial passages.

### Mechanical
Mechanical shunts are used in some cases of CHD to control blood flow or blood pressure. One example is the modern version of the Blalock-Taussig shunt.
CME Category::Cardiology
Cardiac veins

# Overview
The cardiac veins return deoxygenated blood from the myocardium to the right atrium and run parallel to coronary arteries.

# Anatomy
The components of the cardiac venous system are the following:

## Coronary sinus
- It is present in the coronary sulcus.
- It receives most venous return of the heart.
- It empties in the right atrium.

## Great cardiac vein
- It runs parallel to the LAD in the anterior interventricular groove.
- It drains in the coronary sinus.

## Middle cardiac vein
- It runs parallel to the PDA in the posterior interventricular groove.
- It drains in the coronary sinus.

## Small cardiac vein
- It runs parallel to the marginal artery.
- It drains in the coronary sinus.

## Anterior Cardiac Veins
- Drains the anterior right ventricle.
- Empties directly in the right atrium an not in the coronary sinus.
Carotid sinus

# Overview
In human anatomy, the carotid sinus is a localized dilation of the internal carotid artery at its origin, the common carotid artery bifurcation.

# Functions
It contains numerous baroreceptors, which function as a "sampling area" for many homeostatic mechanisms for maintaining blood pressure.  The carotid sinus baroreceptors are innervated by the sinus nerve of Hering, which is a branch of IX (glossopharyngeal nerve).   The glossopharyngeal nerve synapses in the nucleus tractus solitarius (NTS) located in the medulla of the brainstem.  The NTS modulates the activity of sympathetic and parasympathetic (vagal) neurons in the medulla.  These neurons then regulate the autonomic control of the heart and blood vessels. The aortic arch baroreceptors are innervated by the aortic nerve, which combines with X (vagus nerve) and travels to the NTS.

# Disease of the carotid sinus
The carotid sinus often has atherosclerotic plaques because of disturbed hemodynamics (low wall shear stress, flow reversal/recirculation).  Since these plaques, if large and unstable, predispose to ischemic strokes and transient ischemic attacks, carotid endarterectomies are frequently done for prophylaxis.
The carotid sinus can be oversensitive to manual stimulation, a condition known as carotid sinus hypersensitivity, carotid sinus syndrome or carotid sinus syncope, in which manual stimulation causes large changes in heart rate and/or blood pressure.

# Carotid sinus massage
Massage of the carotid sinus, carotid sinus massage is used to diagnose carotid sinus syncope and is sometimes useful for differentiating supraventricular tachycardia (SVT) from ventricular tachycardia.  It, like the valsalva maneuver, is a therapy for SVT. However, it is less effective than pharmaceutical management of SVT with verapamil or adenosine.

# Carotid sinus reflex death
Carotid sinus reflex death is a disputed mechanism of death in which manual stimulation of the carotid sinus allegedly causes strong vagus nerve impulses leading to terminal cardiac arrest. Carotid sinus reflex death has been pointed out as a possible cause of death in cases of strangulation and hanging, but such deductions remain controversial. Studies have however suggested that the carotid sinus reflex can be a contributing factor in other mechanisms of death by reducing blood pressure and heart rate, especially in the elderly or in people suffering from carotid sinus hypersensitivity. A Carotid Massage can also possibly dislodge a thrombus, or some plaque. This could lead to any number of life threatening effects, including, but not limited to; Pulmonary Embolus, Myocardial Infarctions, and Strokes. All of these are potentially lethal.
Caval opening
The caval opening is a hiatus in the diaphragm of humans through which passes the inferior vena cava, the wall of which is adherent to the margins of the opening, and some branches of the right phrenic nerve.
It is located approximately at the level of the eighth thoracic vertebra (T8), and passes through the diaphragm's central tendon.
It is quadrilateral in form, and is placed at the junction of the right and middle leaflets of the central tendon, so that its margins are tendinous.
By being situated in the tendinous part of the diaphragm, it is stretched open every time inspiration occurs.
Since thoracic pressure decreases upon inspiration and draws the caval blood upwards toward the right atrium, increasing the size of the opening allows more blood to return to the heart, maximizing the efficacy of lowered thoracic pressure returning blood to the heart.
Cayo Santiago
Cayo Santiago, also known as Monkey Island, is an uninhabited island, 950 m (0.6 mi) southeast of Punta Santiago, Humacao, Puerto Rico. It extends 600 m (656 yd) north-south and 400 m (437 yd) east-west, including the flat northeastern peninsula which is connected to the main part only by a narrow sandy isthmus. 600 meters west of the southermost point is a shoal, Bajo Evelyn, which has a least depth of 8 fathoms. While the island is flat in the north, it reaches a height of 34.9 m (104.5 ft) 2.9 km (1.8 mi) southwest of the port, in a small rocky hill called El Morrillo, which rises abruptly from the water and the lowland around it. The area of the island is 0.14 km2 (139,179 m2: Census block 2000, Census Block Group 2, Census tract 1801, Humacao Municipio, Puerto Rico), of which the northwestern peninsula accounts for about 0.02 km2. The island is part of Punta Santiago barrio of Humacao.
The island has a free ranging population of about 950 Rhesus monkeys. The monkeys are offspring of an original group of 409 monkeys imported from India that were used for scientific research in 1938. Today the island serves as a research center for the University of Puerto Rico (Caribbean Primate Research Center), the National Institutes of Health, and Harvard University. The station accommodates 11 researchers and technicians who take the short boat trip from Humacao on a daily basis and normally don't stay on the island.
Cayo Batata, the second island belonging to Humacao, is located 5.7 km to the southwest.
Celiac artery
The celiac artery, also known as the celiac trunk and also spelled as coeliac, is the first major branch of the abdominal aorta and branches from the aorta around the level of the T12 vertebra in humans. It is one of three anterior/ midline branches of the abdominal aorta (the others are the superior and inferior mesenteric arteries).

# Region supplied
The celiac artery supplies oxygenated blood to the liver, stomach, abdominal oesophagus, spleen and the superior half of both the duodenum and the pancreas. These structures correspond to the embryonic foregut. (Similarly, the superior mesenteric artery and inferior mesenteric artery feed structures arising from the embryonic midgut and hindgut respectively. Note that these three anterior branches of the abdominal aorta are distinct and cannot substitute for one another, although there are limited connections between their terminal branches.)
The celiac artery is an essential source of blood, since the interconnections with the other major arteries of the gut are not sufficient to sustain adequate perfusion. Thus it cannot be safely ligated in a living person, and obstruction of the celiac artery will lead to necrosis of the structures it supplies.

# Branches
There are three main divisions of the celiac artery, and each in turn has its own named branches.
The celiac artery may also give rise to the inferior phrenic arteries.

# Drainage
The celiac artery is the only major artery that nourishes the abdominal digestive organs that does not have a similarly-named vein.
Most blood returning from the digestive organs (including from the area of distribution of the celiac artery) is diverted to the liver via the portal venous system for further processing and detoxification in the liver before returning to the systemic circulation via the hepatic veins.
In contrast to the drainage of midgut and hindgut structures by the superior mesenteric vein and inferior mesenteric vein respectively, venous return from the celiac artery is through either the splenic vein emptying into the hepatic portal vein or via smaller tributaries of the portal venous system.
Notably, the splenic vein carries bilirubin (the waste product of hemoglobin metabolism) to the liver for excretion via the bile duct.

# Additional images
- Abdominal part of digestive tube and its attachment to the primitive or common mesentery. Human embryo of six weeks.
- The pancreas and duodenum from behind.
- Posterior abdominal wall, after removal of the peritoneum, showing kidneys, suprarenal capsules, and great vessels.
- The anterior surfaces of the kidneys, showing the areas of contact of neighboring viscera.
- Front of abdomen, showing surface markings for arteries and inguinal canal.